From timr at circuitabbey.com  Mon Dec  3 15:04:01 2018
From: timr at circuitabbey.com (Tim Ressel)
Date: Mon, 3 Dec 2018 06:04:01 -0800
Subject: [sdiy] SMT package hell
Message-ID: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>

Did you hear me scream?

I picked a part that sez its SOT-505. Okay, what is that? I look at the 
datasheet which sez its the same as tssop8. Then I look up tssop8. They 
do not match. then I find a sot-505-2. Also doesn't match. This really 
throws generic package names out the window. As I make a custom 
footprint for this part I ponder the state of the industry and the 
ineffectual efforts of the gurus of standards like EIA.

-- 
--Tim Ressel
Circuit Abbey
timr at circuitabbey.com



From modular at go2.pl  Mon Dec  3 15:35:42 2018
From: modular at go2.pl (Roman Sowa)
Date: Mon, 3 Dec 2018 15:35:42 +0100
Subject: [sdiy] SMT package hell
In-Reply-To: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
Message-ID: <2dba4d6c-d738-1fb7-b6e4-8372b2896411@go2.pl>

No, TSSOP are usually the wide ones (4.5mm). SOT505 is the same as MSOP8 
(3mm).
But NXP claims TSSOP is the narrow one, just like MSOP.
Everybody knows that!
:)

Roman

W dniu 2018-12-03 o?15:04, Tim Ressel pisze:
> Did you hear me scream?
> 
> I picked a part that sez its SOT-505. Okay, what is that? I look at the 
> datasheet which sez its the same as tssop8. Then I look up tssop8. They 
> do not match. then I find a sot-505-2. Also doesn't match. This really 
> throws generic package names out the window. As I make a custom 
> footprint for this part I ponder the state of the industry and the 
> ineffectual efforts of the gurus of standards like EIA.
> 


From tom at electricdruid.net  Mon Dec  3 16:02:50 2018
From: tom at electricdruid.net (Tom Wiltshire)
Date: Mon, 3 Dec 2018 15:02:50 +0000
Subject: [sdiy] SMT package hell
In-Reply-To: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
Message-ID: <69022635-29B0-42C9-B488-96FAC562C4CA@electricdruid.net>

I just wish we could all work out whether we?re still using measurements based on a 0.1? grid or whether we?ve gone metric now. Some packages seem to be one, and some the other, and still others don?t even seem to know what they are. It?s a total dog?s breakfast.

Tom

==================
       Electric Druid
Synth & Stompbox DIY
==================

> On 3 Dec 2018, at 14:04, Tim Ressel <timr at circuitabbey.com> wrote:
> 
> Did you hear me scream?
> 
> I picked a part that sez its SOT-505. Okay, what is that? I look at the datasheet which sez its the same as tssop8. Then I look up tssop8. They do not match. then I find a sot-505-2. Also doesn't match. This really throws generic package names out the window. As I make a custom footprint for this part I ponder the state of the industry and the ineffectual efforts of the gurus of standards like EIA.
> 
> -- 
> --Tim Ressel
> Circuit Abbey
> timr at circuitabbey.com
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy




From timr at circuitabbey.com  Mon Dec  3 16:06:34 2018
From: timr at circuitabbey.com (Tim Ressel)
Date: Mon, 3 Dec 2018 07:06:34 -0800
Subject: [sdiy] SMT package hell
In-Reply-To: <69022635-29B0-42C9-B488-96FAC562C4CA@electricdruid.net>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
 <69022635-29B0-42C9-B488-96FAC562C4CA@electricdruid.net>
Message-ID: <4984725c-5a8b-35a0-0ad1-2086a8b2f2ee@circuitabbey.com>

I recall many eons ago being staggered by a dip package IC that was 
smaller than 0.1". I think it was a 68000 processor by Toshiba. Kinda 
shook my world a bit. Little did I know it was an omen of things to come.

--Tim (easily shaken apparently) Ressel

On 12/3/2018 7:02 AM, Tom Wiltshire wrote:
> I just wish we could all work out whether we?re still using measurements based on a 0.1? grid or whether we?ve gone metric now. Some packages seem to be one, and some the other, and still others don?t even seem to know what they are. It?s a total dog?s breakfast.
>
> Tom
>
> ==================
>         Electric Druid
> Synth & Stompbox DIY
> ==================
>
>> On 3 Dec 2018, at 14:04, Tim Ressel <timr at circuitabbey.com> wrote:
>>
>> Did you hear me scream?
>>
>> I picked a part that sez its SOT-505. Okay, what is that? I look at the datasheet which sez its the same as tssop8. Then I look up tssop8. They do not match. then I find a sot-505-2. Also doesn't match. This really throws generic package names out the window. As I make a custom footprint for this part I ponder the state of the industry and the ineffectual efforts of the gurus of standards like EIA.
>>
>> -- 
>> --Tim Ressel
>> Circuit Abbey
>> timr at circuitabbey.com
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>
-- 
--Tim Ressel
Circuit Abbey
timr at circuitabbey.com



From timr at circuitabbey.com  Mon Dec  3 16:12:55 2018
From: timr at circuitabbey.com (Tim Ressel)
Date: Mon, 3 Dec 2018 07:12:55 -0800
Subject: [sdiy] V/Oct accuracy
Message-ID: <e68db40e-80ff-e966-41e6-d7e38a8b0b75@circuitabbey.com>

Good morning,

I am designing a triangle core VCO and have come to the part of the show 
where I get to pick a voltage reference chip. As I'm sure you're all 
aware the cost goes up as accuracy increases. Initial accuracy I mean, 
as I am trying to avoid a trim. This reference will set the amplitude of 
the wave as well as serve as a voltage for a range switch which needs to 
set exact (?) octaves. So the question is: how much accuracy do I need 
to pay for?

The issue is complicated by the fact that the customer is "west coast" 
and shuns all notions of notes. But as I see it, volt per octave has a 
certain meaning and sets up certain expectations. For example, the 
octave switch should jump the oscillator 1 octave +/- some acceptably 
small error.? In my meanderings I concluded the error should be 6 cents 
or less.

The issue is further complicated by my catching the accuracy bug during 
my stint at what is called Keysight this week. I tend to err on the side 
of minimizing err ;-)? It is an expensive obsession to be sure, and as 
it is my customer that has to pay for it, I need to strike a balance. I 
know there is also drift and resistor tolerances to consider. One battle 
at a time.

Thoughts?

-- 
--Tim Ressel
Circuit Abbey
timr at circuitabbey.com



From modular at go2.pl  Mon Dec  3 16:40:54 2018
From: modular at go2.pl (Roman Sowa)
Date: Mon, 3 Dec 2018 16:40:54 +0100
Subject: [sdiy] V/Oct accuracy
In-Reply-To: <e68db40e-80ff-e966-41e6-d7e38a8b0b75@circuitabbey.com>
References: <e68db40e-80ff-e966-41e6-d7e38a8b0b75@circuitabbey.com>
Message-ID: <028b5f78-764f-3b6c-95fd-5920278caa1f@go2.pl>

I usually don't pay attention to Initial Accuracy, as this is always 
later trimmed in hardware or software. What's most important for me are 
temperature stability and long term drift. You may be limiting your 
choices if you focus on Initial Accuracy.

Why do you want to avoid trim? Is it going to be manufactured in 
thousands? If you don't want trimpots, then maybe try non-volatile 
digital pot instead.

And since it's VCO, then maybe add a little microcontroller and 
autotune/autocalibration routine. Maintaining frequency by means of smal 
cheap crystal is easier than maintaining precision voltage over long 
period, so then you could use ultra cheap reference.

Roman

W dniu 2018-12-03 o?16:12, Tim Ressel pisze:
> Good morning,
> 
> I am designing a triangle core VCO and have come to the part of the show 
> where I get to pick a voltage reference chip. As I'm sure you're all 
> aware the cost goes up as accuracy increases. Initial accuracy I mean, 
> as I am trying to avoid a trim. This reference will set the amplitude of 
> the wave as well as serve as a voltage for a range switch which needs to 
> set exact (?) octaves. So the question is: how much accuracy do I need 
> to pay for?
> 
> The issue is complicated by the fact that the customer is "west coast" 
> and shuns all notions of notes. But as I see it, volt per octave has a 
> certain meaning and sets up certain expectations. For example, the 
> octave switch should jump the oscillator 1 octave +/- some acceptably 
> small error.? In my meanderings I concluded the error should be 6 cents 
> or less.
> 
> The issue is further complicated by my catching the accuracy bug during 
> my stint at what is called Keysight this week. I tend to err on the side 
> of minimizing err ;-)? It is an expensive obsession to be sure, and as 
> it is my customer that has to pay for it, I need to strike a balance. I 
> know there is also drift and resistor tolerances to consider. One battle 
> at a time.
> 
> Thoughts?
> 


From jschwich53 at comcast.net  Mon Dec  3 18:17:36 2018
From: jschwich53 at comcast.net (Jay Schwichtenberg)
Date: Mon, 3 Dec 2018 09:17:36 -0800
Subject: [sdiy] SMT package hell
In-Reply-To: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
Message-ID: <000301d48b2c$16c41c80$444c5580$@net>

Stuff like that has got me to the point where I assume nothing and always go
and look at data sheets. Then I at least double and a lot of the time triple
check things before I commit.

Jay S.


-----Original Message-----
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Tim
Ressel
Sent: Monday, December 03, 2018 6:04 AM
To: SYNTH DIY
Subject: [sdiy] SMT package hell

Did you hear me scream?

I picked a part that sez its SOT-505. Okay, what is that? I look at the 
datasheet which sez its the same as tssop8. Then I look up tssop8. They 
do not match. then I find a sot-505-2. Also doesn't match. This really 
throws generic package names out the window. As I make a custom 
footprint for this part I ponder the state of the industry and the 
ineffectual efforts of the gurus of standards like EIA.

-- 
--Tim Ressel
Circuit Abbey
timr at circuitabbey.com

_______________________________________________
Synth-diy mailing list
Synth-diy at synth-diy.org
http://synth-diy.org/mailman/listinfo/synth-diy



From frey at radioles.com  Mon Dec  3 18:33:40 2018
From: frey at radioles.com (Joe Frey)
Date: Mon, 03 Dec 2018 12:33:40 -0500
Subject: [sdiy] circuit to create gate to accompany cv
In-Reply-To: <000301d48b2c$16c41c80$444c5580$@net>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
 <000301d48b2c$16c41c80$444c5580$@net>
Message-ID: <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>

Hello list, I have a EHX 8-step sequencer that is great for live stuff(sliders and tap tempo) but it doesn't have a gate out just cv. I want to use it? with my Lyra-8 which needs a gate pulse, too. I am trying to find a circuit that would make a gate pulse to accompany the cv of the EHX . Ideally small enough to fit in a box that could be considered "inline" and battery powered. 

?Sent from TypeApp ?

On Dec 3, 2018, 12:17 PM, at 12:17 PM, Jay Schwichtenberg <jschwich53 at comcast.net> wrote:
>Stuff like that has got me to the point where I assume nothing and
>always go
>and look at data sheets. Then I at least double and a lot of the time
>triple
>check things before I commit.
>
>Jay S.
>
>
>-----Original Message-----
>From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of
>Tim
>Ressel
>Sent: Monday, December 03, 2018 6:04 AM
>To: SYNTH DIY
>Subject: [sdiy] SMT package hell
>
>Did you hear me scream?
>
>I picked a part that sez its SOT-505. Okay, what is that? I look at the
>
>datasheet which sez its the same as tssop8. Then I look up tssop8. They
>
>do not match. then I find a sot-505-2. Also doesn't match. This really 
>throws generic package names out the window. As I make a custom 
>footprint for this part I ponder the state of the industry and the 
>ineffectual efforts of the gurus of standards like EIA.
>
>-- 
>--Tim Ressel
>Circuit Abbey
>timr at circuitabbey.com
>
>_______________________________________________
>Synth-diy mailing list
>Synth-diy at synth-diy.org
>http://synth-diy.org/mailman/listinfo/synth-diy
>
>_______________________________________________
>Synth-diy mailing list
>Synth-diy at synth-diy.org
>http://synth-diy.org/mailman/listinfo/synth-diy
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From johnspeth at yahoo.com  Mon Dec  3 18:48:10 2018
From: johnspeth at yahoo.com (John Speth)
Date: Mon, 3 Dec 2018 09:48:10 -0800
Subject: [sdiy] circuit to create gate to accompany cv
In-Reply-To: <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
 <000301d48b2c$16c41c80$444c5580$@net>
 <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
Message-ID: <f0d4eb4d-d976-f508-4381-f1b4ce426a6c@yahoo.com>

I don't believe there is any way to extract note-on events from CV 
only.? You'd need a sort of "mind reader" circuit to do that. However, 
I'd love to be wrong about that.

JJS

On 12/3/2018 9:33 AM, Joe Frey wrote:
> Hello list, I have a EHX 8-step sequencer that is great for live 
> stuff(sliders and tap tempo) but it doesn't have a gate out just cv. I 
> want to use it? with my Lyra-8 which needs a gate pulse, too. I am 
> trying to find a circuit that would make a gate pulse to accompany the 
> cv of the EHX . Ideally small enough to fit in a box that could be 
> considered "inline" and battery powered.
>
> Sent from TypeApp <http://www.typeapp.com/r?b=14068>
>
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy

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From tom at electricdruid.net  Mon Dec  3 19:32:33 2018
From: tom at electricdruid.net (Tom Wiltshire)
Date: Mon, 3 Dec 2018 18:32:33 +0000
Subject: [sdiy] circuit to create gate to accompany cv
In-Reply-To: <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
 <000301d48b2c$16c41c80$444c5580$@net>
 <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
Message-ID: <B5B07623-E6E6-4E2F-A529-1511F9CD0823@electricdruid.net>

I?m sure I?ve seen a synth that does that recently, reading through some old schematics. It set a window comparator with the current CV so that a pulse could be triggered when the CV changes. Can?t remember what it was exactly though?gagh! If it comes back to me, I?ll post it.

Alternatively, hack something onto that Rate LED above the tap tempo switch to give you a Gate Out. That?s probably simplest.

HTH,
Tom

==================
       Electric Druid
Synth & Stompbox DIY
==================

> On 3 Dec 2018, at 17:33, Joe Frey <frey at radioles.com> wrote:
> 
> Hello list, I have a EHX 8-step sequencer that is great for live stuff(sliders and tap tempo) but it doesn't have a gate out just cv. I want to use it  with my Lyra-8 which needs a gate pulse, too. I am trying to find a circuit that would make a gate pulse to accompany the cv of the EHX . Ideally small enough to fit in a box that could be considered "inline" and battery powered. 
> 
> Sent from TypeApp
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy




From jason at redfish.net  Mon Dec  3 19:41:08 2018
From: jason at redfish.net (Jason Proctor)
Date: Mon, 3 Dec 2018 10:41:08 -0800
Subject: [sdiy] circuit to create gate to accompany cv
In-Reply-To: <B5B07623-E6E6-4E2F-A529-1511F9CD0823@electricdruid.net>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
 <000301d48b2c$16c41c80$444c5580$@net>
 <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
 <B5B07623-E6E6-4E2F-A529-1511F9CD0823@electricdruid.net>
Message-ID: <CALQanALTpQ87oBo893v7QBCVy1Yx7QpFY+TWOBAwOQ7tkLTc_A@mail.gmail.com>

what does the MIDI input do on that EHX-8? if it's externally
clockable maybe something can be employed to turn the clock signal
into gate pulses.

On Mon, Dec 3, 2018 at 10:35 AM Tom Wiltshire <tom at electricdruid.net> wrote:
>
> I?m sure I?ve seen a synth that does that recently, reading through some old schematics. It set a window comparator with the current CV so that a pulse could be triggered when the CV changes. Can?t remember what it was exactly though?gagh! If it comes back to me, I?ll post it.
>
> Alternatively, hack something onto that Rate LED above the tap tempo switch to give you a Gate Out. That?s probably simplest.
>
> HTH,
> Tom
>
> ==================
>        Electric Druid
> Synth & Stompbox DIY
> ==================
>
> > On 3 Dec 2018, at 17:33, Joe Frey <frey at radioles.com> wrote:
> >
> > Hello list, I have a EHX 8-step sequencer that is great for live stuff(sliders and tap tempo) but it doesn't have a gate out just cv. I want to use it  with my Lyra-8 which needs a gate pulse, too. I am trying to find a circuit that would make a gate pulse to accompany the cv of the EHX . Ideally small enough to fit in a box that could be considered "inline" and battery powered.
> >
> > Sent from TypeApp
> >
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From admin at bugbrand.co.uk  Mon Dec  3 20:29:00 2018
From: admin at bugbrand.co.uk (Tom Bugs)
Date: Mon, 3 Dec 2018 19:29:00 +0000
Subject: [sdiy] circuit to create gate to accompany cv
In-Reply-To: <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
 <000301d48b2c$16c41c80$444c5580$@net>
 <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
Message-ID: <c950728b-37d8-c352-6e67-235f0896075a@bugbrand.co.uk>

I remember getting one early on and thought I modded it for Gate Out - 
but now I found a thread on it I realise it might only have been clock 
out.. (which is right there on the PCB)
https://www.muffwiggler.com/forum/viewtopic.php?t=82632
But there is some mention on Gate out in the long thread.
Tom

On 03/12/2018 17:33, Joe Frey wrote:
> Hello list, I have a EHX 8-step sequencer that is great for live 
> stuff(sliders and tap tempo) but it doesn't have a gate out just cv. I 
> want to use it? with my Lyra-8 which needs a gate pulse, too. I am 
> trying to find a circuit that would make a gate pulse to accompany the 
> cv of the EHX . Ideally small enough to fit in a box that could be 
> considered "inline" and battery powered.
>
> Sent from TypeApp <http://www.typeapp.com/r?b=14068>
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy

-- 
BugBrand LTD
UK company No. 07199808
VAT No. GB 988 2629 57
1 Ninetree Hill
BRISTOL BS1 3SB
United Kingdom
www.bugbrand.co.uk



---
This email has been checked for viruses by AVG.
https://www.avg.com
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From mattslunch at hotmail.com  Mon Dec  3 20:29:00 2018
From: mattslunch at hotmail.com (Matt Hartman)
Date: Mon, 3 Dec 2018 19:29:00 +0000
Subject: [sdiy] circuit to create gate to accompany cv
In-Reply-To: <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
 <000301d48b2c$16c41c80$444c5580$@net>
 <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
Message-ID: <CY4PR01MB3224CCD6850B590D494F17ABCCAE0@CY4PR01MB3224.prod.exchangelabs.com>

Hello list too.  The EHX 8 step sequencer actually has an open clock out pad if you open it up.  It sends out a square wave at the sequencer rate regardless if its running or not.  I have no trouble triggering modular envelopes with it.  Maybe you can use/condition this signal?


On 12/3/18 9:33 AM, Joe Frey wrote:
Hello list, I have a EHX 8-step sequencer that is great for live stuff(sliders and tap tempo) but it doesn't have a gate out just cv. I want to use it  with my Lyra-8 which needs a gate pulse, too. I am trying to find a circuit that would make a gate pulse to accompany the cv of the EHX . Ideally small enough to fit in a box that could be considered "inline" and battery powered.

Sent from TypeApp<http://www.typeapp.com/r?b=14068>






_______________________________________________
Synth-diy mailing list
Synth-diy at synth-diy.org<mailto:Synth-diy at synth-diy.org>
http://synth-diy.org/mailman/listinfo/synth-diy


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From gordonjcp at gjcp.net  Mon Dec  3 22:47:08 2018
From: gordonjcp at gjcp.net (Gordonjcp)
Date: Mon, 3 Dec 2018 21:47:08 +0000
Subject: [sdiy] circuit to create gate to accompany cv
In-Reply-To: <f0d4eb4d-d976-f508-4381-f1b4ce426a6c@yahoo.com>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
 <000301d48b2c$16c41c80$444c5580$@net>
 <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
 <f0d4eb4d-d976-f508-4381-f1b4ce426a6c@yahoo.com>
Message-ID: <20181203214708.GA18586@ilyushin>

On Mon, Dec 03, 2018 at 09:48:10AM -0800, John Speth wrote:
> I don't believe there is any way to extract note-on events from CV
> only.? You'd need a sort of "mind reader" circuit to do that.
> However, I'd love to be wrong about that.

Of course there is!  How do you think "New Pitch Detector" circuits in
monosynths work? ;-)

Take a look at the keyboard controller circuit for the Powertran
Transcendent 2000 for a good example...

-- 
Gordonjcp



From johnspeth at yahoo.com  Mon Dec  3 23:17:59 2018
From: johnspeth at yahoo.com (John Speth)
Date: Mon, 3 Dec 2018 14:17:59 -0800
Subject: [sdiy] circuit to create gate to accompany cv
In-Reply-To: <20181203214708.GA18586@ilyushin>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
 <000301d48b2c$16c41c80$444c5580$@net>
 <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
 <f0d4eb4d-d976-f508-4381-f1b4ce426a6c@yahoo.com>
 <20181203214708.GA18586@ilyushin>
Message-ID: <8de5c630-9700-eb1b-42f7-3faae1b1a104@yahoo.com>

There is no way to reliably capture note-on events from a single CV 
line.? Consider the case of unchanging voltage that might involve two or 
more consecutive note-on events at the same pitch, a common occurrence.? 
There's no way to discern note-on events because the voltage never changes.

JJS


On 12/3/2018 1:47 PM, Gordonjcp wrote:
> On Mon, Dec 03, 2018 at 09:48:10AM -0800, John Speth wrote:
>> I don't believe there is any way to extract note-on events from CV
>> only.? You'd need a sort of "mind reader" circuit to do that.
>> However, I'd love to be wrong about that.
> Of course there is!  How do you think "New Pitch Detector" circuits in
> monosynths work? ;-)
>
> Take a look at the keyboard controller circuit for the Powertran
> Transcendent 2000 for a good example...
>



From tom at electricdruid.net  Mon Dec  3 23:45:56 2018
From: tom at electricdruid.net (Tom Wiltshire)
Date: Mon, 3 Dec 2018 22:45:56 +0000
Subject: [sdiy] circuit to create gate to accompany cv
In-Reply-To: <8de5c630-9700-eb1b-42f7-3faae1b1a104@yahoo.com>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
 <000301d48b2c$16c41c80$444c5580$@net>
 <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
 <f0d4eb4d-d976-f508-4381-f1b4ce426a6c@yahoo.com>
 <20181203214708.GA18586@ilyushin>
 <8de5c630-9700-eb1b-42f7-3faae1b1a104@yahoo.com>
Message-ID: <518C0253-8A95-4D92-B99B-0D60DD0A39E4@electricdruid.net>

In the case of the EHX 8-step program, that might be regarded as a feature not a fault, since it would allow you to string two or more sliders together into a longer note.

Just a thought.

Tom

==================
       Electric Druid
Synth & Stompbox DIY
==================

> On 3 Dec 2018, at 22:17, John Speth <johnspeth at yahoo.com> wrote:
> 
> There is no way to reliably capture note-on events from a single CV line.  Consider the case of unchanging voltage that might involve two or more consecutive note-on events at the same pitch, a common occurrence.  There's no way to discern note-on events because the voltage never changes.
> 
> JJS
> 
> 
> On 12/3/2018 1:47 PM, Gordonjcp wrote:
>> On Mon, Dec 03, 2018 at 09:48:10AM -0800, John Speth wrote:
>>> I don't believe there is any way to extract note-on events from CV
>>> only.  You'd need a sort of "mind reader" circuit to do that.
>>> However, I'd love to be wrong about that.
>> Of course there is!  How do you think "New Pitch Detector" circuits in
>> monosynths work? ;-)
>> 
>> Take a look at the keyboard controller circuit for the Powertran
>> Transcendent 2000 for a good example...
>> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy




From davebr at modularsynthesis.com  Tue Dec  4 01:13:08 2018
From: davebr at modularsynthesis.com (Dave Brown)
Date: Mon, 3 Dec 2018 16:13:08 -0800
Subject: [sdiy] circuit to create gate to accompany cv
In-Reply-To: <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
 <000301d48b2c$16c41c80$444c5580$@net>
 <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
Message-ID: <005c01d48b66$22e44fa0$68aceee0$@modularsynthesis.com>

You use a two stage analog shift register and run the CV through it.  Clock it at a high speed.  Run the two outputs to an exclusive NOR.  If the stages are equal, you have a high which is your gate.  When the CV changes, for one clock cycle they will be unequal and your gate will fall.  Your gate is delayed from your CV, so use the second output of your analog shift register as the CV.

 

If instead you want a trigger, then use an exclusive OR gate.

 

If you want to generate a gate from two non-changing notes then you can simply create a trigger from the clock (assuming you have access to the clock) by detecting the appropriate edge.  You can use this as a trigger or invert it to use as a gate.

 

I would do this simply by programming up a microcontroller and using the on-board A/Ds and logic output.


Dave

 

 

From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Joe Frey
Sent: Monday, December 03, 2018 9:34 AM
To: 'SDIY List'
Subject: [sdiy] circuit to create gate to accompany cv

 

Hello list, I have a EHX 8-step sequencer that is great for live stuff(sliders and tap tempo) but it doesn't have a gate out just cv. I want to use it  with my Lyra-8 which needs a gate pulse, too. I am trying to find a circuit that would make a gate pulse to accompany the cv of the EHX . Ideally small enough to fit in a box that could be considered "inline" and battery powered. 

Sent from TypeApp <http://www.typeapp.com/r?b=14068>  

 

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From dixon at mail.ubc.ca  Tue Dec  4 07:22:27 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Mon, 3 Dec 2018 22:22:27 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
Message-ID: <2F3184E9CC31440394294B0ADD3CA027@galvanox01>

Hello SDIY Team,

This is the next sorry chapter in my saga with this 9-channel scanner.

You may recall that I was shocked to learn that TL074 saturates to different
voltages positive and negative, and that this was causing me grief with a
3-bit comparator ADC that I built to drive a couple of 8-channel analog
muxes (DG408).

Well, I solved that problem pretty easily: 3.3k current-limiting resistors
to back-to-back 5.1V zener diodes off the comparator outputs.  I
hand-selected the zener pairs to give me exactly +5.52V and -5.52V
(subsequently fed to the logic inputs of the DG408 through 30k resistors),
and was able to size the divider resistors accordingly to get exactly the
threshold voltages I needed for the ADC.  This all worked perfectly.

HOWEVER...

The scanner is creating wicked clicks when it switches the muxes.  After a
bunch of thinking and reading, I have come to the conclusion that this is an
issue of charge injection in the DG408s.

Here is what I have done to try to fix the problem:

1) Decoupled the rails at the TL074 hosting the ADC comparators with 100nF
caps directly at the power pins (no effect).

2) Decoupled the rails at the DG408 power pins with 10uF electrolytic caps
(no effect).

Obviously, the power rails are not the source of the clicks.  This was my
big clue that it was charge injection and not dirty rails.

3) Added 1N4148 diodes at the DG408 logic inputs to limit the negative logic
voltage excursions to about -0.5V (instead of the -5.5V that the zeners are
providing)(no effect).  It turns out that the DG4XX switch family can take
the full voltage range at the logic pins, all the way down to -22V.

4) Added 10nF caps off of the DG408 switch output pins, as shown in the
datasheet (no effect).

5) Increased these caps to 2.2uF.  This didn't really eliminate the clicks,
but it did attenuate the signals something fierce.

6) Ran the scanner output through a 6dB filter (the first output of my Doc
Oc filter) -- this did eliminate the clicks, but only at a cutoff frequency
which seriously filters the audio signals as well.  Hence, adding a simple
RC filter to the output isn't really a viable option.

7) I tried a different pair of DG408s (no effect).

The one thing I haven't tried is decreasing the downstream impedance of the
switch outputs.  They are going to the multiplier circuit through 100k
resistors.  I could change all the resistors in that circuit to 30k, or even
10k, but something tells me that this is a fool's errand.

So, I'm stumped, and about to give up.  My customer has told me that the
unit is useless to him with this clicking (I concur -- it would be useless
to me too), and I basically see no alternative to offering him his money
back and throwing the whole mess in the trash.  I'm very surprised at the
extreme level of charge injection in these DG408 switches.  I didn't notice
it to nearly the same extent (if at all) with the DG409 switch in my
5-channel scanner.  Earlier today, I realized that there is a dual 8-channel
switch, the DG407 -- perhaps if I had used this instead of two DG408s, the
clicking would be lesser.  However, I'm not prepared to order new chips and
create a third layout for this stupid circuit.

Do any of you have any insight that might help me solve (or, at least,
minimize) this clicking problem that I haven't already thought of?

Anyone who can help me solve this problem gets a free scanner PCB, or any
other PCB that I make by hand.

Thanks,
Dave Dixon



From Peter.Ullrich at kapsch.net  Tue Dec  4 08:17:12 2018
From: Peter.Ullrich at kapsch.net (Ullrich Peter)
Date: Tue, 4 Dec 2018 07:17:12 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
Message-ID: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>

Hi David!

There are special "slow" switchest hat alsoo have make before break characteristics so that they allow clickless/popless switching.
Some information can be found here and also a list for such parts:

https://www.maximintegrated.com/en/app-notes/index.mvp/id/5299  (search for "Audio Switches and the Break-Before-Make Capability")

Ciao
Peter

http://www.ullrich.at.tt (my webpage)
http://www.rc100-usb.at.tt (Roland Sampler Tool)
http://synpro.heimat.eu/datadial.htm (DataDial Synth Addon)



-----Urspr?ngliche Nachricht-----
Von: Synth-diy <synth-diy-bounces at synth-diy.org> Im Auftrag von David G Dixon
Gesendet: Dienstag, 4. Dezember 2018 07:22
An: synth-diy at synth-diy.org
Betreff: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)

Hello SDIY Team,

This is the next sorry chapter in my saga with this 9-channel scanner.

You may recall that I was shocked to learn that TL074 saturates to different voltages positive and negative, and that this was causing me grief with a 3-bit comparator ADC that I built to drive a couple of 8-channel analog muxes (DG408).

Well, I solved that problem pretty easily: 3.3k current-limiting resistors to back-to-back 5.1V zener diodes off the comparator outputs.  I hand-selected the zener pairs to give me exactly +5.52V and -5.52V (subsequently fed to the logic inputs of the DG408 through 30k resistors), and was able to size the divider resistors accordingly to get exactly the threshold voltages I needed for the ADC.  This all worked perfectly.

HOWEVER...

The scanner is creating wicked clicks when it switches the muxes.  After a bunch of thinking and reading, I have come to the conclusion that this is an issue of charge injection in the DG408s.

Here is what I have done to try to fix the problem:

1) Decoupled the rails at the TL074 hosting the ADC comparators with 100nF caps directly at the power pins (no effect).

2) Decoupled the rails at the DG408 power pins with 10uF electrolytic caps (no effect).

Obviously, the power rails are not the source of the clicks.  This was my big clue that it was charge injection and not dirty rails.

3) Added 1N4148 diodes at the DG408 logic inputs to limit the negative logic voltage excursions to about -0.5V (instead of the -5.5V that the zeners are providing)(no effect).  It turns out that the DG4XX switch family can take the full voltage range at the logic pins, all the way down to -22V.

4) Added 10nF caps off of the DG408 switch output pins, as shown in the datasheet (no effect).

5) Increased these caps to 2.2uF.  This didn't really eliminate the clicks, but it did attenuate the signals something fierce.

6) Ran the scanner output through a 6dB filter (the first output of my Doc Oc filter) -- this did eliminate the clicks, but only at a cutoff frequency which seriously filters the audio signals as well.  Hence, adding a simple RC filter to the output isn't really a viable option.

7) I tried a different pair of DG408s (no effect).

The one thing I haven't tried is decreasing the downstream impedance of the switch outputs.  They are going to the multiplier circuit through 100k resistors.  I could change all the resistors in that circuit to 30k, or even 10k, but something tells me that this is a fool's errand.

So, I'm stumped, and about to give up.  My customer has told me that the unit is useless to him with this clicking (I concur -- it would be useless to me too), and I basically see no alternative to offering him his money back and throwing the whole mess in the trash.  I'm very surprised at the extreme level of charge injection in these DG408 switches.  I didn't notice it to nearly the same extent (if at all) with the DG409 switch in my 5-channel scanner.  Earlier today, I realized that there is a dual 8-channel switch, the DG407 -- perhaps if I had used this instead of two DG408s, the clicking would be lesser.  However, I'm not prepared to order new chips and create a third layout for this stupid circuit.

Do any of you have any insight that might help me solve (or, at least,
minimize) this clicking problem that I haven't already thought of?

Anyone who can help me solve this problem gets a free scanner PCB, or any other PCB that I make by hand.

Thanks,
Dave Dixon

_______________________________________________
Synth-diy mailing list
Synth-diy at synth-diy.org
http://synth-diy.org/mailman/listinfo/synth-diy



The information contained in this e-mail message is privileged and confidential and is for the exclusive use of the addressee. The person who receives this message and who is not the addressee, one of his employees or an agent entitled to hand it over to the addressee, is informed that he may not use, disclose or reproduce the contents thereof, and is kindly asked to notify the sender and delete the e-mail immediately.




From dixon at mail.ubc.ca  Tue Dec  4 08:52:27 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Mon, 3 Dec 2018 23:52:27 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
Message-ID: <3F170B8B7853401BAB5E5C0A754FEFF9@galvanox01>

Thanks, Peter.

However, I should mention two details about the design.  The two DG408
switches route two signals to a VC crossfader.  When the switching occurs,
the crossfader is only passing one of the two switch outputs.  Also, when
this "active" switch is switching, it is always switching between two of the
same input signals.

For example, let's say that the switches are being switched from their "S5"
inputs to their "S6" inputs.  The signals on each input at the two switches
are as follows:

Switch A: S5 = Input 6.  S6 = Input 6.  This switch is being amplified by
the crossfader.
Switch B: S5 = Input 5.  S6 = Input 7.  This switch is being rejected by the
crossfader.

Hence, either switch's output is only heard during switching when the same
audio signal is being exerted on the two inputs being switched.  In the
example, this means that Switch A is the one being selected by the
crossfader, and it is switching from Input 6 to Input 6 (the two pins are
connected to the same trace).  The other switch is changing signals (from
Input 5 to Input 7) but this switch is not being heard from.  This means
that the usual source of popping, the sudden change of signal voltage due to
the rapid switching between two different signals, never occurs in my
design.

HOWEVER, there is another possibility that I just thought of.  Even though
Switch B in the example is not being heard from, it shares logic pin
connections with Switch A.  That means that if the sudden change of signal
at it's input pins is injecting a big spike into its logic circuit (just the
opposite of the usual concern with charge injection), then that spike will
also propogate to the other chip, and that spike will then make its way into
the signal.  So, the question here is, can charge injection affect these
switches in both directions: logic-to-signal, and signal-to-logic?  If I
separate the logic signals, maybe that'll fix it...  Hmmmm.  I'll try that
tomorrow. 

As usual, Am I smoking crack?
 

> -----Original Message-----
> From: Ullrich Peter [mailto:Peter.Ullrich at kapsch.net] 
> Sent: Monday, December 03, 2018 11:17 PM
> To: David G Dixon; synth-diy at synth-diy.org
> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> 
> Hi David!
> 
> There are special "slow" switchest hat alsoo have make before 
> break characteristics so that they allow clickless/popless switching.
> Some information can be found here and also a list for such parts:
> 
> https://www.maximintegrated.com/en/app-notes/index.mvp/id/5299
>   (search for "Audio Switches and the Break-Before-Make Capability")
> 
> Ciao
> Peter
> 
> http://www.ullrich.at.tt (my webpage)
> http://www.rc100-usb.at.tt (Roland Sampler Tool) 
> http://synpro.heimat.eu/datadial.htm (DataDial Synth Addon)
> 
> 
> 
> -----Urspr?ngliche Nachricht-----
> Von: Synth-diy <synth-diy-bounces at synth-diy.org> Im Auftrag 
> von David G Dixon
> Gesendet: Dienstag, 4. Dezember 2018 07:22
> An: synth-diy at synth-diy.org
> Betreff: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> 
> Hello SDIY Team,
> 
> This is the next sorry chapter in my saga with this 9-channel scanner.
> 
> You may recall that I was shocked to learn that TL074 
> saturates to different voltages positive and negative, and 
> that this was causing me grief with a 3-bit comparator ADC 
> that I built to drive a couple of 8-channel analog muxes (DG408).
> 
> Well, I solved that problem pretty easily: 3.3k 
> current-limiting resistors to back-to-back 5.1V zener diodes 
> off the comparator outputs.  I hand-selected the zener pairs 
> to give me exactly +5.52V and -5.52V (subsequently fed to the 
> logic inputs of the DG408 through 30k resistors), and was 
> able to size the divider resistors accordingly to get exactly 
> the threshold voltages I needed for the ADC.  This all worked 
> perfectly.
> 
> HOWEVER...
> 
> The scanner is creating wicked clicks when it switches the 
> muxes.  After a bunch of thinking and reading, I have come to 
> the conclusion that this is an issue of charge injection in 
> the DG408s.
> 
> Here is what I have done to try to fix the problem:
> 
> 1) Decoupled the rails at the TL074 hosting the ADC 
> comparators with 100nF caps directly at the power pins (no effect).
> 
> 2) Decoupled the rails at the DG408 power pins with 10uF 
> electrolytic caps (no effect).
> 
> Obviously, the power rails are not the source of the clicks.  
> This was my big clue that it was charge injection and not dirty rails.
> 
> 3) Added 1N4148 diodes at the DG408 logic inputs to limit the 
> negative logic voltage excursions to about -0.5V (instead of 
> the -5.5V that the zeners are providing)(no effect).  It 
> turns out that the DG4XX switch family can take the full 
> voltage range at the logic pins, all the way down to -22V.
> 
> 4) Added 10nF caps off of the DG408 switch output pins, as 
> shown in the datasheet (no effect).
> 
> 5) Increased these caps to 2.2uF.  This didn't really 
> eliminate the clicks, but it did attenuate the signals 
> something fierce.
> 
> 6) Ran the scanner output through a 6dB filter (the first 
> output of my Doc Oc filter) -- this did eliminate the clicks, 
> but only at a cutoff frequency which seriously filters the 
> audio signals as well.  Hence, adding a simple RC filter to 
> the output isn't really a viable option.
> 
> 7) I tried a different pair of DG408s (no effect).
> 
> The one thing I haven't tried is decreasing the downstream 
> impedance of the switch outputs.  They are going to the 
> multiplier circuit through 100k resistors.  I could change 
> all the resistors in that circuit to 30k, or even 10k, but 
> something tells me that this is a fool's errand.
> 
> So, I'm stumped, and about to give up.  My customer has told 
> me that the unit is useless to him with this clicking (I 
> concur -- it would be useless to me too), and I basically see 
> no alternative to offering him his money back and throwing 
> the whole mess in the trash.  I'm very surprised at the 
> extreme level of charge injection in these DG408 switches.  I 
> didn't notice it to nearly the same extent (if at all) with 
> the DG409 switch in my 5-channel scanner.  Earlier today, I 
> realized that there is a dual 8-channel switch, the DG407 -- 
> perhaps if I had used this instead of two DG408s, the 
> clicking would be lesser.  However, I'm not prepared to order 
> new chips and create a third layout for this stupid circuit.
> 
> Do any of you have any insight that might help me solve (or, at least,
> minimize) this clicking problem that I haven't already thought of?
> 
> Anyone who can help me solve this problem gets a free scanner 
> PCB, or any other PCB that I make by hand.
> 
> Thanks,
> Dave Dixon
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> 
> 
> 
> The information contained in this e-mail message is 
> privileged and confidential and is for the exclusive use of 
> the addressee. The person who receives this message and who 
> is not the addressee, one of his employees or an agent 
> entitled to hand it over to the addressee, is informed that 
> he may not use, disclose or reproduce the contents thereof, 
> and is kindly asked to notify the sender and delete the 
> e-mail immediately.
> 




From dixon at mail.ubc.ca  Tue Dec  4 09:04:16 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Tue, 4 Dec 2018 00:04:16 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
Message-ID: <4206FF3FD8984E289277A32A206857EE@galvanox01>

The other thing I thought I might try:

I need the back-to-back zeners to create accurate threshold voltages for my
ADC logic circuit.  However, perhaps I should drive the logic pins of the
DG408s directly from the comparator outputs.  The low source impedance of
the opamps should eat any spikes, right?  I already know that the DG4XX
switches happily take voltages on their logic pins up to both rails.

Alternatively, I can put separate resistors between the opamp outputs and
each switch's logic pins.  This might be safer for limiting the current to
the logic pins.  However, I'll happily sacrifice two DG408 switches to solve
this problem, and connecting them directly would allow me to use my current
layout, simply by replacing a few resistors with jumper wires.  The
datasheets say that the logic pins eat 10uA of current, so this should be
true whether I have current-limiting resistors or not, right?

 

> -----Original Message-----
> From: Ullrich Peter [mailto:Peter.Ullrich at kapsch.net] 
> Sent: Monday, December 03, 2018 11:17 PM
> To: David G Dixon; synth-diy at synth-diy.org
> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> 
> Hi David!
> 
> There are special "slow" switchest hat alsoo have make before 
> break characteristics so that they allow clickless/popless switching.
> Some information can be found here and also a list for such parts:
> 
> https://www.maximintegrated.com/en/app-notes/index.mvp/id/5299
>   (search for "Audio Switches and the Break-Before-Make Capability")
> 
> Ciao
> Peter
> 
> http://www.ullrich.at.tt (my webpage)
> http://www.rc100-usb.at.tt (Roland Sampler Tool) 
> http://synpro.heimat.eu/datadial.htm (DataDial Synth Addon)
> 
> 
> 
> -----Urspr?ngliche Nachricht-----
> Von: Synth-diy <synth-diy-bounces at synth-diy.org> Im Auftrag 
> von David G Dixon
> Gesendet: Dienstag, 4. Dezember 2018 07:22
> An: synth-diy at synth-diy.org
> Betreff: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> 
> Hello SDIY Team,
> 
> This is the next sorry chapter in my saga with this 9-channel scanner.
> 
> You may recall that I was shocked to learn that TL074 
> saturates to different voltages positive and negative, and 
> that this was causing me grief with a 3-bit comparator ADC 
> that I built to drive a couple of 8-channel analog muxes (DG408).
> 
> Well, I solved that problem pretty easily: 3.3k 
> current-limiting resistors to back-to-back 5.1V zener diodes 
> off the comparator outputs.  I hand-selected the zener pairs 
> to give me exactly +5.52V and -5.52V (subsequently fed to the 
> logic inputs of the DG408 through 30k resistors), and was 
> able to size the divider resistors accordingly to get exactly 
> the threshold voltages I needed for the ADC.  This all worked 
> perfectly.
> 
> HOWEVER...
> 
> The scanner is creating wicked clicks when it switches the 
> muxes.  After a bunch of thinking and reading, I have come to 
> the conclusion that this is an issue of charge injection in 
> the DG408s.
> 
> Here is what I have done to try to fix the problem:
> 
> 1) Decoupled the rails at the TL074 hosting the ADC 
> comparators with 100nF caps directly at the power pins (no effect).
> 
> 2) Decoupled the rails at the DG408 power pins with 10uF 
> electrolytic caps (no effect).
> 
> Obviously, the power rails are not the source of the clicks.  
> This was my big clue that it was charge injection and not dirty rails.
> 
> 3) Added 1N4148 diodes at the DG408 logic inputs to limit the 
> negative logic voltage excursions to about -0.5V (instead of 
> the -5.5V that the zeners are providing)(no effect).  It 
> turns out that the DG4XX switch family can take the full 
> voltage range at the logic pins, all the way down to -22V.
> 
> 4) Added 10nF caps off of the DG408 switch output pins, as 
> shown in the datasheet (no effect).
> 
> 5) Increased these caps to 2.2uF.  This didn't really 
> eliminate the clicks, but it did attenuate the signals 
> something fierce.
> 
> 6) Ran the scanner output through a 6dB filter (the first 
> output of my Doc Oc filter) -- this did eliminate the clicks, 
> but only at a cutoff frequency which seriously filters the 
> audio signals as well.  Hence, adding a simple RC filter to 
> the output isn't really a viable option.
> 
> 7) I tried a different pair of DG408s (no effect).
> 
> The one thing I haven't tried is decreasing the downstream 
> impedance of the switch outputs.  They are going to the 
> multiplier circuit through 100k resistors.  I could change 
> all the resistors in that circuit to 30k, or even 10k, but 
> something tells me that this is a fool's errand.
> 
> So, I'm stumped, and about to give up.  My customer has told 
> me that the unit is useless to him with this clicking (I 
> concur -- it would be useless to me too), and I basically see 
> no alternative to offering him his money back and throwing 
> the whole mess in the trash.  I'm very surprised at the 
> extreme level of charge injection in these DG408 switches.  I 
> didn't notice it to nearly the same extent (if at all) with 
> the DG409 switch in my 5-channel scanner.  Earlier today, I 
> realized that there is a dual 8-channel switch, the DG407 -- 
> perhaps if I had used this instead of two DG408s, the 
> clicking would be lesser.  However, I'm not prepared to order 
> new chips and create a third layout for this stupid circuit.
> 
> Do any of you have any insight that might help me solve (or, at least,
> minimize) this clicking problem that I haven't already thought of?
> 
> Anyone who can help me solve this problem gets a free scanner 
> PCB, or any other PCB that I make by hand.
> 
> Thanks,
> Dave Dixon
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> 
> 
> 
> The information contained in this e-mail message is 
> privileged and confidential and is for the exclusive use of 
> the addressee. The person who receives this message and who 
> is not the addressee, one of his employees or an agent 
> entitled to hand it over to the addressee, is informed that 
> he may not use, disclose or reproduce the contents thereof, 
> and is kindly asked to notify the sender and delete the 
> e-mail immediately.
> 




From dixon at mail.ubc.ca  Tue Dec  4 09:17:15 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Tue, 4 Dec 2018 00:17:15 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <4206FF3FD8984E289277A32A206857EE@galvanox01>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
 <4206FF3FD8984E289277A32A206857EE@galvanox01>
Message-ID: <3D09B5AF95A24C38898990D92C7AC4DA@galvanox01>

(Sorry for so many postings...)

Actually, connecting the logic pins directly to the zeners without an
intervening resistor should also eat the spikes, cuz that's what zeners do,
no?  If the voltage tries to exceed the zener voltage with a spike, then the
zeners will suck it out.  In that case, all I have to do is replace three
resistors with wire jumpers.  To heck with it... it's 12:16 AM, but I'm
gonna go try it right now.

 

> -----Original Message-----
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On 
> Behalf Of David G Dixon
> Sent: Tuesday, December 04, 2018 12:04 AM
> To: 'Ullrich Peter'; synth-diy at synth-diy.org
> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> 
> The other thing I thought I might try:
> 
> I need the back-to-back zeners to create accurate threshold 
> voltages for my ADC logic circuit.  However, perhaps I should 
> drive the logic pins of the DG408s directly from the 
> comparator outputs.  The low source impedance of the opamps 
> should eat any spikes, right?  I already know that the DG4XX 
> switches happily take voltages on their logic pins up to both rails.
> 
> Alternatively, I can put separate resistors between the opamp 
> outputs and each switch's logic pins.  This might be safer 
> for limiting the current to the logic pins.  However, I'll 
> happily sacrifice two DG408 switches to solve this problem, 
> and connecting them directly would allow me to use my current 
> layout, simply by replacing a few resistors with jumper 
> wires.  The datasheets say that the logic pins eat 10uA of 
> current, so this should be true whether I have 
> current-limiting resistors or not, right?
> 
>  
> 
> > -----Original Message-----
> > From: Ullrich Peter [mailto:Peter.Ullrich at kapsch.net]
> > Sent: Monday, December 03, 2018 11:17 PM
> > To: David G Dixon; synth-diy at synth-diy.org
> > Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection 
> with DG408)
> > 
> > Hi David!
> > 
> > There are special "slow" switchest hat alsoo have make before break 
> > characteristics so that they allow clickless/popless switching.
> > Some information can be found here and also a list for such parts:
> > 
> > https://www.maximintegrated.com/en/app-notes/index.mvp/id/5299
> >   (search for "Audio Switches and the Break-Before-Make Capability")
> > 
> > Ciao
> > Peter
> > 
> > http://www.ullrich.at.tt (my webpage)
> > http://www.rc100-usb.at.tt (Roland Sampler Tool) 
> > http://synpro.heimat.eu/datadial.htm (DataDial Synth Addon)
> > 
> > 
> > 
> > -----Urspr?ngliche Nachricht-----
> > Von: Synth-diy <synth-diy-bounces at synth-diy.org> Im Auftrag 
> von David 
> > G Dixon
> > Gesendet: Dienstag, 4. Dezember 2018 07:22
> > An: synth-diy at synth-diy.org
> > Betreff: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> > 
> > Hello SDIY Team,
> > 
> > This is the next sorry chapter in my saga with this 
> 9-channel scanner.
> > 
> > You may recall that I was shocked to learn that TL074 saturates to 
> > different voltages positive and negative, and that this was 
> causing me 
> > grief with a 3-bit comparator ADC that I built to drive a couple of 
> > 8-channel analog muxes (DG408).
> > 
> > Well, I solved that problem pretty easily: 3.3k current-limiting 
> > resistors to back-to-back 5.1V zener diodes off the comparator 
> > outputs.  I hand-selected the zener pairs to give me exactly +5.52V 
> > and -5.52V (subsequently fed to the logic inputs of the 
> DG408 through 
> > 30k resistors), and was able to size the divider resistors 
> accordingly 
> > to get exactly the threshold voltages I needed for the ADC. 
>  This all 
> > worked perfectly.
> > 
> > HOWEVER...
> > 
> > The scanner is creating wicked clicks when it switches the muxes.  
> > After a bunch of thinking and reading, I have come to the 
> conclusion 
> > that this is an issue of charge injection in the DG408s.
> > 
> > Here is what I have done to try to fix the problem:
> > 
> > 1) Decoupled the rails at the TL074 hosting the ADC 
> comparators with 
> > 100nF caps directly at the power pins (no effect).
> > 
> > 2) Decoupled the rails at the DG408 power pins with 10uF 
> electrolytic 
> > caps (no effect).
> > 
> > Obviously, the power rails are not the source of the clicks.  
> > This was my big clue that it was charge injection and not 
> dirty rails.
> > 
> > 3) Added 1N4148 diodes at the DG408 logic inputs to limit 
> the negative 
> > logic voltage excursions to about -0.5V (instead of the 
> -5.5V that the 
> > zeners are providing)(no effect).  It turns out that the 
> DG4XX switch 
> > family can take the full voltage range at the logic pins, 
> all the way 
> > down to -22V.
> > 
> > 4) Added 10nF caps off of the DG408 switch output pins, as shown in 
> > the datasheet (no effect).
> > 
> > 5) Increased these caps to 2.2uF.  This didn't really eliminate the 
> > clicks, but it did attenuate the signals something fierce.
> > 
> > 6) Ran the scanner output through a 6dB filter (the first 
> output of my 
> > Doc Oc filter) -- this did eliminate the clicks, but only 
> at a cutoff 
> > frequency which seriously filters the audio signals as 
> well.  Hence, 
> > adding a simple RC filter to the output isn't really a 
> viable option.
> > 
> > 7) I tried a different pair of DG408s (no effect).
> > 
> > The one thing I haven't tried is decreasing the downstream 
> impedance 
> > of the switch outputs.  They are going to the multiplier circuit 
> > through 100k resistors.  I could change all the resistors in that 
> > circuit to 30k, or even 10k, but something tells me that this is a 
> > fool's errand.
> > 
> > So, I'm stumped, and about to give up.  My customer has 
> told me that 
> > the unit is useless to him with this clicking (I concur -- 
> it would be 
> > useless to me too), and I basically see no alternative to 
> offering him 
> > his money back and throwing the whole mess in the trash.  I'm very 
> > surprised at the extreme level of charge injection in these DG408 
> > switches.  I didn't notice it to nearly the same extent (if at all) 
> > with the DG409 switch in my 5-channel scanner.  Earlier today, I 
> > realized that there is a dual 8-channel switch, the DG407 
> -- perhaps 
> > if I had used this instead of two DG408s, the clicking would be 
> > lesser.  However, I'm not prepared to order new chips and create a 
> > third layout for this stupid circuit.
> > 
> > Do any of you have any insight that might help me solve 
> (or, at least,
> > minimize) this clicking problem that I haven't already thought of?
> > 
> > Anyone who can help me solve this problem gets a free 
> scanner PCB, or 
> > any other PCB that I make by hand.
> > 
> > Thanks,
> > Dave Dixon
> > 
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
> > 
> > 
> > 
> > The information contained in this e-mail message is privileged and 
> > confidential and is for the exclusive use of the addressee. 
> The person 
> > who receives this message and who is not the addressee, one of his 
> > employees or an agent entitled to hand it over to the addressee, is 
> > informed that he may not use, disclose or reproduce the contents 
> > thereof, and is kindly asked to notify the sender and delete the 
> > e-mail immediately.
> > 
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy




From frey at radioles.com  Tue Dec  4 09:45:04 2018
From: frey at radioles.com (Joe Frey)
Date: Tue, 04 Dec 2018 03:45:04 -0500
Subject: [sdiy] circuit to create gate to accompany cv
In-Reply-To: <B5B07623-E6E6-4E2F-A529-1511F9CD0823@electricdruid.net>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
 <000301d48b2c$16c41c80$444c5580$@net>
 <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
 <B5B07623-E6E6-4E2F-A529-1511F9CD0823@electricdruid.net>
Message-ID: <4a46eb3f-a521-4633-a5dd-f8420680d554@radioles.com>

Tx to all! Looked at the muff wiggler thread and made the mods. It works well enough. The clock pulse is high long enough. In time I will make a proper box but for now I have enough to use this sequencer and the Lyra-8 for a show on the 15th.
Couldn't do it without your rest help. JoeF.

?Sent from TypeApp ?

On Dec 3, 2018, 1:32 PM, at 1:32 PM, Tom Wiltshire <tom at electricdruid.net> wrote:
>I?m sure I?ve seen a synth that does that recently, reading through
>some old schematics. It set a window comparator with the current CV so
>that a pulse could be triggered when the CV changes. Can?t remember
>what it was exactly though?gagh! If it comes back to me, I?ll post it.
>
>Alternatively, hack something onto that Rate LED above the tap tempo
>switch to give you a Gate Out. That?s probably simplest.
>
>HTH,
>Tom
>
>==================
>       Electric Druid
>Synth & Stompbox DIY
>==================
>
>> On 3 Dec 2018, at 17:33, Joe Frey <frey at radioles.com> wrote:
>> 
>> Hello list, I have a EHX 8-step sequencer that is great for live
>stuff(sliders and tap tempo) but it doesn't have a gate out just cv. I
>want to use it  with my Lyra-8 which needs a gate pulse, too. I am
>trying to find a circuit that would make a gate pulse to accompany the
>cv of the EHX . Ideally small enough to fit in a box that could be
>considered "inline" and battery powered. 
>> 
>> Sent from TypeApp
>> 
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
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From steve at bendentech.co.uk  Tue Dec  4 10:28:53 2018
From: steve at bendentech.co.uk (Steve Lenham)
Date: Tue, 4 Dec 2018 09:28:53 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <3D09B5AF95A24C38898990D92C7AC4DA@galvanox01>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
 <4206FF3FD8984E289277A32A206857EE@galvanox01>
 <3D09B5AF95A24C38898990D92C7AC4DA@galvanox01>
Message-ID: <9ce5bead-020d-1afa-83e1-906319e4fa04@bendentech.co.uk>

Hi David,

I feel your pain, especially if time is tight.

My thoughts:

- I do not think that there is likely to be a "reverse crosstalk" issue 
from the analogue pins back to the logic, at least not within the IC. 
There are internal buffers and level-shifters between the two.

- I doubt it is charge injection either, but you can test that by doing 
the thing you mentioned and temporarily lower the load resistance on the 
switch outputs. If it IS charge injection, lower resistance should 
reduce the click at least somewhat.

- Here is my main suggestion as to what it might be. It sounds like (we 
only have your description of the circuit to go on) you are generating 
the three-bit control word for the analogue switch from the outputs of 
several analogue comparators. How sure are you that the transition from 
one digital value to the next is clean, i.e. that all three bits change 
state at exactly the same time? If the three-bit word passes through any 
intermediate "runt" states on its way, the switch will briefly select a 
completely different input and potentially inject spikes of something 
else into the output. This is an issue in digital systems (search "race 
hazards") and is likely to be even worse if comparatively slow and 
imprecise analogue comparators are involved.

Your previous design used a DG409, which only has a two-bit address - 
the problem could theoretically still occur there, but there is less 
scope for it to do so.

- Another possibility, though IMO less likely, is simply DC offsets on 
the different inputs of your analogue switch. Most people AC-couple 
audio signals into an analogue switch, but you also need a pulldown 
resistor at the pin of the switch. Otherwise, when an input is not 
selected, leakage current in the coupling cap can allow an offset 
voltage to appear at the input of the switch. This is then discharged 
when the source gets selected, causing a glitch at the output. (This is 
less likely because you say the switch is selecting from two copies of 
the same signal).

Hope this helps a bit,

Steve L.
Benden Sound Technology


On 04/12/2018 08:17, David G Dixon wrote:
> (Sorry for so many postings...)
> 
> Actually, connecting the logic pins directly to the zeners without an
> intervening resistor should also eat the spikes, cuz that's what zeners do,
> no?  If the voltage tries to exceed the zener voltage with a spike, then the
> zeners will suck it out.  In that case, all I have to do is replace three
> resistors with wire jumpers.  To heck with it... it's 12:16 AM, but I'm
> gonna go try it right now.
> 
>   
> 
>> -----Original Message-----
>> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On
>> Behalf Of David G Dixon
>> Sent: Tuesday, December 04, 2018 12:04 AM
>> To: 'Ullrich Peter'; synth-diy at synth-diy.org
>> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
>>
>> The other thing I thought I might try:
>>
>> I need the back-to-back zeners to create accurate threshold
>> voltages for my ADC logic circuit.  However, perhaps I should
>> drive the logic pins of the DG408s directly from the
>> comparator outputs.  The low source impedance of the opamps
>> should eat any spikes, right?  I already know that the DG4XX
>> switches happily take voltages on their logic pins up to both rails.
>>
>> Alternatively, I can put separate resistors between the opamp
>> outputs and each switch's logic pins.  This might be safer
>> for limiting the current to the logic pins.  However, I'll
>> happily sacrifice two DG408 switches to solve this problem,
>> and connecting them directly would allow me to use my current
>> layout, simply by replacing a few resistors with jumper
>> wires.  The datasheets say that the logic pins eat 10uA of
>> current, so this should be true whether I have
>> current-limiting resistors or not, right?
>>
>>   
>>
>>> -----Original Message-----
>>> From: Ullrich Peter [mailto:Peter.Ullrich at kapsch.net]
>>> Sent: Monday, December 03, 2018 11:17 PM
>>> To: David G Dixon; synth-diy at synth-diy.org
>>> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection
>> with DG408)
>>>
>>> Hi David!
>>>
>>> There are special "slow" switchest hat alsoo have make before break
>>> characteristics so that they allow clickless/popless switching.
>>> Some information can be found here and also a list for such parts:
>>>
>>> https://www.maximintegrated.com/en/app-notes/index.mvp/id/5299
>>>    (search for "Audio Switches and the Break-Before-Make Capability")
>>>
>>> Ciao
>>> Peter
>>>
>>> http://www.ullrich.at.tt (my webpage)
>>> http://www.rc100-usb.at.tt (Roland Sampler Tool)
>>> http://synpro.heimat.eu/datadial.htm (DataDial Synth Addon)
>>>
>>>
>>>
>>> -----Urspr?ngliche Nachricht-----
>>> Von: Synth-diy <synth-diy-bounces at synth-diy.org> Im Auftrag
>> von David
>>> G Dixon
>>> Gesendet: Dienstag, 4. Dezember 2018 07:22
>>> An: synth-diy at synth-diy.org
>>> Betreff: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
>>>
>>> Hello SDIY Team,
>>>
>>> This is the next sorry chapter in my saga with this
>> 9-channel scanner.
>>>
>>> You may recall that I was shocked to learn that TL074 saturates to
>>> different voltages positive and negative, and that this was
>> causing me
>>> grief with a 3-bit comparator ADC that I built to drive a couple of
>>> 8-channel analog muxes (DG408).
>>>
>>> Well, I solved that problem pretty easily: 3.3k current-limiting
>>> resistors to back-to-back 5.1V zener diodes off the comparator
>>> outputs.  I hand-selected the zener pairs to give me exactly +5.52V
>>> and -5.52V (subsequently fed to the logic inputs of the
>> DG408 through
>>> 30k resistors), and was able to size the divider resistors
>> accordingly
>>> to get exactly the threshold voltages I needed for the ADC.
>>   This all
>>> worked perfectly.
>>>
>>> HOWEVER...
>>>
>>> The scanner is creating wicked clicks when it switches the muxes.
>>> After a bunch of thinking and reading, I have come to the
>> conclusion
>>> that this is an issue of charge injection in the DG408s.
>>>
>>> Here is what I have done to try to fix the problem:
>>>
>>> 1) Decoupled the rails at the TL074 hosting the ADC
>> comparators with
>>> 100nF caps directly at the power pins (no effect).
>>>
>>> 2) Decoupled the rails at the DG408 power pins with 10uF
>> electrolytic
>>> caps (no effect).
>>>
>>> Obviously, the power rails are not the source of the clicks.
>>> This was my big clue that it was charge injection and not
>> dirty rails.
>>>
>>> 3) Added 1N4148 diodes at the DG408 logic inputs to limit
>> the negative
>>> logic voltage excursions to about -0.5V (instead of the
>> -5.5V that the
>>> zeners are providing)(no effect).  It turns out that the
>> DG4XX switch
>>> family can take the full voltage range at the logic pins,
>> all the way
>>> down to -22V.
>>>
>>> 4) Added 10nF caps off of the DG408 switch output pins, as shown in
>>> the datasheet (no effect).
>>>
>>> 5) Increased these caps to 2.2uF.  This didn't really eliminate the
>>> clicks, but it did attenuate the signals something fierce.
>>>
>>> 6) Ran the scanner output through a 6dB filter (the first
>> output of my
>>> Doc Oc filter) -- this did eliminate the clicks, but only
>> at a cutoff
>>> frequency which seriously filters the audio signals as
>> well.  Hence,
>>> adding a simple RC filter to the output isn't really a
>> viable option.
>>>
>>> 7) I tried a different pair of DG408s (no effect).
>>>
>>> The one thing I haven't tried is decreasing the downstream
>> impedance
>>> of the switch outputs.  They are going to the multiplier circuit
>>> through 100k resistors.  I could change all the resistors in that
>>> circuit to 30k, or even 10k, but something tells me that this is a
>>> fool's errand.
>>>
>>> So, I'm stumped, and about to give up.  My customer has
>> told me that
>>> the unit is useless to him with this clicking (I concur --
>> it would be
>>> useless to me too), and I basically see no alternative to
>> offering him
>>> his money back and throwing the whole mess in the trash.  I'm very
>>> surprised at the extreme level of charge injection in these DG408
>>> switches.  I didn't notice it to nearly the same extent (if at all)
>>> with the DG409 switch in my 5-channel scanner.  Earlier today, I
>>> realized that there is a dual 8-channel switch, the DG407
>> -- perhaps
>>> if I had used this instead of two DG408s, the clicking would be
>>> lesser.  However, I'm not prepared to order new chips and create a
>>> third layout for this stupid circuit.
>>>
>>> Do any of you have any insight that might help me solve
>> (or, at least,
>>> minimize) this clicking problem that I haven't already thought of?
>>>
>>> Anyone who can help me solve this problem gets a free
>> scanner PCB, or
>>> any other PCB that I make by hand.
>>>
>>> Thanks,
>>> Dave Dixon




From guy.mccusker at gmail.com  Tue Dec  4 10:38:47 2018
From: guy.mccusker at gmail.com (Guy McCusker)
Date: Tue, 4 Dec 2018 09:38:47 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <9ce5bead-020d-1afa-83e1-906319e4fa04@bendentech.co.uk>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
 <4206FF3FD8984E289277A32A206857EE@galvanox01>
 <3D09B5AF95A24C38898990D92C7AC4DA@galvanox01>
 <9ce5bead-020d-1afa-83e1-906319e4fa04@bendentech.co.uk>
Message-ID: <CAPx-PW7khhj=_K5nBr5pXFmS1hC1=rkpDf2xX9ztTZ2MMy6yJg@mail.gmail.com>

> - Here is my main suggestion as to what it might be. It sounds like (we
> only have your description of the circuit to go on) you are generating
> the three-bit control word for the analogue switch from the outputs of
> several analogue comparators. How sure are you that the transition from
> one digital value to the next is clean, i.e. that all three bits change
> state at exactly the same time? If the three-bit word passes through any
> intermediate "runt" states on its way, the switch will briefly select a
> completely different input and potentially inject spikes of something
> else into the output. This is an issue in digital systems (search "race
> hazards") and is likely to be even worse if comparatively slow and
> imprecise analogue comparators are involved.

Ah, this is interesting. I am toying with something that involves
switching with a DG408 too, and had started wondering about using a
CMOS priority encoder (CD4532) to generate the three bit words from an
analog select signal. Might something like that help to get clean
switching signals here too?


From modular at go2.pl  Tue Dec  4 10:50:05 2018
From: modular at go2.pl (Roman Sowa)
Date: Tue, 4 Dec 2018 10:50:05 +0100
Subject: [sdiy] circuit to create gate to accompany cv
In-Reply-To: <B5B07623-E6E6-4E2F-A529-1511F9CD0823@electricdruid.net>
References: <c470dd37-207c-7520-d4ba-83115217ce29@circuitabbey.com>
 <000301d48b2c$16c41c80$444c5580$@net>
 <994cdd2a-c001-4b23-8e2e-96503bfb9d04@radioles.com>
 <B5B07623-E6E6-4E2F-A529-1511F9CD0823@electricdruid.net>
Message-ID: <85978289-30fb-6ad1-a758-65681034115e@go2.pl>

I've seen that also, not too long ago. It was probably some old Yamaha 
but I can't be sure. Gate was one signal together with pitch CV. 
Whenever CV was positive, it meant gate-on. When gate was off, CV went 
negative.

And in case of step sequencer - you have that gate somewhere inside, 
after all it's clocking, right? So it should be no problem finding a 
clock that is 1:1 with step change.

Roman

W dniu 2018-12-03 o?19:32, Tom Wiltshire pisze:
> I?m sure I?ve seen a synth that does that recently, reading through some old schematics. It set a window comparator with the current CV so that a pulse could be triggered when the CV changes. Can?t remember what it was exactly though?gagh! If it comes back to me, I?ll post it.
> 
> Alternatively, hack something onto that Rate LED above the tap tempo switch to give you a Gate Out. That?s probably simplest.
> 
> HTH,
> Tom
> 
> ==================
>         Electric Druid
> Synth & Stompbox DIY
> ==================
> 
>> On 3 Dec 2018, at 17:33, Joe Frey <frey at radioles.com> wrote:
>>
>> Hello list, I have a EHX 8-step sequencer that is great for live stuff(sliders and tap tempo) but it doesn't have a gate out just cv. I want to use it  with my Lyra-8 which needs a gate pulse, too. I am trying to find a circuit that would make a gate pulse to accompany the cv of the EHX . Ideally small enough to fit in a box that could be considered "inline" and battery powered.
>>
>> Sent from TypeApp
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> 


From markverbos at gmail.com  Tue Dec  4 11:09:30 2018
From: markverbos at gmail.com (mark verbos)
Date: Tue, 4 Dec 2018 11:09:30 +0100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <9ce5bead-020d-1afa-83e1-906319e4fa04@bendentech.co.uk>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
 <4206FF3FD8984E289277A32A206857EE@galvanox01>
 <3D09B5AF95A24C38898990D92C7AC4DA@galvanox01>
 <9ce5bead-020d-1afa-83e1-906319e4fa04@bendentech.co.uk>
Message-ID: <FD7DEF4D-9480-4E69-80CF-8E640C615B4E@gmail.com>

What Steve said.

My opinion is that it is much more likely that your ?logic? signals, coming from mere opamps have sloped edges. Since the thresholds of the DG and the comparators in the converters and everything all are different, then the timing of all of this is different. So, each time a transition is about to happen, a flam of changes happens and glitches of unrelated signals leak through. When I have had logic races like this, I just added caps to the fastest of the signals to get them to fall in line with the slower ones. I have done a sequencer that crossfades from the last step to the current step to create a slide as well as a multistage envelope that does something similar and these kinds of problems showed up.

Mark







> On Dec 4, 2018, at 10:28 AM, Steve Lenham <steve at bendentech.co.uk> wrote:
> 
> 
> 
> - Here is my main suggestion as to what it might be. It sounds like (we only have your description of the circuit to go on) you are generating the three-bit control word for the analogue switch from the outputs of several analogue comparators. How sure are you that the transition from one digital value to the next is clean, i.e. that all three bits change state at exactly the same time? If the three-bit word passes through any intermediate "runt" states on its way, the switch will briefly select a completely different input and potentially inject spikes of something else into the output. This is an issue in digital systems (search "race hazards") and is likely to be even worse if comparatively slow and imprecise analogue comparators are involved.
> 
> Your previous design used a DG409, which only has a two-bit address - the problem could theoretically still occur there, but there is less scope for it to do so.
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy




From steve at bendentech.co.uk  Tue Dec  4 11:12:04 2018
From: steve at bendentech.co.uk (Steve Lenham)
Date: Tue, 4 Dec 2018 10:12:04 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <CAPx-PW7khhj=_K5nBr5pXFmS1hC1=rkpDf2xX9ztTZ2MMy6yJg@mail.gmail.com>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
 <4206FF3FD8984E289277A32A206857EE@galvanox01>
 <3D09B5AF95A24C38898990D92C7AC4DA@galvanox01>
 <9ce5bead-020d-1afa-83e1-906319e4fa04@bendentech.co.uk>
 <CAPx-PW7khhj=_K5nBr5pXFmS1hC1=rkpDf2xX9ztTZ2MMy6yJg@mail.gmail.com>
Message-ID: <b3cd923f-65f1-1b8e-6a0b-d3ea597183f0@bendentech.co.uk>

On 04/12/2018 09:38, Guy McCusker wrote:
>> - Here is my main suggestion as to what it might be. It sounds like (we
>> only have your description of the circuit to go on) you are generating
>> the three-bit control word for the analogue switch from the outputs of
>> several analogue comparators. How sure are you that the transition from
>> one digital value to the next is clean, i.e. that all three bits change
>> state at exactly the same time? If the three-bit word passes through any
>> intermediate "runt" states on its way, the switch will briefly select a
>> completely different input and potentially inject spikes of something
>> else into the output. This is an issue in digital systems (search "race
>> hazards") and is likely to be even worse if comparatively slow and
>> imprecise analogue comparators are involved.
> 
> Ah, this is interesting. I am toying with something that involves
> switching with a DG408 too, and had started wondering about using a
> CMOS priority encoder (CD4532) to generate the three bit words from an
> analog select signal. Might something like that help to get clean
> switching signals here too?

It might, but it depends on how you generate the inputs to the priority 
encoder. The 4532 generates an output word corresponding to the highest 
of its eight inputs that is active. If more than one input is active, 
the highest priority input takes precedence (hence the name).

If you had a problem caused by your circuitry activating more than one 
control line simultaneously then the priority encoder might help. If, 
however, the input to the priority encoder travels through intermediate 
states on its way from one value to another then it will NOT help.

For example, if you want to switch from source 1 to source 7 but the 
input to the priority encoder briefly travels through 4 then the output 
of the encoder will faithfully follow that and you will be no better off.

The ideal - though not always possible - way to eliminate these 
intermediate states is to make the system synchronous. You feed the 
asynchronous address lines to the inputs of a D-type latch, then clock 
the latch at a point where you know that all the bits that were going to 
change have had time to do so. The output of the latch then drives your 
analogue switch (or whatever).

Of course, you can only do that if you know the point at which you 
expect the value to change, and it sounds from David's descriptions like 
that is not the case in his design.

If it looks like this might be the problem, we may need to see more of 
the circuit in order to suggest a solution in this case.

Cheers,

Steve L.
Benden Sound Technology




From modular at go2.pl  Tue Dec  4 11:21:50 2018
From: modular at go2.pl (Roman Sowa)
Date: Tue, 4 Dec 2018 11:21:50 +0100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <2F3184E9CC31440394294B0ADD3CA027@galvanox01>
References: <2F3184E9CC31440394294B0ADD3CA027@galvanox01>
Message-ID: <230b043d-8861-7e8a-680a-021b82eafed2@go2.pl>

It's unlikely to be charge injection, especially when you connected 10nF 
at the utput in step 4. Charge injection as name tells, is charging the 
capacitor to some voltage. If you add s much more capacitance, the 
voltage rise will be lower. You haven't see a change, so it's not charge 
injection.

What I don't like in this, and it screams to me "trouble!" is the fact 
that you switch active signal (the one that crossfader is set to at 
100%). Even when switching between 2 inputs tied together, that's still 
unnecessary swithing that may break the path of input signal, or even 
bounce if your ADC is producing oscillations at edges.
Rework the address logic a bit to eliminate that switching and switch 
only that mux which is muted by crossfader. So then you need 2 totally 
separate 1:4 muxes.

Roman

W dniu 2018-12-04 o?07:22, David G Dixon pisze:
> Hello SDIY Team,
> 
> This is the next sorry chapter in my saga with this 9-channel scanner.
> 
> You may recall that I was shocked to learn that TL074 saturates to different
> voltages positive and negative, and that this was causing me grief with a
> 3-bit comparator ADC that I built to drive a couple of 8-channel analog
> muxes (DG408).
> 
> Well, I solved that problem pretty easily: 3.3k current-limiting resistors
> to back-to-back 5.1V zener diodes off the comparator outputs.  I
> hand-selected the zener pairs to give me exactly +5.52V and -5.52V
> (subsequently fed to the logic inputs of the DG408 through 30k resistors),
> and was able to size the divider resistors accordingly to get exactly the
> threshold voltages I needed for the ADC.  This all worked perfectly.
> 
> HOWEVER...
> 
> The scanner is creating wicked clicks when it switches the muxes.  After a
> bunch of thinking and reading, I have come to the conclusion that this is an
> issue of charge injection in the DG408s.
> 
> Here is what I have done to try to fix the problem:
> 
> 1) Decoupled the rails at the TL074 hosting the ADC comparators with 100nF
> caps directly at the power pins (no effect).
> 
> 2) Decoupled the rails at the DG408 power pins with 10uF electrolytic caps
> (no effect).
> 
> Obviously, the power rails are not the source of the clicks.  This was my
> big clue that it was charge injection and not dirty rails.
> 
> 3) Added 1N4148 diodes at the DG408 logic inputs to limit the negative logic
> voltage excursions to about -0.5V (instead of the -5.5V that the zeners are
> providing)(no effect).  It turns out that the DG4XX switch family can take
> the full voltage range at the logic pins, all the way down to -22V.
> 
> 4) Added 10nF caps off of the DG408 switch output pins, as shown in the
> datasheet (no effect).
> 
> 5) Increased these caps to 2.2uF.  This didn't really eliminate the clicks,
> but it did attenuate the signals something fierce.
> 
> 6) Ran the scanner output through a 6dB filter (the first output of my Doc
> Oc filter) -- this did eliminate the clicks, but only at a cutoff frequency
> which seriously filters the audio signals as well.  Hence, adding a simple
> RC filter to the output isn't really a viable option.
> 
> 7) I tried a different pair of DG408s (no effect).
> 
> The one thing I haven't tried is decreasing the downstream impedance of the
> switch outputs.  They are going to the multiplier circuit through 100k
> resistors.  I could change all the resistors in that circuit to 30k, or even
> 10k, but something tells me that this is a fool's errand.
> 
> So, I'm stumped, and about to give up.  My customer has told me that the
> unit is useless to him with this clicking (I concur -- it would be useless
> to me too), and I basically see no alternative to offering him his money
> back and throwing the whole mess in the trash.  I'm very surprised at the
> extreme level of charge injection in these DG408 switches.  I didn't notice
> it to nearly the same extent (if at all) with the DG409 switch in my
> 5-channel scanner.  Earlier today, I realized that there is a dual 8-channel
> switch, the DG407 -- perhaps if I had used this instead of two DG408s, the
> clicking would be lesser.  However, I'm not prepared to order new chips and
> create a third layout for this stupid circuit.
> 
> Do any of you have any insight that might help me solve (or, at least,
> minimize) this clicking problem that I haven't already thought of?
> 
> Anyone who can help me solve this problem gets a free scanner PCB, or any
> other PCB that I make by hand.
> 
> Thanks,
> Dave Dixon
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> 


From uwe.schueler at uni-tuebingen.de  Tue Dec  4 11:36:25 2018
From: uwe.schueler at uni-tuebingen.de (Uwe Schueler)
Date: Tue, 04 Dec 2018 11:36:25 +0100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <9ce5bead-020d-1afa-83e1-906319e4fa04@bendentech.co.uk>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
 <4206FF3FD8984E289277A32A206857EE@galvanox01>
 <3D09B5AF95A24C38898990D92C7AC4DA@galvanox01>
 <9ce5bead-020d-1afa-83e1-906319e4fa04@bendentech.co.uk>
Message-ID: <20181204113625.Horde.dP7hYxalbvSV_24pvzNN2z7@webmail.uni-tuebingen.de>


> ... How sure are you that the transition from one digital value to  
> the next is clean, i.e. that all three bits change state at exactly  
> the same time?
good point ! When controlling a MUX by asynchronous logic I use a one  
shot monostable @ ENable pin to suppress
glitches. A simple diode,C,Rpullup one shot driven by the (inverted)  
first spiking line might do it.



From mskala at ansuz.sooke.bc.ca  Tue Dec  4 15:47:17 2018
From: mskala at ansuz.sooke.bc.ca (mskala at ansuz.sooke.bc.ca)
Date: Tue, 4 Dec 2018 09:47:17 -0500 (EST)
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <b3cd923f-65f1-1b8e-6a0b-d3ea597183f0@bendentech.co.uk>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
 <4206FF3FD8984E289277A32A206857EE@galvanox01>
 <3D09B5AF95A24C38898990D92C7AC4DA@galvanox01>
 <9ce5bead-020d-1afa-83e1-906319e4fa04@bendentech.co.uk>
 <CAPx-PW7khhj=_K5nBr5pXFmS1hC1=rkpDf2xX9ztTZ2MMy6yJg@mail.gmail.com>
 <b3cd923f-65f1-1b8e-6a0b-d3ea597183f0@bendentech.co.uk>
Message-ID: <alpine.LNX.2.20.1812040936500.5581@localhost.localdomain>

On Tue, 4 Dec 2018, Steve Lenham wrote:
> The ideal - though not always possible - way to eliminate these intermediate
> states is to make the system synchronous. You feed the asynchronous address
> lines to the inputs of a D-type latch, then clock the latch at a point where

Another thing often done to reduce glitches in this sort of situation is
to use a Gray code.  Instead of using the digital words in the sequence
000, 001, 010, 011, 100, 101, 110, 111, where all of them can change
between successive values, one might use them in the sequence 000, 001,
011, 010, 110, 111, 101, 100.  That way, only one bit changes between
successive words.  This is done for things like absolute position encoders
where you have a slow mechanical system driving digital logic and you
can't depend on both bits changing at the same time when two change.

I don't really understand how the digital logic is being used in David's
design and I fear that trying to retrofit Gray coding onto what he's
currently got might require so much change to the way the comparators are
being used, as to be impractical.  But it *is* a useful way to reduce
glitches when it's applicable.

-- 
Matthew Skala
mskala at ansuz.sooke.bc.ca                 People before tribes.
http://ansuz.sooke.bc.ca/


From dixon at mail.ubc.ca  Tue Dec  4 18:13:10 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Tue, 4 Dec 2018 09:13:10 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <alpine.LNX.2.20.1812040936500.5581@localhost.localdomain>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
 <4206FF3FD8984E289277A32A206857EE@galvanox01>
 <3D09B5AF95A24C38898990D92C7AC4DA@galvanox01>
 <9ce5bead-020d-1afa-83e1-906319e4fa04@bendentech.co.uk>
 <CAPx-PW7khhj=_K5nBr5pXFmS1hC1=rkpDf2xX9ztTZ2MMy6yJg@mail.gmail.com>
 <b3cd923f-65f1-1b8e-6a0b-d3ea597183f0@bendentech.co.uk>
 <alpine.LNX.2.20.1812040936500.5581@localhost.localdomain>
Message-ID: <5F1BFDA0B9EC4CCFBC498B4F85CFB6D0@galvanox01>

Thank you everyone for the excellent suggestions!

I also decided lastnight that it couldn't be charge injection.  The glitches
are just too big and not really filterable.

I concur that it is probably an issue with the logic source.  Each
more-significant-bit comparator is feeding the threshold to the next
comparator, so there is probably a natural cascading effect in these bits.
I've also not used any positive feedback, and maybe this will speed up the
comparators a bit.  I also thought briefly at one point about using Gray
code, but didn't act on it.  It might not require a huge change to the
circuit... just a different approach to controlling the comparators.  Lots
to think about.  I am also veering towards the idea of using a DG407, as I
think having only one chip will help, as it did with the DG409.

I have a bit more experimenting to do with the circuit, but can't get to it
until later today -- doctor's appointment and department Christmas party
await.
 

> -----Original Message-----
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On 
> Behalf Of mskala at ansuz.sooke.bc.ca
> Sent: Tuesday, December 04, 2018 6:47 AM
> To: Steve Lenham
> Cc: synth-diy at synth-diy.org
> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> 
> On Tue, 4 Dec 2018, Steve Lenham wrote:
> > The ideal - though not always possible - way to eliminate these 
> > intermediate states is to make the system synchronous. You feed the 
> > asynchronous address lines to the inputs of a D-type latch, 
> then clock 
> > the latch at a point where
> 
> Another thing often done to reduce glitches in this sort of 
> situation is to use a Gray code.  Instead of using the 
> digital words in the sequence 000, 001, 010, 011, 100, 101, 
> 110, 111, where all of them can change between successive 
> values, one might use them in the sequence 000, 001, 011, 
> 010, 110, 111, 101, 100.  That way, only one bit changes 
> between successive words.  This is done for things like 
> absolute position encoders where you have a slow mechanical 
> system driving digital logic and you can't depend on both 
> bits changing at the same time when two change.
> 
> I don't really understand how the digital logic is being used 
> in David's design and I fear that trying to retrofit Gray 
> coding onto what he's currently got might require so much 
> change to the way the comparators are being used, as to be 
> impractical.  But it *is* a useful way to reduce glitches 
> when it's applicable.
> 
> --
> Matthew Skala
> mskala at ansuz.sooke.bc.ca                 People before tribes.
> http://ansuz.sooke.bc.ca/
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From dixon at mail.ubc.ca  Wed Dec  5 07:55:46 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Tue, 4 Dec 2018 22:55:46 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <3F170B8B7853401BAB5E5C0A754FEFF9@galvanox01>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
 <3F170B8B7853401BAB5E5C0A754FEFF9@galvanox01>
Message-ID: <5a9efad3-b5bb-4aba-a9f8-a9cdd33702cb@S-ITSV-HUB01P.ead.ubc.ca>

Hello SDIY Team,

Today, I thought deeply about the switching glitch problem, and I think I
concur with Steve Lenham.

The switching time of the DG408 is about 250ns.  The slew rate of TL074 is
about 13V/us, so it takes about 2us or 2000ns for the comparators to change
state.  Also, the thresholds cascade from one comparator to the next, so the
times are probably roughly additive.  Hence, it could take as long as 6000ns
for all three comparators to change state, and this is a veritable eternity
from the perspective of the DG408 -- about 24 switchings could occur during
that time.  Hence, when two or three comparators have to change state, the
switches blow through a bunch of different audio inputs, creating classic
audio pop.

So, I now believe that the best approach is to use Gray code to drive the
switches, so that only one bit ever has to change.  This consists of two
things: 1) changing the logic circuit to generate Gray code from the CV
signal, and 2) reconnecting the switch inputs to conform to Gray code.  The
second part is trivially easy.  The first part is not so easy.

However, I have discovered that 3-bit binary can be converted to 3-bit Gray
code fairly directly, since the 1st Gray and binary bits are equivalent, the
2nd Gray bit is the XOR of the 1st and 2nd binary bits, and the 3rd Gray bit
is the XOR of the 2nd and 3rd binary bits.  An analog XOR circuit like the
one on Ian Fritz's website (inspired by Electronotes) would fulfill the XOR
function from my existing 3-bit hack-job ADC.

However, I am going to rethink this entire logic and switching circuit,
because it is getting fairly complicated.  I believe that proper comparators
with pullup resistors to 5V would be better than the opamps with zener
diodes, and I'll figure out some other way to generate the threshold
voltages.  With proper logic levels, I'll probably just use proper logic
chips.

In any case, I need to stop thinking about this project for a little while
because I have other more pressing things to do, so I'll return to this in a
few days.



From tom at electricdruid.net  Wed Dec  5 09:38:54 2018
From: tom at electricdruid.net (Tom Wiltshire)
Date: Wed, 5 Dec 2018 08:38:54 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <5a9efad3-b5bb-4aba-a9f8-a9cdd33702cb@S-ITSV-HUB01P.ead.ubc.ca>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
 <3F170B8B7853401BAB5E5C0A754FEFF9@galvanox01>
 <5a9efad3-b5bb-4aba-a9f8-a9cdd33702cb@S-ITSV-HUB01P.ead.ubc.ca>
Message-ID: <4E096F56-6A93-4DE4-AE5B-E14D9999C598@electricdruid.net>

I have to say it - this really sounds like a job for $0.50 of microcontroller.

==================
       Electric Druid
Synth & Stompbox DIY
==================

> On 5 Dec 2018, at 06:55, David G Dixon <dixon at mail.ubc.ca> wrote:
> 
> Hello SDIY Team,
> 
> Today, I thought deeply about the switching glitch problem, and I think I
> concur with Steve Lenham.
> 
> The switching time of the DG408 is about 250ns.  The slew rate of TL074 is
> about 13V/us, so it takes about 2us or 2000ns for the comparators to change
> state.  Also, the thresholds cascade from one comparator to the next, so the
> times are probably roughly additive.  Hence, it could take as long as 6000ns
> for all three comparators to change state, and this is a veritable eternity
> from the perspective of the DG408 -- about 24 switchings could occur during
> that time.  Hence, when two or three comparators have to change state, the
> switches blow through a bunch of different audio inputs, creating classic
> audio pop.
> 
> So, I now believe that the best approach is to use Gray code to drive the
> switches, so that only one bit ever has to change.  This consists of two
> things: 1) changing the logic circuit to generate Gray code from the CV
> signal, and 2) reconnecting the switch inputs to conform to Gray code.  The
> second part is trivially easy.  The first part is not so easy.
> 
> However, I have discovered that 3-bit binary can be converted to 3-bit Gray
> code fairly directly, since the 1st Gray and binary bits are equivalent, the
> 2nd Gray bit is the XOR of the 1st and 2nd binary bits, and the 3rd Gray bit
> is the XOR of the 2nd and 3rd binary bits.  An analog XOR circuit like the
> one on Ian Fritz's website (inspired by Electronotes) would fulfill the XOR
> function from my existing 3-bit hack-job ADC.
> 
> However, I am going to rethink this entire logic and switching circuit,
> because it is getting fairly complicated.  I believe that proper comparators
> with pullup resistors to 5V would be better than the opamps with zener
> diodes, and I'll figure out some other way to generate the threshold
> voltages.  With proper logic levels, I'll probably just use proper logic
> chips.
> 
> In any case, I need to stop thinking about this project for a little while
> because I have other more pressing things to do, so I'll return to this in a
> few days.
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy




From indigoid at oldcorollas.org  Wed Dec  5 10:29:51 2018
From: indigoid at oldcorollas.org (john slee)
Date: Wed, 5 Dec 2018 20:29:51 +1100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <4E096F56-6A93-4DE4-AE5B-E14D9999C598@electricdruid.net>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
 <3F170B8B7853401BAB5E5C0A754FEFF9@galvanox01>
 <5a9efad3-b5bb-4aba-a9f8-a9cdd33702cb@S-ITSV-HUB01P.ead.ubc.ca>
 <4E096F56-6A93-4DE4-AE5B-E14D9999C598@electricdruid.net>
Message-ID: <CAK+JDy3HDBzFGH7dN=pTF2MVe2ggLWDPQy2NE9eKOD8+JEYFLg@mail.gmail.com>

Tom,

I was contemplating the same. However while browsing some AVR datasheets
I've not found a spec indicating any guarantees about what happens when you
write to a register representing multiple GPIO pins ? eg. the PORTA, PORTB,
et al "ports" in AVR land that each represent 8 pins. If the GPIO edges are
not synchronised to a reasonable degree, the same problems may well manifest

Though I suppose at 16Mhz, the DG408's 250ns transition time is
approximately four cycles. It should still be way ahead of TL07x

Speaking of TL07x... David wrote:

> The slew rate of TL074 is about 13V/us, so it takes about 2us or 2000ns
for the comparators to change state

The Vishay DG408 datasheet I'm reading[1] appears to indicate that you only
need to swing the "logic high" voltage to 2.8V, which should give a slew
time of around 215ns, if my math is right. You may be able to get slightly
faster again by using a value above 0V for "logic low", but that's pushing
a bit close to the Vishay specs. Nowhere near as fast as a microcontroller,
but a lot faster than a full-range swing.

[1] https://www.vishay.com/docs/70062/dg408.pdf

John

On Wed, 5 Dec 2018 at 19:39, Tom Wiltshire <tom at electricdruid.net> wrote:

> I have to say it - this really sounds like a job for $0.50 of
> microcontroller.
>
> ==================
>        Electric Druid
> Synth & Stompbox DIY
> ==================
>
> > On 5 Dec 2018, at 06:55, David G Dixon <dixon at mail.ubc.ca> wrote:
> >
> > Hello SDIY Team,
> >
> > Today, I thought deeply about the switching glitch problem, and I think I
> > concur with Steve Lenham.
> >
> > The switching time of the DG408 is about 250ns.  The slew rate of TL074
> is
> > about 13V/us, so it takes about 2us or 2000ns for the comparators to
> change
> > state.  Also, the thresholds cascade from one comparator to the next, so
> the
> > times are probably roughly additive.  Hence, it could take as long as
> 6000ns
> > for all three comparators to change state, and this is a veritable
> eternity
> > from the perspective of the DG408 -- about 24 switchings could occur
> during
> > that time.  Hence, when two or three comparators have to change state,
> the
> > switches blow through a bunch of different audio inputs, creating classic
> > audio pop.
> >
> > So, I now believe that the best approach is to use Gray code to drive the
> > switches, so that only one bit ever has to change.  This consists of two
> > things: 1) changing the logic circuit to generate Gray code from the CV
> > signal, and 2) reconnecting the switch inputs to conform to Gray code.
> The
> > second part is trivially easy.  The first part is not so easy.
> >
> > However, I have discovered that 3-bit binary can be converted to 3-bit
> Gray
> > code fairly directly, since the 1st Gray and binary bits are equivalent,
> the
> > 2nd Gray bit is the XOR of the 1st and 2nd binary bits, and the 3rd Gray
> bit
> > is the XOR of the 2nd and 3rd binary bits.  An analog XOR circuit like
> the
> > one on Ian Fritz's website (inspired by Electronotes) would fulfill the
> XOR
> > function from my existing 3-bit hack-job ADC.
> >
> > However, I am going to rethink this entire logic and switching circuit,
> > because it is getting fairly complicated.  I believe that proper
> comparators
> > with pullup resistors to 5V would be better than the opamps with zener
> > diodes, and I'll figure out some other way to generate the threshold
> > voltages.  With proper logic levels, I'll probably just use proper logic
> > chips.
> >
> > In any case, I need to stop thinking about this project for a little
> while
> > because I have other more pressing things to do, so I'll return to this
> in a
> > few days.
> >
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
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From indigoid at oldcorollas.org  Wed Dec  5 10:33:30 2018
From: indigoid at oldcorollas.org (john slee)
Date: Wed, 5 Dec 2018 20:33:30 +1100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <CAK+JDy3HDBzFGH7dN=pTF2MVe2ggLWDPQy2NE9eKOD8+JEYFLg@mail.gmail.com>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
 <3F170B8B7853401BAB5E5C0A754FEFF9@galvanox01>
 <5a9efad3-b5bb-4aba-a9f8-a9cdd33702cb@S-ITSV-HUB01P.ead.ubc.ca>
 <4E096F56-6A93-4DE4-AE5B-E14D9999C598@electricdruid.net>
 <CAK+JDy3HDBzFGH7dN=pTF2MVe2ggLWDPQy2NE9eKOD8+JEYFLg@mail.gmail.com>
Message-ID: <CAK+JDy3QP6_zeaR6ofRWdf0fhG91dNrBiZNF0TN4y4g-CF+wAQ@mail.gmail.com>

Ugh, ignore me, I neglected to check the rail specs for the TL074. Oopsie.
0-5V swing would take 384ns, definitely too slow

John

On Wed, 5 Dec 2018 at 20:29, john slee <indigoid at oldcorollas.org> wrote:

> Tom,
>
> I was contemplating the same. However while browsing some AVR datasheets
> I've not found a spec indicating any guarantees about what happens when you
> write to a register representing multiple GPIO pins ? eg. the PORTA, PORTB,
> et al "ports" in AVR land that each represent 8 pins. If the GPIO edges are
> not synchronised to a reasonable degree, the same problems may well manifest
>
> Though I suppose at 16Mhz, the DG408's 250ns transition time is
> approximately four cycles. It should still be way ahead of TL07x
>
> Speaking of TL07x... David wrote:
>
> > The slew rate of TL074 is about 13V/us, so it takes about 2us or 2000ns
> for the comparators to change state
>
> The Vishay DG408 datasheet I'm reading[1] appears to indicate that you
> only need to swing the "logic high" voltage to 2.8V, which should give a
> slew time of around 215ns, if my math is right. You may be able to get
> slightly faster again by using a value above 0V for "logic low", but that's
> pushing a bit close to the Vishay specs. Nowhere near as fast as a
> microcontroller, but a lot faster than a full-range swing.
>
> [1] https://www.vishay.com/docs/70062/dg408.pdf
>
> John
>
> On Wed, 5 Dec 2018 at 19:39, Tom Wiltshire <tom at electricdruid.net> wrote:
>
>> I have to say it - this really sounds like a job for $0.50 of
>> microcontroller.
>>
>> ==================
>>        Electric Druid
>> Synth & Stompbox DIY
>> ==================
>>
>> > On 5 Dec 2018, at 06:55, David G Dixon <dixon at mail.ubc.ca> wrote:
>> >
>> > Hello SDIY Team,
>> >
>> > Today, I thought deeply about the switching glitch problem, and I think
>> I
>> > concur with Steve Lenham.
>> >
>> > The switching time of the DG408 is about 250ns.  The slew rate of TL074
>> is
>> > about 13V/us, so it takes about 2us or 2000ns for the comparators to
>> change
>> > state.  Also, the thresholds cascade from one comparator to the next,
>> so the
>> > times are probably roughly additive.  Hence, it could take as long as
>> 6000ns
>> > for all three comparators to change state, and this is a veritable
>> eternity
>> > from the perspective of the DG408 -- about 24 switchings could occur
>> during
>> > that time.  Hence, when two or three comparators have to change state,
>> the
>> > switches blow through a bunch of different audio inputs, creating
>> classic
>> > audio pop.
>> >
>> > So, I now believe that the best approach is to use Gray code to drive
>> the
>> > switches, so that only one bit ever has to change.  This consists of two
>> > things: 1) changing the logic circuit to generate Gray code from the CV
>> > signal, and 2) reconnecting the switch inputs to conform to Gray code.
>> The
>> > second part is trivially easy.  The first part is not so easy.
>> >
>> > However, I have discovered that 3-bit binary can be converted to 3-bit
>> Gray
>> > code fairly directly, since the 1st Gray and binary bits are
>> equivalent, the
>> > 2nd Gray bit is the XOR of the 1st and 2nd binary bits, and the 3rd
>> Gray bit
>> > is the XOR of the 2nd and 3rd binary bits.  An analog XOR circuit like
>> the
>> > one on Ian Fritz's website (inspired by Electronotes) would fulfill the
>> XOR
>> > function from my existing 3-bit hack-job ADC.
>> >
>> > However, I am going to rethink this entire logic and switching circuit,
>> > because it is getting fairly complicated.  I believe that proper
>> comparators
>> > with pullup resistors to 5V would be better than the opamps with zener
>> > diodes, and I'll figure out some other way to generate the threshold
>> > voltages.  With proper logic levels, I'll probably just use proper logic
>> > chips.
>> >
>> > In any case, I need to stop thinking about this project for a little
>> while
>> > because I have other more pressing things to do, so I'll return to this
>> in a
>> > few days.
>> >
>> > _______________________________________________
>> > Synth-diy mailing list
>> > Synth-diy at synth-diy.org
>> > http://synth-diy.org/mailman/listinfo/synth-diy
>>
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>>
>
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From steve at bendentech.co.uk  Wed Dec  5 10:47:49 2018
From: steve at bendentech.co.uk (Steve Lenham)
Date: Wed, 5 Dec 2018 09:47:49 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <CAK+JDy3HDBzFGH7dN=pTF2MVe2ggLWDPQy2NE9eKOD8+JEYFLg@mail.gmail.com>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
 <3F170B8B7853401BAB5E5C0A754FEFF9@galvanox01>
 <5a9efad3-b5bb-4aba-a9f8-a9cdd33702cb@S-ITSV-HUB01P.ead.ubc.ca>
 <4E096F56-6A93-4DE4-AE5B-E14D9999C598@electricdruid.net>
 <CAK+JDy3HDBzFGH7dN=pTF2MVe2ggLWDPQy2NE9eKOD8+JEYFLg@mail.gmail.com>
Message-ID: <d271b18b-9f57-3949-789f-dd90d9786a09@bendentech.co.uk>

On 05/12/2018 09:29, john slee wrote:

> I was contemplating the same. However while browsing some AVR datasheets 
> I've not found a spec indicating any guarantees about what happens when 
> you write to a register representing multiple GPIO pins ? eg. the PORTA, 
> PORTB, et al "ports" in AVR land that each represent 8 pins. If the GPIO 
> edges are not synchronised to a reasonable degree, the same problems may 
> well manifest

Microcontroller GPIO ports are effectively an 8-bit D-type latch - the 
data is set up in one part of the instruction cycle then clocked through 
to the output by a single clock pulse. So multiple pins on the same port 
change state at exactly the same time.

Steve L.


From igg.debus at gmail.com  Wed Dec  5 12:51:41 2018
From: igg.debus at gmail.com (Ingo Debus)
Date: Wed, 5 Dec 2018 12:51:41 +0100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <5a9efad3-b5bb-4aba-a9f8-a9cdd33702cb@S-ITSV-HUB01P.ead.ubc.ca>
References: <AM6PR03MB35282138F0D6CA3E91600CA694AF0@AM6PR03MB3528.eurprd03.prod.outlook.com>
 <3F170B8B7853401BAB5E5C0A754FEFF9@galvanox01>
 <5a9efad3-b5bb-4aba-a9f8-a9cdd33702cb@S-ITSV-HUB01P.ead.ubc.ca>
Message-ID: <E5F53C40-BC76-486F-AC63-42CEECC28012@gmail.com>


> Am 05.12.2018 um 07:55 schrieb David G Dixon <dixon at mail.ubc.ca>:
> 
> However, I have discovered that 3-bit binary can be converted to 3-bit Gray
> code fairly directly, since the 1st Gray and binary bits are equivalent, the
> 2nd Gray bit is the XOR of the 1st and 2nd binary bits, and the 3rd Gray bit
> is the XOR of the 2nd and 3rd binary bits.

Would that really help? I mean, if the binary output of your ADC goes through a ?forbidden? state while switching from one state to another, the Gray code will do so as well, no?

Ingo


From steve at bendentech.co.uk  Wed Dec  5 13:05:21 2018
From: steve at bendentech.co.uk (Steve Lenham)
Date: Wed, 5 Dec 2018 12:05:21 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
Message-ID: <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>

On 05/12/2018 06:55, David G Dixon wrote:

> Today, I thought deeply about the switching glitch problem, and I think I
> concur with Steve Lenham.

Go me! ;-)

<snip>
> 
> So, I now believe that the best approach is to use Gray code to drive the
> switches, so that only one bit ever has to change.  This consists of two
> things: 1) changing the logic circuit to generate Gray code from the CV
> signal, and 2) reconnecting the switch inputs to conform to Gray code.  The
> second part is trivially easy.  The first part is not so easy.
> 
> However, I have discovered that 3-bit binary can be converted to 3-bit Gray
> code fairly directly, since the 1st Gray and binary bits are equivalent, the
> 2nd Gray bit is the XOR of the 1st and 2nd binary bits, and the 3rd Gray bit
> is the XOR of the 2nd and 3rd binary bits.  An analog XOR circuit like the
> one on Ian Fritz's website (inspired by Electronotes) would fulfill the XOR
> function from my existing 3-bit hack-job ADC.

Gray code will not help you unless you can generate it directly.

Taking a binary address that passes through multiple transitional states 
and converting it to Gray code will give you a Gray code sequence that 
does exactly the same.

If your binary address is supposed to be changing from 1 to 2, but also 
temporarily passes through 3, then passing this value through a Gray 
encoder will simply give you an address that goes from the Gray code for 
1 (001) to the Gray code for 2 (011) but also temporarily passing 
through the Gray code for 3 (010). Nothing will have been gained.

Also, Gray code is only beneficial when the encoded value is guaranteed 
to only increment or decrement by one unit at a time (for example in 
rotary encoders). Otherwise, the statement that "only one bit of a Gray 
code value changes at a time" does not hold!

The Gray code values corresponding to decimal 0-7 are:

000, 001, 011, 010, 110, 111, 101, 100

Clearly a change in the value greater than one often involves changing 
more than one bit of the Gray code.

> However, I am going to rethink this entire logic and switching circuit,
> because it is getting fairly complicated.  I believe that proper comparators
> with pullup resistors to 5V would be better than the opamps with zener
> diodes, and I'll figure out some other way to generate the threshold
> voltages.  With proper logic levels, I'll probably just use proper logic
> chips.

I can't help agreeing with Tom in that one of the 8-pin PICs with an 
onboard ADC would kill the problem stone dead very inexpensively, but I 
appreciate that not everyone has the facilities/experience/inclination 
to take that approach.

As an alternative I would offer the following:

- Generate a clock signal at a fairly high frequency.
- Use the rising edge of that clock to trigger a sample-and-hold circuit 
(could be just a CMOS analogue switch).
- Feed the sampled signal to your comparators.
- Take the comparator outputs to a D-type latch.
- Clock the latch with the falling edge of your sample clock.
- Control your analogue multiplexer with the outputs of the latch.

That is effectively what the PIC would be doing, just in discrete form. 
The comparators then have half the clock period to settle to their final 
values.

Good luck!

Steve L.
Benden Sound Technology





From modular at go2.pl  Wed Dec  5 13:58:28 2018
From: modular at go2.pl (Roman Sowa)
Date: Wed, 5 Dec 2018 13:58:28 +0100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
Message-ID: <8133648f-3f80-a69f-df2e-35ebffa1a6cc@go2.pl>

Why not simply LM3914 and 4066?

Roman

W dniu 2018-12-05 o?13:05, Steve Lenham pisze:
> On 05/12/2018 06:55, David G Dixon wrote:
> 
>> Today, I thought deeply about the switching glitch problem, and I think I
>> concur with Steve Lenham.
> 
> Go me! ;-)
> 
> <snip>
>>
>> So, I now believe that the best approach is to use Gray code to drive the
>> switches, so that only one bit ever has to change.? This consists of two
>> things: 1) changing the logic circuit to generate Gray code from the CV
>> signal, and 2) reconnecting the switch inputs to conform to Gray 
>> code.? The
>> second part is trivially easy.? The first part is not so easy.
>>
>> However, I have discovered that 3-bit binary can be converted to 3-bit 
>> Gray
>> code fairly directly, since the 1st Gray and binary bits are 
>> equivalent, the
>> 2nd Gray bit is the XOR of the 1st and 2nd binary bits, and the 3rd 
>> Gray bit
>> is the XOR of the 2nd and 3rd binary bits.? An analog XOR circuit like 
>> the
>> one on Ian Fritz's website (inspired by Electronotes) would fulfill 
>> the XOR
>> function from my existing 3-bit hack-job ADC.
> 
> Gray code will not help you unless you can generate it directly.
> 
> Taking a binary address that passes through multiple transitional states 
> and converting it to Gray code will give you a Gray code sequence that 
> does exactly the same.
> 
> If your binary address is supposed to be changing from 1 to 2, but also 
> temporarily passes through 3, then passing this value through a Gray 
> encoder will simply give you an address that goes from the Gray code for 
> 1 (001) to the Gray code for 2 (011) but also temporarily passing 
> through the Gray code for 3 (010). Nothing will have been gained.
> 
> Also, Gray code is only beneficial when the encoded value is guaranteed 
> to only increment or decrement by one unit at a time (for example in 
> rotary encoders). Otherwise, the statement that "only one bit of a Gray 
> code value changes at a time" does not hold!
> 
> The Gray code values corresponding to decimal 0-7 are:
> 
> 000, 001, 011, 010, 110, 111, 101, 100
> 
> Clearly a change in the value greater than one often involves changing 
> more than one bit of the Gray code.
> 
>> However, I am going to rethink this entire logic and switching circuit,
>> because it is getting fairly complicated.? I believe that proper 
>> comparators
>> with pullup resistors to 5V would be better than the opamps with zener
>> diodes, and I'll figure out some other way to generate the threshold
>> voltages.? With proper logic levels, I'll probably just use proper logic
>> chips.
> 
> I can't help agreeing with Tom in that one of the 8-pin PICs with an 
> onboard ADC would kill the problem stone dead very inexpensively, but I 
> appreciate that not everyone has the facilities/experience/inclination 
> to take that approach.
> 
> As an alternative I would offer the following:
> 
> - Generate a clock signal at a fairly high frequency.
> - Use the rising edge of that clock to trigger a sample-and-hold circuit 
> (could be just a CMOS analogue switch).
> - Feed the sampled signal to your comparators.
> - Take the comparator outputs to a D-type latch.
> - Clock the latch with the falling edge of your sample clock.
> - Control your analogue multiplexer with the outputs of the latch.
> 
> That is effectively what the PIC would be doing, just in discrete form. 
> The comparators then have half the clock period to settle to their final 
> values.
> 
> Good luck!
> 
> Steve L.
> Benden Sound Technology
> 
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> 


From rburnett at richieburnett.co.uk  Wed Dec  5 14:28:12 2018
From: rburnett at richieburnett.co.uk (rburnett at richieburnett.co.uk)
Date: Wed, 05 Dec 2018 13:28:12 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
Message-ID: <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>

It's perhaps also worth pointing out that if you put a low-cost micro in 
there (as Tom suggested) you then have the opportunity to build in some 
"rules".

You can add in conditional statements that don't allow values to jump to 
invalid states in a sequence, or suppress brief new states until they 
have persisted for some duration.  Add hysteresis to comparator 
thresholds, etc. etc.  All done in software, without even having to heat 
up your soldering iron!  ;-)

-Richie,



On 2018-12-05 12:05, Steve Lenham wrote:
> On 05/12/2018 06:55, David G Dixon wrote:
> 
>> Today, I thought deeply about the switching glitch problem, and I 
>> think I
>> concur with Steve Lenham.
> 
> Go me! ;-)
> 
> <snip>
>> 
>> So, I now believe that the best approach is to use Gray code to drive 
>> the
>> switches, so that only one bit ever has to change.  This consists of 
>> two
>> things: 1) changing the logic circuit to generate Gray code from the 
>> CV
>> signal, and 2) reconnecting the switch inputs to conform to Gray code. 
>>  The
>> second part is trivially easy.  The first part is not so easy.
>> 
>> However, I have discovered that 3-bit binary can be converted to 3-bit 
>> Gray
>> code fairly directly, since the 1st Gray and binary bits are 
>> equivalent, the
>> 2nd Gray bit is the XOR of the 1st and 2nd binary bits, and the 3rd 
>> Gray bit
>> is the XOR of the 2nd and 3rd binary bits.  An analog XOR circuit like 
>> the
>> one on Ian Fritz's website (inspired by Electronotes) would fulfill 
>> the XOR
>> function from my existing 3-bit hack-job ADC.
> 
> Gray code will not help you unless you can generate it directly.
> 
> Taking a binary address that passes through multiple transitional
> states and converting it to Gray code will give you a Gray code
> sequence that does exactly the same.
> 
> If your binary address is supposed to be changing from 1 to 2, but
> also temporarily passes through 3, then passing this value through a
> Gray encoder will simply give you an address that goes from the Gray
> code for 1 (001) to the Gray code for 2 (011) but also temporarily
> passing through the Gray code for 3 (010). Nothing will have been
> gained.
> 
> Also, Gray code is only beneficial when the encoded value is
> guaranteed to only increment or decrement by one unit at a time (for
> example in rotary encoders). Otherwise, the statement that "only one
> bit of a Gray code value changes at a time" does not hold!
> 
> The Gray code values corresponding to decimal 0-7 are:
> 
> 000, 001, 011, 010, 110, 111, 101, 100
> 
> Clearly a change in the value greater than one often involves changing
> more than one bit of the Gray code.
> 
>> However, I am going to rethink this entire logic and switching 
>> circuit,
>> because it is getting fairly complicated.  I believe that proper 
>> comparators
>> with pullup resistors to 5V would be better than the opamps with zener
>> diodes, and I'll figure out some other way to generate the threshold
>> voltages.  With proper logic levels, I'll probably just use proper 
>> logic
>> chips.
> 
> I can't help agreeing with Tom in that one of the 8-pin PICs with an
> onboard ADC would kill the problem stone dead very inexpensively, but
> I appreciate that not everyone has the
> facilities/experience/inclination to take that approach.
> 
> As an alternative I would offer the following:
> 
> - Generate a clock signal at a fairly high frequency.
> - Use the rising edge of that clock to trigger a sample-and-hold
> circuit (could be just a CMOS analogue switch).
> - Feed the sampled signal to your comparators.
> - Take the comparator outputs to a D-type latch.
> - Clock the latch with the falling edge of your sample clock.
> - Control your analogue multiplexer with the outputs of the latch.
> 
> That is effectively what the PIC would be doing, just in discrete
> form. The comparators then have half the clock period to settle to
> their final values.
> 
> Good luck!
> 
> Steve L.
> Benden Sound Technology
> 
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy


From dixon at mail.ubc.ca  Wed Dec  5 18:30:00 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Wed, 5 Dec 2018 09:30:00 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
Message-ID: <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>

I don't know how to use microcontrollers, and I'm not going to learn on this
project.  I have been meaning to learn about them, but I'm afraid that will
have to wait until I retire.  It has to be something discrete.

What about the LM3914 (as Roman suggested), or even two LM339s arranged into
a flash cascade, into an 8-to-3 encoder such as MC14532?  Would this give a
clean enough binary output for controlling DG408?  I actually have those on
hand, so could try.  The delay times of the MC14532 seem to be in the right
ballpark, and only one bit in (of the 8) would ever be changing at any time.

I'm not quite sure about Roman's suggestion of 4066.  4097 would be more
appropriate, but this has the wrong voltage range, and is no slower than
DG408.
 

> -----Original Message-----
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On 
> Behalf Of rburnett at richieburnett.co.uk
> Sent: Wednesday, December 05, 2018 5:28 AM
> To: synth-diy at synth-diy.org DIY
> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> 
> It's perhaps also worth pointing out that if you put a 
> low-cost micro in there (as Tom suggested) you then have the 
> opportunity to build in some "rules".
> 
> You can add in conditional statements that don't allow values 
> to jump to invalid states in a sequence, or suppress brief 
> new states until they have persisted for some duration.  Add 
> hysteresis to comparator thresholds, etc. etc.  All done in 
> software, without even having to heat up your soldering iron!  ;-)
> 
> -Richie,
> 
> 
> 
> On 2018-12-05 12:05, Steve Lenham wrote:
> > On 05/12/2018 06:55, David G Dixon wrote:
> > 
> >> Today, I thought deeply about the switching glitch problem, and I 
> >> think I concur with Steve Lenham.
> > 
> > Go me! ;-)
> > 
> > <snip>
> >> 
> >> So, I now believe that the best approach is to use Gray 
> code to drive 
> >> the switches, so that only one bit ever has to change.  
> This consists 
> >> of two
> >> things: 1) changing the logic circuit to generate Gray 
> code from the 
> >> CV signal, and 2) reconnecting the switch inputs to 
> conform to Gray 
> >> code.
> >>  The
> >> second part is trivially easy.  The first part is not so easy.
> >> 
> >> However, I have discovered that 3-bit binary can be converted to 
> >> 3-bit Gray code fairly directly, since the 1st Gray and 
> binary bits 
> >> are equivalent, the 2nd Gray bit is the XOR of the 1st and 
> 2nd binary 
> >> bits, and the 3rd Gray bit is the XOR of the 2nd and 3rd 
> binary bits.  
> >> An analog XOR circuit like the one on Ian Fritz's website 
> (inspired 
> >> by Electronotes) would fulfill the XOR function from my existing 
> >> 3-bit hack-job ADC.
> > 
> > Gray code will not help you unless you can generate it directly.
> > 
> > Taking a binary address that passes through multiple transitional 
> > states and converting it to Gray code will give you a Gray code 
> > sequence that does exactly the same.
> > 
> > If your binary address is supposed to be changing from 1 to 2, but 
> > also temporarily passes through 3, then passing this value 
> through a 
> > Gray encoder will simply give you an address that goes from 
> the Gray 
> > code for 1 (001) to the Gray code for 2 (011) but also temporarily 
> > passing through the Gray code for 3 (010). Nothing will have been 
> > gained.
> > 
> > Also, Gray code is only beneficial when the encoded value is 
> > guaranteed to only increment or decrement by one unit at a 
> time (for 
> > example in rotary encoders). Otherwise, the statement that 
> "only one 
> > bit of a Gray code value changes at a time" does not hold!
> > 
> > The Gray code values corresponding to decimal 0-7 are:
> > 
> > 000, 001, 011, 010, 110, 111, 101, 100
> > 
> > Clearly a change in the value greater than one often 
> involves changing 
> > more than one bit of the Gray code.
> > 
> >> However, I am going to rethink this entire logic and switching 
> >> circuit, because it is getting fairly complicated.  I believe that 
> >> proper comparators with pullup resistors to 5V would be 
> better than 
> >> the opamps with zener diodes, and I'll figure out some 
> other way to 
> >> generate the threshold voltages.  With proper logic levels, I'll 
> >> probably just use proper logic chips.
> > 
> > I can't help agreeing with Tom in that one of the 8-pin 
> PICs with an 
> > onboard ADC would kill the problem stone dead very 
> inexpensively, but 
> > I appreciate that not everyone has the 
> > facilities/experience/inclination to take that approach.
> > 
> > As an alternative I would offer the following:
> > 
> > - Generate a clock signal at a fairly high frequency.
> > - Use the rising edge of that clock to trigger a sample-and-hold 
> > circuit (could be just a CMOS analogue switch).
> > - Feed the sampled signal to your comparators.
> > - Take the comparator outputs to a D-type latch.
> > - Clock the latch with the falling edge of your sample clock.
> > - Control your analogue multiplexer with the outputs of the latch.
> > 
> > That is effectively what the PIC would be doing, just in discrete 
> > form. The comparators then have half the clock period to settle to 
> > their final values.
> > 
> > Good luck!
> > 
> > Steve L.
> > Benden Sound Technology
> > 
> > 
> > 
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From barryklein at cox.net  Wed Dec  5 19:13:17 2018
From: barryklein at cox.net (Barry Klein)
Date: Wed, 5 Dec 2018 10:13:17 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>
Message-ID: <850AE1D3-8B94-4030-977F-C2E987E9D976@cox.net>

Lm3914 is in last time buy status, although thousands available for sale.
Is there a block diagram of this circuit?  I?d like to better understand what you want this module to do.

Barry

> On Dec 5, 2018, at 9:30 AM, David G Dixon <dixon at mail.ubc.ca> wrote:
> 
> I don't know how to use microcontrollers, and I'm not going to learn on this
> project.  I have been meaning to learn about them, but I'm afraid that will
> have to wait until I retire.  It has to be something discrete.
> 
> What about the LM3914 (as Roman suggested), or even two LM339s arranged into
> a flash cascade, into an 8-to-3 encoder such as MC14532?  Would this give a
> clean enough binary output for controlling DG408?  I actually have those on
> hand, so could try.  The delay times of the MC14532 seem to be in the right
> ballpark, and only one bit in (of the 8) would ever be changing at any time.
> 
> I'm not quite sure about Roman's suggestion of 4066.  4097 would be more
> appropriate, but this has the wrong voltage range, and is no slower than
> DG408.
> 
> 
>> -----Original Message-----
>> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On 
>> Behalf Of rburnett at richieburnett.co.uk
>> Sent: Wednesday, December 05, 2018 5:28 AM
>> To: synth-diy at synth-diy.org DIY
>> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
>> 
>> It's perhaps also worth pointing out that if you put a 
>> low-cost micro in there (as Tom suggested) you then have the 
>> opportunity to build in some "rules".
>> 
>> You can add in conditional statements that don't allow values 
>> to jump to invalid states in a sequence, or suppress brief 
>> new states until they have persisted for some duration.  Add 
>> hysteresis to comparator thresholds, etc. etc.  All done in 
>> software, without even having to heat up your soldering iron!  ;-)
>> 
>> -Richie,
>> 
>> 
>> 
>>> On 2018-12-05 12:05, Steve Lenham wrote:
>>>> On 05/12/2018 06:55, David G Dixon wrote:
>>>> 
>>>> Today, I thought deeply about the switching glitch problem, and I 
>>>> think I concur with Steve Lenham.
>>> 
>>> Go me! ;-)
>>> 
>>> <snip>
>>>> 
>>>> So, I now believe that the best approach is to use Gray 
>> code to drive 
>>>> the switches, so that only one bit ever has to change.  
>> This consists 
>>>> of two
>>>> things: 1) changing the logic circuit to generate Gray 
>> code from the 
>>>> CV signal, and 2) reconnecting the switch inputs to 
>> conform to Gray 
>>>> code.
>>>> The
>>>> second part is trivially easy.  The first part is not so easy.
>>>> 
>>>> However, I have discovered that 3-bit binary can be converted to 
>>>> 3-bit Gray code fairly directly, since the 1st Gray and 
>> binary bits 
>>>> are equivalent, the 2nd Gray bit is the XOR of the 1st and 
>> 2nd binary 
>>>> bits, and the 3rd Gray bit is the XOR of the 2nd and 3rd 
>> binary bits.  
>>>> An analog XOR circuit like the one on Ian Fritz's website 
>> (inspired 
>>>> by Electronotes) would fulfill the XOR function from my existing 
>>>> 3-bit hack-job ADC.
>>> 
>>> Gray code will not help you unless you can generate it directly.
>>> 
>>> Taking a binary address that passes through multiple transitional 
>>> states and converting it to Gray code will give you a Gray code 
>>> sequence that does exactly the same.
>>> 
>>> If your binary address is supposed to be changing from 1 to 2, but 
>>> also temporarily passes through 3, then passing this value 
>> through a 
>>> Gray encoder will simply give you an address that goes from 
>> the Gray 
>>> code for 1 (001) to the Gray code for 2 (011) but also temporarily 
>>> passing through the Gray code for 3 (010). Nothing will have been 
>>> gained.
>>> 
>>> Also, Gray code is only beneficial when the encoded value is 
>>> guaranteed to only increment or decrement by one unit at a 
>> time (for 
>>> example in rotary encoders). Otherwise, the statement that 
>> "only one 
>>> bit of a Gray code value changes at a time" does not hold!
>>> 
>>> The Gray code values corresponding to decimal 0-7 are:
>>> 
>>> 000, 001, 011, 010, 110, 111, 101, 100
>>> 
>>> Clearly a change in the value greater than one often 
>> involves changing 
>>> more than one bit of the Gray code.
>>> 
>>>> However, I am going to rethink this entire logic and switching 
>>>> circuit, because it is getting fairly complicated.  I believe that 
>>>> proper comparators with pullup resistors to 5V would be 
>> better than 
>>>> the opamps with zener diodes, and I'll figure out some 
>> other way to 
>>>> generate the threshold voltages.  With proper logic levels, I'll 
>>>> probably just use proper logic chips.
>>> 
>>> I can't help agreeing with Tom in that one of the 8-pin 
>> PICs with an 
>>> onboard ADC would kill the problem stone dead very 
>> inexpensively, but 
>>> I appreciate that not everyone has the 
>>> facilities/experience/inclination to take that approach.
>>> 
>>> As an alternative I would offer the following:
>>> 
>>> - Generate a clock signal at a fairly high frequency.
>>> - Use the rising edge of that clock to trigger a sample-and-hold 
>>> circuit (could be just a CMOS analogue switch).
>>> - Feed the sampled signal to your comparators.
>>> - Take the comparator outputs to a D-type latch.
>>> - Clock the latch with the falling edge of your sample clock.
>>> - Control your analogue multiplexer with the outputs of the latch.
>>> 
>>> That is effectively what the PIC would be doing, just in discrete 
>>> form. The comparators then have half the clock period to settle to 
>>> their final values.
>>> 
>>> Good luck!
>>> 
>>> Steve L.
>>> Benden Sound Technology
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy




From dixon at mail.ubc.ca  Wed Dec  5 19:33:15 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Wed, 5 Dec 2018 10:33:15 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <850AE1D3-8B94-4030-977F-C2E987E9D976@cox.net>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>
 <850AE1D3-8B94-4030-977F-C2E987E9D976@cox.net>
Message-ID: <A55D33440A004521B3A6013AF73F9D83@galvanox01>

> Lm3914 is in last time buy status, although thousands 
> available for sale.
> Is there a block diagram of this circuit?  I'd like to better 
> understand what you want this module to do.


OK, I've figured out what I'm going to try next.  Forget LM3914.  I'm simply
going to use two LM339 quad comparators.  I'm going to convert my -5V to +5V
CV to a 0 to 5V CV (one opamp), then create a seven-comparator flash cascade
driven between 0 and 5V to generate the input to a CD4532 8-to-3 bit
priority encoder.  All logic levels will be between 0 and 5V, so there will
be no problems with CMOS input level incompatibility.  The CD4532 will drive
the DG408 chips.

I'm thinking that this will work well because the comparator cascade will
give me very clean signals that will only change one-at-a-time, so at most
the 4532 will only ever toggle between two states.  The delay between
successive output bits of the 4532 firing should be well within the time it
takes for the DG408 to switch, so not using Gray code should not be an
issue.

If this doesn't provide suitable logic inputs to those multiplexers, then
I'm going to set my workbench on fire and take up basket weaving.



From dixon at mail.ubc.ca  Thu Dec  6 09:55:25 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Thu, 6 Dec 2018 00:55:25 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <A55D33440A004521B3A6013AF73F9D83@galvanox01>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>
 <850AE1D3-8B94-4030-977F-C2E987E9D976@cox.net>
 <A55D33440A004521B3A6013AF73F9D83@galvanox01>
Message-ID: <2AFA990289864B28925397E2BF7D64C8@galvanox01>

Today I designed a new version of my scanner circuit which uses a
7-comparator cascade from two LM339s to a CD4532 8-to-3 bit priority encoder
to form a 3-bit flash ADC.  The output of the 4532 drives the two DG408
switches.  I am confident that this will work well and be more or less
switching-noise free.  The speed of the comparators is completely irrelevant
in this case, as only one is ever changing at any given time.  The only
thing that matters is that the 3 output bits of the 4532 must be reasonably
synchronous, and there is no reason to believe otherwise, since they all
share more or less the same gate structure.  I don't fully understand the
propogation delay specs in the CD4532 datasheet, but I have to assume that
they relate to the time it takes to change the output code when a change is
exerted at the data pins, and not any delay between successive bits turning
on or off.  In any case, the proof will be in the pudding, as they say.
I've laid out a new board, but I won't get a chance to build and test it
until Friday, so y'all will just have to think about something else between
now and then.

Nighty-night!



From modular at go2.pl  Thu Dec  6 15:00:55 2018
From: modular at go2.pl (Roman Sowa)
Date: Thu, 6 Dec 2018 15:00:55 +0100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>
Message-ID: <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>

By "4066" I meant general idea that you can control 8 switches directly 
from 3914 outputs. In case if explicitly 4066 that needs also logic 
inverters, but if you use DG444 instead, they are not needed.

Why bother encoding 8 inputs into 3 address and then decoding that back 
in a mux since 3914 gives you all what's needed for an input scanner.

Roman

W dniu 2018-12-05 o?18:30, David G Dixon pisze:
> I don't know how to use microcontrollers, and I'm not going to learn on this
> project.  I have been meaning to learn about them, but I'm afraid that will
> have to wait until I retire.  It has to be something discrete.
> 
> What about the LM3914 (as Roman suggested), or even two LM339s arranged into
> a flash cascade, into an 8-to-3 encoder such as MC14532?  Would this give a
> clean enough binary output for controlling DG408?  I actually have those on
> hand, so could try.  The delay times of the MC14532 seem to be in the right
> ballpark, and only one bit in (of the 8) would ever be changing at any time.
> 
> I'm not quite sure about Roman's suggestion of 4066.  4097 would be more
> appropriate, but this has the wrong voltage range, and is no slower than
> DG408.
>   
> 
>> -----Original Message-----
>> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On
>> Behalf Of rburnett at richieburnett.co.uk
>> Sent: Wednesday, December 05, 2018 5:28 AM
>> To: synth-diy at synth-diy.org DIY
>> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
>>
>> It's perhaps also worth pointing out that if you put a
>> low-cost micro in there (as Tom suggested) you then have the
>> opportunity to build in some "rules".
>>
>> You can add in conditional statements that don't allow values
>> to jump to invalid states in a sequence, or suppress brief
>> new states until they have persisted for some duration.  Add
>> hysteresis to comparator thresholds, etc. etc.  All done in
>> software, without even having to heat up your soldering iron!  ;-)
>>
>> -Richie,
>>
>>
>>
>> On 2018-12-05 12:05, Steve Lenham wrote:
>>> On 05/12/2018 06:55, David G Dixon wrote:
>>>
>>>> Today, I thought deeply about the switching glitch problem, and I
>>>> think I concur with Steve Lenham.
>>>
>>> Go me! ;-)
>>>
>>> <snip>
>>>>
>>>> So, I now believe that the best approach is to use Gray
>> code to drive
>>>> the switches, so that only one bit ever has to change.
>> This consists
>>>> of two
>>>> things: 1) changing the logic circuit to generate Gray
>> code from the
>>>> CV signal, and 2) reconnecting the switch inputs to
>> conform to Gray
>>>> code.
>>>>   The
>>>> second part is trivially easy.  The first part is not so easy.
>>>>
>>>> However, I have discovered that 3-bit binary can be converted to
>>>> 3-bit Gray code fairly directly, since the 1st Gray and
>> binary bits
>>>> are equivalent, the 2nd Gray bit is the XOR of the 1st and
>> 2nd binary
>>>> bits, and the 3rd Gray bit is the XOR of the 2nd and 3rd
>> binary bits.
>>>> An analog XOR circuit like the one on Ian Fritz's website
>> (inspired
>>>> by Electronotes) would fulfill the XOR function from my existing
>>>> 3-bit hack-job ADC.
>>>
>>> Gray code will not help you unless you can generate it directly.
>>>
>>> Taking a binary address that passes through multiple transitional
>>> states and converting it to Gray code will give you a Gray code
>>> sequence that does exactly the same.
>>>
>>> If your binary address is supposed to be changing from 1 to 2, but
>>> also temporarily passes through 3, then passing this value
>> through a
>>> Gray encoder will simply give you an address that goes from
>> the Gray
>>> code for 1 (001) to the Gray code for 2 (011) but also temporarily
>>> passing through the Gray code for 3 (010). Nothing will have been
>>> gained.
>>>
>>> Also, Gray code is only beneficial when the encoded value is
>>> guaranteed to only increment or decrement by one unit at a
>> time (for
>>> example in rotary encoders). Otherwise, the statement that
>> "only one
>>> bit of a Gray code value changes at a time" does not hold!
>>>
>>> The Gray code values corresponding to decimal 0-7 are:
>>>
>>> 000, 001, 011, 010, 110, 111, 101, 100
>>>
>>> Clearly a change in the value greater than one often
>> involves changing
>>> more than one bit of the Gray code.
>>>
>>>> However, I am going to rethink this entire logic and switching
>>>> circuit, because it is getting fairly complicated.  I believe that
>>>> proper comparators with pullup resistors to 5V would be
>> better than
>>>> the opamps with zener diodes, and I'll figure out some
>> other way to
>>>> generate the threshold voltages.  With proper logic levels, I'll
>>>> probably just use proper logic chips.
>>>
>>> I can't help agreeing with Tom in that one of the 8-pin
>> PICs with an
>>> onboard ADC would kill the problem stone dead very
>> inexpensively, but
>>> I appreciate that not everyone has the
>>> facilities/experience/inclination to take that approach.
>>>
>>> As an alternative I would offer the following:
>>>
>>> - Generate a clock signal at a fairly high frequency.
>>> - Use the rising edge of that clock to trigger a sample-and-hold
>>> circuit (could be just a CMOS analogue switch).
>>> - Feed the sampled signal to your comparators.
>>> - Take the comparator outputs to a D-type latch.
>>> - Clock the latch with the falling edge of your sample clock.
>>> - Control your analogue multiplexer with the outputs of the latch.
>>>
>>> That is effectively what the PIC would be doing, just in discrete
>>> form. The comparators then have half the clock period to settle to
>>> their final values.
>>>
>>> Good luck!
>>>
>>> Steve L.
>>> Benden Sound Technology
>>>
>>>
>>>
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> 


From dixon at mail.ubc.ca  Thu Dec  6 19:01:41 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Thu, 6 Dec 2018 10:01:41 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
Message-ID: <46480845C1D149C4BC4B869921C52F57@galvanox01>

> Why bother encoding 8 inputs into 3 address and then decoding 
> that back in a mux since 3914 gives you all what's needed for 
> an input scanner.

1) The 3914 is set up to drive LEDs, and I didn't want to have to figure out
how to use it to generate logic levels.  I found the datasheet to be
somewhat cryptic in that regard.  It's probably easy to do (with one
resistor per comparator), but I just couldn't be bothered learning how.

2) The 3914 has 10 comparators, and I only want 7 (or 8, but the lowest one
is always on), so I was going to have to figure out how to alter the voltage
range into the chip so that 5V fell exactly between the 8th and 9th
comparators.  Again, it's forcing a chip to do something that it wasn't
really designed to do.  The only part of that chip I wanted was the
comparators, and so why not just use comparators?  Also, with the 7
comparators, the voltage range I need is exactly given by my 5V reference
and 8 1% 10k resistors, so I know it will be accurate.

3) The 3914 is already obsolete.

4) The 3914 generates the equivalent of reverse logic (because the
comparators suck current when on), which would require interfacing with the
'148, which also generates reverse logic, but the DG408 requires positive
logic.  One is just the other in the wrong direction, but I didn't want to
deal with that.  Hence, I preferred to use the 4532, which accepts and
generates positive logic.  The 4532 is nicely driven by comparators.

5) The "mux" here is a pair of 8-channel analog switches which are
processing audio signals.  I'm not decoding the 3-bit code.  I'm using it to
drive those switches.




From modular at go2.pl  Fri Dec  7 14:53:20 2018
From: modular at go2.pl (Roman Sowa)
Date: Fri, 7 Dec 2018 14:53:20 +0100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <46480845C1D149C4BC4B869921C52F57@galvanox01>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845C1D149C4BC4B869921C52F57@galvanox01>
Message-ID: <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>

Before it turns into pointless flame war, let me say "I quit". I'm not 
here to tell anybody how to make things. Just wanted to express my 
admiration for simplicity of 3914 with SPST.

But since you took the time to nicely comment in such detail, it would 
be rude to leave this unanswered. So inline then...

> 1) The 3914 is set up to drive LEDs, and I didn't want to have to figure out
> how to use it to generate logic levels.  I found the datasheet to be
> somewhat cryptic in that regard.  It's probably easy to do (with one
> resistor per comparator), but I just couldn't be bothered learning how.

That's open collector outputs. No magic in there.

> 
> 2) The 3914 has 10 comparators, and I only want 7 (or 8, but the lowest one
> is always on), so I was going to have to figure out how to alter the voltage
> range into the chip so that 5V fell exactly between the 8th and 9th

Scale the input voltage accordingly. You scale it somehow already, so 
just change resistor values.

> comparators.  Again, it's forcing a chip to do something that it wasn't
> really designed to do.  The only part of that chip I wanted was the
> comparators, and so why not just use comparators?  Also, with the 7
> comparators, the voltage range I need is exactly given by my 5V reference
> and 8 1% 10k resistors, so I know it will be accurate.

Luckily, 3914 also contains voltage reference!
And I would never expect to hear "the chip wasn't designed for it" from 
someone using VCA as VCO core ;)

> 
> 3) The 3914 is already obsolete.

Is it going to be produced in thousands over span of several years? I 
think you mentioned it's one-off custom job. Still plenty of 3914 around.

> 
> 4) The 3914 generates the equivalent of reverse logic (because the
> comparators suck current when on), which would require interfacing with the
> '148, which also generates reverse logic, but the DG408 requires positive
> logic.

That's why I mentioned DG444

> 5) The "mux" here is a pair of 8-channel analog switches which are
> processing audio signals.  I'm not decoding the 3-bit code.  I'm using it to
> drive those switches.

I meant that DG408 is actually a decoder too.

Roman


From declareupdate at gmail.com  Fri Dec  7 19:29:12 2018
From: declareupdate at gmail.com (Chris McDowell)
Date: Fri, 7 Dec 2018 12:29:12 -0600
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845C1D149C4BC4B869921C52F57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
Message-ID: <4A9F5A30-954A-4FDD-927D-896A67CA7F26@gmail.com>

Too late, Roman, I'm triggered! 

jk. apparently they intend to keep producing the LM3914 in the odd PLCC-20 package. ?\_(?)_/? 


> On Dec 7, 2018, at 7:53 AM, Roman Sowa <modular at go2.pl> wrote:
> 
> Before it turns into pointless flame war, let me say "I quit". I'm not here to tell anybody how to make things. Just wanted to express my admiration for simplicity of 3914 with SPST.
> 
> But since you took the time to nicely comment in such detail, it would be rude to leave this unanswered. So inline then...
> 
>> 1) The 3914 is set up to drive LEDs, and I didn't want to have to figure out
>> how to use it to generate logic levels.  I found the datasheet to be
>> somewhat cryptic in that regard.  It's probably easy to do (with one
>> resistor per comparator), but I just couldn't be bothered learning how.
> 
> That's open collector outputs. No magic in there.
> 
>> 2) The 3914 has 10 comparators, and I only want 7 (or 8, but the lowest one
>> is always on), so I was going to have to figure out how to alter the voltage
>> range into the chip so that 5V fell exactly between the 8th and 9th
> 
> Scale the input voltage accordingly. You scale it somehow already, so just change resistor values.
> 
>> comparators.  Again, it's forcing a chip to do something that it wasn't
>> really designed to do.  The only part of that chip I wanted was the
>> comparators, and so why not just use comparators?  Also, with the 7
>> comparators, the voltage range I need is exactly given by my 5V reference
>> and 8 1% 10k resistors, so I know it will be accurate.
> 
> Luckily, 3914 also contains voltage reference!
> And I would never expect to hear "the chip wasn't designed for it" from someone using VCA as VCO core ;)
> 
>> 3) The 3914 is already obsolete.
> 
> Is it going to be produced in thousands over span of several years? I think you mentioned it's one-off custom job. Still plenty of 3914 around.
> 
>> 4) The 3914 generates the equivalent of reverse logic (because the
>> comparators suck current when on), which would require interfacing with the
>> '148, which also generates reverse logic, but the DG408 requires positive
>> logic.
> 
> That's why I mentioned DG444
> 
>> 5) The "mux" here is a pair of 8-channel analog switches which are
>> processing audio signals.  I'm not decoding the 3-bit code.  I'm using it to
>> drive those switches.
> 
> I meant that DG408 is actually a decoder too.
> 
> Roman
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy




From dixon at mail.ubc.ca  Fri Dec  7 21:33:17 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Fri, 7 Dec 2018 12:33:17 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845C1D149C4BC4B869921C52F57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
Message-ID: <DDA338DA412D4A62930AB5980EF49255@galvanox01>

Hello Roman,

Thanks for your thoughtful replies.  I do appreciate them.

I actually have some 3914s, which I bought for some purpose which I now
can't remember.

As far as the reference voltage, it would have to be larger than 5V (about
6.25V, I think), which means that I would have to amplify my 5V reference
with another opamp, because I wouldn't take it straight from the rail.  I
already have a buffered 5V reference which I am using all over the board, so
it was just easier to use that.

At the end of the day, the two 339s take up about the same space as the 3914
(for which I have no sockets on hand), and the only real inconvenience is
that they require 8 resistors for the external voltage ladder, which would
be internal to the 3914, but they don't require any other opamps or
resistors.  Hence, the 3914 really represented no added convenience here.
It might have saved me 4 or 5 resistors, but cost me another TL072, and I
would have had to jerry-rig a socket.

The DG444 is an inappropriate chip for my circuit.  I need two 8-channel
multiplexers.  The DG407 would have been ideal, but I only had DG408s, so I
used two of those.  As far as the reverse logic, this is no big deal, since
the binary sequences are exactly backwards.  All I would have had to do was
to reverse the polarity of my CV, or just re-number the inputs in reverse
order.

In any case, the layout is done, and I'm just about to go up to the printer
and make the board.

Cheers!
Dave


> -----Original Message-----
> From: Roman Sowa [mailto:modular at go2.pl] 
> Sent: Friday, December 07, 2018 5:53 AM
> To: David G Dixon; synth-diy at synth-diy.org
> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> 
> Before it turns into pointless flame war, let me say "I 
> quit". I'm not here to tell anybody how to make things. Just 
> wanted to express my admiration for simplicity of 3914 with SPST.
> 
> But since you took the time to nicely comment in such detail, 
> it would be rude to leave this unanswered. So inline then...
> 
> > 1) The 3914 is set up to drive LEDs, and I didn't want to have to 
> > figure out how to use it to generate logic levels.  I found the 
> > datasheet to be somewhat cryptic in that regard.  It's 
> probably easy 
> > to do (with one resistor per comparator), but I just 
> couldn't be bothered learning how.
> 
> That's open collector outputs. No magic in there.
> 
> > 
> > 2) The 3914 has 10 comparators, and I only want 7 (or 8, but the 
> > lowest one is always on), so I was going to have to figure 
> out how to 
> > alter the voltage range into the chip so that 5V fell 
> exactly between 
> > the 8th and 9th
> 
> Scale the input voltage accordingly. You scale it somehow 
> already, so just change resistor values.
> 
> > comparators.  Again, it's forcing a chip to do something that it 
> > wasn't really designed to do.  The only part of that chip I 
> wanted was 
> > the comparators, and so why not just use comparators?  
> Also, with the 
> > 7 comparators, the voltage range I need is exactly given by my 5V 
> > reference and 8 1% 10k resistors, so I know it will be accurate.
> 
> Luckily, 3914 also contains voltage reference!
> And I would never expect to hear "the chip wasn't designed 
> for it" from someone using VCA as VCO core ;)
> 
> > 
> > 3) The 3914 is already obsolete.
> 
> Is it going to be produced in thousands over span of several 
> years? I think you mentioned it's one-off custom job. Still 
> plenty of 3914 around.
> 
> > 
> > 4) The 3914 generates the equivalent of reverse logic (because the 
> > comparators suck current when on), which would require interfacing 
> > with the '148, which also generates reverse logic, but the DG408 
> > requires positive logic.
> 
> That's why I mentioned DG444
> 
> > 5) The "mux" here is a pair of 8-channel analog switches which are 
> > processing audio signals.  I'm not decoding the 3-bit code. 
>  I'm using 
> > it to drive those switches.
> 
> I meant that DG408 is actually a decoder too.
> 
> Roman



From crystals at sonic.net  Sat Dec  8 02:58:41 2018
From: crystals at sonic.net (Crys)
Date: Fri, 7 Dec 2018 18:58:41 -0700
Subject: [sdiy] FS: CEM 3394
In-Reply-To: <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845C1D149C4BC4B869921C52F57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
Message-ID: <b3b554f6-efd1-d5c6-47bb-35c8d43e74ff@sonic.net>

Hiya List,

i have some CEM 3394s that are pulls from two electronically functioning 
but physically damaged beyond repair SC Six Traks. Contact me off list 
if interested.


happy prototyping,

Crystal dude



From mr at analogue.org  Sun Dec  9 12:57:56 2018
From: mr at analogue.org (Mattias Rickardsson)
Date: Sun, 9 Dec 2018 12:57:56 +0100
Subject: [sdiy] Mind blown -- TL074 saturated outputs different
In-Reply-To: <b9021091-54c4-cc38-ce8e-e609c4650eef@bendentech.co.uk>
References: <22FDF271339C4B6D91A9EBCEB8A8CCF0@galvanox01>
 <e849b3cf-d8bd-a421-aaaa-894fc44c67ce@schmitzbits.de>
 <9ACE521DFE9C481F89E1A28F89D6A21B@galvanox01>
 <b9021091-54c4-cc38-ce8e-e609c4650eef@bendentech.co.uk>
Message-ID: <CAP92RBUW1Y1hbvo_KpDt9y_HsT=XBUKv8v5Bpq1JXswSaOtHnQ@mail.gmail.com>

On Wed, 28 Nov 2018 at 10:18, Steve Lenham <steve at bendentech.co.uk> wrote:

> ...
> If, however, it is only bipolar symmetry that you are after rather than
> an exact level, consider putting a single Zener inside a diode bridge.
> That makes the positive and negative clip levels identical.


Sorry to be late on this ball, but I remember seeing (and saving) a
schematic example of this, a single zener surrounded by 2 or 4 diodes in
some bridge configuration - but now I cannot find it. The main point of it
as I remember was to get a very symmetric output by avoiding having more
than one zeners (since they are rarely as well matched as regular diodes),
and instead use the same zener as the level reference for both the positive
and the negative side. I guess a TL431 could give an even better result.

Can anybody give a pointer to where this has been described?

Thanks :-)

/mr
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From steve at bendentech.co.uk  Sun Dec  9 15:58:02 2018
From: steve at bendentech.co.uk (Steve Lenham)
Date: Sun, 9 Dec 2018 14:58:02 +0000
Subject: [sdiy] Mind blown -- TL074 saturated outputs different
In-Reply-To: <CAP92RBUW1Y1hbvo_KpDt9y_HsT=XBUKv8v5Bpq1JXswSaOtHnQ@mail.gmail.com>
References: <22FDF271339C4B6D91A9EBCEB8A8CCF0@galvanox01>
 <e849b3cf-d8bd-a421-aaaa-894fc44c67ce@schmitzbits.de>
 <9ACE521DFE9C481F89E1A28F89D6A21B@galvanox01>
 <b9021091-54c4-cc38-ce8e-e609c4650eef@bendentech.co.uk>
 <CAP92RBUW1Y1hbvo_KpDt9y_HsT=XBUKv8v5Bpq1JXswSaOtHnQ@mail.gmail.com>
Message-ID: <6ed9e45c-da6a-2953-cc75-edfb1803870e@bendentech.co.uk>


>     If, however, it is only bipolar symmetry that you are after rather than
>     an exact level, consider putting a single Zener inside a diode bridge.
>     That makes the positive and negative clip levels identical.
> 
> 
> Sorry to be late on this ball, but I remember seeing (and saving) a 
> schematic example of this, a single zener surrounded by 2 or 4 diodes in 
> some bridge configuration - but now I cannot find it. The main point of 
> it as I remember was to get a very symmetric output by avoiding having 
> more than one zeners (since they are rarely as well matched as regular 
> diodes), and instead use the same zener as the level reference for both 
> the positive and the negative side. I guess a TL431 could give an even 
> better result.
> 
> Can anybody give a pointer to where this has been described?

It is the same bridge configuration of four diodes that you would find 
in a power supply. Your signal goes to the two input pins (which would 
usually be marked "AC" in a power supply scenario) and your Zener (or 
TL431, or whatever) connects across the two output pins (usually marked 
+ and -, and where you would find the big smoothing capacitor in a power 
supply).

That's all there is to it! The resulting configuration will clamp in 
both directions at the Zener (etc) voltage plus two diode forward 
voltages (you can use Schottky diodes for the bridge to minimise this if 
you want). Don't forget that you still need a current limiting resistor 
as you would with a normal Zener circuit.

HTH,

Steve L.


From dixon at mail.ubc.ca  Mon Dec 10 08:36:30 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Sun, 9 Dec 2018 23:36:30 -0800
Subject: [sdiy] [Potential SPAM] Re: Mind blown -- TL074 saturated
 outputs different
In-Reply-To: <CAP92RBUW1Y1hbvo_KpDt9y_HsT=XBUKv8v5Bpq1JXswSaOtHnQ@mail.gmail.com>
References: <22FDF271339C4B6D91A9EBCEB8A8CCF0@galvanox01>
 <e849b3cf-d8bd-a421-aaaa-894fc44c67ce@schmitzbits.de>
 <9ACE521DFE9C481F89E1A28F89D6A21B@galvanox01>
 <b9021091-54c4-cc38-ce8e-e609c4650eef@bendentech.co.uk>
 <CAP92RBUW1Y1hbvo_KpDt9y_HsT=XBUKv8v5Bpq1JXswSaOtHnQ@mail.gmail.com>
Message-ID: <C02A76A5931A40C3B56B758CD1E0958F@galvanox01>

Such a "zener bridge" is at the heart of every Dixie, Rubicon, and Atlantis
VCO.
 
The idea is that the zener bridge gives more symmetrical results than two
back-to-back zeners.  However, it relies upon the assumption that the two
pairs of regular diodes are identical.  This is probably more true than
assuming that any two zeners of the same nominal voltage are identical, but
it is still an assumption.


On Wed, 28 Nov 2018 at 10:18, Steve Lenham <steve at bendentech.co.uk> wrote:


...
If, however, it is only bipolar symmetry that you are after rather than 
an exact level, consider putting a single Zener inside a diode bridge. 
That makes the positive and negative clip levels identical.


Sorry to be late on this ball, but I remember seeing (and saving) a
schematic example of this, a single zener surrounded by 2 or 4 diodes in
some bridge configuration - but now I cannot find it. The main point of it
as I remember was to get a very symmetric output by avoiding having more
than one zeners (since they are rarely as well matched as regular diodes),
and instead use the same zener as the level reference for both the positive
and the negative side. I guess a TL431 could give an even better result.

Can anybody give a pointer to where this has been described?

Thanks :-)

/mr

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From synth at schmitzbits.de  Mon Dec 10 21:04:51 2018
From: synth at schmitzbits.de (=?UTF-8?Q?Ren=c3=a9_Schmitz?=)
Date: Mon, 10 Dec 2018 21:04:51 +0100
Subject: [sdiy] [Potential SPAM] Re: Mind blown -- TL074 saturated
 outputs different
In-Reply-To: <C02A76A5931A40C3B56B758CD1E0958F@galvanox01>
References: <22FDF271339C4B6D91A9EBCEB8A8CCF0@galvanox01>
 <e849b3cf-d8bd-a421-aaaa-894fc44c67ce@schmitzbits.de>
 <9ACE521DFE9C481F89E1A28F89D6A21B@galvanox01>
 <b9021091-54c4-cc38-ce8e-e609c4650eef@bendentech.co.uk>
 <CAP92RBUW1Y1hbvo_KpDt9y_HsT=XBUKv8v5Bpq1JXswSaOtHnQ@mail.gmail.com>
 <C02A76A5931A40C3B56B758CD1E0958F@galvanox01>
Message-ID: <8abb70dc-75b0-1d6f-f8ed-e10980dbadea@schmitzbits.de>

Hi David,

On 10.12.2018 08:36, David G Dixon wrote:
> Such a "zener bridge" is at the heart of every Dixie, Rubicon, and 
> Atlantis VCO.

Have you posted these schematics somewhere?

Best,
  Ren?

--
synth at schmitzbits.de
http://schmitzbits.de


From neil.johnson71 at gmail.com  Mon Dec 10 22:41:31 2018
From: neil.johnson71 at gmail.com (Neil Johnson)
Date: Mon, 10 Dec 2018 21:41:31 +0000
Subject: [sdiy] [Potential SPAM] Re: Mind blown -- TL074 saturated
 outputs different
In-Reply-To: <C02A76A5931A40C3B56B758CD1E0958F@galvanox01>
References: <22FDF271339C4B6D91A9EBCEB8A8CCF0@galvanox01>
 <e849b3cf-d8bd-a421-aaaa-894fc44c67ce@schmitzbits.de>
 <9ACE521DFE9C481F89E1A28F89D6A21B@galvanox01>
 <b9021091-54c4-cc38-ce8e-e609c4650eef@bendentech.co.uk>
 <CAP92RBUW1Y1hbvo_KpDt9y_HsT=XBUKv8v5Bpq1JXswSaOtHnQ@mail.gmail.com>
 <C02A76A5931A40C3B56B758CD1E0958F@galvanox01>
Message-ID: <CACZGMxLVcFdkyrSpCVyKcNkhKTp2ajUCr0vgDwiDsuZ47F9w4Q@mail.gmail.com>

Hi,

Matthias wrote:
> Sorry to be late on this ball, but I remember seeing (and saving) a schematic example of this, a single zener surrounded by 2 or 4 diodes in some bridge configuration - but now I cannot find it. The main point of it as I remember was to get a very symmetric output by avoiding having more than one zeners (since they are rarely as well matched as regular diodes), and instead use the same zener as the level reference for both the positive and the negative side. I guess a TL431 could give an even better result.
>
> Can anybody give a pointer to where this has been described?

One example from the literature is Figure 10.6 in Sergio Franco's
"Design With Operational Amplifiers And Analog Integrated Circuits"...
see page 234 of the PDF in the web archive:
https://archive.org/details/SFrancoDesignWithOperationalAmplifiersAndAnalogIntegratedCircuits1Pdf

David G Dixon wrote:
> The idea is that the zener bridge gives more symmetrical results than two back-to-back zeners.  However, it relies upon the assumption that the two pairs of regular diodes are identical.  This is probably more true than assuming that any two zeners of the same nominal voltage are identical, but it is still an assumption.

Well, almost, except without the ASSumption.  We don't ASSume the
bridge diodes are identical, it works on the basis that any two
randomly-selected silicon diodes' forward voltage drops are
significantly closer to each other than the reverse avalanche/zener
voltages of two randomly-selected Zener diodes.  For example, if we
consider a Vishay BZX85C5V1 zener diode its VZ is 5V1 +/- 300mV (the
spread gets wider for higher voltage diodes).  Compare this to, say,
BAT85 schottky diode, or 1N4148 silicon switching diode, and the VF  -
while still having some spread, is much tighter (in the region of a
few mV).  So no, we don't ASSume the diodes are identical, but for the
cost of four extremely cheap silicon diodes we get a much better match
of the positive and negative clamp limits without the cost of either
hand-selecting zener diodes or paying for tighter VZ binning, and as
others have suggested you can also use more esoteric devices like
TL431 and so on.

Neil
-- 
http://www.njohnson.co.uk



From dixon at mail.ubc.ca  Tue Dec 11 04:49:57 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Mon, 10 Dec 2018 19:49:57 -0800
Subject: [sdiy] [Potential SPAM] Re: Mind blown -- TL074 saturated
 outputs different
In-Reply-To: <8abb70dc-75b0-1d6f-f8ed-e10980dbadea@schmitzbits.de>
References: <22FDF271339C4B6D91A9EBCEB8A8CCF0@galvanox01>
 <e849b3cf-d8bd-a421-aaaa-894fc44c67ce@schmitzbits.de>
 <9ACE521DFE9C481F89E1A28F89D6A21B@galvanox01>
 <b9021091-54c4-cc38-ce8e-e609c4650eef@bendentech.co.uk>
 <CAP92RBUW1Y1hbvo_KpDt9y_HsT=XBUKv8v5Bpq1JXswSaOtHnQ@mail.gmail.com>
 <C02A76A5931A40C3B56B758CD1E0958F@galvanox01>
 <8abb70dc-75b0-1d6f-f8ed-e10980dbadea@schmitzbits.de>
Message-ID: <9614729606EA406A9CF8FACB88A8708E@galvanox01>

> Have you posted these schematics somewhere?

No.  I generally don't post Intellijel schematics.  However, the Dixie and
its variants are all tri-square oscillators, and the square amplitude is
defined by a zener bridge. 



From dixon at mail.ubc.ca  Tue Dec 11 04:54:47 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Mon, 10 Dec 2018 19:54:47 -0800
Subject: [sdiy] [Potential SPAM] Re: Mind blown -- TL074 saturated
 outputs different
In-Reply-To: <CACZGMxLVcFdkyrSpCVyKcNkhKTp2ajUCr0vgDwiDsuZ47F9w4Q@mail.gmail.com>
References: <22FDF271339C4B6D91A9EBCEB8A8CCF0@galvanox01>
 <e849b3cf-d8bd-a421-aaaa-894fc44c67ce@schmitzbits.de>
 <9ACE521DFE9C481F89E1A28F89D6A21B@galvanox01>
 <b9021091-54c4-cc38-ce8e-e609c4650eef@bendentech.co.uk>
 <CAP92RBUW1Y1hbvo_KpDt9y_HsT=XBUKv8v5Bpq1JXswSaOtHnQ@mail.gmail.com>
 <C02A76A5931A40C3B56B758CD1E0958F@galvanox01>
 <CACZGMxLVcFdkyrSpCVyKcNkhKTp2ajUCr0vgDwiDsuZ47F9w4Q@mail.gmail.com>
Message-ID: <10FD541D27FB4C4082D1BF970B192D82@galvanox01>

Yeah, Neil, that's more or less what I was trying to say, but since I didn't
do my doctoral thesis on 1N4148 diodes, I couldn't find the words. 

> -----Original Message-----
> From: Neil Johnson [mailto:neil.johnson71 at gmail.com] 
> Sent: Monday, December 10, 2018 1:42 PM
> To: David G Dixon
> Cc: Mattias Rickardsson; Steve Lenham; SDIY List
> Subject: Re: [sdiy] [Potential SPAM] Re: Mind blown -- TL074 
> saturated outputs different
> 
> Hi,
> 
> Matthias wrote:
> > Sorry to be late on this ball, but I remember seeing (and 
> saving) a schematic example of this, a single zener 
> surrounded by 2 or 4 diodes in some bridge configuration - 
> but now I cannot find it. The main point of it as I remember 
> was to get a very symmetric output by avoiding having more 
> than one zeners (since they are rarely as well matched as 
> regular diodes), and instead use the same zener as the level 
> reference for both the positive and the negative side. I 
> guess a TL431 could give an even better result.
> >
> > Can anybody give a pointer to where this has been described?
> 
> One example from the literature is Figure 10.6 in Sergio 
> Franco's "Design With Operational Amplifiers And Analog 
> Integrated Circuits"...
> see page 234 of the PDF in the web archive:
> https://archive.org/details/SFrancoDesignWithOperationalAmplif
> iersAndAnalogIntegratedCircuits1Pdf
> 
> David G Dixon wrote:
> > The idea is that the zener bridge gives more symmetrical 
> results than two back-to-back zeners.  However, it relies 
> upon the assumption that the two pairs of regular diodes are 
> identical.  This is probably more true than assuming that any 
> two zeners of the same nominal voltage are identical, but it 
> is still an assumption.
> 
> Well, almost, except without the ASSumption.  We don't ASSume 
> the bridge diodes are identical, it works on the basis that 
> any two randomly-selected silicon diodes' forward voltage 
> drops are significantly closer to each other than the reverse 
> avalanche/zener voltages of two randomly-selected Zener 
> diodes.  For example, if we consider a Vishay BZX85C5V1 zener 
> diode its VZ is 5V1 +/- 300mV (the spread gets wider for 
> higher voltage diodes).  Compare this to, say,
> BAT85 schottky diode, or 1N4148 silicon switching diode, and 
> the VF  - while still having some spread, is much tighter (in 
> the region of a few mV).  So no, we don't ASSume the diodes 
> are identical, but for the cost of four extremely cheap 
> silicon diodes we get a much better match of the positive and 
> negative clamp limits without the cost of either 
> hand-selecting zener diodes or paying for tighter VZ binning, 
> and as others have suggested you can also use more esoteric 
> devices like
> TL431 and so on.
> 
> Neil
> --
> http://www.njohnson.co.uk



From dixon at mail.ubc.ca  Tue Dec 11 08:10:35 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Mon, 10 Dec 2018 23:10:35 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <DDA338DA412D4A62930AB5980EF49255@galvanox01>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845C1D149C4BC4B869921C52F57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <DDA338DA412D4A62930AB5980EF49255@galvanox01>
Message-ID: <38C3FAFAA9E4486E98933DDDC7D7DED2@galvanox01>

OK, so to continue the saga:

I rebuilt my circuit with a flash-ADC comparator chain, and it all worked
reasonably well, except that when the CV was stuck at 0V (right in the
middle, where my fader has a detent) one of the comparators was oscillating
like a mo-fo, and this was causing the DG408s to freak right out, putting
all sorts of noise onto the audio output.

So, I decided to put hysteresis on the comparators.  This required an input
resistor (10k) to the + input of each comparator, plus a large hysteresis
resistor (2.2M).  I also added 10k resistors to the - inputs, so added 21
resistors to the circuit overall.  Somehow, I managed to lay this all out
with just 0.4" of additional length.  I didn't want to rebuild the entire
board to test this, so I built a daughterboard with just the two LM339s and
the CD4532 on it, and I removed all of these components from the main board,
and wired up the daughterboard at seven connection points.  This worked
great, and the daughterboard floated above the main board on the stiffness
of the connecting wires.

Result?  Now it works ALMOST perfectly.  The noise has disappeared (as I
knew it would) and the comparators do not oscillate at all.  There is now
only one tiny problem: There is still an almost imperceptible click when the
CV crosses 0V (and the logic control voltage crosses 2.5V) in the positive
direction.  This is when the logic switches from 011 to 100 (i.e., all three
bits change).  Interestingly, I don't hear the click at all when the CV goes
in the other direction (100 to 011).  Hence, what I think I am hearing now
is just charge injection from the A2 bit, which only occurs in one direction
according to a document I found on the web about it.  Also, the click is
very faint, and could thus be about 20pC of charge as per the datasheet.

So, I believe that I have now eliminated all of the problems I had
introduced to this circuit with my naive approach to logic design.  I don't
know if I'll be able to get rid of this tiny click, but I'm going to try two
things:

1) Adding 10nF caps to ground from the switch outputs, as suggested in the
datasheet and the document I found, and
2) Reducing the input impedance on the downstream circuitry from 100k to
10k, which the datasheet suggests should help (lower impedance is better).

According to what I've read, these things should reduce the effect of charge
injection.  (If it is charge injection, then I would have been no better off
with digital SPST switches.)  However, this is going to have to wait until
tomorrow afternoon.



From ulfurh at gmail.com  Tue Dec 11 14:19:57 2018
From: ulfurh at gmail.com (ulfur hansson)
Date: Tue, 11 Dec 2018 08:19:57 -0500
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <38C3FAFAA9E4486E98933DDDC7D7DED2@galvanox01>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845C1D149C4BC4B869921C52F57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <DDA338DA412D4A62930AB5980EF49255@galvanox01>
 <38C3FAFAA9E4486E98933DDDC7D7DED2@galvanox01>
Message-ID: <EF0ED602-8252-4D8E-B03D-061273FEC763@gmail.com>

what an intense saga!!

cannot wait to play around with the fruits of your labor dave, hats off to you for persevering!

best,
-?

Sent from outer space

> On Dec 11, 2018, at 2:10 AM, David G Dixon <dixon at mail.ubc.ca> wrote:
> 
> OK, so to continue the saga:
> 
> I rebuilt my circuit with a flash-ADC comparator chain, and it all worked
> reasonably well, except that when the CV was stuck at 0V (right in the
> middle, where my fader has a detent) one of the comparators was oscillating
> like a mo-fo, and this was causing the DG408s to freak right out, putting
> all sorts of noise onto the audio output.
> 
> So, I decided to put hysteresis on the comparators.  This required an input
> resistor (10k) to the + input of each comparator, plus a large hysteresis
> resistor (2.2M).  I also added 10k resistors to the - inputs, so added 21
> resistors to the circuit overall.  Somehow, I managed to lay this all out
> with just 0.4" of additional length.  I didn't want to rebuild the entire
> board to test this, so I built a daughterboard with just the two LM339s and
> the CD4532 on it, and I removed all of these components from the main board,
> and wired up the daughterboard at seven connection points.  This worked
> great, and the daughterboard floated above the main board on the stiffness
> of the connecting wires.
> 
> Result?  Now it works ALMOST perfectly.  The noise has disappeared (as I
> knew it would) and the comparators do not oscillate at all.  There is now
> only one tiny problem: There is still an almost imperceptible click when the
> CV crosses 0V (and the logic control voltage crosses 2.5V) in the positive
> direction.  This is when the logic switches from 011 to 100 (i.e., all three
> bits change).  Interestingly, I don't hear the click at all when the CV goes
> in the other direction (100 to 011).  Hence, what I think I am hearing now
> is just charge injection from the A2 bit, which only occurs in one direction
> according to a document I found on the web about it.  Also, the click is
> very faint, and could thus be about 20pC of charge as per the datasheet.
> 
> So, I believe that I have now eliminated all of the problems I had
> introduced to this circuit with my naive approach to logic design.  I don't
> know if I'll be able to get rid of this tiny click, but I'm going to try two
> things:
> 
> 1) Adding 10nF caps to ground from the switch outputs, as suggested in the
> datasheet and the document I found, and
> 2) Reducing the input impedance on the downstream circuitry from 100k to
> 10k, which the datasheet suggests should help (lower impedance is better).
> 
> According to what I've read, these things should reduce the effect of charge
> injection.  (If it is charge injection, then I would have been no better off
> with digital SPST switches.)  However, this is going to have to wait until
> tomorrow afternoon.
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From timr at circuitabbey.com  Tue Dec 11 17:34:42 2018
From: timr at circuitabbey.com (Tim Ressel)
Date: Tue, 11 Dec 2018 08:34:42 -0800
Subject: [sdiy] [Potential SPAM] Re: Mind blown -- TL074 saturated
 outputs different
In-Reply-To: <CACZGMxLVcFdkyrSpCVyKcNkhKTp2ajUCr0vgDwiDsuZ47F9w4Q@mail.gmail.com>
References: <22FDF271339C4B6D91A9EBCEB8A8CCF0@galvanox01>
 <e849b3cf-d8bd-a421-aaaa-894fc44c67ce@schmitzbits.de>
 <9ACE521DFE9C481F89E1A28F89D6A21B@galvanox01>
 <b9021091-54c4-cc38-ce8e-e609c4650eef@bendentech.co.uk>
 <CAP92RBUW1Y1hbvo_KpDt9y_HsT=XBUKv8v5Bpq1JXswSaOtHnQ@mail.gmail.com>
 <C02A76A5931A40C3B56B758CD1E0958F@galvanox01>
 <CACZGMxLVcFdkyrSpCVyKcNkhKTp2ajUCr0vgDwiDsuZ47F9w4Q@mail.gmail.com>
Message-ID: <c94e6788-98c8-4bbd-8a97-da16418730eb@circuitabbey.com>

Check out IC Op-Amp Cookbook by Jung. Chapter 5 has the clamps you seek. 
The book is an excellent read, especially if you want a deep dive into 
how an opamp really works, as well as a good history of op amps.

--timbo

On 12/10/2018 1:41 PM, Neil Johnson wrote:
> Hi,
>
> Matthias wrote:
>> Sorry to be late on this ball, but I remember seeing (and saving) a schematic example of this, a single zener surrounded by 2 or 4 diodes in some bridge configuration - but now I cannot find it. The main point of it as I remember was to get a very symmetric output by avoiding having more than one zeners (since they are rarely as well matched as regular diodes), and instead use the same zener as the level reference for both the positive and the negative side. I guess a TL431 could give an even better result.
>>
>> Can anybody give a pointer to where this has been described?
> One example from the literature is Figure 10.6 in Sergio Franco's
> "Design With Operational Amplifiers And Analog Integrated Circuits"...
> see page 234 of the PDF in the web archive:
> https://archive.org/details/SFrancoDesignWithOperationalAmplifiersAndAnalogIntegratedCircuits1Pdf
>
> David G Dixon wrote:
>> The idea is that the zener bridge gives more symmetrical results than two back-to-back zeners.  However, it relies upon the assumption that the two pairs of regular diodes are identical.  This is probably more true than assuming that any two zeners of the same nominal voltage are identical, but it is still an assumption.
> Well, almost, except without the ASSumption.  We don't ASSume the
> bridge diodes are identical, it works on the basis that any two
> randomly-selected silicon diodes' forward voltage drops are
> significantly closer to each other than the reverse avalanche/zener
> voltages of two randomly-selected Zener diodes.  For example, if we
> consider a Vishay BZX85C5V1 zener diode its VZ is 5V1 +/- 300mV (the
> spread gets wider for higher voltage diodes).  Compare this to, say,
> BAT85 schottky diode, or 1N4148 silicon switching diode, and the VF  -
> while still having some spread, is much tighter (in the region of a
> few mV).  So no, we don't ASSume the diodes are identical, but for the
> cost of four extremely cheap silicon diodes we get a much better match
> of the positive and negative clamp limits without the cost of either
> hand-selecting zener diodes or paying for tighter VZ binning, and as
> others have suggested you can also use more esoteric devices like
> TL431 and so on.
>
> Neil

-- 
--Tim Ressel
Circuit Abbey
timr at circuitabbey.com



From igg.debus at gmail.com  Tue Dec 11 18:19:43 2018
From: igg.debus at gmail.com (Ingo Debus)
Date: Tue, 11 Dec 2018 18:19:43 +0100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <38C3FAFAA9E4486E98933DDDC7D7DED2@galvanox01>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99E8DAAC539343C9BE2C166F95E7D675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845C1D149C4BC4B869921C52F57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <DDA338DA412D4A62930AB5980EF49255@galvanox01>
 <38C3FAFAA9E4486E98933DDDC7D7DED2@galvanox01>
Message-ID: <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>


> Am 11.12.2018 um 08:10 schrieb David G Dixon <dixon at mail.ubc.ca>:
> 
> There is now
> only one tiny problem: There is still an almost imperceptible click when the
> CV crosses 0V (and the logic control voltage crosses 2.5V) in the positive
> direction.  This is when the logic switches from 011 to 100 (i.e., all three
> bits change).  Interestingly, I don't hear the click at all when the CV goes
> in the other direction (100 to 011). 

Couldn?t this still be caused by a very brief ?forbidden state? during the transition from 011 to 100? In your case, the forbidden state would be 000 (MSBit changes slower that the other two) or 111 (MSBit changes faster). Probably just a difference between rising and falling slope. Can you check with a scope?

Ingo


From modular at go2.pl  Tue Dec 11 22:19:43 2018
From: modular at go2.pl (Roman)
Date: Tue, 11 Dec 2018 22:19:43 +0100
Subject: [sdiy]
 =?utf-8?q?Help=2C_I=27m_Desperate!_=28Charge_Injection_wi?=
 =?utf-8?q?th_DG408=29?=
In-Reply-To: <<2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
Message-ID: <87047a284558469ca7b973d8be4d423a@grupawp.pl>

I know it&#39;s too late, as the circuit at this stage has already gone slightly different path, and I already gave up, but couldn&#39;t help drawing this little schemo that explains my idea of using single switches with that obsoleted chip. Switches should be DG444 or similar (0=closed, 1=open), or replace diodes with NAND gates and use any regular dirt cheap switch like 4066.  There&#39;s no switching happening while VCA is open, provided that VCA control triangles match the edges of LM3914 stages. The only switched channels are the ones routed to muted VCA, so in theory there should be no clicking audible.  Basicaly this is just the circuit that makes this input switching sequence:  VCA-A:12233445566..  VCA-B:11223344556...  by creating one step overlap between stages. Only 6 inputs in this example, but can be extended to any other number.  www.synthdiy.eu www.synthdiy.eu   IMHO switching active channel will always produce some clicking for many reasons: not matched channels, difference between transistion times H-&gt;L and L-&gt;H as Ingo said, break-before-make feature of DG407, slow response of 4532, and who knows if not also charge injection.   Roman  Dnia 11 grudnia 2018 18:24 Ingo Debus &lt;igg.debus at gmail.com&gt; napisa?(a):  Am 11.12.2018 um 08:10 schrieb David G Dixon &lt;dixon at mail.ubc.ca&gt;:   There is now  only one tiny problem: There is still an almost imperceptible click when the  CV crosses 0V (and the logic control voltage crosses 2.5V) in the positive  direction. ?This is when the logic switches from 011 to 100 (i.e., all three  bits change). ?Interestingly, I don&#39;t hear the click at all when the CV goes  in the other direction (100 to 011).   Couldn?t this still be caused by a very brief ?forbidden state? during the transition from 011 to 100? In your case, the forbidden state would be 000 (MSBit changes slower that the other two) or 111 (MSBit changes faster). Probably just a difference between rising and falling slope. Can you check with a scope?   Ingo  ______________________________  Synth-diy mailing list   Synth-diy at synth-diy.org  synth-diy.org synth-diy.org
-------------- next part --------------
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From dixon at mail.ubc.ca  Wed Dec 12 03:53:54 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Tue, 11 Dec 2018 18:53:54 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <87047a284558469ca7b973d8be4d423a@grupawp.pl>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
Message-ID: <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>

Roman,
 
You're right.  Your suggestion is superior.  I was simply unaware of what a
complete shit-show all this digital circuitry is.  This is exactly the
reason why I avoid digital solutions whenever possible.  This module should
be a pretty straightforward application of an analog multiplexer, but you
are basically saying (and I concur based on my experience) that I can't use
such a thing for clean audio, and to me, that is a sad indictment of these
ICs.  I'm now switching these DG408s about as cleanly as is humanly
possible, and they're still misbehaving.  It just shouldn't be this hard.
 
So, I'm going to try to implement your idea, but I don't have the ICs I
need.  I'm also still trying to understand exactly how the switching works.
I'm presuming that the 3914 must be in Dot mode, because only one comparator
can be on at a time for this to work, and therefore, this circuit ONLY works
with 3914, and cannot be implemented with a generic flash comparator chain.
 
So, I'm going to finish off the circuit as it is, because it works pretty
well, but I concede that I basically cannot use these fucked up digital
chips to switch active audio circuits, and will build the next one your way.
 
Cheers,
Dave
 
  _____  

From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Roman
Sent: Tuesday, December 11, 2018 1:20 PM
To: synth-diy at synth-diy.org
Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)



I know it's too late, as the circuit at this stage has already gone slightly
different path, and I already gave up, but couldn't help drawing this little
schemo that explains my idea of using single switches with that obsoleted
chip. Switches should be DG444 or similar (0=closed, 1=open), or replace
diodes with NAND gates and use any regular dirt cheap switch like 4066.

There's no switching happening while VCA is open, provided that VCA control
triangles match the edges of LM3914 stages. The only switched channels are
the ones routed to muted VCA, so in theory there should be no clicking
audible.

Basicaly this is just the circuit that makes this input switching sequence:

VCA-A:12233445566..

VCA-B:11223344556...

by creating one step overlap between stages. Only 6 inputs in this example,
but can be extended to any other number.

http://www.synthdiy.eu/files/scanner.png


IMHO switching active channel will always produce some clicking for many
reasons: not matched channels, difference between transistion times H->L and
L->H as Ingo said, break-before-make feature of DG407, slow response of
4532, and who knows if not also charge injection.


Roman


Dnia 11 grudnia 2018 18:24 Ingo Debus <igg.debus at gmail.com> napisa?(a):


Am 11.12.2018 um 08:10 schrieb David G Dixon <dixon at mail.ubc.ca>:


There is now

only one tiny problem: There is still an almost imperceptible click when the

CV crosses 0V (and the logic control voltage crosses 2.5V) in the positive

direction.  This is when the logic switches from 011 to 100 (i.e., all three

bits change).  Interestingly, I don't hear the click at all when the CV goes

in the other direction (100 to 011).



Couldn't this still be caused by a very brief "forbidden state" during the
transition from 011 to 100? In your case, the forbidden state would be 000
(MSBit changes slower that the other two) or 111 (MSBit changes faster).
Probably just a difference between rising and falling slope. Can you check
with a scope?


Ingo

_______________________________________________

Synth-diy mailing list

Synth-diy at synth-diy.org

http://synth-diy.org/mailman/listinfo/synth-diy



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From modular at go2.pl  Wed Dec 12 10:04:36 2018
From: modular at go2.pl (Roman Sowa)
Date: Wed, 12 Dec 2018 10:04:36 +0100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
Message-ID: <45eaa7fb-44c1-34f6-b239-6a6792065dce@go2.pl>

I'm glad I could help.

Yes, it must work in dot mode. One way of making dot mode out of 
comparator chain is this:
http://www.synthdiy.eu/files/dotmode.png
with different wiring there's 1 of 8 dot mode possible or the one that 
does what's needed for crossfader based scanner - 2 of 8 dot mode.

Roman

W dniu 2018-12-12 o?03:53, David G Dixon pisze:
> Roman,
> You're right.? Your suggestion is superior.? I was simply unaware of 
> what a complete shit-show all this digital circuitry is. This is exactly 
> the reason why I avoid digital solutions whenever possible.? This module 
> should be a pretty straightforward application of an analog multiplexer, 
> but you are basically saying (and I concur based on my experience) that 
> I can't use such a thing for clean audio, and to me, that is a 
> sad?indictment of these ICs.? I'm now switching these DG408s about as 
> cleanly as is?humanly possible, and they're still misbehaving.? It just 
> shouldn't be this hard.
> So, I'm going to try to implement your idea, but I don't have the ICs I 
> need.? I'm also still trying to understand?exactly how?the switching 
> works.? I'm presuming that the 3914 must be in Dot mode, because only 
> one comparator can be on at a time for this to work, and therefore, this 
> circuit ONLY works with 3914, and cannot be implemented with a generic 
> flash comparator chain.
> So, I'm going to finish off the circuit as it is, because it works 
> pretty well, but I concede that I basically cannot use these fucked up 
> digital chips to switch active audio circuits, and will build the next 
> one your way.
> Cheers,
> Dave
> ------------------------------------------------------------------------
> *From:* Synth-diy [mailto:synth-diy-bounces at synth-diy.org] *On Behalf Of 
> *Roman
> *Sent:* Tuesday, December 11, 2018 1:20 PM
> *To:* synth-diy at synth-diy.org
> *Subject:* Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> 
>     I know it's too late, as the circuit at this stage has already gone
>     slightly different path, and I already gave up, but couldn't help
>     drawing this little schemo that explains my idea of using single
>     switches with that obsoleted chip. Switches should be DG444 or
>     similar (0=closed, 1=open), or replace diodes with NAND gates and
>     use any regular dirt cheap switch like 4066.
>     There's no switching happening while VCA is open, provided that VCA
>     control triangles match the edges of LM3914 stages. The only
>     switched channels are the ones routed to muted VCA, so in theory
>     there should be no clicking audible.
>     Basicaly this is just the circuit that makes this input switching
>     sequence:
>     VCA-A:12233445566..
>     VCA-B:11223344556...
>     by creating one step overlap between stages. Only 6 inputs in this
>     example, but can be extended to any other number.
>     http://www.synthdiy.eu/files/scanner.png
> 
>     IMHO switching active channel will always produce some clicking for
>     many reasons: not matched channels, difference between transistion
>     times H->L and L->H as Ingo said, break-before-make feature of
>     DG407, slow response of 4532, and who knows if not also charge
>     injection.
> 
>     Roman
> 
>     Dnia 11 grudnia 2018 18:24 Ingo Debus <igg.debus at gmail.com> napisa?(a):
> 
>             Am 11.12.2018 um 08:10 schrieb David G Dixon
>             <dixon at mail.ubc.ca>:
> 
>             There is now
>             only one tiny problem: There is still an almost
>             imperceptible click when the
>             CV crosses 0V (and the logic control voltage crosses 2.5V)
>             in the positive
>             direction. ?This is when the logic switches from 011 to 100
>             (i.e., all three
>             bits change). ?Interestingly, I don't hear the click at all
>             when the CV goes
>             in the other direction (100 to 011).
> 
> 
>         Couldn?t this still be caused by a very brief ?forbidden state?
>         during the transition from 011 to 100? In your case, the
>         forbidden state would be 000 (MSBit changes slower that the
>         other two) or 111 (MSBit changes faster). Probably just a
>         difference between rising and falling slope. Can you check with
>         a scope?
> 
>         Ingo
>         _______________________________________________
>         Synth-diy mailing list
>         Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
>         http://synth-diy.org/mailman/listinfo/synth-diy
> 
> 


From indigoid at oldcorollas.org  Wed Dec 12 11:02:01 2018
From: indigoid at oldcorollas.org (john slee)
Date: Wed, 12 Dec 2018 21:02:01 +1100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
Message-ID: <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>

I suspect a more-digital solution would be easier to get right, for people
more inclined toward such things, just more expensive

9 VCAs, 9 DACs to control the VCAs, and a microcontroller to control the
DACs.

No need for switching at all, if I understand your intent correctly?

I readily acknowledge that digital isn't for everyone, though.

John

On Wed, 12 Dec 2018 at 13:57, David G Dixon <dixon at mail.ubc.ca> wrote:

> Roman,
>
> You're right.  Your suggestion is superior.  I was simply unaware of what
> a complete shit-show all this digital circuitry is.  This is exactly the
> reason why I avoid digital solutions whenever possible.  This module should
> be a pretty straightforward application of an analog multiplexer, but you
> are basically saying (and I concur based on my experience) that I can't use
> such a thing for clean audio, and to me, that is a sad indictment of these
> ICs.  I'm now switching these DG408s about as cleanly as is humanly
> possible, and they're still misbehaving.  It just shouldn't be this hard.
>
> So, I'm going to try to implement your idea, but I don't have the ICs I
> need.  I'm also still trying to understand exactly how the switching
> works.  I'm presuming that the 3914 must be in Dot mode, because only one
> comparator can be on at a time for this to work, and therefore, this
> circuit ONLY works with 3914, and cannot be implemented with a generic
> flash comparator chain.
>
> So, I'm going to finish off the circuit as it is, because it works pretty
> well, but I concede that I basically cannot use these fucked up digital
> chips to switch active audio circuits, and will build the next one your way.
>
> Cheers,
> Dave
>
> ------------------------------
> *From:* Synth-diy [mailto:synth-diy-bounces at synth-diy.org] *On Behalf Of *
> Roman
> *Sent:* Tuesday, December 11, 2018 1:20 PM
> *To:* synth-diy at synth-diy.org
> *Subject:* Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
>
> I know it's too late, as the circuit at this stage has already gone
> slightly different path, and I already gave up, but couldn't help drawing
> this little schemo that explains my idea of using single switches with that
> obsoleted chip. Switches should be DG444 or similar (0=closed, 1=open), or
> replace diodes with NAND gates and use any regular dirt cheap switch like
> 4066.
> There's no switching happening while VCA is open, provided that VCA
> control triangles match the edges of LM3914 stages. The only switched
> channels are the ones routed to muted VCA, so in theory there should be no
> clicking audible.
> Basicaly this is just the circuit that makes this input switching sequence:
> VCA-A:12233445566..
> VCA-B:11223344556...
> by creating one step overlap between stages. Only 6 inputs in this
> example, but can be extended to any other number.
> http://www.synthdiy.eu/files/scanner.png
>
> IMHO switching active channel will always produce some clicking for many
> reasons: not matched channels, difference between transistion times H->L
> and L->H as Ingo said, break-before-make feature of DG407, slow response of
> 4532, and who knows if not also charge injection.
>
> Roman
>
> Dnia 11 grudnia 2018 18:24 Ingo Debus <igg.debus at gmail.com> napisa?(a):
>
> Am 11.12.2018 um 08:10 schrieb David G Dixon <dixon at mail.ubc.ca>:
>
> There is now
> only one tiny problem: There is still an almost imperceptible click when
> the
> CV crosses 0V (and the logic control voltage crosses 2.5V) in the positive
> direction.  This is when the logic switches from 011 to 100 (i.e., all
> three
> bits change).  Interestingly, I don't hear the click at all when the CV
> goes
> in the other direction (100 to 011).
>
>
> Couldn?t this still be caused by a very brief ?forbidden state? during the
> transition from 011 to 100? In your case, the forbidden state would be 000
> (MSBit changes slower that the other two) or 111 (MSBit changes faster).
> Probably just a difference between rising and falling slope. Can you check
> with a scope?
>
> Ingo
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
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From tom at electricdruid.net  Wed Dec 12 12:41:22 2018
From: tom at electricdruid.net (Tom Wiltshire)
Date: Wed, 12 Dec 2018 11:41:22 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
Message-ID: <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>

Nine VCAs and DAC channels seems like too much hardware.

There?s nothing wrong with the switches, but I?d do it with two switches to select the inputs to two VCAs controlled by two DACs, and then a uP to control the switches and DACs. You can easily make sure that the VCA is shut off when the multiplexer switches, so there shouldn?t be any clicks even if the switch generates one.

==================
       Electric Druid
Synth & Stompbox DIY
==================

> On 12 Dec 2018, at 10:02, john slee <indigoid at oldcorollas.org> wrote:
> 
> I suspect a more-digital solution would be easier to get right, for people more inclined toward such things, just more expensive
> 
> 9 VCAs, 9 DACs to control the VCAs, and a microcontroller to control the DACs.
> 
> No need for switching at all, if I understand your intent correctly?
> 
> I readily acknowledge that digital isn't for everyone, though.
> 
> John
> 
> On Wed, 12 Dec 2018 at 13:57, David G Dixon <dixon at mail.ubc.ca> wrote:
> Roman,
>  
> You're right.  Your suggestion is superior.  I was simply unaware of what a complete shit-show all this digital circuitry is.  This is exactly the reason why I avoid digital solutions whenever possible.  This module should be a pretty straightforward application of an analog multiplexer, but you are basically saying (and I concur based on my experience) that I can't use such a thing for clean audio, and to me, that is a sad indictment of these ICs.  I'm now switching these DG408s about as cleanly as is humanly possible, and they're still misbehaving.  It just shouldn't be this hard.
>  
> So, I'm going to try to implement your idea, but I don't have the ICs I need.  I'm also still trying to understand exactly how the switching works.  I'm presuming that the 3914 must be in Dot mode, because only one comparator can be on at a time for this to work, and therefore, this circuit ONLY works with 3914,  and cannot be implemented with a generic flash comparator chain.
>  
> So, I'm going to finish off the circuit as it is, because it works pretty well, but I concede that I basically cannot use these fucked up digital chips to switch active audio circuits, and will build the next one your way.
>  
> Cheers,
> Dave
>  
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Roman
> Sent: Tuesday, December 11, 2018 1:20 PM
> To: synth-diy at synth-diy.org
> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> 
> I know it's too late, as the circuit at this stage has already gone slightly different path, and I already gave up, but couldn't help drawing this little schemo that explains my idea of using single switches with that obsoleted chip. Switches should be DG444 or similar (0=closed, 1=open), or replace diodes with NAND gates and use any regular dirt cheap switch like 4066.
> There's no switching happening while VCA is open, provided that VCA control triangles match the edges of LM3914 stages. The only switched channels are the ones routed to muted VCA, so in theory there should be no clicking audible.
> Basicaly this is just the circuit that makes this input switching sequence:
> VCA-A:12233445566..
> VCA-B:11223344556...
> by creating one step overlap between stages. Only 6 inputs in this example, but can be extended to any other number.
> http://www.synthdiy.eu/files/scanner.png
> 
> IMHO switching active channel will always produce some clicking for many reasons: not matched channels, difference between transistion times H->L and L->H as Ingo said, break-before-make feature of DG407, slow response of 4532, and who knows if not also charge injection.
> 
> Roman
> Dnia 11 grudnia 2018 18:24 Ingo Debus <igg.debus at gmail.com> napisa?(a):
> 
> Am 11.12.2018 um 08:10 schrieb David G Dixon <dixon at mail.ubc.ca>:
> 
> There is now
> only one tiny problem: There is still an almost imperceptible click when the
> CV crosses 0V (and the logic control voltage crosses 2.5V) in the positive
> direction.  This is when the logic switches from 011 to 100 (i.e., all three
> bits change).  Interestingly, I don't hear the click at all when the CV goes
> in the other direction (100 to 011).
> 
> Couldn?t this still be caused by a very brief ?forbidden state? during the transition from 011 to 100? In your case, the forbidden state would be 000 (MSBit changes slower that the other two) or 111 (MSBit changes faster). Probably just a difference between rising and falling slope. Can you check with a scope?
> 
> Ingo
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy




From rburnett at richieburnett.co.uk  Wed Dec 12 12:56:26 2018
From: rburnett at richieburnett.co.uk (rburnett at richieburnett.co.uk)
Date: Wed, 12 Dec 2018 11:56:26 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
 <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
Message-ID: <383419f8cb02c1c04667c5af1b268485@richieburnett.co.uk>

Agree with Tom and Roman.

It's not a case of "...if the switch generates a click".  If it's 
switching instantaneously between two arbitrary waveforms it's almost 
guaranteed to click, even if it switches cleanly without any rogue 
intermediate states!

-Richie,


On 2018-12-12 11:41, Tom Wiltshire wrote:
> Nine VCAs and DAC channels seems like too much hardware.
> 
> There?s nothing wrong with the switches, but I?d do it with two
> switches to select the inputs to two VCAs controlled by two DACs, and
> then a uP to control the switches and DACs. You can easily make sure
> that the VCA is shut off when the multiplexer switches, so there
> shouldn?t be any clicks even if the switch generates one.
> 
> ==================
>        Electric Druid
> Synth & Stompbox DIY
> ==================
> 
>> On 12 Dec 2018, at 10:02, john slee <indigoid at oldcorollas.org> wrote:
>> 
>> I suspect a more-digital solution would be easier to get right, for 
>> people more inclined toward such things, just more expensive
>> 
>> 9 VCAs, 9 DACs to control the VCAs, and a microcontroller to control 
>> the DACs.
>> 
>> No need for switching at all, if I understand your intent correctly?
>> 
>> I readily acknowledge that digital isn't for everyone, though.
>> 
>> John
>> 
>> On Wed, 12 Dec 2018 at 13:57, David G Dixon <dixon at mail.ubc.ca> wrote:
>> Roman,
>> 
>> You're right.  Your suggestion is superior.  I was simply unaware of 
>> what a complete shit-show all this digital circuitry is.  This is 
>> exactly the reason why I avoid digital solutions whenever possible.  
>> This module should be a pretty straightforward application of an 
>> analog multiplexer, but you are basically saying (and I concur based 
>> on my experience) that I can't use such a thing for clean audio, and 
>> to me, that is a sad indictment of these ICs.  I'm now switching these 
>> DG408s about as cleanly as is humanly possible, and they're still 
>> misbehaving.  It just shouldn't be this hard.
>> 
>> So, I'm going to try to implement your idea, but I don't have the ICs 
>> I need.  I'm also still trying to understand exactly how the switching 
>> works.  I'm presuming that the 3914 must be in Dot mode, because only 
>> one comparator can be on at a time for this to work, and therefore, 
>> this circuit ONLY works with 3914,  and cannot be implemented with a 
>> generic flash comparator chain.
>> 
>> So, I'm going to finish off the circuit as it is, because it works 
>> pretty well, but I concede that I basically cannot use these fucked up 
>> digital chips to switch active audio circuits, and will build the next 
>> one your way.
>> 
>> Cheers,
>> Dave
>> 
>> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of 
>> Roman
>> Sent: Tuesday, December 11, 2018 1:20 PM
>> To: synth-diy at synth-diy.org
>> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
>> 
>> I know it's too late, as the circuit at this stage has already gone 
>> slightly different path, and I already gave up, but couldn't help 
>> drawing this little schemo that explains my idea of using single 
>> switches with that obsoleted chip. Switches should be DG444 or similar 
>> (0=closed, 1=open), or replace diodes with NAND gates and use any 
>> regular dirt cheap switch like 4066.
>> There's no switching happening while VCA is open, provided that VCA 
>> control triangles match the edges of LM3914 stages. The only switched 
>> channels are the ones routed to muted VCA, so in theory there should 
>> be no clicking audible.
>> Basicaly this is just the circuit that makes this input switching 
>> sequence:
>> VCA-A:12233445566..
>> VCA-B:11223344556...
>> by creating one step overlap between stages. Only 6 inputs in this 
>> example, but can be extended to any other number.
>> http://www.synthdiy.eu/files/scanner.png
>> 
>> IMHO switching active channel will always produce some clicking for 
>> many reasons: not matched channels, difference between transistion 
>> times H->L and L->H as Ingo said, break-before-make feature of DG407, 
>> slow response of 4532, and who knows if not also charge injection.
>> 
>> Roman
>> Dnia 11 grudnia 2018 18:24 Ingo Debus <igg.debus at gmail.com> 
>> napisa?(a):
>> 
>> Am 11.12.2018 um 08:10 schrieb David G Dixon <dixon at mail.ubc.ca>:
>> 
>> There is now
>> only one tiny problem: There is still an almost imperceptible click 
>> when the
>> CV crosses 0V (and the logic control voltage crosses 2.5V) in the 
>> positive
>> direction.  This is when the logic switches from 011 to 100 (i.e., all 
>> three
>> bits change).  Interestingly, I don't hear the click at all when the 
>> CV goes
>> in the other direction (100 to 011).
>> 
>> Couldn?t this still be caused by a very brief ?forbidden state? during 
>> the transition from 011 to 100? In your case, the forbidden state 
>> would be 000 (MSBit changes slower that the other two) or 111 (MSBit 
>> changes faster). Probably just a difference between rising and falling 
>> slope. Can you check with a scope?
>> 
>> Ingo
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>> 
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy


From mars at pingdynasty.com  Wed Dec 12 14:42:29 2018
From: mars at pingdynasty.com (Martin Klang)
Date: Wed, 12 Dec 2018 13:42:29 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
 <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
Message-ID: <63ed0741-a0c8-0ee7-7c2a-979015777937@pingdynasty.com>

I understand you don't do microcontrollers David, but some of us are 
less fussy!


This is something I'm planning to prototype:

8 input channels going into two analogue switches, into two VCAs, with 
switches and VCAs controlled by an MCU. The MCU decides to switch an 
input only when the corresponding VCA is at -inf (ie when the other VCA 
is fully on).

Using an MCU means it's easy to do a bunch of things that would be very 
hard with analogue comparators:

- configurable cross-fade slopes using lookup tables

- cross-fade to start function (let the last input be crossfaded back to 
the first one so that a ramp input will produce a continuous, circular scan)

- adjustable range of active inputs

- LEDs to show which inputs are active and audible

- different modes: tracking, triggered, cycling


I was going to use two VCAs of a V2164 for the cross fading between the 
two multiplexed inputs. Driven by two 12bit DACs, controlled by CV read 
by a 12bit ADC. I think I'll be able to run both ADC and DAC at a pretty 
high rate, to achieve something like 16x oversampling at audio rate, 
which should give performance / dynamic range nearer to 16 bits.


The second two VCAs on the 2164 I was going to use to add a regular VCA 
with adjustable linearisation. With the input normalled to +10V and CV 
to the output from the scanner, this would let you control the 
'exponentiality' of the output. Alternatively you could use the scanner 
in triggered mode as an 8-stage envelope and VCA.


Martin



On 12/12/2018 11:41, Tom Wiltshire wrote:
> Nine VCAs and DAC channels seems like too much hardware.
>
> There?s nothing wrong with the switches, but I?d do it with two switches to select the inputs to two VCAs controlled by two DACs, and then a uP to control the switches and DACs. You can easily make sure that the VCA is shut off when the multiplexer switches, so there shouldn?t be any clicks even if the switch generates one.
>
> ==================
>         Electric Druid
> Synth & Stompbox DIY
> ==================
>
>> On 12 Dec 2018, at 10:02, john slee <indigoid at oldcorollas.org> wrote:
>>
>> I suspect a more-digital solution would be easier to get right, for people more inclined toward such things, just more expensive
>>
>> 9 VCAs, 9 DACs to control the VCAs, and a microcontroller to control the DACs.
>>
>> No need for switching at all, if I understand your intent correctly?
>>
>> I readily acknowledge that digital isn't for everyone, though.
>>
>> John
>>
>> On Wed, 12 Dec 2018 at 13:57, David G Dixon <dixon at mail.ubc.ca> wrote:
>> Roman,
>>   
>> You're right.  Your suggestion is superior.  I was simply unaware of what a complete shit-show all this digital circuitry is.  This is exactly the reason why I avoid digital solutions whenever possible.  This module should be a pretty straightforward application of an analog multiplexer, but you are basically saying (and I concur based on my experience) that I can't use such a thing for clean audio, and to me, that is a sad indictment of these ICs.  I'm now switching these DG408s about as cleanly as is humanly possible, and they're still misbehaving.  It just shouldn't be this hard.
>>   
>> So, I'm going to try to implement your idea, but I don't have the ICs I need.  I'm also still trying to understand exactly how the switching works.  I'm presuming that the 3914 must be in Dot mode, because only one comparator can be on at a time for this to work, and therefore, this circuit ONLY works with 3914,  and cannot be implemented with a generic flash comparator chain.
>>   
>> So, I'm going to finish off the circuit as it is, because it works pretty well, but I concede that I basically cannot use these fucked up digital chips to switch active audio circuits, and will build the next one your way.
>>   
>> Cheers,
>> Dave
>>   
>> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Roman
>> Sent: Tuesday, December 11, 2018 1:20 PM
>> To: synth-diy at synth-diy.org
>> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
>>
>> I know it's too late, as the circuit at this stage has already gone slightly different path, and I already gave up, but couldn't help drawing this little schemo that explains my idea of using single switches with that obsoleted chip. Switches should be DG444 or similar (0=closed, 1=open), or replace diodes with NAND gates and use any regular dirt cheap switch like 4066.
>> There's no switching happening while VCA is open, provided that VCA control triangles match the edges of LM3914 stages. The only switched channels are the ones routed to muted VCA, so in theory there should be no clicking audible.
>> Basicaly this is just the circuit that makes this input switching sequence:
>> VCA-A:12233445566..
>> VCA-B:11223344556...
>> by creating one step overlap between stages. Only 6 inputs in this example, but can be extended to any other number.
>> http://www.synthdiy.eu/files/scanner.png
>>
>> IMHO switching active channel will always produce some clicking for many reasons: not matched channels, difference between transistion times H->L and L->H as Ingo said, break-before-make feature of DG407, slow response of 4532, and who knows if not also charge injection.
>>
>> Roman
>> Dnia 11 grudnia 2018 18:24 Ingo Debus <igg.debus at gmail.com> napisa?(a):
>>
>> Am 11.12.2018 um 08:10 schrieb David G Dixon <dixon at mail.ubc.ca>:
>>
>> There is now
>> only one tiny problem: There is still an almost imperceptible click when the
>> CV crosses 0V (and the logic control voltage crosses 2.5V) in the positive
>> direction.  This is when the logic switches from 011 to 100 (i.e., all three
>> bits change).  Interestingly, I don't hear the click at all when the CV goes
>> in the other direction (100 to 011).
>>
>> Couldn?t this still be caused by a very brief ?forbidden state? during the transition from 011 to 100? In your case, the forbidden state would be 000 (MSBit changes slower that the other two) or 111 (MSBit changes faster). Probably just a difference between rising and falling slope. Can you check with a scope?
>>
>> Ingo
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy


From electronicpresskit at gmail.com  Wed Dec 12 15:47:42 2018
From: electronicpresskit at gmail.com (Erik Dower)
Date: Wed, 12 Dec 2018 15:47:42 +0100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
Message-ID: <BF787287-37FC-45D3-B14F-BF19168D34BE@gmail.com>

FWIW, the quad panner I made for the Poltergeist uses separate vcas for each output, and DG444 with LM339 to switch the control circuitry between them. As others have mentioned, the switching occurs when the vcas are totally off so clicks are not heard.

epk

> On Dec 12, 2018, at 3:53 AM, David G Dixon <dixon at mail.ubc.ca> wrote:
> 
> Roman,
>  
> You're right.  Your suggestion is superior.  I was simply unaware of what a complete shit-show all this digital circuitry is.  This is exactly the reason why I avoid digital solutions whenever possible.  This module should be a pretty straightforward application of an analog multiplexer, but you are basically saying (and I concur based on my experience) that I can't use such a thing for clean audio, and to me, that is a sad indictment of these ICs.  I'm now switching these DG408s about as cleanly as is humanly possible, and they're still misbehaving.  It just shouldn't be this hard.
-------------- next part --------------
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From rburnett at richieburnett.co.uk  Wed Dec 12 15:51:35 2018
From: rburnett at richieburnett.co.uk (rburnett at richieburnett.co.uk)
Date: Wed, 12 Dec 2018 14:51:35 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <63ed0741-a0c8-0ee7-7c2a-979015777937@pingdynasty.com>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
 <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
 <63ed0741-a0c8-0ee7-7c2a-979015777937@pingdynasty.com>
Message-ID: <6cd10597ba36475515a601624c91a5c8@richieburnett.co.uk>

I haven't done the calculations, but I'm left wondering whether or not 
you can do this "multi-input crossfade scanner" thing well enough using 
just fast PWM of the analogue switches themselves, and ditch the VCA's 
altogether.

-Richie,



On 2018-12-12 13:42, Martin Klang wrote:
> I understand you don't do microcontrollers David, but some of us are 
> less fussy!
> 
> 
> This is something I'm planning to prototype:
> 
> 8 input channels going into two analogue switches, into two VCAs, with
> switches and VCAs controlled by an MCU. The MCU decides to switch an
> input only when the corresponding VCA is at -inf (ie when the other
> VCA is fully on).
> 
> Using an MCU means it's easy to do a bunch of things that would be
> very hard with analogue comparators:
> 
> - configurable cross-fade slopes using lookup tables
> 
> - cross-fade to start function (let the last input be crossfaded back
> to the first one so that a ramp input will produce a continuous,
> circular scan)
> 
> - adjustable range of active inputs
> 
> - LEDs to show which inputs are active and audible
> 
> - different modes: tracking, triggered, cycling
> 
> 
> I was going to use two VCAs of a V2164 for the cross fading between
> the two multiplexed inputs. Driven by two 12bit DACs, controlled by CV
> read by a 12bit ADC. I think I'll be able to run both ADC and DAC at a
> pretty high rate, to achieve something like 16x oversampling at audio
> rate, which should give performance / dynamic range nearer to 16 bits.
> 
> 
> The second two VCAs on the 2164 I was going to use to add a regular
> VCA with adjustable linearisation. With the input normalled to +10V
> and CV to the output from the scanner, this would let you control the
> 'exponentiality' of the output. Alternatively you could use the
> scanner in triggered mode as an 8-stage envelope and VCA.
> 
> 
> Martin
> 
> 
> 
> On 12/12/2018 11:41, Tom Wiltshire wrote:
>> Nine VCAs and DAC channels seems like too much hardware.
>> 
>> There?s nothing wrong with the switches, but I?d do it with two 
>> switches to select the inputs to two VCAs controlled by two DACs, and 
>> then a uP to control the switches and DACs. You can easily make sure 
>> that the VCA is shut off when the multiplexer switches, so there 
>> shouldn?t be any clicks even if the switch generates one.
>> 
>> ==================
>>         Electric Druid
>> Synth & Stompbox DIY
>> ==================
>> 
>>> On 12 Dec 2018, at 10:02, john slee <indigoid at oldcorollas.org> wrote:
>>> 
>>> I suspect a more-digital solution would be easier to get right, for 
>>> people more inclined toward such things, just more expensive
>>> 
>>> 9 VCAs, 9 DACs to control the VCAs, and a microcontroller to control 
>>> the DACs.
>>> 
>>> No need for switching at all, if I understand your intent correctly?
>>> 
>>> I readily acknowledge that digital isn't for everyone, though.
>>> 
>>> John
>>> 
>>> On Wed, 12 Dec 2018 at 13:57, David G Dixon <dixon at mail.ubc.ca> 
>>> wrote:
>>> Roman,
>>>   You're right.  Your suggestion is superior.  I was simply unaware 
>>> of what a complete shit-show all this digital circuitry is.  This is 
>>> exactly the reason why I avoid digital solutions whenever possible.  
>>> This module should be a pretty straightforward application of an 
>>> analog multiplexer, but you are basically saying (and I concur based 
>>> on my experience) that I can't use such a thing for clean audio, and 
>>> to me, that is a sad indictment of these ICs.  I'm now switching 
>>> these DG408s about as cleanly as is humanly possible, and they're 
>>> still misbehaving.  It just shouldn't be this hard.
>>>   So, I'm going to try to implement your idea, but I don't have the 
>>> ICs I need.  I'm also still trying to understand exactly how the 
>>> switching works.  I'm presuming that the 3914 must be in Dot mode, 
>>> because only one comparator can be on at a time for this to work, and 
>>> therefore, this circuit ONLY works with 3914,  and cannot be 
>>> implemented with a generic flash comparator chain.
>>>   So, I'm going to finish off the circuit as it is, because it works 
>>> pretty well, but I concede that I basically cannot use these fucked 
>>> up digital chips to switch active audio circuits, and will build the 
>>> next one your way.
>>>   Cheers,
>>> Dave
>>>   From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf 
>>> Of Roman
>>> Sent: Tuesday, December 11, 2018 1:20 PM
>>> To: synth-diy at synth-diy.org
>>> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with 
>>> DG408)
>>> 
>>> I know it's too late, as the circuit at this stage has already gone 
>>> slightly different path, and I already gave up, but couldn't help 
>>> drawing this little schemo that explains my idea of using single 
>>> switches with that obsoleted chip. Switches should be DG444 or 
>>> similar (0=closed, 1=open), or replace diodes with NAND gates and use 
>>> any regular dirt cheap switch like 4066.
>>> There's no switching happening while VCA is open, provided that VCA 
>>> control triangles match the edges of LM3914 stages. The only switched 
>>> channels are the ones routed to muted VCA, so in theory there should 
>>> be no clicking audible.
>>> Basicaly this is just the circuit that makes this input switching 
>>> sequence:
>>> VCA-A:12233445566..
>>> VCA-B:11223344556...
>>> by creating one step overlap between stages. Only 6 inputs in this 
>>> example, but can be extended to any other number.
>>> http://www.synthdiy.eu/files/scanner.png
>>> 
>>> IMHO switching active channel will always produce some clicking for 
>>> many reasons: not matched channels, difference between transistion 
>>> times H->L and L->H as Ingo said, break-before-make feature of DG407, 
>>> slow response of 4532, and who knows if not also charge injection.
>>> 
>>> Roman
>>> Dnia 11 grudnia 2018 18:24 Ingo Debus <igg.debus at gmail.com> 
>>> napisa?(a):
>>> 
>>> Am 11.12.2018 um 08:10 schrieb David G Dixon <dixon at mail.ubc.ca>:
>>> 
>>> There is now
>>> only one tiny problem: There is still an almost imperceptible click 
>>> when the
>>> CV crosses 0V (and the logic control voltage crosses 2.5V) in the 
>>> positive
>>> direction.  This is when the logic switches from 011 to 100 (i.e., 
>>> all three
>>> bits change).  Interestingly, I don't hear the click at all when the 
>>> CV goes
>>> in the other direction (100 to 011).
>>> 
>>> Couldn?t this still be caused by a very brief ?forbidden state? 
>>> during the transition from 011 to 100? In your case, the forbidden 
>>> state would be 000 (MSBit changes slower that the other two) or 111 
>>> (MSBit changes faster). Probably just a difference between rising and 
>>> falling slope. Can you check with a scope?
>>> 
>>> Ingo
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>> 
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy
>> 
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy


From guy.mccusker at gmail.com  Wed Dec 12 16:07:15 2018
From: guy.mccusker at gmail.com (Guy McCusker)
Date: Wed, 12 Dec 2018 15:07:15 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <6cd10597ba36475515a601624c91a5c8@richieburnett.co.uk>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
 <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
 <63ed0741-a0c8-0ee7-7c2a-979015777937@pingdynasty.com>
 <6cd10597ba36475515a601624c91a5c8@richieburnett.co.uk>
Message-ID: <CAPx-PW7dPFkUVm9U1xtNW4oeeK3rvMT_4O0ZSvCYMTm2zJ-69A@mail.gmail.com>

On Wed, Dec 12, 2018 at 2:52 PM <rburnett at richieburnett.co.uk> wrote:
>
> I haven't done the calculations, but I'm left wondering whether or not
> you can do this "multi-input crossfade scanner" thing well enough using
> just fast PWM of the analogue switches themselves, and ditch the VCA's
> altogether.

Interesting idea. But how would we overcome the clicking issue?

Grant Richter's Electro-Optical Mixer used an LM3914 with a
"dithering" i.e. PWM controller to create crossfades using vactrols.
https://web.archive.org/web/20110720183735/http://www.musicsynthesizer.com/Corpse/VCEOM.html
Somehow the PWM idea feels similar to that. Richter's circuit takes
advantage of the slow response of the vactrols to smooth out the
response. Presumably your idea would involve some explicit integration
for the same purpose? Could that also reduce the clicking, without
low-pass-filtering the audio too much?


From vladoman at gmail.com  Wed Dec 12 16:42:21 2018
From: vladoman at gmail.com (Vladimir Pantelic)
Date: Wed, 12 Dec 2018 16:42:21 +0100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <6cd10597ba36475515a601624c91a5c8@richieburnett.co.uk>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
 <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
 <63ed0741-a0c8-0ee7-7c2a-979015777937@pingdynasty.com>
 <6cd10597ba36475515a601624c91a5c8@richieburnett.co.uk>
Message-ID: <474253d1-ddf9-fad6-2f8b-c93a5bca7757@gmail.com>

On 12.12.2018 15:51, rburnett at richieburnett.co.uk wrote:
> I haven't done the calculations, but I'm left wondering whether or not
> you can do this "multi-input crossfade scanner" thing well enough using
> just fast PWM of the analogue switches themselves, and ditch the VCA's
> altogether.
> 
> -Richie,

I had the same idea to do this with my 8x8 summing matrix by updating
the analog switches at the highest rate possible, but never got down to
write the code ;)


From rburnett at richieburnett.co.uk  Wed Dec 12 17:21:12 2018
From: rburnett at richieburnett.co.uk (rburnett at richieburnett.co.uk)
Date: Wed, 12 Dec 2018 16:21:12 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <CAPx-PW7dPFkUVm9U1xtNW4oeeK3rvMT_4O0ZSvCYMTm2zJ-69A@mail.gmail.com>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
 <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
 <63ed0741-a0c8-0ee7-7c2a-979015777937@pingdynasty.com>
 <6cd10597ba36475515a601624c91a5c8@richieburnett.co.uk>
 <CAPx-PW7dPFkUVm9U1xtNW4oeeK3rvMT_4O0ZSvCYMTm2zJ-69A@mail.gmail.com>
Message-ID: <c31bfe9a72c41ce99120ac6bd16f4ebf@richieburnett.co.uk>

You connect each input to a summing amplifier via its own analogue 
switch.  Each analogue switch mimics the behaviour of a VCA by 
Pulse-Width-Modulating it's control signal, and then low-pass filtering 
the output from the summing amplifier.  A low-cost micro generates the 
PWM signals to control the crossfade...

One switch's control signal has duty ratio ramping down from 100% to 0%, 
whilst another switch's control signal has duty ratio ramping up from 0% 
to 100%.  (Use whatever control law you want for the crossfade:  Linear, 
Constant power, etc...)  Only two PWM streams are active and need to be 
generated at any given time so shouldn't be too demanding on a low-end 
micro.

Where PWM "VCAs" fall down is the dynamic range.  Since the control is 
linear it's hard to get perceptually fine control when the gain is down 
at -50dB or so.  For a volume control I can see that this is a 
significant shortfall.  However, for a crossfader it might be less of a 
problem because presumably the signal "coming in" perceptually masks the 
tail of the very quiet signal "going out" ?

-Richie,


On 2018-12-12 15:07, Guy McCusker wrote:
> On Wed, Dec 12, 2018 at 2:52 PM <rburnett at richieburnett.co.uk> wrote:
>> 
>> I haven't done the calculations, but I'm left wondering whether or not
>> you can do this "multi-input crossfade scanner" thing well enough 
>> using
>> just fast PWM of the analogue switches themselves, and ditch the VCA's
>> altogether.
> 
> Interesting idea. But how would we overcome the clicking issue?
> 
> Grant Richter's Electro-Optical Mixer used an LM3914 with a
> "dithering" i.e. PWM controller to create crossfades using vactrols.
> https://web.archive.org/web/20110720183735/http://www.musicsynthesizer.com/Corpse/VCEOM.html
> Somehow the PWM idea feels similar to that. Richter's circuit takes
> advantage of the slow response of the vactrols to smooth out the
> response. Presumably your idea would involve some explicit integration
> for the same purpose? Could that also reduce the clicking, without
> low-pass-filtering the audio too much?
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy


From guy.mccusker at gmail.com  Wed Dec 12 17:27:59 2018
From: guy.mccusker at gmail.com (Guy McCusker)
Date: Wed, 12 Dec 2018 16:27:59 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <c31bfe9a72c41ce99120ac6bd16f4ebf@richieburnett.co.uk>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
 <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
 <63ed0741-a0c8-0ee7-7c2a-979015777937@pingdynasty.com>
 <6cd10597ba36475515a601624c91a5c8@richieburnett.co.uk>
 <CAPx-PW7dPFkUVm9U1xtNW4oeeK3rvMT_4O0ZSvCYMTm2zJ-69A@mail.gmail.com>
 <c31bfe9a72c41ce99120ac6bd16f4ebf@richieburnett.co.uk>
Message-ID: <CAPx-PW5NoC7W+J16HqzZ6SytBGVdj0WJ_t_6dW_M2+6KFyw70g@mail.gmail.com>

On Wed, Dec 12, 2018 at 4:21 PM <rburnett at richieburnett.co.uk> wrote:

> One switch's control signal has duty ratio ramping down from 100% to 0%,
> whilst another switch's control signal has duty ratio ramping up from 0%
> to 100%.  (Use whatever control law you want for the crossfade:  Linear,
> Constant power, etc...)  Only two PWM streams are active and need to be
> generated at any given time so shouldn't be too demanding on a low-end
> micro.

Thanks for spelling it out.

This is exactly the control regimen that the Richter circuit achieves
with the LM3914 and dithering oscillator. In that circuit the LM3914
outputs were used to drive vactrols which attenuate the input to the
summing amplifier but it seems to me one could use them to drive the
switches in this design instead. Richter's oscillator runs at 44kHz,
which is presumably fast enough for this design too?


From rburnett at richieburnett.co.uk  Wed Dec 12 19:54:18 2018
From: rburnett at richieburnett.co.uk (Richie Burnett)
Date: Wed, 12 Dec 2018 18:54:18 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <CAPx-PW5NoC7W+J16HqzZ6SytBGVdj0WJ_t_6dW_M2+6KFyw70g@mail.gmail.com>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
 <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
 <63ed0741-a0c8-0ee7-7c2a-979015777937@pingdynasty.com>
 <6cd10597ba36475515a601624c91a5c8@richieburnett.co.uk>
 <CAPx-PW7dPFkUVm9U1xtNW4oeeK3rvMT_4O0ZSvCYMTm2zJ-69A@mail.gmail.com>
 <c31bfe9a72c41ce99120ac6bd16f4ebf@richieburnett.co.uk>
 <CAPx-PW5NoC7W+J16HqzZ6SytBGVdj0WJ_t_6dW_M2+6KFyw70g@mail.gmail.com>
Message-ID: <a72k53sh7tkf0es4wiklhxrx.1544640858113@email.android.com>

Probably represents the bare minimum.

It depends how much you want to filter out the HF switching carrier. 

-Richie,

Sent from my Xperia SP on O2

---- Guy McCusker wrote ----

>On Wed, Dec 12, 2018 at 4:21 PM <rburnett at richieburnett.co.uk> wrote:
>
>> One switch's control signal has duty ratio ramping down from 100% to 0%,
>> whilst another switch's control signal has duty ratio ramping up from 0%
>> to 100%.  (Use whatever control law you want for the crossfade:  Linear,
>> Constant power, etc...)  Only two PWM streams are active and need to be
>> generated at any given time so shouldn't be too demanding on a low-end
>> micro.
>
>Thanks for spelling it out.
>
>This is exactly the control regimen that the Richter circuit achieves
>with the LM3914 and dithering oscillator. In that circuit the LM3914
>outputs were used to drive vactrols which attenuate the input to the
>summing amplifier but it seems to me one could use them to drive the
>switches in this design instead. Richter's oscillator runs at 44kHz,
>which is presumably fast enough for this design too?
>_______________________________________________
>Synth-diy mailing list
>Synth-diy at synth-diy.org
>http://synth-diy.org/mailman/listinfo/synth-diy



From dixon at mail.ubc.ca  Wed Dec 12 23:26:43 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Wed, 12 Dec 2018 14:26:43 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <45eaa7fb-44c1-34f6-b239-6a6792065dce@go2.pl>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <45eaa7fb-44c1-34f6-b239-6a6792065dce@go2.pl>
Message-ID: <8DA0C02F96EB43A1B238E536AB937074@galvanox01>

I guess that's easier than what I was thinking of (encoder to decoder),
although not really more efficient parts-count-wise. 

> -----Original Message-----
> From: Roman Sowa [mailto:modular at go2.pl] 
> Sent: Wednesday, December 12, 2018 1:05 AM
> To: David G Dixon; synth-diy at synth-diy.org
> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> 
> I'm glad I could help.
> 
> Yes, it must work in dot mode. One way of making dot mode out 
> of comparator chain is this:
> http://www.synthdiy.eu/files/dotmode.png
> with different wiring there's 1 of 8 dot mode possible or the 
> one that does what's needed for crossfader based scanner - 2 
> of 8 dot mode.
> 
> Roman
> 
> W dniu 2018-12-12 o?03:53, David G Dixon pisze:
> > Roman,
> > You're right.? Your suggestion is superior.? I was simply 
> unaware of 
> > what a complete shit-show all this digital circuitry is. This is 
> > exactly the reason why I avoid digital solutions whenever 
> possible.? 
> > This module should be a pretty straightforward application of an 
> > analog multiplexer, but you are basically saying (and I 
> concur based 
> > on my experience) that I can't use such a thing for clean 
> audio, and 
> > to me, that is a sad?indictment of these ICs.? I'm now 
> switching these 
> > DG408s about as cleanly as is?humanly possible, and they're still 
> > misbehaving.? It just shouldn't be this hard.
> > So, I'm going to try to implement your idea, but I don't 
> have the ICs 
> > I need.? I'm also still trying to understand?exactly how?
> the switching 
> > works.? I'm presuming that the 3914 must be in Dot mode, 
> because only 
> > one comparator can be on at a time for this to work, and therefore, 
> > this circuit ONLY works with 3914, and cannot be implemented with a 
> > generic flash comparator chain.
> > So, I'm going to finish off the circuit as it is, because it works 
> > pretty well, but I concede that I basically cannot use 
> these fucked up 
> > digital chips to switch active audio circuits, and will 
> build the next 
> > one your way.
> > Cheers,
> > Dave
> > 
> ----------------------------------------------------------------------
> > --
> > *From:* Synth-diy [mailto:synth-diy-bounces at synth-diy.org] 
> *On Behalf 
> > Of *Roman
> > *Sent:* Tuesday, December 11, 2018 1:20 PM
> > *To:* synth-diy at synth-diy.org
> > *Subject:* Re: [sdiy] Help, I'm Desperate! (Charge Injection with 
> > DG408)
> > 
> >     I know it's too late, as the circuit at this stage has 
> already gone
> >     slightly different path, and I already gave up, but 
> couldn't help
> >     drawing this little schemo that explains my idea of using single
> >     switches with that obsoleted chip. Switches should be DG444 or
> >     similar (0=closed, 1=open), or replace diodes with NAND 
> gates and
> >     use any regular dirt cheap switch like 4066.
> >     There's no switching happening while VCA is open, 
> provided that VCA
> >     control triangles match the edges of LM3914 stages. The only
> >     switched channels are the ones routed to muted VCA, so in theory
> >     there should be no clicking audible.
> >     Basicaly this is just the circuit that makes this input 
> switching
> >     sequence:
> >     VCA-A:12233445566..
> >     VCA-B:11223344556...
> >     by creating one step overlap between stages. Only 6 
> inputs in this
> >     example, but can be extended to any other number.
> >     http://www.synthdiy.eu/files/scanner.png
> > 
> >     IMHO switching active channel will always produce some 
> clicking for
> >     many reasons: not matched channels, difference between 
> transistion
> >     times H->L and L->H as Ingo said, break-before-make feature of
> >     DG407, slow response of 4532, and who knows if not also charge
> >     injection.
> > 
> >     Roman
> > 
> >     Dnia 11 grudnia 2018 18:24 Ingo Debus 
> <igg.debus at gmail.com> napisa?(a):
> > 
> >             Am 11.12.2018 um 08:10 schrieb David G Dixon
> >             <dixon at mail.ubc.ca>:
> > 
> >             There is now
> >             only one tiny problem: There is still an almost
> >             imperceptible click when the
> >             CV crosses 0V (and the logic control voltage 
> crosses 2.5V)
> >             in the positive
> >             direction. ?This is when the logic switches 
> from 011 to 100
> >             (i.e., all three
> >             bits change). ?Interestingly, I don't hear the 
> click at all
> >             when the CV goes
> >             in the other direction (100 to 011).
> > 
> > 
> >         Couldn't this still be caused by a very brief 
> "forbidden state"
> >         during the transition from 011 to 100? In your case, the
> >         forbidden state would be 000 (MSBit changes slower that the
> >         other two) or 111 (MSBit changes faster). Probably just a
> >         difference between rising and falling slope. Can 
> you check with
> >         a scope?
> > 
> >         Ingo
> >         _______________________________________________
> >         Synth-diy mailing list
> >         Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
> >         http://synth-diy.org/mailman/listinfo/synth-diy
> > 
> > 




From dixon at mail.ubc.ca  Wed Dec 12 23:29:32 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Wed, 12 Dec 2018 14:29:32 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <383419f8cb02c1c04667c5af1b268485@richieburnett.co.uk>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
 <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
 <383419f8cb02c1c04667c5af1b268485@richieburnett.co.uk>
Message-ID: <84383B620F12480BA0AC2FC31EA57BD1@galvanox01>

> Agree with Tom and Roman.
> 
> It's not a case of "...if the switch generates a click".  If 
> it's switching instantaneously between two arbitrary 
> waveforms it's almost guaranteed to click, even if it 
> switches cleanly without any rogue intermediate states!

Yes, but it's switching between the same inputs.  Literally, two adjacent
pins of the multiplexer are soldered to the same trace.  There is still a
click (but, as I said, now only one, at the switch from S4 to S5, and only
in one direction, and it's very faint and doesn't even happen every time).



From dixon at mail.ubc.ca  Wed Dec 12 23:36:35 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Wed, 12 Dec 2018 14:36:35 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <63ed0741-a0c8-0ee7-7c2a-979015777937@pingdynasty.com>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
 <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
 <63ed0741-a0c8-0ee7-7c2a-979015777937@pingdynasty.com>
Message-ID: <391E86CDE72844ECB0B673894861C769@galvanox01>

Sounds cool, Martin.

I already had a scanner with separate VCAs for each channel, and it worked
great, but involved too much circuitry.  It did some of the things you
mention -- there's a video of it on Youtube -- but I wanted something
simpler, and the multiplexer thing seemed really elegant.  I didn't realize
that these logic issues were such a pain in the ass. 

> -----Original Message-----
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On 
> Behalf Of Martin Klang
> Sent: Wednesday, December 12, 2018 5:42 AM
> To: synth-diy at synth-diy.org
> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> 
> I understand you don't do microcontrollers David, but some of 
> us are less fussy!
> 
> 
> This is something I'm planning to prototype:
> 
> 8 input channels going into two analogue switches, into two 
> VCAs, with 
> switches and VCAs controlled by an MCU. The MCU decides to switch an 
> input only when the corresponding VCA is at -inf (ie when the 
> other VCA 
> is fully on).
> 
> Using an MCU means it's easy to do a bunch of things that 
> would be very 
> hard with analogue comparators:
> 
> - configurable cross-fade slopes using lookup tables
> 
> - cross-fade to start function (let the last input be 
> crossfaded back to 
> the first one so that a ramp input will produce a continuous, 
> circular scan)
> 
> - adjustable range of active inputs
> 
> - LEDs to show which inputs are active and audible
> 
> - different modes: tracking, triggered, cycling
> 
> 
> I was going to use two VCAs of a V2164 for the cross fading 
> between the 
> two multiplexed inputs. Driven by two 12bit DACs, controlled 
> by CV read 
> by a 12bit ADC. I think I'll be able to run both ADC and DAC 
> at a pretty 
> high rate, to achieve something like 16x oversampling at audio rate, 
> which should give performance / dynamic range nearer to 16 bits.
> 
> 
> The second two VCAs on the 2164 I was going to use to add a 
> regular VCA 
> with adjustable linearisation. With the input normalled to 
> +10V and CV 
> to the output from the scanner, this would let you control the 
> 'exponentiality' of the output. Alternatively you could use 
> the scanner 
> in triggered mode as an 8-stage envelope and VCA.
> 
> 
> Martin
> 
> 
> 
> On 12/12/2018 11:41, Tom Wiltshire wrote:
> > Nine VCAs and DAC channels seems like too much hardware.
> >
> > There's nothing wrong with the switches, but I'd do it with 
> two switches to select the inputs to two VCAs controlled by 
> two DACs, and then a uP to control the switches and DACs. You 
> can easily make sure that the VCA is shut off when the 
> multiplexer switches, so there shouldn't be any clicks even 
> if the switch generates one.
> >
> > ==================
> >         Electric Druid
> > Synth & Stompbox DIY
> > ==================
> >
> >> On 12 Dec 2018, at 10:02, john slee 
> <indigoid at oldcorollas.org> wrote:
> >>
> >> I suspect a more-digital solution would be easier to get 
> right, for people more inclined toward such things, just more 
> expensive
> >>
> >> 9 VCAs, 9 DACs to control the VCAs, and a microcontroller 
> to control the DACs.
> >>
> >> No need for switching at all, if I understand your intent 
> correctly?
> >>
> >> I readily acknowledge that digital isn't for everyone, though.
> >>
> >> John
> >>
> >> On Wed, 12 Dec 2018 at 13:57, David G Dixon 
> <dixon at mail.ubc.ca> wrote:
> >> Roman,
> >>   
> >> You're right.  Your suggestion is superior.  I was simply 
> unaware of what a complete shit-show all this digital 
> circuitry is.  This is exactly the reason why I avoid digital 
> solutions whenever possible.  This module should be a pretty 
> straightforward application of an analog multiplexer, but you 
> are basically saying (and I concur based on my experience) 
> that I can't use such a thing for clean audio, and to me, 
> that is a sad indictment of these ICs.  I'm now switching 
> these DG408s about as cleanly as is humanly possible, and 
> they're still misbehaving.  It just shouldn't be this hard.
> >>   
> >> So, I'm going to try to implement your idea, but I don't 
> have the ICs I need.  I'm also still trying to understand 
> exactly how the switching works.  I'm presuming that the 3914 
> must be in Dot mode, because only one comparator can be on at 
> a time for this to work, and therefore, this circuit ONLY 
> works with 3914,  and cannot be implemented with a generic 
> flash comparator chain.
> >>   
> >> So, I'm going to finish off the circuit as it is, because 
> it works pretty well, but I concede that I basically cannot 
> use these fucked up digital chips to switch active audio 
> circuits, and will build the next one your way.
> >>   
> >> Cheers,
> >> Dave
> >>   
> >> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] 
> On Behalf Of Roman
> >> Sent: Tuesday, December 11, 2018 1:20 PM
> >> To: synth-diy at synth-diy.org
> >> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection 
> with DG408)
> >>
> >> I know it's too late, as the circuit at this stage has 
> already gone slightly different path, and I already gave up, 
> but couldn't help drawing this little schemo that explains my 
> idea of using single switches with that obsoleted chip. 
> Switches should be DG444 or similar (0=closed, 1=open), or 
> replace diodes with NAND gates and use any regular dirt cheap 
> switch like 4066.
> >> There's no switching happening while VCA is open, provided 
> that VCA control triangles match the edges of LM3914 stages. 
> The only switched channels are the ones routed to muted VCA, 
> so in theory there should be no clicking audible.
> >> Basicaly this is just the circuit that makes this input 
> switching sequence:
> >> VCA-A:12233445566..
> >> VCA-B:11223344556...
> >> by creating one step overlap between stages. Only 6 inputs 
> in this example, but can be extended to any other number.
> >> http://www.synthdiy.eu/files/scanner.png
> >>
> >> IMHO switching active channel will always produce some 
> clicking for many reasons: not matched channels, difference 
> between transistion times H->L and L->H as Ingo said, 
> break-before-make feature of DG407, slow response of 4532, 
> and who knows if not also charge injection.
> >>
> >> Roman
> >> Dnia 11 grudnia 2018 18:24 Ingo Debus 
> <igg.debus at gmail.com> napisa?(a):
> >>
> >> Am 11.12.2018 um 08:10 schrieb David G Dixon <dixon at mail.ubc.ca>:
> >>
> >> There is now
> >> only one tiny problem: There is still an almost 
> imperceptible click when the
> >> CV crosses 0V (and the logic control voltage crosses 2.5V) 
> in the positive
> >> direction.  This is when the logic switches from 011 to 
> 100 (i.e., all three
> >> bits change).  Interestingly, I don't hear the click at 
> all when the CV goes
> >> in the other direction (100 to 011).
> >>
> >> Couldn't this still be caused by a very brief "forbidden 
> state" during the transition from 011 to 100? In your case, 
> the forbidden state would be 000 (MSBit changes slower that 
> the other two) or 111 (MSBit changes faster). Probably just a 
> difference between rising and falling slope. Can you check 
> with a scope?
> >>
> >> Ingo
> >> _______________________________________________
> >> Synth-diy mailing list
> >> Synth-diy at synth-diy.org
> >> http://synth-diy.org/mailman/listinfo/synth-diy
> >>
> >> _______________________________________________
> >> Synth-diy mailing list
> >> Synth-diy at synth-diy.org
> >> http://synth-diy.org/mailman/listinfo/synth-diy
> >> _______________________________________________
> >> Synth-diy mailing list
> >> Synth-diy at synth-diy.org
> >> http://synth-diy.org/mailman/listinfo/synth-diy
> >
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> 




From indigoid at oldcorollas.org  Thu Dec 13 00:15:29 2018
From: indigoid at oldcorollas.org (john slee)
Date: Thu, 13 Dec 2018 10:15:29 +1100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
 <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
Message-ID: <CAK+JDy3mBo2vksAvaDJOxPOFMFGL0EJMqW4X9LCoT0x9wk6P=Q@mail.gmail.com>

It is a lot of hardware, yes. However it would let you have any arbitrary
mix of inputs mixed into the output, rather than being a scanner.

I?m thinking here of the Radiate control on the Make Noise RxMx, where the
?channel span? of the scanner is voltage-controlled. AFAIK their
implementation is all analog, so clearly it doesn?t need to be digital.

John


On Wed, 12 Dec 2018 at 22:41, Tom Wiltshire <tom at electricdruid.net> wrote:

> Nine VCAs and DAC channels seems like too much hardware.
>
> There?s nothing wrong with the switches, but I?d do it with two switches
> to select the inputs to two VCAs controlled by two DACs, and then a uP to
> control the switches and DACs. You can easily make sure that the VCA is
> shut off when the multiplexer switches, so there shouldn?t be any clicks
> even if the switch generates one.
>
> ==================
>        Electric Druid
> Synth & Stompbox DIY
> ==================
>
> > On 12 Dec 2018, at 10:02, john slee <indigoid at oldcorollas.org> wrote:
> >
> > I suspect a more-digital solution would be easier to get right, for
> people more inclined toward such things, just more expensive
> >
> > 9 VCAs, 9 DACs to control the VCAs, and a microcontroller to control the
> DACs.
> >
> > No need for switching at all, if I understand your intent correctly?
> >
> > I readily acknowledge that digital isn't for everyone, though.
> >
> > John
> >
> > On Wed, 12 Dec 2018 at 13:57, David G Dixon <dixon at mail.ubc.ca> wrote:
> > Roman,
> >
> > You're right.  Your suggestion is superior.  I was simply unaware of
> what a complete shit-show all this digital circuitry is.  This is exactly
> the reason why I avoid digital solutions whenever possible.  This module
> should be a pretty straightforward application of an analog multiplexer,
> but you are basically saying (and I concur based on my experience) that I
> can't use such a thing for clean audio, and to me, that is a sad indictment
> of these ICs.  I'm now switching these DG408s about as cleanly as is
> humanly possible, and they're still misbehaving.  It just shouldn't be this
> hard.
> >
> > So, I'm going to try to implement your idea, but I don't have the ICs I
> need.  I'm also still trying to understand exactly how the switching
> works.  I'm presuming that the 3914 must be in Dot mode, because only one
> comparator can be on at a time for this to work, and therefore, this
> circuit ONLY works with 3914,  and cannot be implemented with a generic
> flash comparator chain.
> >
> > So, I'm going to finish off the circuit as it is, because it works
> pretty well, but I concede that I basically cannot use these fucked up
> digital chips to switch active audio circuits, and will build the next one
> your way.
> >
> > Cheers,
> > Dave
> >
> > From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of
> Roman
> > Sent: Tuesday, December 11, 2018 1:20 PM
> > To: synth-diy at synth-diy.org
> > Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> >
> > I know it's too late, as the circuit at this stage has already gone
> slightly different path, and I already gave up, but couldn't help drawing
> this little schemo that explains my idea of using single switches with that
> obsoleted chip. Switches should be DG444 or similar (0=closed, 1=open), or
> replace diodes with NAND gates and use any regular dirt cheap switch like
> 4066.
> > There's no switching happening while VCA is open, provided that VCA
> control triangles match the edges of LM3914 stages. The only switched
> channels are the ones routed to muted VCA, so in theory there should be no
> clicking audible.
> > Basicaly this is just the circuit that makes this input switching
> sequence:
> > VCA-A:12233445566..
> > VCA-B:11223344556...
> > by creating one step overlap between stages. Only 6 inputs in this
> example, but can be extended to any other number.
> > http://www.synthdiy.eu/files/scanner.png
> >
> > IMHO switching active channel will always produce some clicking for many
> reasons: not matched channels, difference between transistion times H->L
> and L->H as Ingo said, break-before-make feature of DG407, slow response of
> 4532, and who knows if not also charge injection.
> >
> > Roman
> > Dnia 11 grudnia 2018 18:24 Ingo Debus <igg.debus at gmail.com> napisa?(a):
> >
> > Am 11.12.2018 um 08:10 schrieb David G Dixon <dixon at mail.ubc.ca>:
> >
> > There is now
> > only one tiny problem: There is still an almost imperceptible click when
> the
> > CV crosses 0V (and the logic control voltage crosses 2.5V) in the
> positive
> > direction.  This is when the logic switches from 011 to 100 (i.e., all
> three
> > bits change).  Interestingly, I don't hear the click at all when the CV
> goes
> > in the other direction (100 to 011).
> >
> > Couldn?t this still be caused by a very brief ?forbidden state? during
> the transition from 011 to 100? In your case, the forbidden state would be
> 000 (MSBit changes slower that the other two) or 111 (MSBit changes
> faster). Probably just a difference between rising and falling slope. Can
> you check with a scope?
> >
> > Ingo
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
> >
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
>
>
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From guy.mccusker at gmail.com  Thu Dec 13 11:08:24 2018
From: guy.mccusker at gmail.com (Guy McCusker)
Date: Thu, 13 Dec 2018 10:08:24 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <CAK+JDy3mBo2vksAvaDJOxPOFMFGL0EJMqW4X9LCoT0x9wk6P=Q@mail.gmail.com>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
 <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
 <CAK+JDy3mBo2vksAvaDJOxPOFMFGL0EJMqW4X9LCoT0x9wk6P=Q@mail.gmail.com>
Message-ID: <CAPx-PW5ppjpPiiyEtyANhfdaFOJfb=nvUUr5WK-_bMYccpcuhQ@mail.gmail.com>

> I?m thinking here of the Radiate control on the Make Noise RxMx, where the ?channel span? of the scanner is voltage-controlled. AFAIK their implementation is all analog, so clearly it doesn?t need to be digital.

I believe (though I'm not sure -- basing this on the marketing copy)
the RxMx is derived from Grant Richter's circuit that I mentioned
before :)



From markverbos at gmail.com  Thu Dec 13 12:07:17 2018
From: markverbos at gmail.com (mark verbos)
Date: Thu, 13 Dec 2018 12:07:17 +0100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <6cd10597ba36475515a601624c91a5c8@richieburnett.co.uk>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAK+JDy2A_+LihOHUjk6LT59r+7A87-5cs5JZ7HyEWeePzeA0Cw@mail.gmail.com>
 <B46A5C1C-3D3F-457A-89E3-F323D33B4F22@electricdruid.net>
 <63ed0741-a0c8-0ee7-7c2a-979015777937@pingdynasty.com>
 <6cd10597ba36475515a601624c91a5c8@richieburnett.co.uk>
Message-ID: <5362F6BF-2B3C-49C1-9A10-E4FE9DC5B198@gmail.com>

That?s what I did on the Multi-Envelope, but that?s only crossfading between DC voltages not audio. I use 2 DG409?s (1 of 4 multiplexers) and PWM the enable pins to do the crossfade. The benefit is that you get 2 channels automatically. You do need to lopass filter the output. I think you could do audio if you clocked it REALLY high. I?m only clocking at 50k or something. 


Mark



> On Dec 12, 2018, at 3:51 PM, rburnett at richieburnett.co.uk wrote:
> 
> I haven't done the calculations, but I'm left wondering whether or not you can do this "multi-input crossfade scanner" thing well enough using just fast PWM of the analogue switches themselves, and ditch the VCA's altogether.
> 
> -Richie,
> 
> 
> 
> On 2018-12-12 13:42, Martin Klang wrote:
>> I understand you don't do microcontrollers David, but some of us are less fussy!
>> This is something I'm planning to prototype:
>> 8 input channels going into two analogue switches, into two VCAs, with
>> switches and VCAs controlled by an MCU. The MCU decides to switch an
>> input only when the corresponding VCA is at -inf (ie when the other
>> VCA is fully on).
>> Using an MCU means it's easy to do a bunch of things that would be
>> very hard with analogue comparators:
>> - configurable cross-fade slopes using lookup tables
>> - cross-fade to start function (let the last input be crossfaded back
>> to the first one so that a ramp input will produce a continuous,
>> circular scan)
>> - adjustable range of active inputs
>> - LEDs to show which inputs are active and audible
>> - different modes: tracking, triggered, cycling
>> I was going to use two VCAs of a V2164 for the cross fading between
>> the two multiplexed inputs. Driven by two 12bit DACs, controlled by CV
>> read by a 12bit ADC. I think I'll be able to run both ADC and DAC at a
>> pretty high rate, to achieve something like 16x oversampling at audio
>> rate, which should give performance / dynamic range nearer to 16 bits.
>> The second two VCAs on the 2164 I was going to use to add a regular
>> VCA with adjustable linearisation. With the input normalled to +10V
>> and CV to the output from the scanner, this would let you control the
>> 'exponentiality' of the output. Alternatively you could use the
>> scanner in triggered mode as an 8-stage envelope and VCA.
>> Martin
>> On 12/12/2018 11:41, Tom Wiltshire wrote:
>>> Nine VCAs and DAC channels seems like too much hardware.
>>> There?s nothing wrong with the switches, but I?d do it with two switches to select the inputs to two VCAs controlled by two DACs, and then a uP to control the switches and DACs. You can easily make sure that the VCA is shut off when the multiplexer switches, so there shouldn?t be any clicks even if the switch generates one.
>>> ==================
>>>        Electric Druid
>>> Synth & Stompbox DIY
>>> ==================
>>>> On 12 Dec 2018, at 10:02, john slee <indigoid at oldcorollas.org> wrote:
>>>> I suspect a more-digital solution would be easier to get right, for people more inclined toward such things, just more expensive
>>>> 9 VCAs, 9 DACs to control the VCAs, and a microcontroller to control the DACs.
>>>> No need for switching at all, if I understand your intent correctly?
>>>> I readily acknowledge that digital isn't for everyone, though.
>>>> John
>>>> On Wed, 12 Dec 2018 at 13:57, David G Dixon <dixon at mail.ubc.ca> wrote:
>>>> Roman,
>>>>  You're right.  Your suggestion is superior.  I was simply unaware of what a complete shit-show all this digital circuitry is.  This is exactly the reason why I avoid digital solutions whenever possible.  This module should be a pretty straightforward application of an analog multiplexer, but you are basically saying (and I concur based on my experience) that I can't use such a thing for clean audio, and to me, that is a sad indictment of these ICs.  I'm now switching these DG408s about as cleanly as is humanly possible, and they're still misbehaving.  It just shouldn't be this hard.
>>>>  So, I'm going to try to implement your idea, but I don't have the ICs I need.  I'm also still trying to understand exactly how the switching works.  I'm presuming that the 3914 must be in Dot mode, because only one comparator can be on at a time for this to work, and therefore, this circuit ONLY works with 3914,  and cannot be implemented with a generic flash comparator chain.
>>>>  So, I'm going to finish off the circuit as it is, because it works pretty well, but I concede that I basically cannot use these fucked up digital chips to switch active audio circuits, and will build the next one your way.
>>>>  Cheers,
>>>> Dave
>>>>  From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Roman
>>>> Sent: Tuesday, December 11, 2018 1:20 PM
>>>> To: synth-diy at synth-diy.org
>>>> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
>>>> I know it's too late, as the circuit at this stage has already gone slightly different path, and I already gave up, but couldn't help drawing this little schemo that explains my idea of using single switches with that obsoleted chip. Switches should be DG444 or similar (0=closed, 1=open), or replace diodes with NAND gates and use any regular dirt cheap switch like 4066.
>>>> There's no switching happening while VCA is open, provided that VCA control triangles match the edges of LM3914 stages. The only switched channels are the ones routed to muted VCA, so in theory there should be no clicking audible.
>>>> Basicaly this is just the circuit that makes this input switching sequence:
>>>> VCA-A:12233445566..
>>>> VCA-B:11223344556...
>>>> by creating one step overlap between stages. Only 6 inputs in this example, but can be extended to any other number.
>>>> http://www.synthdiy.eu/files/scanner.png
>>>> IMHO switching active channel will always produce some clicking for many reasons: not matched channels, difference between transistion times H->L and L->H as Ingo said, break-before-make feature of DG407, slow response of 4532, and who knows if not also charge injection.
>>>> Roman
>>>> Dnia 11 grudnia 2018 18:24 Ingo Debus <igg.debus at gmail.com> napisa?(a):
>>>> Am 11.12.2018 um 08:10 schrieb David G Dixon <dixon at mail.ubc.ca>:
>>>> There is now
>>>> only one tiny problem: There is still an almost imperceptible click when the
>>>> CV crosses 0V (and the logic control voltage crosses 2.5V) in the positive
>>>> direction.  This is when the logic switches from 011 to 100 (i.e., all three
>>>> bits change).  Interestingly, I don't hear the click at all when the CV goes
>>>> in the other direction (100 to 011).
>>>> Couldn?t this still be caused by a very brief ?forbidden state? during the transition from 011 to 100? In your case, the forbidden state would be 000 (MSBit changes slower that the other two) or 111 (MSBit changes faster). Probably just a difference between rising and falling slope. Can you check with a scope?
>>>> Ingo
>>>> _______________________________________________
>>>> Synth-diy mailing list
>>>> Synth-diy at synth-diy.org
>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>> _______________________________________________
>>>> Synth-diy mailing list
>>>> Synth-diy at synth-diy.org
>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>> _______________________________________________
>>>> Synth-diy mailing list
>>>> Synth-diy at synth-diy.org
>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy




From rutgervlek at gmail.com  Fri Dec 14 14:35:47 2018
From: rutgervlek at gmail.com (Rutger Vlek)
Date: Fri, 14 Dec 2018 14:35:47 +0100
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
Message-ID: <CAJ2Txe22UbyMLvY3ziat=XcFHcJ9AvfWuj65=brJFayr4aFL3A@mail.gmail.com>

| It just shouldn't be this hard.

Ha, I totally agree! I once explored an approach to ring-modulation using a
single VCA and an inverting switch. It seemed like a nice, cost-effective,
approach (especially since I wanted to use a discrete VCA that would be too
bulky for another approach). After two prototypes of this circuit, I simply
gave up. In the analog domain it was simply too difficult to trigger the
switch exactly at the point where the VCA was fully closed, due to circuit
accuracy and noise. It was a hard lesson in the reality of analog
electronics. I went down the route of simply duplicating the discrete
circuit for the negative quadrants, and it works extremely well albeit not
super-linear, but that was a deliberate choice.

Regards,

Rutger

Op wo 12 dec. 2018 om 03:56 schreef David G Dixon <dixon at mail.ubc.ca>:

> It just shouldn't be this hard.
>
>
> ------------------------------
> *From:* Synth-diy [mailto:synth-diy-bounces at synth-diy.org] *On Behalf Of *
> Roman
> *Sent:* Tuesday, December 11, 2018 1:20 PM
> *To:* synth-diy at synth-diy.org
> *Subject:* Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
>
> I know it's too late, as the circuit at this stage has already gone
> slightly different path, and I already gave up, but couldn't help drawing
> this little schemo that explains my idea of using single switches with that
> obsoleted chip. Switches should be DG444 or similar (0=closed, 1=open), or
> replace diodes with NAND gates and use any regular dirt cheap switch like
> 4066.
> There's no switching happening while VCA is open, provided that VCA
> control triangles match the edges of LM3914 stages. The only switched
> channels are the ones routed to muted VCA, so in theory there should be no
> clicking audible.
> Basicaly this is just the circuit that makes this input switching sequence:
> VCA-A:12233445566..
> VCA-B:11223344556...
> by creating one step overlap between stages. Only 6 inputs in this
> example, but can be extended to any other number.
> http://www.synthdiy.eu/files/scanner.png
>
> IMHO switching active channel will always produce some clicking for many
> reasons: not matched channels, difference between transistion times H->L
> and L->H as Ingo said, break-before-make feature of DG407, slow response of
> 4532, and who knows if not also charge injection.
>
> Roman
>
> Dnia 11 grudnia 2018 18:24 Ingo Debus <igg.debus at gmail.com> napisa?(a):
>
> Am 11.12.2018 um 08:10 schrieb David G Dixon <dixon at mail.ubc.ca>:
>
> There is now
> only one tiny problem: There is still an almost imperceptible click when
> the
> CV crosses 0V (and the logic control voltage crosses 2.5V) in the positive
> direction.  This is when the logic switches from 011 to 100 (i.e., all
> three
> bits change).  Interestingly, I don't hear the click at all when the CV
> goes
> in the other direction (100 to 011).
>
>
> Couldn?t this still be caused by a very brief ?forbidden state? during the
> transition from 011 to 100? In your case, the forbidden state would be 000
> (MSBit changes slower that the other two) or 111 (MSBit changes faster).
> Probably just a difference between rising and falling slope. Can you check
> with a scope?
>
> Ingo
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
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From dixon at mail.ubc.ca  Fri Dec 14 21:09:41 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Fri, 14 Dec 2018 12:09:41 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <CAJ2Txe22UbyMLvY3ziat=XcFHcJ9AvfWuj65=brJFayr4aFL3A@mail.gmail.com>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAJ2Txe22UbyMLvY3ziat=XcFHcJ9AvfWuj65=brJFayr4aFL3A@mail.gmail.com>
Message-ID: <9040F25BCE0D4A408056B2024B7DEBB3@galvanox01>

I never have problems with analog electronics.  In the case of this scanner,
for example, I designed the analog part so that there are plateaus in the
control voltage when switching occurs, which gives me about 200mV of slop in
the CV for switching.  This circuit worked the very first time (even though
I've rebuilt it three times).  The problem here was all digital.
 
Later today, I'm ordering some DG444 and DG445, and also some single SPST
switches (don't know the DG number yet) and I'm going to rebuild this thing
Roman's way (with a few minor modifiations).  The analog part is perfect and
won't have to change at all.
 
On the digital side, I'm worried about the fact that the LM3914 comparators
do not have built-in hysteresis, and there is no way to install it, so I'm
worried that the comparators will oscillate.  I'm going to stick with LM339,
fully rigged for hysteresis (about 10mV worth) as this worked well.  Does
anyone here have any experience with oscillating LM3914?


  _____  

From: Rutger Vlek [mailto:rutgervlek at gmail.com] 
Sent: Friday, December 14, 2018 5:36 AM
To: David G Dixon; SDIY List
Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)


| It just shouldn't be this hard.   

Ha, I totally agree! I once explored an approach to ring-modulation using a
single VCA and an inverting switch. It seemed like a nice, cost-effective,
approach (especially since I wanted to use a discrete VCA that would be too
bulky for another approach). After two prototypes of this circuit, I simply
gave up. In the analog domain it was simply too difficult to trigger the
switch exactly at the point where the VCA was fully closed, due to circuit
accuracy and noise. It was a hard lesson in the reality of analog
electronics. I went down the route of simply duplicating the discrete
circuit for the negative quadrants, and it works extremely well albeit not
super-linear, but that was a deliberate choice.

Regards,


Rutger

Op wo 12 dec. 2018 om 03:56 schreef David G Dixon <dixon at mail.ubc.ca>:



It just shouldn't be this hard.

 
 
  _____  

From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Roman
Sent: Tuesday, December 11, 2018 1:20 PM
To: synth-diy at synth-diy.org
Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)



I know it's too late, as the circuit at this stage has already gone slightly
different path, and I already gave up, but couldn't help drawing this little
schemo that explains my idea of using single switches with that obsoleted
chip. Switches should be DG444 or similar (0=closed, 1=open), or replace
diodes with NAND gates and use any regular dirt cheap switch like 4066.

There's no switching happening while VCA is open, provided that VCA control
triangles match the edges of LM3914 stages. The only switched channels are
the ones routed to muted VCA, so in theory there should be no clicking
audible.

Basicaly this is just the circuit that makes this input switching sequence:

VCA-A:12233445566..

VCA-B:11223344556...

by creating one step overlap between stages. Only 6 inputs in this example,
but can be extended to any other number.

http://www.synthdiy.eu/files/scanner.png


IMHO switching active channel will always produce some clicking for many
reasons: not matched channels, difference between transistion times H->L and
L->H as Ingo said, break-before-make feature of DG407, slow response of
4532, and who knows if not also charge injection.


Roman


Dnia 11 grudnia 2018 18:24 Ingo Debus <igg.debus at gmail.com> napisa?(a):


Am 11.12.2018 um 08:10 schrieb David G Dixon <dixon at mail.ubc.ca>:


There is now

only one tiny problem: There is still an almost imperceptible click when the

CV crosses 0V (and the logic control voltage crosses 2.5V) in the positive

direction.  This is when the logic switches from 011 to 100 (i.e., all three

bits change).  Interestingly, I don't hear the click at all when the CV goes

in the other direction (100 to 011).



Couldn't this still be caused by a very brief "forbidden state" during the
transition from 011 to 100? In your case, the forbidden state would be 000
(MSBit changes slower that the other two) or 111 (MSBit changes faster).
Probably just a difference between rising and falling slope. Can you check
with a scope?


Ingo

_______________________________________________

Synth-diy mailing list

Synth-diy at synth-diy.org

http://synth-diy.org/mailman/listinfo/synth-diy



_______________________________________________
Synth-diy mailing list
Synth-diy at synth-diy.org
http://synth-diy.org/mailman/listinfo/synth-diy


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From admin at bugbrand.co.uk  Sat Dec 15 11:58:27 2018
From: admin at bugbrand.co.uk (Tom Bugs)
Date: Sat, 15 Dec 2018 10:58:27 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <9040F25BCE0D4A408056B2024B7DEBB3@galvanox01>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAJ2Txe22UbyMLvY3ziat=XcFHcJ9AvfWuj65=brJFayr4aFL3A@mail.gmail.com>
 <9040F25BCE0D4A408056B2024B7DEBB3@galvanox01>
Message-ID: <6e07c18c-5ce0-5d0c-fa24-06268c70d8fa@bugbrand.co.uk>

For single switches try DG417/8/9
DG417 is SPST NC
DG418 is SPST NO
DG419 is SPDT

Useful little chips.

On 14/12/2018 20:09, David G Dixon wrote:
> I never have problems with analog electronics.? In the case of this 
> scanner, for example, I designed the analog part so that there?are 
> plateaus in the control voltage when switching occurs, which gives me 
> about 200mV of slop in the CV for switching. This?circuit worked the 
> very first time (even though?I've rebuilt it three times).? The 
> problem here was all digital.
> Later today, I'm ordering some DG444 and DG445, and also some single 
> SPST switches (don't know the DG number yet) and I'm going to rebuild 
> this thing Roman's way (with a few minor modifiations).? The analog 
> part is perfect and won't have to change at all.
> On the digital side, I'm worried about the fact that the LM3914 
> comparators do not have built-in hysteresis, and there is no way to 
> install it, so I'm worried that the comparators will oscillate.? I'm 
> going to stick with LM339, fully rigged for hysteresis (about 10mV 
> worth) as this worked well.? Does anyone here have any experience with 
> oscillating LM3914?
>
>     ------------------------------------------------------------------------
>     *From:* Rutger Vlek [mailto:rutgervlek at gmail.com]
>     *Sent:* Friday, December 14, 2018 5:36 AM
>     *To:* David G Dixon; SDIY List
>     *Subject:* Re: [sdiy] Help, I'm Desperate! (Charge Injection with
>     DG408)
>
>     | It just shouldn't be this hard.
>
>     Ha, I totally agree! I once explored an approach to
>     ring-modulation using a single VCA and an inverting switch. It
>     seemed like a nice, cost-effective, approach (especially since I
>     wanted to use a discrete VCA that would be too bulky for another
>     approach). After two prototypes of this circuit, I simply gave up.
>     In the analog domain it was simply too difficult to trigger the
>     switch exactly at the point where the VCA was fully closed, due to
>     circuit accuracy and noise. It was a hard lesson in the reality of
>     analog electronics. I went down the route of simply duplicating
>     the discrete circuit for the negative quadrants, and it works
>     extremely well albeit not super-linear, but that was a deliberate
>     choice.
>
>     Regards,
>
>     Rutger
>
>     Op wo 12 dec. 2018 om 03:56 schreef David G Dixon
>     <dixon at mail.ubc.ca <mailto:dixon at mail.ubc.ca>>:
>
>         It just shouldn't be this hard.
>         ------------------------------------------------------------------------
>         *From:* Synth-diy [mailto:synth-diy-bounces at synth-diy.org
>         <mailto:synth-diy-bounces at synth-diy.org>] *On Behalf Of *Roman
>         *Sent:* Tuesday, December 11, 2018 1:20 PM
>         *To:* synth-diy at synth-diy.org <mailto:synth-diy at synth-diy.org>
>         *Subject:* Re: [sdiy] Help, I'm Desperate! (Charge Injection
>         with DG408)
>
>             I know it's too late, as the circuit at this stage has
>             already gone slightly different path, and I already gave
>             up, but couldn't help drawing this little schemo that
>             explains my idea of using single switches with that
>             obsoleted chip. Switches should be DG444 or similar
>             (0=closed, 1=open), or replace diodes with NAND gates and
>             use any regular dirt cheap switch like 4066.
>             There's no switching happening while VCA is open, provided
>             that VCA control triangles match the edges of LM3914
>             stages. The only switched channels are the ones routed to
>             muted VCA, so in theory there should be no clicking audible.
>             Basicaly this is just the circuit that makes this input
>             switching sequence:
>             VCA-A:12233445566..
>             VCA-B:11223344556...
>             by creating one step overlap between stages. Only 6 inputs
>             in this example, but can be extended to any other number.
>             http://www.synthdiy.eu/files/scanner.png
>
>             IMHO switching active channel will always produce some
>             clicking for many reasons: not matched channels,
>             difference between transistion times H->L and L->H as Ingo
>             said, break-before-make feature of DG407, slow response of
>             4532, and who knows if not also charge injection.
>
>             Roman
>
>             Dnia 11 grudnia 2018 18:24 Ingo Debus <igg.debus at gmail.com
>             <mailto:igg.debus at gmail.com>> napisa?(a):
>
>                     Am 11.12.2018 um 08:10 schrieb David G Dixon
>                     <dixon at mail.ubc.ca <mailto:dixon at mail.ubc.ca>>:
>
>                     There is now
>                     only one tiny problem: There is still an almost
>                     imperceptible click when the
>                     CV crosses 0V (and the logic control voltage
>                     crosses 2.5V) in the positive
>                     direction.? This is when the logic switches from
>                     011 to 100 (i.e., all three
>                     bits change).? Interestingly, I don't hear the
>                     click at all when the CV goes
>                     in the other direction (100 to 011).
>
>
>                 Couldn?t this still be caused by a very brief
>                 ?forbidden state? during the transition from 011 to
>                 100? In your case, the forbidden state would be 000
>                 (MSBit changes slower that the other two) or 111
>                 (MSBit changes faster). Probably just a difference
>                 between rising and falling slope. Can you check with a
>                 scope?
>
>                 Ingo
>                 _______________________________________________
>                 Synth-diy mailing list
>                 Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
>                 http://synth-diy.org/mailman/listinfo/synth-diy
>
>
>         _______________________________________________
>         Synth-diy mailing list
>         Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
>         http://synth-diy.org/mailman/listinfo/synth-diy
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy

-- 
BugBrand LTD
UK company No. 07199808
VAT No. GB 988 2629 57
1 Ninetree Hill
BRISTOL BS1 3SB
United Kingdom
www.bugbrand.co.uk



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From oakleysound at btinternet.com  Sat Dec 15 12:11:14 2018
From: oakleysound at btinternet.com (Oakley Sound)
Date: Sat, 15 Dec 2018 11:11:14 +0000
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <6e07c18c-5ce0-5d0c-fa24-06268c70d8fa@bugbrand.co.uk>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAJ2Txe22UbyMLvY3ziat=XcFHcJ9AvfWuj65=brJFayr4aFL3A@mail.gmail.com>
 <9040F25BCE0D4A408056B2024B7DEBB3@galvanox01>
 <6e07c18c-5ce0-5d0c-fa24-06268c70d8fa@bugbrand.co.uk>
Message-ID: <71333af6-9c7a-53ee-616c-4eacd0a8db98@btinternet.com>

I have always found that in practice the 4016 and 4051 produce less 
charge injection that the DG4XX series. It's a bit of pain to deal with 
the differing voltage levels of the logic control and the signal 
compared to the DG4XX though.

I have also had some joy in routing, via a small capacitor, the logic 
control line into the output signal. If it's the right way up it can 
cancel any charge injection pulse created inside the switch.

Tony

www.oakleysound.com


From sleepy_dog at gmx.de  Sat Dec 15 12:14:19 2018
From: sleepy_dog at gmx.de (sleepy_dog at gmx.de)
Date: Sat, 15 Dec 2018 12:14:19 +0100
Subject: [sdiy] Yo, check out this plate reverb
Message-ID: <5fb2e465-c7e5-17ed-f943-2d1c1cd98d9a@gmx.de>

Despite that DAW you are seeing.... keep looking longer... not a 
software plugin...
but rather out of IKEA parts :-D

https://www.youtube.com/watch?v=5OcRMA2FNUE&t=13m22s





From dixon at mail.ubc.ca  Sun Dec 16 01:44:59 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Sat, 15 Dec 2018 16:44:59 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <6e07c18c-5ce0-5d0c-fa24-06268c70d8fa@bugbrand.co.uk>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAJ2Txe22UbyMLvY3ziat=XcFHcJ9AvfWuj65=brJFayr4aFL3A@mail.gmail.com>
 <9040F25BCE0D4A408056B2024B7DEBB3@galvanox01>
 <6e07c18c-5ce0-5d0c-fa24-06268c70d8fa@bugbrand.co.uk>
Message-ID: <7780F06F09064B038AD9507B68501007@galvanox01>

Yes, but it's a little disconcerting that the DG444 (with four switches) is
cheaper than any of the single or dual switches in the DG family, at least
on Digikey.  Also, I wonder why the DG445 is slightly more expensive than
the DG444, when the only difference is the logic polarity.
 
I'll probably go with two DG444s and one DG417 to get the nine channels.  It
would be easier to do eight channels, but my CV-to-trapezoid converter
circuit is naturally geared to 2^n+1 channels.  To avoid channel nine would
create complications in the CV circuit.  This was a perfect fit and very
elegant with the multiplexers (DG408 and DG409) -- I'm really choked that
they don't work well enough.


  _____  

From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Tom
Bugs
Sent: Saturday, December 15, 2018 2:58 AM
To: synth-diy at synth-diy.org
Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)



For single switches try DG417/8/9 
DG417 is SPST NC
DG418 is SPST NO
DG419 is SPDT

Useful little chips.


On 14/12/2018 20:09, David G Dixon wrote:


I never have problems with analog electronics.  In the case of this scanner,
for example, I designed the analog part so that there are plateaus in the
control voltage when switching occurs, which gives me about 200mV of slop in
the CV for switching.  This circuit worked the very first time (even though
I've rebuilt it three times).  The problem here was all digital.
 
Later today, I'm ordering some DG444 and DG445, and also some single SPST
switches (don't know the DG number yet) and I'm going to rebuild this thing
Roman's way (with a few minor modifiations).  The analog part is perfect and
won't have to change at all.
 
On the digital side, I'm worried about the fact that the LM3914 comparators
do not have built-in hysteresis, and there is no way to install it, so I'm
worried that the comparators will oscillate.  I'm going to stick with LM339,
fully rigged for hysteresis (about 10mV worth) as this worked well.  Does
anyone here have any experience with oscillating LM3914?


  _____  

From: Rutger Vlek [mailto:rutgervlek at gmail.com] 
Sent: Friday, December 14, 2018 5:36 AM
To: David G Dixon; SDIY List
Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)


| It just shouldn't be this hard.   

Ha, I totally agree! I once explored an approach to ring-modulation using a
single VCA and an inverting switch. It seemed like a nice, cost-effective,
approach (especially since I wanted to use a discrete VCA that would be too
bulky for another approach). After two prototypes of this circuit, I simply
gave up. In the analog domain it was simply too difficult to trigger the
switch exactly at the point where the VCA was fully closed, due to circuit
accuracy and noise. It was a hard lesson in the reality of analog
electronics. I went down the route of simply duplicating the discrete
circuit for the negative quadrants, and it works extremely well albeit not
super-linear, but that was a deliberate choice.

Regards,


Rutger

Op wo 12 dec. 2018 om 03:56 schreef David G Dixon <dixon at mail.ubc.ca>:


It just shouldn't be this hard.

 
 
  _____  

From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Roman
Sent: Tuesday, December 11, 2018 1:20 PM
To: synth-diy at synth-diy.org
Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)



I know it's too late, as the circuit at this stage has already gone slightly
different path, and I already gave up, but couldn't help drawing this little
schemo that explains my idea of using single switches with that obsoleted
chip. Switches should be DG444 or similar (0=closed, 1=open), or replace
diodes with NAND gates and use any regular dirt cheap switch like 4066.

There's no switching happening while VCA is open, provided that VCA control
triangles match the edges of LM3914 stages. The only switched channels are
the ones routed to muted VCA, so in theory there should be no clicking
audible.

Basicaly this is just the circuit that makes this input switching sequence:

VCA-A:12233445566..

VCA-B:11223344556...

by creating one step overlap between stages. Only 6 inputs in this example,
but can be extended to any other number.

http://www.synthdiy.eu/files/scanner.png


IMHO switching active channel will always produce some clicking for many
reasons: not matched channels, difference between transistion times H->L and
L->H as Ingo said, break-before-make feature of DG407, slow response of
4532, and who knows if not also charge injection.


Roman


Dnia 11 grudnia 2018 18:24 Ingo Debus <igg.debus at gmail.com> napisa?(a):


Am 11.12.2018 um 08:10 schrieb David G Dixon <dixon at mail.ubc.ca>:


There is now

only one tiny problem: There is still an almost imperceptible click when the

CV crosses 0V (and the logic control voltage crosses 2.5V) in the positive

direction.  This is when the logic switches from 011 to 100 (i.e., all three

bits change).  Interestingly, I don't hear the click at all when the CV goes

in the other direction (100 to 011).



Couldn't this still be caused by a very brief "forbidden state" during the
transition from 011 to 100? In your case, the forbidden state would be 000
(MSBit changes slower that the other two) or 111 (MSBit changes faster).
Probably just a difference between rising and falling slope. Can you check
with a scope?


Ingo

_______________________________________________

Synth-diy mailing list

Synth-diy at synth-diy.org

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Synth-diy at synth-diy.org
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From dixon at mail.ubc.ca  Sun Dec 16 01:45:30 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Sat, 15 Dec 2018 16:45:30 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <71333af6-9c7a-53ee-616c-4eacd0a8db98@btinternet.com>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAJ2Txe22UbyMLvY3ziat=XcFHcJ9AvfWuj65=brJFayr4aFL3A@mail.gmail.com>
 <9040F25BCE0D4A408056B2024B7DEBB3@galvanox01>
 <6e07c18c-5ce0-5d0c-fa24-06268c70d8fa@bugbrand.co.uk>
 <71333af6-9c7a-53ee-616c-4eacd0a8db98@btinternet.com>
Message-ID: <8A1202FEEFD441D794564DD4394DAA3F@galvanox01>

Thanks for the hot tip!  I'm going to try this to see if I can't save my
current build. 

> -----Original Message-----
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On 
> Behalf Of Oakley Sound
> Sent: Saturday, December 15, 2018 3:11 AM
> To: Synth DIY
> Subject: Re: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
> 
> I have always found that in practice the 4016 and 4051 
> produce less charge injection that the DG4XX series. It's a 
> bit of pain to deal with the differing voltage levels of the 
> logic control and the signal compared to the DG4XX though.
> 
> I have also had some joy in routing, via a small capacitor, 
> the logic control line into the output signal. If it's the 
> right way up it can cancel any charge injection pulse created 
> inside the switch.
> 
> Tony
> 
> www.oakleysound.com
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From johnspeth at yahoo.com  Sun Dec 16 14:58:23 2018
From: johnspeth at yahoo.com (John Speth)
Date: Sun, 16 Dec 2018 05:58:23 -0800
Subject: [sdiy] Free UV erasable EPROMs (Portland, OR pickup only)
Message-ID: <a0b49d59-d419-6adb-5bcd-efcab0a47fd1@yahoo.com>

Free to the next taker, for local pickup only in Portland, OR, will not 
ship.

three 2764
one 2708
seven 27C256
six 27C64

They probably still work.? They are programmed but never used.? Parts 
only, no programmer or eraser.? Please contact me privately to arrange 
pickup.

JJS


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From kristian.borgstedt at gmail.com  Sun Dec 16 15:24:13 2018
From: kristian.borgstedt at gmail.com (=?UTF-8?Q?Kristian_Bl=C3=A5sol?=)
Date: Sun, 16 Dec 2018 15:24:13 +0100
Subject: [sdiy] Rene Schmitz VCADSR
Message-ID: <CA+XQpGvjucNTVD0PHAgP+ZKd+N-RkPS_GX8Vg33EJ-oopW-t5Q@mail.gmail.com>

Hello,

I would like to build Rene Schmitz VCADSR, and have been studying the
schematics. It seems to be a very versatile VCADSR that can be tweaked to
do tons of stuff...

I just wonder if anyone could explain all the switches in the schematics?
In his notes I havent found anything about these. Only all the stuff one
can do with it ;) I havent either seen a front panel of someone who have
built it to see if they have 8 switches on them?

I know Rene is on this mailing list and maybe wants to answer himself :)
Or  if anyone else has done this and could share their notes?

Oh, a link to the schematics maybe :)
https://www.schmitzbits.de/vcadsr.html

Thanks in advance, and Thanks Rene for the very nice VCADSR (at least on
paper so far ;)

/Kristian

-- 
---
Kristian Bl?sol
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From fluxmonk at gmail.com  Sun Dec 16 15:33:37 2018
From: fluxmonk at gmail.com (bbob)
Date: Sun, 16 Dec 2018 09:33:37 -0500
Subject: [sdiy] Rene Schmitz VCADSR
In-Reply-To: <CA+XQpGvjucNTVD0PHAgP+ZKd+N-RkPS_GX8Vg33EJ-oopW-t5Q@mail.gmail.com>
References: <CA+XQpGvjucNTVD0PHAgP+ZKd+N-RkPS_GX8Vg33EJ-oopW-t5Q@mail.gmail.com>
Message-ID: <CABbX2d94gb=DFxNT5gJiBrNjFw8JtV=P4XjAfhy-0hFrHK2M+Q@mail.gmail.com>

Doesn't look like it's labeled on the schematic, but those are all CMOS
electronic switches, probably a pair of 4066s.  Generally, they trigger in
sequence as the A, D, S, and R phases of the envelope become active.

On Sun, Dec 16, 2018 at 9:26 AM Kristian Bl?sol <
kristian.borgstedt at gmail.com> wrote:

> Hello,
>
> I would like to build Rene Schmitz VCADSR, and have been studying the
> schematics. It seems to be a very versatile VCADSR that can be tweaked to
> do tons of stuff...
>
> I just wonder if anyone could explain all the switches in the schematics?
> In his notes I havent found anything about these. Only all the stuff one
> can do with it ;) I havent either seen a front panel of someone who have
> built it to see if they have 8 switches on them?
>
> I know Rene is on this mailing list and maybe wants to answer himself :)
> Or  if anyone else has done this and could share their notes?
>
> Oh, a link to the schematics maybe :)
> https://www.schmitzbits.de/vcadsr.html
>
> Thanks in advance, and Thanks Rene for the very nice VCADSR (at least on
> paper so far ;)
>
> /Kristian
>
> --
> ---
> Kristian Bl?sol
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
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From kristian.borgstedt at gmail.com  Sun Dec 16 15:42:12 2018
From: kristian.borgstedt at gmail.com (=?UTF-8?Q?Kristian_Bl=C3=A5sol?=)
Date: Sun, 16 Dec 2018 15:42:12 +0100
Subject: [sdiy] Rene Schmitz VCADSR
In-Reply-To: <CABbX2d94gb=DFxNT5gJiBrNjFw8JtV=P4XjAfhy-0hFrHK2M+Q@mail.gmail.com>
References: <CA+XQpGvjucNTVD0PHAgP+ZKd+N-RkPS_GX8Vg33EJ-oopW-t5Q@mail.gmail.com>
 <CABbX2d94gb=DFxNT5gJiBrNjFw8JtV=P4XjAfhy-0hFrHK2M+Q@mail.gmail.com>
Message-ID: <CA+XQpGvOjHYsVvDr=E=XQqcgnr9gh=nzjdov_By+Jusx6w9rqg@mail.gmail.com>

Thanks for a really fast respons. :) Ok that explains a lot (and makes so
much more sense). So would I read that symbol as the connection to the
middle is the control pin and the other two connections are the two pins
that should be connected? It seems obvious but I might as well ask. :)

s?n 16 dec. 2018 kl. 15:33 skrev bbob <fluxmonk at gmail.com>:

> Doesn't look like it's labeled on the schematic, but those are all CMOS
> electronic switches, probably a pair of 4066s.  Generally, they trigger in
> sequence as the A, D, S, and R phases of the envelope become active.
>
> On Sun, Dec 16, 2018 at 9:26 AM Kristian Bl?sol <
> kristian.borgstedt at gmail.com> wrote:
>
>> Hello,
>>
>> I would like to build Rene Schmitz VCADSR, and have been studying the
>> schematics. It seems to be a very versatile VCADSR that can be tweaked to
>> do tons of stuff...
>>
>> I just wonder if anyone could explain all the switches in the schematics?
>> In his notes I havent found anything about these. Only all the stuff one
>> can do with it ;) I havent either seen a front panel of someone who have
>> built it to see if they have 8 switches on them?
>>
>> I know Rene is on this mailing list and maybe wants to answer himself :)
>> Or  if anyone else has done this and could share their notes?
>>
>> Oh, a link to the schematics maybe :)
>> https://www.schmitzbits.de/vcadsr.html
>>
>> Thanks in advance, and Thanks Rene for the very nice VCADSR (at least on
>> paper so far ;)
>>
>> /Kristian
>>
>> --
>> ---
>> Kristian Bl?sol
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>>
> --
---
Kristian Bl?sol
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From synth at schmitzbits.de  Sun Dec 16 20:53:23 2018
From: synth at schmitzbits.de (=?UTF-8?Q?Ren=c3=a9_Schmitz?=)
Date: Sun, 16 Dec 2018 20:53:23 +0100
Subject: [sdiy] Rene Schmitz VCADSR
In-Reply-To: <CABbX2d94gb=DFxNT5gJiBrNjFw8JtV=P4XjAfhy-0hFrHK2M+Q@mail.gmail.com>
References: <CA+XQpGvjucNTVD0PHAgP+ZKd+N-RkPS_GX8Vg33EJ-oopW-t5Q@mail.gmail.com>
 <CABbX2d94gb=DFxNT5gJiBrNjFw8JtV=P4XjAfhy-0hFrHK2M+Q@mail.gmail.com>
Message-ID: <1bb89f1c-ec8d-9a57-4639-6936b5513859@schmitzbits.de>

Hi Kristian and all,

Yes, exactly these are 4066s, two of them.

Best,
  Ren?

On 16.12.2018 15:33, bbob wrote:
> Doesn't look like it's labeled on the schematic, but those are all CMOS 
> electronic switches, probably a pair of 4066s.? Generally, they trigger 
> in sequence as the A, D, S, and R phases of the envelope become active.
> 
> On Sun, Dec 16, 2018 at 9:26 AM Kristian Bl?sol 
> <kristian.borgstedt at gmail.com <mailto:kristian.borgstedt at gmail.com>> wrote:
> 
>     Hello,
> 
>     I would like to build Rene Schmitz VCADSR, and have been studying
>     the schematics. It seems to be a very versatile VCADSR that can be
>     tweaked to do tons of stuff...
> 
>     I just wonder if anyone could explain all the switches in the
>     schematics? In his notes I havent found anything about these. Only
>     all the stuff one can do with it ;) I havent either seen a front
>     panel of someone who have built it to see if they have 8 switches on
>     them?
> 
>     I know Rene is on this mailing list and maybe wants to answer
>     himself :) Or? if anyone else has done this and could share their notes?
> 
>     Oh, a link to the schematics maybe :)
>     https://www.schmitzbits.de/vcadsr.html
> 
>     Thanks in advance, and Thanks Rene for the very nice VCADSR (at
>     least on paper so far ;)
> 
>     /Kristian
> 
>     -- 
>     ---
>     Kristian Bl?sol
> 
>     _______________________________________________
>     Synth-diy mailing list
>     Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
>     http://synth-diy.org/mailman/listinfo/synth-diy
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> 


-- 
--
synth at schmitzbits.de
http://schmitzbits.de


From mec.forumreader at gmail.com  Mon Dec 17 03:06:49 2018
From: mec.forumreader at gmail.com (Michael E Caloroso)
Date: Sun, 16 Dec 2018 21:06:49 -0500
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <CAJ2Txe22UbyMLvY3ziat=XcFHcJ9AvfWuj65=brJFayr4aFL3A@mail.gmail.com>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAJ2Txe22UbyMLvY3ziat=XcFHcJ9AvfWuj65=brJFayr4aFL3A@mail.gmail.com>
Message-ID: <CAAv6=UBEBWwX_vT4YbUsb521RBMQXBUanU+3uu+_1rj7wNK_7Q@mail.gmail.com>

On 12/14/18, Rutger Vlek <rutgervlek at gmail.com> wrote:

> Ha, I totally agree! I once explored an approach to ring-modulation using a
> single VCA and an inverting switch. It seemed like a nice, cost-effective,
> approach (especially since I wanted to use a discrete VCA that would be too
> bulky for another approach). After two prototypes of this circuit, I simply
> gave up. In the analog domain it was simply too difficult to trigger the
> switch exactly at the point where the VCA was fully closed, due to circuit
> accuracy and noise. It was a hard lesson in the reality of analog
> electronics. I went down the route of simply duplicating the discrete
> circuit for the negative quadrants, and it works extremely well albeit not
> super-linear, but that was a deliberate choice.

Don Buchla stated in 1982 that he had tried to design a multiplier
that could function as both VCA and ring modulator, and he couldn't
come up with a suitable design that balanced low distortion, ample CV
rejection, and linear/nonlinear operation in both modes.  Mixing the
control and audio realms in the audio domain can force some
compromises.  And this is a designer who sought multiple functions out
of a single module.  Yes PAiA had a 47xx module that did both, but not
that well either.

MC


From timr at circuitabbey.com  Mon Dec 17 04:58:00 2018
From: timr at circuitabbey.com (Tim Ressel)
Date: Sun, 16 Dec 2018 19:58:00 -0800
Subject: [sdiy] Rene Schmitz VCADSR
In-Reply-To: <CA+XQpGvjucNTVD0PHAgP+ZKd+N-RkPS_GX8Vg33EJ-oopW-t5Q@mail.gmail.com>
References: <CA+XQpGvjucNTVD0PHAgP+ZKd+N-RkPS_GX8Vg33EJ-oopW-t5Q@mail.gmail.com>
Message-ID: <e5bca674-1963-c9c0-b2c8-11ee63aa34aa@circuitabbey.com>

Norton opamps? cool! That takes me back...

Tim ( really old) Ressel

P.S. Get off my lawn!

On 12/16/2018 6:24 AM, Kristian Bl?sol wrote:
> Hello,
>
> I would like to build Rene Schmitz VCADSR, and have been studying the 
> schematics. It seems to be a very versatile VCADSR that can be tweaked 
> to do tons of stuff...
>
> I just wonder if anyone could explain all the switches in the 
> schematics? In his notes I havent found anything about these. Only all 
> the stuff one can do with it ;) I havent either seen a front panel of 
> someone who have built it to see if they have 8 switches on them?
>
> I know Rene is on this mailing list and maybe wants to answer himself 
> :) Or? if anyone else has done this and could share their notes?
>
> Oh, a link to the schematics maybe :)
> https://www.schmitzbits.de/vcadsr.html
>
> Thanks in advance, and Thanks Rene for the very nice VCADSR (at least 
> on paper so far ;)
>
> /Kristian
>
> -- 
> ---
> Kristian Bl?sol
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy

-- 
--Tim Ressel
Circuit Abbey
timr at circuitabbey.com

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From 21pointy at tpg.com.au  Mon Dec 17 05:57:47 2018
From: 21pointy at tpg.com.au (Adam Inglis)
Date: Mon, 17 Dec 2018 14:57:47 +1000
Subject: [sdiy] Mind blown -- TL074 saturated outputs different
In-Reply-To: <8abb70dc-75b0-1d6f-f8ed-e10980dbadea@schmitzbits.de>
References: <22FDF271339C4B6D91A9EBCEB8A8CCF0@galvanox01>
 <e849b3cf-d8bd-a421-aaaa-894fc44c67ce@schmitzbits.de>
 <9ACE521DFE9C481F89E1A28F89D6A21B@galvanox01>
 <b9021091-54c4-cc38-ce8e-e609c4650eef@bendentech.co.uk>
 <CAP92RBUW1Y1hbvo_KpDt9y_HsT=XBUKv8v5Bpq1JXswSaOtHnQ@mail.gmail.com>
 <C02A76A5931A40C3B56B758CD1E0958F@galvanox01>
 <8abb70dc-75b0-1d6f-f8ed-e10980dbadea@schmitzbits.de>
Message-ID: <AD0C5BCF-1822-4270-9733-0DB9A390F53F@tpg.com.au>

Hi Rene
> On 11 Dec 2018, at 6:04 AM, Ren? Schmitz <synth at schmitzbits.de> wrote:
> 
> Hi David,
> 
> On 10.12.2018 08:36, David G Dixon wrote:
>> Such a "zener bridge" is at the heart of every Dixie, Rubicon, and Atlantis VCO.
> 
> Have you posted these schematics somewhere?

Just found this VCO schematic online that features this:

page 16
dual integrator quadrature VCO (sinusoidal, not sure how useful for synths) using 3080 OTA

https://www.americanradiohistory.com/Archive-Electronics-Today/Canada/70s/ETI-CA-1978-12.pdf <https://www.americanradiohistory.com/Archive-Electronics-Today/Canada/70s/ETI-CA-1978-12.pdf>

Article is by Tim Orr, who I think used to work for EMS?

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From mr at analogue.org  Mon Dec 17 07:42:14 2018
From: mr at analogue.org (Mattias Rickardsson)
Date: Mon, 17 Dec 2018 07:42:14 +0100
Subject: [sdiy] Rene Schmitz VCADSR
In-Reply-To: <CA+XQpGvjucNTVD0PHAgP+ZKd+N-RkPS_GX8Vg33EJ-oopW-t5Q@mail.gmail.com>
References: <CA+XQpGvjucNTVD0PHAgP+ZKd+N-RkPS_GX8Vg33EJ-oopW-t5Q@mail.gmail.com>
Message-ID: <CAP92RBXifbEdYe+jL5hwsRqQwk7qqHW=ycE1h_LPacZMhKS6wA@mail.gmail.com>

Den s?n 16 dec. 2018 15:24 skrev Kristian Bl?sol <
kristian.borgstedt at gmail.com>:

> ...
> Oh, a link to the schematics maybe :)
> https://www.schmitzbits.de/vcadsr.html
>

Nice & compact design. Note though that it's a linear-slope envelope, which
IMHO is not what one typically wants for shorter sounds. :-)

/mr
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From kristian.borgstedt at gmail.com  Mon Dec 17 11:43:27 2018
From: kristian.borgstedt at gmail.com (=?UTF-8?Q?Kristian_Bl=C3=A5sol?=)
Date: Mon, 17 Dec 2018 11:43:27 +0100
Subject: [sdiy] Rene Schmitz VCADSR
In-Reply-To: <CAP92RBXifbEdYe+jL5hwsRqQwk7qqHW=ycE1h_LPacZMhKS6wA@mail.gmail.com>
References: <CA+XQpGvjucNTVD0PHAgP+ZKd+N-RkPS_GX8Vg33EJ-oopW-t5Q@mail.gmail.com>
 <CAP92RBXifbEdYe+jL5hwsRqQwk7qqHW=ycE1h_LPacZMhKS6wA@mail.gmail.com>
Message-ID: <CA+XQpGtnsH8ZL5akPj_LOeMnf6hBh2akb9UKHEtWkB+zqwfssg@mail.gmail.com>

Thanks everyone, but wow, that design went up in parts count when I started
to add all the ifs and maybe's :D Ive been doing a lot of "simple" designs
on veroboard, and I thought this would be quite simple to build, but with
the summing opamps on each cv-input, the two 4066, buffers for status-LEDs
and the NOR gate to that, the build got quite a lot more complex :) It
might take a bit longer than I thought...

Mattias: Thanks for the heads up, but right now I am looking more for
simplicity than nice slopes ;) For short sounds I built PHObos AD/AR last
week. It is very nice at short sounds at least I think so :)

/Kristian - putting this module on ice for the christmas vacation :)


On Mon, Dec 17, 2018 at 7:42 AM Mattias Rickardsson <mr at analogue.org> wrote:

>
>
> Den s?n 16 dec. 2018 15:24 skrev Kristian Bl?sol <
> kristian.borgstedt at gmail.com>:
>
>> ...
>> Oh, a link to the schematics maybe :)
>> https://www.schmitzbits.de/vcadsr.html
>>
>
> Nice & compact design. Note though that it's a linear-slope envelope,
> which IMHO is not what one typically wants for shorter sounds. :-)
>
> /mr
>
>

-- 
---
Kristian Bl?sol
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From neil.johnson71 at gmail.com  Mon Dec 17 12:42:47 2018
From: neil.johnson71 at gmail.com (Neil Johnson)
Date: Mon, 17 Dec 2018 11:42:47 +0000
Subject: [sdiy] [Potential SPAM] Re: Mind blown -- TL074 saturated
 outputs different
In-Reply-To: <10FD541D27FB4C4082D1BF970B192D82@galvanox01>
References: <22FDF271339C4B6D91A9EBCEB8A8CCF0@galvanox01>
 <e849b3cf-d8bd-a421-aaaa-894fc44c67ce@schmitzbits.de>
 <9ACE521DFE9C481F89E1A28F89D6A21B@galvanox01>
 <b9021091-54c4-cc38-ce8e-e609c4650eef@bendentech.co.uk>
 <CAP92RBUW1Y1hbvo_KpDt9y_HsT=XBUKv8v5Bpq1JXswSaOtHnQ@mail.gmail.com>
 <C02A76A5931A40C3B56B758CD1E0958F@galvanox01>
 <CACZGMxLVcFdkyrSpCVyKcNkhKTp2ajUCr0vgDwiDsuZ47F9w4Q@mail.gmail.com>
 <10FD541D27FB4C4082D1BF970B192D82@galvanox01>
Message-ID: <CACZGMx+YuPN73_NpmGtP-xwv=_xzRDE6Y2+W4wRed8VxhQZuUg@mail.gmail.com>

Hi Dave,

> Yeah, Neil, that's more or less what I was trying to say, but since I didn't
> do my doctoral thesis on 1N4148 diodes, I couldn't find the words.

Funnily enough my doctoral thesis wasn't on 1N4148 diodes either, but
a basic understanding of Shockley's diode equation is all you need to
realise that getting two diodes to match exactly in a circuit is nigh
impossible.
If the clamp voltage needs a very tight tolerance on it then better
options include op-amp based clamps which can then be tied to a
precision reference, e.g., REF-02.

Cheers,
Neil
--
http://www.njohnson.co.uk


From tom at electricdruid.net  Mon Dec 17 14:38:58 2018
From: tom at electricdruid.net (Tom Wiltshire)
Date: Mon, 17 Dec 2018 13:38:58 +0000
Subject: [sdiy] Rene Schmitz VCADSR
In-Reply-To: <CA+XQpGtnsH8ZL5akPj_LOeMnf6hBh2akb9UKHEtWkB+zqwfssg@mail.gmail.com>
References: <CA+XQpGvjucNTVD0PHAgP+ZKd+N-RkPS_GX8Vg33EJ-oopW-t5Q@mail.gmail.com>
 <CAP92RBXifbEdYe+jL5hwsRqQwk7qqHW=ycE1h_LPacZMhKS6wA@mail.gmail.com>
 <CA+XQpGtnsH8ZL5akPj_LOeMnf6hBh2akb9UKHEtWkB+zqwfssg@mail.gmail.com>
Message-ID: <895B2005-F430-458F-A743-65111BF92A36@electricdruid.net>

For a simple VCADSR, the AS3310 or my own EnvGen8 PIC-based envelope generator are pretty low parts count.

Tom

==================
       Electric Druid
Synth & Stompbox DIY
==================

> On 17 Dec 2018, at 10:43, Kristian Bl?sol <kristian.borgstedt at gmail.com> wrote:
> 
> Thanks everyone, but wow, that design went up in parts count when I started to add all the ifs and maybe's :D Ive been doing a lot of "simple" designs on veroboard, and I thought this would be quite simple to build, but with the summing opamps on each cv-input, the two 4066, buffers for status-LEDs  and the NOR gate to that, the build got quite a lot more complex :) It might take a bit longer than I thought...
> 
> Mattias: Thanks for the heads up, but right now I am looking more for simplicity than nice slopes ;) For short sounds I built PHObos AD/AR last week. It is very nice at short sounds at least I think so :)
> 
> /Kristian - putting this module on ice for the christmas vacation :)
> 
> 
> On Mon, Dec 17, 2018 at 7:42 AM Mattias Rickardsson <mr at analogue.org> wrote:
> 
> 
> Den s?n 16 dec. 2018 15:24 skrev Kristian Bl?sol <kristian.borgstedt at gmail.com>:
> ...
> Oh, a link to the schematics maybe :) 
> https://www.schmitzbits.de/vcadsr.html
> 
> Nice & compact design. Note though that it's a linear-slope envelope, which IMHO is not what one typically wants for shorter sounds. :-)
> 
> /mr
> 
> 
> 
> -- 
> ---
> Kristian Bl?sol
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy




From weplar at gmail.com  Mon Dec 17 16:17:37 2018
From: weplar at gmail.com (Tony Kalomiris)
Date: Mon, 17 Dec 2018 10:17:37 -0500
Subject: [sdiy] [Potential SPAM] Re: Mind blown -- TL074 saturated
 outputs different
In-Reply-To: <CACZGMx+YuPN73_NpmGtP-xwv=_xzRDE6Y2+W4wRed8VxhQZuUg@mail.gmail.com>
Message-ID: <D83D2621.A964%weplar@gmail.com>

Yes, but the RCA CA3019 came pretty darn close at a typical forward
voltage drop difference between any two diodes at 1 mV (1 mA forward bias.)

Tony K


On 18-12-17 6:42 AM, "Neil Johnson" <neil.johnson71 at gmail.com> wrote:

>getting two diodes to match exactly in a circuit is nigh
>impossible.




From abide at dmdrafting.com  Mon Dec 17 16:28:06 2018
From: abide at dmdrafting.com (Dave Magnuson)
Date: Mon, 17 Dec 2018 10:28:06 -0500
Subject: [sdiy] Yo, check out this plate reverb
In-Reply-To: <5fb2e465-c7e5-17ed-f943-2d1c1cd98d9a@gmx.de>
References: <5fb2e465-c7e5-17ed-f943-2d1c1cd98d9a@gmx.de>
Message-ID: <005301d4961d$1c468a70$54d39f50$@dmdrafting.com>



-----Original Message-----
From: Synth-diy <synth-diy-bounces at synth-diy.org> On Behalf Of
sleepy_dog at gmx.de
Sent: Saturday, December 15, 2018 6:14 AM
To: synth-diy mailing list <synth-diy at synth-diy.org>
Subject: [sdiy] Yo, check out this plate reverb

Despite that DAW you are seeing.... keep looking longer... not a software
plugin...
but rather out of IKEA parts :-D

https://www.youtube.com/watch?v=5OcRMA2FNUE&t=13m22s



I've been watching this build.  Sounds quite good, actually!

Dave



From neil.johnson71 at gmail.com  Mon Dec 17 16:46:36 2018
From: neil.johnson71 at gmail.com (Neil Johnson)
Date: Mon, 17 Dec 2018 15:46:36 +0000
Subject: [sdiy] [Potential SPAM] Re: Mind blown -- TL074 saturated
 outputs different
In-Reply-To: <D83D2621.A964%weplar@gmail.com>
References: <CACZGMx+YuPN73_NpmGtP-xwv=_xzRDE6Y2+W4wRed8VxhQZuUg@mail.gmail.com>
 <D83D2621.A964%weplar@gmail.com>
Message-ID: <CACZGMx+ArVsqxtLETbGj69QaCcA2vBJvBe8zrRjfWZad48FjkQ@mail.gmail.com>

Tony Kalomiris wrote:
> Yes, but the RCA CA3019 came pretty darn close at a typical forward
> voltage drop difference between any two diodes at 1 mV (1 mA forward bias.)

That's 1mV _TYPICAL_, worst case is 5mV.  And that's for diodes on a
single substrate (so Is and T are going to track pretty well) so
that's about as best as you can get.
And unfortunately no longer available :(

Neil
-- 
http://www.njohnson.co.uk


From sines_list at scale.la  Mon Dec 17 16:47:29 2018
From: sines_list at scale.la (sines)
Date: Mon, 17 Dec 2018 10:47:29 -0500
Subject: [sdiy] Yo, check out this plate reverb
In-Reply-To: <005301d4961d$1c468a70$54d39f50$@dmdrafting.com>
References: <5fb2e465-c7e5-17ed-f943-2d1c1cd98d9a@gmx.de>
 <005301d4961d$1c468a70$54d39f50$@dmdrafting.com>
Message-ID: <4C771C10-680D-471D-B6C6-DFEDA41CB59E@scale.la>

First thought ? it would be infinitely cheaper / easier to buy a new steel plate that isn?t already covered in power coated paint.
But because Ikea buys in such great quantities it?s probably cheaper to buy a finished plate from Ikea and sand it versus a new raw sheet from a local steel supplier. Just sounds like a lot of unnecessary dust exposure and elbow grease.

Making a stereo version would be great. But also adding some kind of electroacoustic / mechanical damping mechanism would be cool. Like a locking brake caliper [like that for a bicycle] with cotton pads to adjust the damping, thus reducing the hi-to-mid range ring. Positioning the piezo elements seems to have a great amount of impact on the resonant frequencies, which would also be nice to control as well.

After I build the next 30 some Deckard?s Dream, Buchla + Euro modules on my bench, I swear I?m going to build my own. ;) 


Todd

> On Dec 17, 2018, at 10:28 AM, Dave Magnuson <abide at dmdrafting.com> wrote:
> 
> 
> 
> -----Original Message-----
> From: Synth-diy <synth-diy-bounces at synth-diy.org> On Behalf Of
> sleepy_dog at gmx.de
> Sent: Saturday, December 15, 2018 6:14 AM
> To: synth-diy mailing list <synth-diy at synth-diy.org>
> Subject: [sdiy] Yo, check out this plate reverb
> 
> Despite that DAW you are seeing.... keep looking longer... not a software
> plugin...
> but rather out of IKEA parts :-D
> 
> https://www.youtube.com/watch?v=5OcRMA2FNUE&t=13m22s
> 
> 
> 
> I've been watching this build.  Sounds quite good, actually!
> 
> Dave
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy




From weplar at gmail.com  Mon Dec 17 16:47:31 2018
From: weplar at gmail.com (Tony Kalomiris)
Date: Mon, 17 Dec 2018 10:47:31 -0500
Subject: [sdiy] Mind blown -- TL074 saturated outputs different
In-Reply-To: <AD0C5BCF-1822-4270-9733-0DB9A390F53F@tpg.com.au>
Message-ID: <D83D296F.AB42%weplar@gmail.com>

ETI Canada featured many of Tim Orr's electro music articles and circuits.

He wrote for PE (Practical Electronics UK) as well. Excellent series on
op-amps.(Feb '79)
And of course Wireless World Elektor Formant synthesizer with D.W. Thomas.
(Aug. ? Oct. 1973)

Yes he did work for EMS in the early 70s but forget which designs are
credited to him.

Tony K

From:  Adam Inglis <21pointy at tpg.com.au>
Date:  Mon, 17 Dec 2018 14:57:47 +1000
To:  Ren? Schmitz <synth at schmitzbits.de>
Cc:  <synth-diy at synth-diy.org>
Subject:  Re: [sdiy] Mind blown -- TL074 saturated outputs different

> Just found this VCO schematic online that features this:
> 
> page 16
> dual integrator quadrature VCO (sinusoidal, not sure how useful for synths)
> using 3080 OTA
> 
> https://www.americanradiohistory.com/Archive-Electronics-Today/Canada/70s/ETI-
> CA-1978-12.pdf
> 
> Article is by Tim Orr, who I think used to work for EMS?
> 


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From weplar at gmail.com  Mon Dec 17 17:08:19 2018
From: weplar at gmail.com (Tony Kalomiris)
Date: Mon, 17 Dec 2018 11:08:19 -0500
Subject: [sdiy] [Potential SPAM] Re: Mind blown -- TL074 saturated
 outputs different
In-Reply-To: <CACZGMx+ArVsqxtLETbGj69QaCcA2vBJvBe8zrRjfWZad48FjkQ@mail.gmail.com>
Message-ID: <D83D3125.AB9E%weplar@gmail.com>

Yes sir, I neglected to mention the max, or worst case value.

I "typically" only go with the middle number when designing. Bad habit.

Yes, matched transistors are the way to go, or at least diode-connected
transistors.
I may be able to get my hands on one to play with however.
Still, may be pleasantly surprised.

Tony K

On 18-12-17 10:46 AM, "Neil Johnson" <neil.johnson71 at gmail.com> wrote:

>That's 1mV _TYPICAL_, worst case is 5mV.




From neil.johnson71 at gmail.com  Mon Dec 17 17:13:21 2018
From: neil.johnson71 at gmail.com (Neil Johnson)
Date: Mon, 17 Dec 2018 16:13:21 +0000
Subject: [sdiy] Mind blown -- TL074 saturated outputs different
In-Reply-To: <D83D296F.AB42%weplar@gmail.com>
References: <AD0C5BCF-1822-4270-9733-0DB9A390F53F@tpg.com.au>
 <D83D296F.AB42%weplar@gmail.com>
Message-ID: <CACZGMxKd-3G5pZm4JKqSpkQqR9XFyywW800TdX-s7=VOY4Eiag@mail.gmail.com>

Tony Kalomiris wrote:
>
> ETI Canada featured many of Tim Orr's electro music articles and circuits.
>
> He wrote for PE (Practical Electronics UK) as well. Excellent series on op-amps.(Feb '79)
> And of course Wireless World Elektor Formant synthesizer with D.W. Thomas. (Aug. ? Oct. 1973)
>
> Yes he did work for EMS in the early 70s but forget which designs are credited to him.

In the mid-90s Tim worked for Akai - I still have a copy of the job ad
he posted looking for SW engineers to work on Akai samplers.
He's now running a little company building low-frequency network analysers:
http://www.cypherinstruments.co.uk/

Neil
-- 
http://www.njohnson.co.uk



From weplar at gmail.com  Mon Dec 17 17:46:31 2018
From: weplar at gmail.com (Tony Kalomiris)
Date: Mon, 17 Dec 2018 11:46:31 -0500
Subject: [sdiy] Mind blown -- TL074 saturated outputs different
In-Reply-To: <CACZGMxKd-3G5pZm4JKqSpkQqR9XFyywW800TdX-s7=VOY4Eiag@mail.gmail.com>
Message-ID: <D83D3BDD.ABC2%weplar@gmail.com>

That might be a hoot to take a look at. <nudge, nudge, wink, wink>
I remember the young Digidesign job ad looking for "music lovers".

Tony K

On 18-12-17 11:13 AM, "Neil Johnson" <neil.johnson71 at gmail.com> wrote:

>In the mid-90s Tim worked for Akai - I still have a copy of the job ad
>he posted looking for SW engineers to work on Akai samplers.




From timr at circuitabbey.com  Mon Dec 17 19:11:26 2018
From: timr at circuitabbey.com (Tim Ressel)
Date: Mon, 17 Dec 2018 10:11:26 -0800
Subject: [sdiy] Tri-core oscillator sync
Message-ID: <7f92cbde-bb75-6141-6815-40f22a869be1@circuitabbey.com>

Hi,

I have made a triangle core oscillator that works really well except for 
the sync. I implemented what I thought would be hard and soft sync but 
the results were disappointing. As I understand it my "hard sync" is 
known as "reversing sync" i.e. a rising edge causes the steering flip 
flop to change state and thus the wave reverses. My "soft sync" changes 
the upper set point on the window comparator.

I would like the soft sync to sound like the Doepfer A-110-2 oscillator 
soft sync if possible.? Thoughts?

-- 
--Tim Ressel
Circuit Abbey
timr at circuitabbey.com



From frey at radioles.com  Mon Dec 17 20:03:32 2018
From: frey at radioles.com (Joe Frey)
Date: Mon, 17 Dec 2018 14:03:32 -0500
Subject: [sdiy] clock pulse to vtrig
Message-ID: <5068ebfe-7c4d-4bcb-a606-e61465a39eb9@radioles.com>

Hello all, this is a follow-up to an email from 2 weeks ago some may remember. Anyway, I am using a clock out from my EHX 8-step sequencer to trigger my Lyra-8. The Lyra-8 plays for as long as the clock pulse. I want to be able to create a longer and variable pulse using a circuit. I am not interested in tackling programming a microcontroller, yet.
Can anyone point me in the direction of some circuitry that can do this? Thanks. JoeF.

?Sent from TypeApp ?
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From admin at bugbrand.co.uk  Mon Dec 17 20:17:32 2018
From: admin at bugbrand.co.uk (Tom Bugs)
Date: Mon, 17 Dec 2018 19:17:32 +0000
Subject: [sdiy] clock pulse to vtrig
In-Reply-To: <5068ebfe-7c4d-4bcb-a606-e61465a39eb9@radioles.com>
References: <5068ebfe-7c4d-4bcb-a606-e61465a39eb9@radioles.com>
Message-ID: <8b878475-1968-a520-3169-ea56dea8b35d@bugbrand.co.uk>

A Yusynth module design sprung to mind: 
http://www.yusynth.net/Modular/EN/PULSEDELAY/index.html
Pulse Delay (1mS to 1S) followed by a variable length pulse (again 1mS 
to 1S)
Just drop the delay part if you don't want that.

There'd maybe be other ways, eg. using Mickey Mouse logic -> 
http://musicfromouterspace.com/analogsynth_new/ELECTRONICS/mickeymouselogic.html
Look at the pulse stretcher - just change the 100k to variable (eg. 4k7 
fixed resistor + 500k Log pot or so would probably be a good start point)
Just watch the polarity / use further inverter stages.

On 17/12/2018 19:03, Joe Frey wrote:
> Hello all, this is a follow-up to an email from 2 weeks ago some may 
> remember. Anyway, I am using a clock out from my EHX 8-step sequencer 
> to trigger my Lyra-8. The Lyra-8 plays for as long as the clock pulse. 
> I want to be able to create a longer and variable pulse using a 
> circuit. I am not interested in tackling programming a 
> microcontroller, yet.
> Can anyone point me in the direction of some circuitry that can do 
> this? Thanks. JoeF.
>
> Sent from TypeApp <http://www.typeapp.com/r?b=14068>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy

-- 
BugBrand LTD
UK company No. 07199808
VAT No. GB 988 2629 57
1 Ninetree Hill
BRISTOL BS1 3SB
United Kingdom
www.bugbrand.co.uk



---
This email has been checked for viruses by AVG.
https://www.avg.com
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From matthias.herrmann at fonik.de  Mon Dec 17 20:25:45 2018
From: matthias.herrmann at fonik.de (Matthias Herrmann)
Date: Mon, 17 Dec 2018 20:25:45 +0100
Subject: [sdiy] clock pulse to vtrig
In-Reply-To: <5068ebfe-7c4d-4bcb-a606-e61465a39eb9@radioles.com>
References: <5068ebfe-7c4d-4bcb-a606-e61465a39eb9@radioles.com>
Message-ID: <000e01d4963e$4f28a6f0$ed79f4d0$@herrmann@fonik.de>

Without voltage control I would use a CMOS based pulse stretcher (Google CMOS Mickey Mouse Logic).

Cheers,
Mathtias

 

 

From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Joe Frey
Sent: Monday, December 17, 2018 8:04 PM
To: 'SDIY List'
Subject: [sdiy] clock pulse to vtrig

 

Hello all, this is a follow-up to an email from 2 weeks ago some may remember. Anyway, I am using a clock out from my EHX 8-step sequencer to trigger my Lyra-8. The Lyra-8 plays for as long as the clock pulse. I want to be able to create a longer and variable pulse using a circuit. I am not interested in tackling programming a microcontroller, yet.

Can anyone point me in the direction of some circuitry that can do this? Thanks. JoeF.

Sent from TypeApp <http://www.typeapp.com/r?b=14068>  

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From weplar at gmail.com  Tue Dec 18 02:44:52 2018
From: weplar at gmail.com (Tony K)
Date: Mon, 17 Dec 2018 20:44:52 -0500
Subject: [sdiy] clock pulse to vtrig
In-Reply-To: <5068ebfe-7c4d-4bcb-a606-e61465a39eb9@radioles.com>
References: <5068ebfe-7c4d-4bcb-a606-e61465a39eb9@radioles.com>
Message-ID: <2EC1C987-333A-40F3-8FB7-592DFCF01F26@gmail.com>

Dual retriggerable monostable multivibrator: 74123 TTL, 4528 CMOS. Or it's modern equivalents.

First for delay, triggers second with adjustable pulse with, positive or negative going. 

Been a while, but I've used it for purposes other than music exactly as above. Not sure how "long" you need it, or what level your skills are at. 

Tony K

> On Dec 17, 2018, at 2:03 PM, Joe Frey <frey at radioles.com> wrote:
> 
> Hello all, this is a follow-up to an email from 2 weeks ago some may remember. Anyway, I am using a clock out from my EHX 8-step sequencer to trigger my Lyra-8. The Lyra-8 plays for as long as the clock pulse. I want to be able to create a longer and variable pulse using a circuit. I am not interested in tackling programming a microcontroller, yet.
> Can anyone point me in the direction of some circuitry that can do this? Thanks. JoeF.
> 
> Sent from TypeApp
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
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From mec.forumreader at gmail.com  Tue Dec 18 06:44:14 2018
From: mec.forumreader at gmail.com (Michael E Caloroso)
Date: Tue, 18 Dec 2018 00:44:14 -0500
Subject: [sdiy] Tri-core oscillator sync
In-Reply-To: <7f92cbde-bb75-6141-6815-40f22a869be1@circuitabbey.com>
References: <7f92cbde-bb75-6141-6815-40f22a869be1@circuitabbey.com>
Message-ID: <CAAv6=UAOZaC4-mtDsqG-2F39oXLAECJMhO0OuFRY2N8Hr732fQ@mail.gmail.com>

"Hard sync" means that the charging core is prematurely reset by an
external trigger.  It is intended to create a complex waveshape with
altered harmonics.  By altering the frequency of the sync'd VCO above
that of the master VCO, you sweep the harmonics.

"Soft Sync" means the slave VCO is oscillating at the same frequency
of the master VCO.

MC

On 12/17/18, Tim Ressel <timr at circuitabbey.com> wrote:
> Hi,
>
> I have made a triangle core oscillator that works really well except for
> the sync. I implemented what I thought would be hard and soft sync but
> the results were disappointing. As I understand it my "hard sync" is
> known as "reversing sync" i.e. a rising edge causes the steering flip
> flop to change state and thus the wave reverses. My "soft sync" changes
> the upper set point on the window comparator.
>
> I would like the soft sync to sound like the Doepfer A-110-2 oscillator
> soft sync if possible.? Thoughts?
>
> --
> --Tim Ressel
> Circuit Abbey
> timr at circuitabbey.com
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>



From sdiy at haraldswerk.de  Tue Dec 18 09:31:08 2018
From: sdiy at haraldswerk.de (Harald)
Date: Tue, 18 Dec 2018 09:31:08 +0100
Subject: [sdiy] clock pulse to vtrig
In-Reply-To: <5068ebfe-7c4d-4bcb-a606-e61465a39eb9@radioles.com>
References: <5068ebfe-7c4d-4bcb-a606-e61465a39eb9@radioles.com>
Message-ID: <f8cee4be-ef6a-5169-3cfc-d39292d55aa7@haraldswerk.de>

Maybe this one can help: 
https://www.haraldswerk.de/Gate_and_Trigger/Trigger_Delay/Trigger_Delay.html. 
Just leave the delay part out and adjust the C value in the length part 
to your needs.

Am 17.12.18 um 20:03 schrieb Joe Frey:
> Hello all, this is a follow-up to an email from 2 weeks ago some may remember.
> Anyway, I am using a clock out from my EHX 8-step sequencer to trigger my
> Lyra-8. The Lyra-8 plays for as long as the clock pulse. I want to be able to
> create a longer and variable pulse using a circuit. I am not interested in
> tackling programming a microcontroller, yet.
> Can anyone point me in the direction of some circuitry that can do this? Thanks.
> JoeF.
> 
> Sent from TypeApp <http://www.typeapp.com/r?b=14068>
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> 


From scouttrooper69er at gmail.com  Tue Dec 18 09:37:46 2018
From: scouttrooper69er at gmail.com (dave flood)
Date: Tue, 18 Dec 2018 18:37:46 +1000
Subject: [sdiy] messages
Message-ID: <CA+HK6V5yLHCROJd_8AsyepLrN6V8=dzmNoLLGoSXEhbm9qgd9w@mail.gmail.com>

stop sending me so many emails, had a gutful of whingers, buy a book, do a
course, and don't send any more thAnkyiou
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From mr at analogue.org  Tue Dec 18 13:12:03 2018
From: mr at analogue.org (Mattias Rickardsson)
Date: Tue, 18 Dec 2018 13:12:03 +0100
Subject: [sdiy] Tri-core oscillator sync
In-Reply-To: <CAAv6=UAOZaC4-mtDsqG-2F39oXLAECJMhO0OuFRY2N8Hr732fQ@mail.gmail.com>
References: <7f92cbde-bb75-6141-6815-40f22a869be1@circuitabbey.com>
 <CAAv6=UAOZaC4-mtDsqG-2F39oXLAECJMhO0OuFRY2N8Hr732fQ@mail.gmail.com>
Message-ID: <CAP92RBUoNi2-Hkip_xphc1gF0itKcNhgFESCGMjvysdq9uQi4w@mail.gmail.com>

I'd rather define it like:

"Hard sync" syncs the slave every time,

"soft sync" syncs the slave sometimes, i.e., when it has completed enough
of its cycle.

Then the actual sync type in both these above sync methods can be either
"reset sync" or "reversing sync".

/mr


On Tue, 18 Dec 2018 at 06:45, Michael E Caloroso <mec.forumreader at gmail.com>
wrote:

> "Hard sync" means that the charging core is prematurely reset by an
> external trigger.  It is intended to create a complex waveshape with
> altered harmonics.  By altering the frequency of the sync'd VCO above
> that of the master VCO, you sweep the harmonics.
>
> "Soft Sync" means the slave VCO is oscillating at the same frequency
> of the master VCO.
>
> MC
>
> On 12/17/18, Tim Ressel <timr at circuitabbey.com> wrote:
> > Hi,
> >
> > I have made a triangle core oscillator that works really well except for
> > the sync. I implemented what I thought would be hard and soft sync but
> > the results were disappointing. As I understand it my "hard sync" is
> > known as "reversing sync" i.e. a rising edge causes the steering flip
> > flop to change state and thus the wave reverses. My "soft sync" changes
> > the upper set point on the window comparator.
> >
> > I would like the soft sync to sound like the Doepfer A-110-2 oscillator
> > soft sync if possible.  Thoughts?
> >
> > --
> > --Tim Ressel
> > Circuit Abbey
> > timr at circuitabbey.com
> >
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
> >
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
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From ulfurh at gmail.com  Tue Dec 18 13:33:26 2018
From: ulfurh at gmail.com (ulfur hansson)
Date: Tue, 18 Dec 2018 12:33:26 +0000
Subject: [sdiy] Tri-core oscillator sync
In-Reply-To: <CAP92RBUoNi2-Hkip_xphc1gF0itKcNhgFESCGMjvysdq9uQi4w@mail.gmail.com>
References: <7f92cbde-bb75-6141-6815-40f22a869be1@circuitabbey.com>
 <CAAv6=UAOZaC4-mtDsqG-2F39oXLAECJMhO0OuFRY2N8Hr732fQ@mail.gmail.com>
 <CAP92RBUoNi2-Hkip_xphc1gF0itKcNhgFESCGMjvysdq9uQi4w@mail.gmail.com>
Message-ID: <A09C8C2B-F0B8-4679-AC60-E11080A9A983@gmail.com>

regarding reversing sync, i imagine the output amplitude will drop if the sync input exceeds the oscillator base frequency (just like the common DCO design problem)

am i misguided or is this a problem that has to be addressed while designing a soft-syncable oscillator?

Sent from outer space

> On Dec 18, 2018, at 12:12 PM, Mattias Rickardsson <mr at analogue.org> wrote:
> 
> I'd rather define it like:
> 
> "Hard sync" syncs the slave every time,
> 
> "soft sync" syncs the slave sometimes, i.e., when it has completed enough of its cycle.
> 
> Then the actual sync type in both these above sync methods can be either "reset sync" or "reversing sync".
> 
> /mr
> 
> 
>> On Tue, 18 Dec 2018 at 06:45, Michael E Caloroso <mec.forumreader at gmail.com> wrote:
>> "Hard sync" means that the charging core is prematurely reset by an
>> external trigger.  It is intended to create a complex waveshape with
>> altered harmonics.  By altering the frequency of the sync'd VCO above
>> that of the master VCO, you sweep the harmonics.
>> 
>> "Soft Sync" means the slave VCO is oscillating at the same frequency
>> of the master VCO.
>> 
>> MC
>> 
>> On 12/17/18, Tim Ressel <timr at circuitabbey.com> wrote:
>> > Hi,
>> >
>> > I have made a triangle core oscillator that works really well except for
>> > the sync. I implemented what I thought would be hard and soft sync but
>> > the results were disappointing. As I understand it my "hard sync" is
>> > known as "reversing sync" i.e. a rising edge causes the steering flip
>> > flop to change state and thus the wave reverses. My "soft sync" changes
>> > the upper set point on the window comparator.
>> >
>> > I would like the soft sync to sound like the Doepfer A-110-2 oscillator
>> > soft sync if possible.  Thoughts?
>> >
>> > --
>> > --Tim Ressel
>> > Circuit Abbey
>> > timr at circuitabbey.com
>> >
>> > _______________________________________________
>> > Synth-diy mailing list
>> > Synth-diy at synth-diy.org
>> > http://synth-diy.org/mailman/listinfo/synth-diy
>> >
>> 
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
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From mr at analogue.org  Tue Dec 18 13:36:43 2018
From: mr at analogue.org (Mattias Rickardsson)
Date: Tue, 18 Dec 2018 13:36:43 +0100
Subject: [sdiy] Tri-core oscillator sync
In-Reply-To: <A09C8C2B-F0B8-4679-AC60-E11080A9A983@gmail.com>
References: <7f92cbde-bb75-6141-6815-40f22a869be1@circuitabbey.com>
 <CAAv6=UAOZaC4-mtDsqG-2F39oXLAECJMhO0OuFRY2N8Hr732fQ@mail.gmail.com>
 <CAP92RBUoNi2-Hkip_xphc1gF0itKcNhgFESCGMjvysdq9uQi4w@mail.gmail.com>
 <A09C8C2B-F0B8-4679-AC60-E11080A9A983@gmail.com>
Message-ID: <CAP92RBXVeyfxnyx=HU4nFD=VC1p0X22sONxtvNT94NU2+b7+NA@mail.gmail.com>

If you do soft sync with your reversing sync, you let it perform most of
its cycle before allowing it to sync, so I don't see any problem there.

With hard-synced reversing sync OTOH the resulting amplitude can get
arbitrarily small just as you say.

/mr

On Tue, 18 Dec 2018 at 13:33, ulfur hansson <ulfurh at gmail.com> wrote:

> regarding reversing sync, i imagine the output amplitude will drop if the
> sync input exceeds the oscillator base frequency (just like the common DCO
> design problem)
>
> am i misguided or is this a problem that has to be addressed while
> designing a soft-syncable oscillator?
>
> Sent from outer space
>
> On Dec 18, 2018, at 12:12 PM, Mattias Rickardsson <mr at analogue.org> wrote:
>
> I'd rather define it like:
>
> "Hard sync" syncs the slave every time,
>
> "soft sync" syncs the slave sometimes, i.e., when it has completed enough
> of its cycle.
>
> Then the actual sync type in both these above sync methods can be either
> "reset sync" or "reversing sync".
>
> /mr
>
>
> On Tue, 18 Dec 2018 at 06:45, Michael E Caloroso <
> mec.forumreader at gmail.com> wrote:
>
>> "Hard sync" means that the charging core is prematurely reset by an
>> external trigger.  It is intended to create a complex waveshape with
>> altered harmonics.  By altering the frequency of the sync'd VCO above
>> that of the master VCO, you sweep the harmonics.
>>
>> "Soft Sync" means the slave VCO is oscillating at the same frequency
>> of the master VCO.
>>
>> MC
>>
>> On 12/17/18, Tim Ressel <timr at circuitabbey.com> wrote:
>> > Hi,
>> >
>> > I have made a triangle core oscillator that works really well except for
>> > the sync. I implemented what I thought would be hard and soft sync but
>> > the results were disappointing. As I understand it my "hard sync" is
>> > known as "reversing sync" i.e. a rising edge causes the steering flip
>> > flop to change state and thus the wave reverses. My "soft sync" changes
>> > the upper set point on the window comparator.
>> >
>> > I would like the soft sync to sound like the Doepfer A-110-2 oscillator
>> > soft sync if possible.  Thoughts?
>> >
>> > --
>> > --Tim Ressel
>> > Circuit Abbey
>> > timr at circuitabbey.com
>> >
>> > _______________________________________________
>> > Synth-diy mailing list
>> > Synth-diy at synth-diy.org
>> > http://synth-diy.org/mailman/listinfo/synth-diy
>> >
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
>
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From pinoaffe at airmail.cc  Tue Dec 18 16:10:52 2018
From: pinoaffe at airmail.cc (pinoaffe)
Date: Tue, 18 Dec 2018 16:10:52 +0100
Subject: [sdiy] height and footprints of pcbmount banana jack, ts jack,
 and pot
Message-ID: <043f8609-651d-ea59-4b0e-9fa71a176cf8@airmail.cc>

Hi everybody,

I'm currently working on a bunch of modules with PCBs parallel to the
front plate.

Does anyone know of any PCB-mount banana jacks that would work in such a
situation,
preferably with a rather long screwing thread, to allow for thicker
front plates.

Similarly, I'm looking for long-threaded PCB-mount pots and "eurorack"
jacks.

Thonkiconns wouldn't work for me, as a 4mm thread is way too little for
the wooden front plates I'm working with,
and I'd prefer not to have to drill shallow holes in the back of the
front plates.

Thanks in advance!




From chromatest at azburners.org  Tue Dec 18 16:49:34 2018
From: chromatest at azburners.org (Chromatest J. Pantsmaker)
Date: Tue, 18 Dec 2018 08:49:34 -0700
Subject: [sdiy] messages
In-Reply-To: <CA+HK6V5yLHCROJd_8AsyepLrN6V8=dzmNoLLGoSXEhbm9qgd9w@mail.gmail.com>
References: <CA+HK6V5yLHCROJd_8AsyepLrN6V8=dzmNoLLGoSXEhbm9qgd9w@mail.gmail.com>
Message-ID: <CADpm=3ENzESB-fiSXjKOcmpeJOv4wJ1=RQXYwufvJF7U+doi=Q@mail.gmail.com>

This is an email list.  It generates emails.  If there weren't any emails,
then the list would cease to exist!

At the bottom of every email is a handy link (here it is again)
http://synth-diy.org/mailman/listinfo/synth-diy
If you go there, you can set your delivery options to "Daily Digest" or
something that includes the word "Digest".  You'll want that.

On Tue, Dec 18, 2018 at 1:38 AM dave flood <scouttrooper69er at gmail.com>
wrote:

> stop sending me so many emails, had a gutful of whingers, buy a book, do a
> course, and don't send any more thAnkyiou
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
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From dixon at mail.ubc.ca  Tue Dec 18 19:47:05 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Tue, 18 Dec 2018 10:47:05 -0800
Subject: [sdiy] Tri-core oscillator sync
In-Reply-To: <CAAv6=UAOZaC4-mtDsqG-2F39oXLAECJMhO0OuFRY2N8Hr732fQ@mail.gmail.com>
References: <7f92cbde-bb75-6141-6815-40f22a869be1@circuitabbey.com>
 <CAAv6=UAOZaC4-mtDsqG-2F39oXLAECJMhO0OuFRY2N8Hr732fQ@mail.gmail.com>
Message-ID: <F188DB8737BF40D594AE4BC4C6218425@galvanox01>

The way I have done this will all my tricore VCOs (including Dixie, Rubicon,
and Atlantis) is to apply the syncing signal to the threshold of the tricore
comparator for "soft" (reversing) sync, and to apply a sync-derived pulse to
a JFET across the integrator capacitor for "hard" (resetting) sync.  This
seems to work well.  I prefer the resetting sync sound in tricore VCOs
myself.

> -----Original Message-----
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On 
> Behalf Of Michael E Caloroso
> Sent: Monday, December 17, 2018 9:44 PM
> To: Tim Ressel
> Cc: SYNTH DIY
> Subject: Re: [sdiy] Tri-core oscillator sync
> 
> "Hard sync" means that the charging core is prematurely reset 
> by an external trigger.  It is intended to create a complex 
> waveshape with altered harmonics.  By altering the frequency 
> of the sync'd VCO above that of the master VCO, you sweep the 
> harmonics.
> 
> "Soft Sync" means the slave VCO is oscillating at the same 
> frequency of the master VCO.
> 
> MC
> 
> On 12/17/18, Tim Ressel <timr at circuitabbey.com> wrote:
> > Hi,
> >
> > I have made a triangle core oscillator that works really 
> well except 
> > for the sync. I implemented what I thought would be hard 
> and soft sync 
> > but the results were disappointing. As I understand it my 
> "hard sync" 
> > is known as "reversing sync" i.e. a rising edge causes the steering 
> > flip flop to change state and thus the wave reverses. My 
> "soft sync" 
> > changes the upper set point on the window comparator.
> >
> > I would like the soft sync to sound like the Doepfer A-110-2 
> > oscillator soft sync if possible.? Thoughts?
> >
> > --
> > --Tim Ressel
> > Circuit Abbey
> > timr at circuitabbey.com
> >
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
> >
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> 




From timr at circuitabbey.com  Tue Dec 18 21:26:55 2018
From: timr at circuitabbey.com (Tim Ressel)
Date: Tue, 18 Dec 2018 12:26:55 -0800
Subject: [sdiy] Tri-core oscillator sync
In-Reply-To: <F188DB8737BF40D594AE4BC4C6218425@galvanox01>
References: <7f92cbde-bb75-6141-6815-40f22a869be1@circuitabbey.com>
 <CAAv6=UAOZaC4-mtDsqG-2F39oXLAECJMhO0OuFRY2N8Hr732fQ@mail.gmail.com>
 <F188DB8737BF40D594AE4BC4C6218425@galvanox01>
Message-ID: <735fc758-f623-7a33-bd56-038e81daee26@circuitabbey.com>

Interesting.

I'm using a window comparator and a D flip flop to do the switching. The 
comparators drive the set/reset inputs and the hard sync drives the 
clock input. As I understand it this is reversing sync. My soft sync 
drives the reference input on the upper comparator on the window 
comparator, thus shifting the upper trigger point.

My design has the cap voltage bouncing between two positive points. If I 
add A reset FET the cap voltage will go to zero which is below the lower 
set point. Do your designs have the cap voltage going to zero as a 
matter of course?

--TimR

On 12/18/2018 10:47 AM, David G Dixon wrote:
> The way I have done this will all my tricore VCOs (including Dixie, Rubicon,
> and Atlantis) is to apply the syncing signal to the threshold of the tricore
> comparator for "soft" (reversing) sync, and to apply a sync-derived pulse to
> a JFET across the integrator capacitor for "hard" (resetting) sync.  This
> seems to work well.  I prefer the resetting sync sound in tricore VCOs
> myself.
>
>> -----Original Message-----
>> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On
>> Behalf Of Michael E Caloroso
>> Sent: Monday, December 17, 2018 9:44 PM
>> To: Tim Ressel
>> Cc: SYNTH DIY
>> Subject: Re: [sdiy] Tri-core oscillator sync
>>
>> "Hard sync" means that the charging core is prematurely reset
>> by an external trigger.  It is intended to create a complex
>> waveshape with altered harmonics.  By altering the frequency
>> of the sync'd VCO above that of the master VCO, you sweep the
>> harmonics.
>>
>> "Soft Sync" means the slave VCO is oscillating at the same
>> frequency of the master VCO.
>>
>> MC
>>
>> On 12/17/18, Tim Ressel <timr at circuitabbey.com> wrote:
>>> Hi,
>>>
>>> I have made a triangle core oscillator that works really
>> well except
>>> for the sync. I implemented what I thought would be hard
>> and soft sync
>>> but the results were disappointing. As I understand it my
>> "hard sync"
>>> is known as "reversing sync" i.e. a rising edge causes the steering
>>> flip flop to change state and thus the wave reverses. My
>> "soft sync"
>>> changes the upper set point on the window comparator.
>>>
>>> I would like the soft sync to sound like the Doepfer A-110-2
>>> oscillator soft sync if possible.? Thoughts?
>>>
>>> --
>>> --Tim Ressel
>>> Circuit Abbey
>>> timr at circuitabbey.com
>>>
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
-- 
--Tim Ressel
Circuit Abbey
timr at circuitabbey.com



From dixon at mail.ubc.ca  Wed Dec 19 02:01:42 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Tue, 18 Dec 2018 17:01:42 -0800
Subject: [sdiy] Tri-core oscillator sync
In-Reply-To: <735fc758-f623-7a33-bd56-038e81daee26@circuitabbey.com>
References: <7f92cbde-bb75-6141-6815-40f22a869be1@circuitabbey.com>
 <CAAv6=UAOZaC4-mtDsqG-2F39oXLAECJMhO0OuFRY2N8Hr732fQ@mail.gmail.com>
 <F188DB8737BF40D594AE4BC4C6218425@galvanox01>
 <735fc758-f623-7a33-bd56-038e81daee26@circuitabbey.com>
Message-ID: <0A90C7FB42C64C299E5462276D3AD80B@galvanox01>

> Interesting.
> 
> I'm using a window comparator and a D flip flop to do the 
> switching. The comparators drive the set/reset inputs and the 
> hard sync drives the clock input. As I understand it this is 
> reversing sync. My soft sync drives the reference input on 
> the upper comparator on the window comparator, thus shifting 
> the upper trigger point.

Um.  Sounds complicated.  Mine is a fairly standard tri-square oscillator.
The integrator triangle output is summed with the square output (which gives
the famous "zigzag" waveform for free) and this drives the + input of the
comparator.  The - input is typically grounded (through a 1k resistor), and
the "reversing" sync input drives it through a 3.3nF capacitor.  The output
of the comparator is limited to +/-5V by one of those zener bridges we were
talking about last week, thus creating the square output.  This square wave
drives the integrator through a 2164 VCA acting as a 1V/oct expo converter,
thus closing the loop.  A linearized 2164 VCA in the loop provides linear
FM.  This is the basic Dixie VCO.

> My design has the cap voltage bouncing between two positive 
> points. If I add A reset FET the cap voltage will go to zero 
> which is below the lower set point. Do your designs have the 
> cap voltage going to zero as a matter of course?

Yes.  The triangle integrator's - input is grounded.



From neil.johnson71 at gmail.com  Tue Dec 25 00:01:14 2018
From: neil.johnson71 at gmail.com (Neil Johnson)
Date: Mon, 24 Dec 2018 23:01:14 +0000
Subject: [sdiy] Merry Christmas!
Message-ID: <CACZGMxJhBn2x=Cg_jHjkCuNZ5RB9Zmt00gfZ3cXN=KPcr2xNRQ@mail.gmail.com>

To all list members who celebrate Christmas at this time of year, may
I wish you all a very merry Christmas!

And to everyone, wishing you all a very synthtastic new year!

Cheers
Neil
-- 
http://www.njohnson.co.uk


From weplar at gmail.com  Tue Dec 25 02:06:56 2018
From: weplar at gmail.com (Tony K)
Date: Mon, 24 Dec 2018 20:06:56 -0500
Subject: [sdiy] Merry Christmas!
In-Reply-To: <CACZGMxJhBn2x=Cg_jHjkCuNZ5RB9Zmt00gfZ3cXN=KPcr2xNRQ@mail.gmail.com>
References: <CACZGMxJhBn2x=Cg_jHjkCuNZ5RB9Zmt00gfZ3cXN=KPcr2xNRQ@mail.gmail.com>
Message-ID: <81DB62C6-551E-4091-8B4E-6EAB1DFDA612@gmail.com>

Thank you, and may I also take this opportunity to extend my sincerest wishes for a happy and healthy new year to all. 

Happy experimenting everybody!

Tony Kalomiris

> On Dec 24, 2018, at 6:01 PM, Neil Johnson <neil.johnson71 at gmail.com> wrote:
> 
> To all list members who celebrate Christmas at this time of year, may
> I wish you all a very merry Christmas!
> 
> And to everyone, wishing you all a very synthtastic new year!
> 
> Cheers
> Neil
> -- 
> http://www.njohnson.co.uk
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From cjuried at yahoo.com  Tue Dec 25 02:16:08 2018
From: cjuried at yahoo.com (Chris Juried)
Date: Tue, 25 Dec 2018 01:16:08 +0000 (UTC)
Subject: [sdiy] Merry Christmas!
In-Reply-To: <CACZGMxJhBn2x=Cg_jHjkCuNZ5RB9Zmt00gfZ3cXN=KPcr2xNRQ@mail.gmail.com>
References: <CACZGMxJhBn2x=Cg_jHjkCuNZ5RB9Zmt00gfZ3cXN=KPcr2xNRQ@mail.gmail.com>
Message-ID: <1700643969.2294572.1545700568873@mail.yahoo.com>

Merry Christmas and Happy Holidays!
Sincerely,???
??Chris Juried,?WRCB719 ?
Audio Engineering Society (AES)?Member? 
InfoComm-Recognized AV Technologist
http://www.JuriedEngineering.com 
http://www.TubeEquipment.com 
http://www.HistoryOfRecording.com 
http://www.linkedin.com/in/chrisjuried
Email:?CJuried at yahoo.com? 
Voice: (954) 478-4355 


This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any distribution or copying of this email, and any attachments thereto, is strictly prohibited. If you have received this email in error, please immediately notify me at (954) 300-9972 and permanently delete the original and any copy of any e-mail and any printout thereof.
 

    On Monday, December 24, 2018, 6:09:21 PM EST, Neil Johnson <neil.johnson71 at gmail.com> wrote:  
 
 To all list members who celebrate Christmas at this time of year, may
I wish you all a very merry Christmas!

And to everyone, wishing you all a very synthtastic new year!

Cheers
Neil
-- 
http://www.njohnson.co.uk
_______________________________________________
Synth-diy mailing list
Synth-diy at synth-diy.org
http://synth-diy.org/mailman/listinfo/synth-diy
  
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From philgallo at gmail.com  Tue Dec 25 08:41:07 2018
From: philgallo at gmail.com (Phillip Gallo)
Date: Tue, 25 Dec 2018 00:41:07 -0700
Subject: [sdiy] Merry Christmas!
In-Reply-To: <CACZGMxJhBn2x=Cg_jHjkCuNZ5RB9Zmt00gfZ3cXN=KPcr2xNRQ@mail.gmail.com>
References: <CACZGMxJhBn2x=Cg_jHjkCuNZ5RB9Zmt00gfZ3cXN=KPcr2xNRQ@mail.gmail.com>
Message-ID: <CAN4YM6eKYgLchOnqqNE0N-mRDZ2n4Sdo4Mf0qJ_3g-jx__gh-w@mail.gmail.com>

Best wishes for this holiday season, the coming new year, and fruitful SDIY.

regards,
p


<http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
Virus-free.
www.avg.com
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<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

On Mon, Dec 24, 2018, 4:04 PM Neil Johnson <neil.johnson71 at gmail.com wrote:

> To all list members who celebrate Christmas at this time of year, may
> I wish you all a very merry Christmas!
>
> And to everyone, wishing you all a very synthtastic new year!
>
> Cheers
> Neil
> --
> http://www.njohnson.co.uk
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
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From indigoid at oldcorollas.org  Tue Dec 25 10:47:11 2018
From: indigoid at oldcorollas.org (john slee)
Date: Tue, 25 Dec 2018 20:47:11 +1100
Subject: [sdiy] Merry Christmas!
In-Reply-To: <CAN4YM6eKYgLchOnqqNE0N-mRDZ2n4Sdo4Mf0qJ_3g-jx__gh-w@mail.gmail.com>
References: <CACZGMxJhBn2x=Cg_jHjkCuNZ5RB9Zmt00gfZ3cXN=KPcr2xNRQ@mail.gmail.com>
 <CAN4YM6eKYgLchOnqqNE0N-mRDZ2n4Sdo4Mf0qJ_3g-jx__gh-w@mail.gmail.com>
Message-ID: <CAK+JDy29_TSCav3EWWur==87CYo=4q-tPBd-PJ8cDfPwm2j6DQ@mail.gmail.com>

Indeed!

May at least some of your projects not *quite* work as desired, and may you
then learn useful things fixing them :-)

John

On Tue, 25 Dec 2018 at 18:45, Phillip Gallo <philgallo at gmail.com> wrote:

> Best wishes for this holiday season, the coming new year, and fruitful
> SDIY.
>
> regards,
> p
>
>
>
> <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> Virus-free.
> www.avg.com
> <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
> <#m_2036250903675030729_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
>
> On Mon, Dec 24, 2018, 4:04 PM Neil Johnson <neil.johnson71 at gmail.com
> wrote:
>
>> To all list members who celebrate Christmas at this time of year, may
>> I wish you all a very merry Christmas!
>>
>> And to everyone, wishing you all a very synthtastic new year!
>>
>> Cheers
>> Neil
>> --
>> http://www.njohnson.co.uk
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
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From dixon at mail.ubc.ca  Tue Dec 25 10:56:29 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Tue, 25 Dec 2018 01:56:29 -0800
Subject: [sdiy] Merry Christmas!
Message-ID: <0779762F330A4667AE63D8690B9E39F4@galvanox01>

...and thanks for all the help!  Especially when I was cranky and
recalcitrant.

Oh, and a happy, healthy (especially that) and synthy new year.



From cheater00 at gmail.com  Tue Dec 25 20:49:17 2018
From: cheater00 at gmail.com (cheater00 cheater00)
Date: Tue, 25 Dec 2018 20:49:17 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission idea
Message-ID: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>

Hi everyone,
I was thinking again about how you could do a modular polysynth well,
and it occurred to me that you might be able to use frequency domain
multiplexing (FDM) to put several signals over a single conductor
pair. A quick search found the Si4710 which is a bit pricey at ~$12 on
digikey but it's a tiny 3x3mm QFN device that performs complete FM
transmission. In a 16 voice system, at about 5 output functions per
module, and 12 modules, you can easily use up ~1000 of those, which
drops the price to $4. I was wondering what everyone thinks about this
sort of scheme.

Given that metal patch cables could function as antennas and cause
both cross talk and external signal pick up, one could also use
multimode glass fiber and transmit signals this way. The question is,
does anyone know whether support electronics could be found that are
integrated enough (small in footprint) and inexpensive? The idea would
be to build an electronics module that takes 16 analog audio channels
and outputs a signal that can be then converted to glass media
signalling.

Merry Christmas everyone!


From list at mikebeauchamp.com  Tue Dec 25 21:01:34 2018
From: list at mikebeauchamp.com (Mike Beauchamp)
Date: Tue, 25 Dec 2018 15:01:34 -0500
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
Message-ID: <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>


> transmission. In a 16 voice system, at about 5 output functions per
> module, and 12 modules, you can easily use up ~1000 of those, which
> drops the price to $4. I was wondering what everyone thinks about this
> sort of scheme.

So there's $4000 worth of just one IC in a single complete polysynth?





From orenlevysticky at gmail.com  Tue Dec 25 21:16:52 2018
From: orenlevysticky at gmail.com (oren levy)
Date: Tue, 25 Dec 2018 10:16:52 -1000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
Message-ID: <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>

I think you?d be better off using FPGAs so you can mux the signals however you want along with data. Either a bunch of small ones or one big one per module. 
If you just want to share audio and don?t want to mess around with FPGAs, you can probably use a protocol like MADI. Not sure if MADI has a DC coupling requirement but if not, CV could also be passed. 
You?d probably want a very stable clock to sync all the modules to and optimize clock phase delays so everything can mux/demux in sync.

Rock & Roll,
Oren Levy

> On Dec 25, 2018, at 10:01, Mike Beauchamp <list at mikebeauchamp.com> wrote:
> 
> 
>> transmission. In a 16 voice system, at about 5 output functions per
>> module, and 12 modules, you can easily use up ~1000 of those, which
>> drops the price to $4. I was wondering what everyone thinks about this
>> sort of scheme.
> 
> So there's $4000 worth of just one IC in a single complete polysynth?
> 
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From cheater00 at gmail.com  Tue Dec 25 22:12:14 2018
From: cheater00 at gmail.com (cheater00 cheater00)
Date: Tue, 25 Dec 2018 22:12:14 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
Message-ID: <CA+9GZUjuBDK+3iCVTPpEM6mr7YbD2-mYb1R_MPbcW5DPDhrz+w@mail.gmail.com>

when you're making a system of a dozen modules, each replicated 16
times, you've got better problems than that a patch cord costs $16.

On Tue, Dec 25, 2018 at 9:03 PM Mike Beauchamp <list at mikebeauchamp.com> wrote:
>
>
> > transmission. In a 16 voice system, at about 5 output functions per
> > module, and 12 modules, you can easily use up ~1000 of those, which
> > drops the price to $4. I was wondering what everyone thinks about this
> > sort of scheme.
>
> So there's $4000 worth of just one IC in a single complete polysynth?
>
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy


From cheater00 at gmail.com  Tue Dec 25 22:13:40 2018
From: cheater00 at gmail.com (cheater00 cheater00)
Date: Tue, 25 Dec 2018 22:13:40 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
Message-ID: <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>

The objective is to be able to create a way for a single patch cord to
carry 16 voices. I'm not sure how an FPGA in itself will help me, have
you got any ideas?

MADI interfaces are prohibitively expensive.

On Tue, Dec 25, 2018 at 9:19 PM oren levy <orenlevysticky at gmail.com> wrote:
>
> I think you?d be better off using FPGAs so you can mux the signals however you want along with data. Either a bunch of small ones or one big one per module.
> If you just want to share audio and don?t want to mess around with FPGAs, you can probably use a protocol like MADI. Not sure if MADI has a DC coupling requirement but if not, CV could also be passed.
> You?d probably want a very stable clock to sync all the modules to and optimize clock phase delays so everything can mux/demux in sync.
>
> Rock & Roll,
> Oren Levy
>
> > On Dec 25, 2018, at 10:01, Mike Beauchamp <list at mikebeauchamp.com> wrote:
> >
> >
> >> transmission. In a 16 voice system, at about 5 output functions per
> >> module, and 12 modules, you can easily use up ~1000 of those, which
> >> drops the price to $4. I was wondering what everyone thinks about this
> >> sort of scheme.
> >
> > So there's $4000 worth of just one IC in a single complete polysynth?
> >
> >
> >
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From jason at redfish.net  Tue Dec 25 22:20:20 2018
From: jason at redfish.net (Jason Proctor)
Date: Tue, 25 Dec 2018 13:20:20 -0800
Subject: [sdiy] Merry Christmas!
In-Reply-To: <CAK+JDy29_TSCav3EWWur==87CYo=4q-tPBd-PJ8cDfPwm2j6DQ@mail.gmail.com>
References: <CACZGMxJhBn2x=Cg_jHjkCuNZ5RB9Zmt00gfZ3cXN=KPcr2xNRQ@mail.gmail.com>
 <CAN4YM6eKYgLchOnqqNE0N-mRDZ2n4Sdo4Mf0qJ_3g-jx__gh-w@mail.gmail.com>
 <CAK+JDy29_TSCav3EWWur==87CYo=4q-tPBd-PJ8cDfPwm2j6DQ@mail.gmail.com>
Message-ID: <CALQanA+UWi9XYwgrppPei-=KZr=Ye1nEp+zKGNpddT9O1_fgSg@mail.gmail.com>

happy (synthy) holidays y'all



On Tue, Dec 25, 2018 at 1:50 AM john slee <indigoid at oldcorollas.org> wrote:

> Indeed!
>
> May at least some of your projects not *quite* work as desired, and may
> you then learn useful things fixing them :-)
>
> John
>
> On Tue, 25 Dec 2018 at 18:45, Phillip Gallo <philgallo at gmail.com> wrote:
>
>> Best wishes for this holiday season, the coming new year, and fruitful
>> SDIY.
>>
>> regards,
>> p
>>
>>
>>
>> <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> Virus-free.
>> www.avg.com
>> <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
>> <#m_-2399161900551051184_m_2036250903675030729_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
>>
>> On Mon, Dec 24, 2018, 4:04 PM Neil Johnson <neil.johnson71 at gmail.com
>> wrote:
>>
>>> To all list members who celebrate Christmas at this time of year, may
>>> I wish you all a very merry Christmas!
>>>
>>> And to everyone, wishing you all a very synthtastic new year!
>>>
>>> Cheers
>>> Neil
>>> --
>>> http://www.njohnson.co.uk
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
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From dlmanley at sonic.net  Tue Dec 25 22:53:27 2018
From: dlmanley at sonic.net (David Manley)
Date: Tue, 25 Dec 2018 13:53:27 -0800
Subject: [sdiy] rca female to male adaptor source?
Message-ID: <f1cd066c-e7f6-6627-b902-8de3da7cc1e1@sonic.net>

Hi All,

Anyone have a source for an RCA female-> RCA male adapter that would fit 
an attenuator (2 resistors)?

Something like this: 
https://www.canford.co.uk/Images/ItemImages/large/20-901_01.jpg

There are expensive products available (Harrison Labs, Roth, etc) that 
go for $25-40, that is triggering my cheepnis.? I could also kludge 
something together with separate male and female connectors held 
together with heat shrink, etc, but would prefer something like the image.

The closest I've found, and what I'll probably end up buying and 
modifying is linked below which unfortunately is only 1dB, when I'm 
looking for something like 6dB or 12dB:

https://www.w5swl.com/Line-Atennuator-MCM-1-dB-RCA-Male-to-RCA-Female-_p_499.html


Thanks,

Dave



From orenlevysticky at gmail.com  Tue Dec 25 22:57:36 2018
From: orenlevysticky at gmail.com (oren levy)
Date: Tue, 25 Dec 2018 11:57:36 -1000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
Message-ID: <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>

You can use the FPGA to combine all the data you are trying to transmit into a single stream that you can transmit over a single cable.
MADI interfaces are expensive as a unit. There are various ways to implement MADI at a board level with microcontrollers and FPGAs. 
Other options would be to make your own protocol. Using a TRRS cable should be able to provide enough bandwidth at more manageable speeds that won?t require you to think about transmission line theory.


Rock & Roll,
Oren Levy

> On Dec 25, 2018, at 11:13, cheater00 cheater00 <cheater00 at gmail.com> wrote:
> 
> The objective is to be able to create a way for a single patch cord to
> carry 16 voices. I'm not sure how an FPGA in itself will help me, have
> you got any ideas?
> 
> MADI interfaces are prohibitively expensive.
> 
>> On Tue, Dec 25, 2018 at 9:19 PM oren levy <orenlevysticky at gmail.com> wrote:
>> 
>> I think you?d be better off using FPGAs so you can mux the signals however you want along with data. Either a bunch of small ones or one big one per module.
>> If you just want to share audio and don?t want to mess around with FPGAs, you can probably use a protocol like MADI. Not sure if MADI has a DC coupling requirement but if not, CV could also be passed.
>> You?d probably want a very stable clock to sync all the modules to and optimize clock phase delays so everything can mux/demux in sync.
>> 
>> Rock & Roll,
>> Oren Levy
>> 
>>> On Dec 25, 2018, at 10:01, Mike Beauchamp <list at mikebeauchamp.com> wrote:
>>> 
>>> 
>>>> transmission. In a 16 voice system, at about 5 output functions per
>>>> module, and 12 modules, you can easily use up ~1000 of those, which
>>>> drops the price to $4. I was wondering what everyone thinks about this
>>>> sort of scheme.
>>> 
>>> So there's $4000 worth of just one IC in a single complete polysynth?
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy
>> 
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy



From rburnett at richieburnett.co.uk  Tue Dec 25 23:12:58 2018
From: rburnett at richieburnett.co.uk (Richie Burnett)
Date: Tue, 25 Dec 2018 22:12:58 +0000
Subject: [sdiy] Merry Christmas!
In-Reply-To: <CALQanA+UWi9XYwgrppPei-=KZr=Ye1nEp+zKGNpddT9O1_fgSg@mail.gmail.com>
References: <CACZGMxJhBn2x=Cg_jHjkCuNZ5RB9Zmt00gfZ3cXN=KPcr2xNRQ@mail.gmail.com>
 <CAN4YM6eKYgLchOnqqNE0N-mRDZ2n4Sdo4Mf0qJ_3g-jx__gh-w@mail.gmail.com>
 <CAK+JDy29_TSCav3EWWur==87CYo=4q-tPBd-PJ8cDfPwm2j6DQ@mail.gmail.com>
 <CALQanA+UWi9XYwgrppPei-=KZr=Ye1nEp+zKGNpddT9O1_fgSg@mail.gmail.com>
Message-ID: <rn1x8j5b4nr4afibgcccp5v8.1545775978193@email.android.com>

Merry Christmas and happy holidays to all !

-Richie,



From ben.pi.bradley at gmail.com  Tue Dec 25 23:22:54 2018
From: ben.pi.bradley at gmail.com (Ben Bradley)
Date: Tue, 25 Dec 2018 17:22:54 -0500
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
Message-ID: <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>

What you're describing sounds all-digital.

It seems to me a crosspoint switch would be the thing to have on each
(analog) voice, and have them controlled by the usual microcontroller
for a polyphonic analog-signal-path synthesizer. Of course, this is a
woefully incomplete description.

On Tue, Dec 25, 2018 at 4:58 PM oren levy <orenlevysticky at gmail.com> wrote:
>
> You can use the FPGA to combine all the data you are trying to transmit into a single stream that you can transmit over a single cable.
> MADI interfaces are expensive as a unit. There are various ways to implement MADI at a board level with microcontrollers and FPGAs.
> Other options would be to make your own protocol. Using a TRRS cable should be able to provide enough bandwidth at more manageable speeds that won?t require you to think about transmission line theory.
>
>
> Rock & Roll,
> Oren Levy
>
> > On Dec 25, 2018, at 11:13, cheater00 cheater00 <cheater00 at gmail.com> wrote:
> >
> > The objective is to be able to create a way for a single patch cord to
> > carry 16 voices. I'm not sure how an FPGA in itself will help me, have
> > you got any ideas?
> >
> > MADI interfaces are prohibitively expensive.
> >
> >> On Tue, Dec 25, 2018 at 9:19 PM oren levy <orenlevysticky at gmail.com> wrote:
> >>
> >> I think you?d be better off using FPGAs so you can mux the signals however you want along with data. Either a bunch of small ones or one big one per module.
> >> If you just want to share audio and don?t want to mess around with FPGAs, you can probably use a protocol like MADI. Not sure if MADI has a DC coupling requirement but if not, CV could also be passed.
> >> You?d probably want a very stable clock to sync all the modules to and optimize clock phase delays so everything can mux/demux in sync.
> >>
> >> Rock & Roll,
> >> Oren Levy
> >>
> >>> On Dec 25, 2018, at 10:01, Mike Beauchamp <list at mikebeauchamp.com> wrote:
> >>>
> >>>
> >>>> transmission. In a 16 voice system, at about 5 output functions per
> >>>> module, and 12 modules, you can easily use up ~1000 of those, which
> >>>> drops the price to $4. I was wondering what everyone thinks about this
> >>>> sort of scheme.
> >>>
> >>> So there's $4000 worth of just one IC in a single complete polysynth?
> >>>
> >>>
> >>>
> >>> _______________________________________________
> >>> Synth-diy mailing list
> >>> Synth-diy at synth-diy.org
> >>> http://synth-diy.org/mailman/listinfo/synth-diy
> >>
> >> _______________________________________________
> >> Synth-diy mailing list
> >> Synth-diy at synth-diy.org
> >> http://synth-diy.org/mailman/listinfo/synth-diy
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From cheater00 at gmail.com  Tue Dec 25 23:40:24 2018
From: cheater00 at gmail.com (cheater00 cheater00)
Date: Tue, 25 Dec 2018 23:40:24 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
Message-ID: <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>

I want to make this work for an all-analog synthesizer, but rather
than use crosspoint switches I want to use patch cables which makes
things much less annoyingly complex and expensive. The thing is, where
on a monosynth you have a single patch cable, on a patchable polysynth
you have n patch cables, one for each voice. So I am currently trying
to work out how to do this using a single patch cable, and frequency
domain multiplexing came to mind. I'm 100% certain an FPGA cannot do
FDM, since almost all of this is analog, so I'm looking at dedicated
radio transmitter chips. At $4 per chip, it's not so bad. The question
is how to make the chips talk to a single medium without fighting each
other.

On Tue, Dec 25, 2018 at 11:24 PM Ben Bradley <ben.pi.bradley at gmail.com> wrote:
>
> What you're describing sounds all-digital.
>
> It seems to me a crosspoint switch would be the thing to have on each
> (analog) voice, and have them controlled by the usual microcontroller
> for a polyphonic analog-signal-path synthesizer. Of course, this is a
> woefully incomplete description.
>
> On Tue, Dec 25, 2018 at 4:58 PM oren levy <orenlevysticky at gmail.com> wrote:
> >
> > You can use the FPGA to combine all the data you are trying to transmit into a single stream that you can transmit over a single cable.
> > MADI interfaces are expensive as a unit. There are various ways to implement MADI at a board level with microcontrollers and FPGAs.
> > Other options would be to make your own protocol. Using a TRRS cable should be able to provide enough bandwidth at more manageable speeds that won?t require you to think about transmission line theory.
> >
> >
> > Rock & Roll,
> > Oren Levy
> >
> > > On Dec 25, 2018, at 11:13, cheater00 cheater00 <cheater00 at gmail.com> wrote:
> > >
> > > The objective is to be able to create a way for a single patch cord to
> > > carry 16 voices. I'm not sure how an FPGA in itself will help me, have
> > > you got any ideas?
> > >
> > > MADI interfaces are prohibitively expensive.
> > >
> > >> On Tue, Dec 25, 2018 at 9:19 PM oren levy <orenlevysticky at gmail.com> wrote:
> > >>
> > >> I think you?d be better off using FPGAs so you can mux the signals however you want along with data. Either a bunch of small ones or one big one per module.
> > >> If you just want to share audio and don?t want to mess around with FPGAs, you can probably use a protocol like MADI. Not sure if MADI has a DC coupling requirement but if not, CV could also be passed.
> > >> You?d probably want a very stable clock to sync all the modules to and optimize clock phase delays so everything can mux/demux in sync.
> > >>
> > >> Rock & Roll,
> > >> Oren Levy
> > >>
> > >>> On Dec 25, 2018, at 10:01, Mike Beauchamp <list at mikebeauchamp.com> wrote:
> > >>>
> > >>>
> > >>>> transmission. In a 16 voice system, at about 5 output functions per
> > >>>> module, and 12 modules, you can easily use up ~1000 of those, which
> > >>>> drops the price to $4. I was wondering what everyone thinks about this
> > >>>> sort of scheme.
> > >>>
> > >>> So there's $4000 worth of just one IC in a single complete polysynth?
> > >>>
> > >>>
> > >>>
> > >>> _______________________________________________
> > >>> Synth-diy mailing list
> > >>> Synth-diy at synth-diy.org
> > >>> http://synth-diy.org/mailman/listinfo/synth-diy
> > >>
> > >> _______________________________________________
> > >> Synth-diy mailing list
> > >> Synth-diy at synth-diy.org
> > >> http://synth-diy.org/mailman/listinfo/synth-diy
> >
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From info at extrinia.com  Wed Dec 26 00:22:43 2018
From: info at extrinia.com (John P Shea)
Date: Wed, 26 Dec 2018 09:22:43 +1000
Subject: [sdiy] Element 14 Australia sale
Message-ID: <CAFBTNJfR3ct9FCVsc9SZX2cyNTg3Jmy-ga4aws5E6TJQ5Xu81A@mail.gmail.com>

Just got an email from them, 20% off storewide for next 2 days.

Use code: SALEAU20

https://au.element14.com/

Not a plug (but I?m sure you can buy some ;).

Regards,
JPS
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From onephatcat at earthlink.net  Wed Dec 26 05:25:39 2018
From: onephatcat at earthlink.net (Joel B)
Date: Tue, 25 Dec 2018 20:25:39 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
Message-ID: <B5035A94-9970-467C-9345-261B6652C471@earthlink.net>

3.5mm TRRRS jacks - should be able to carry 4 signals over that for a four voice patchable synth? 

https://m.alibaba.com/product/60708756554/OEM-ODM-GuangZhou-YIVO-Wholesales-Hi.html?s=p

Sent from my iPhone 

> On Dec 25, 2018, at 2:40 PM, cheater00 cheater00 <cheater00 at gmail.com> wrote:
> 
> I want to make this work for an all-analog synthesizer, but rather
> than use crosspoint switches I want to use patch cables which makes
> things much less annoyingly complex and expensive. The thing is, where
> on a monosynth you have a single patch cable, on a patchable polysynth
> you have n patch cables, one for each voice. So I am currently trying
> to work out how to do this using a single patch cable, and frequency
> domain multiplexing came to mind. I'm 100% certain an FPGA cannot do
> FDM, since almost all of this is analog, so I'm looking at dedicated
> radio transmitter chips. At $4 per chip, it's not so bad. The question
> is how to make the chips talk to a single medium without fighting each
> other.
> 
>> On Tue, Dec 25, 2018 at 11:24 PM Ben Bradley <ben.pi.bradley at gmail.com> wrote:
>> 
>> What you're describing sounds all-digital.
>> 
>> It seems to me a crosspoint switch would be the thing to have on each
>> (analog) voice, and have them controlled by the usual microcontroller
>> for a polyphonic analog-signal-path synthesizer. Of course, this is a
>> woefully incomplete description.
>> 
>>> On Tue, Dec 25, 2018 at 4:58 PM oren levy <orenlevysticky at gmail.com> wrote:
>>> 
>>> You can use the FPGA to combine all the data you are trying to transmit into a single stream that you can transmit over a single cable.
>>> MADI interfaces are expensive as a unit. There are various ways to implement MADI at a board level with microcontrollers and FPGAs.
>>> Other options would be to make your own protocol. Using a TRRS cable should be able to provide enough bandwidth at more manageable speeds that won?t require you to think about transmission line theory.
>>> 
>>> 
>>> Rock & Roll,
>>> Oren Levy
>>> 
>>>> On Dec 25, 2018, at 11:13, cheater00 cheater00 <cheater00 at gmail.com> wrote:
>>>> 
>>>> The objective is to be able to create a way for a single patch cord to
>>>> carry 16 voices. I'm not sure how an FPGA in itself will help me, have
>>>> you got any ideas?
>>>> 
>>>> MADI interfaces are prohibitively expensive.
>>>> 
>>>>> On Tue, Dec 25, 2018 at 9:19 PM oren levy <orenlevysticky at gmail.com> wrote:
>>>>> 
>>>>> I think you?d be better off using FPGAs so you can mux the signals however you want along with data. Either a bunch of small ones or one big one per module.
>>>>> If you just want to share audio and don?t want to mess around with FPGAs, you can probably use a protocol like MADI. Not sure if MADI has a DC coupling requirement but if not, CV could also be passed.
>>>>> You?d probably want a very stable clock to sync all the modules to and optimize clock phase delays so everything can mux/demux in sync.
>>>>> 
>>>>> Rock & Roll,
>>>>> Oren Levy
>>>>> 
>>>>>> On Dec 25, 2018, at 10:01, Mike Beauchamp <list at mikebeauchamp.com> wrote:
>>>>>> 
>>>>>> 
>>>>>>> transmission. In a 16 voice system, at about 5 output functions per
>>>>>>> module, and 12 modules, you can easily use up ~1000 of those, which
>>>>>>> drops the price to $4. I was wondering what everyone thinks about this
>>>>>>> sort of scheme.
>>>>>> 
>>>>>> So there's $4000 worth of just one IC in a single complete polysynth?
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> _______________________________________________
>>>>>> Synth-diy mailing list
>>>>>> Synth-diy at synth-diy.org
>>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>>> 
>>>>> _______________________________________________
>>>>> Synth-diy mailing list
>>>>> Synth-diy at synth-diy.org
>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>> 
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy
>> 
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
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From rburnett at richieburnett.co.uk  Wed Dec 26 11:53:51 2018
From: rburnett at richieburnett.co.uk (Richie Burnett)
Date: Wed, 26 Dec 2018 10:53:51 +0000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
Message-ID: <39vsotdreuhiekj8pkl379pm.1545821253157@email.android.com>

I'd definitely take a look at digital multiplexing options.

The "FM transmitter/receiver for every signal" approach sounds like an expensive and complicated way to add lots of noise, distortion and cross-channel interference to your signals on each modulation/demodulation cycle. Not to mention any potential FCC/Ofcom wranglings if you end up radiating significant RF energy from the metal enclosure or your RF-tight patch leads, and cause interference to a some nearby FM radio listener!

-Richie,

---- cheater00 cheater00 wrote ----

>I want to make this work for an all-analog synthesizer, but rather
>than use crosspoint switches I want to use patch cables which makes
>things much less annoyingly complex and expensive. The thing is, where
>on a monosynth you have a single patch cable, on a patchable polysynth
>you have n patch cables, one for each voice. So I am currently trying
>to work out how to do this using a single patch cable, and frequency
>domain multiplexing came to mind. I'm 100% certain an FPGA cannot do
>FDM, since almost all of this is analog, so I'm looking at dedicated
>radio transmitter chips. At $4 per chip, it's not so bad. The question
>is how to make the chips talk to a single medium without fighting each
>other.
>
>On Tue, Dec 25, 2018 at 11:24 PM Ben Bradley <ben.pi.bradley at gmail.com> wrote:
>>
>> What you're describing sounds all-digital.
>>
>> It seems to me a crosspoint switch would be the thing to have on each
>> (analog) voice, and have them controlled by the usual microcontroller
>> for a polyphonic analog-signal-path synthesizer. Of course, this is a
>> woefully incomplete description.
>>
>> On Tue, Dec 25, 2018 at 4:58 PM oren levy <orenlevysticky at gmail.com> wrote:
>> >
>> > You can use the FPGA to combine all the data you are trying to transmit into a single stream that you can transmit over a single cable.
>> > MADI interfaces are expensive as a unit. There are various ways to implement MADI at a board level with microcontrollers and FPGAs.
>> > Other options would be to make your own protocol. Using a TRRS cable should be able to provide enough bandwidth at more manageable speeds that won?t require you to think about transmission line theory.
>> >
>> >
>> > Rock & Roll,
>> > Oren Levy
>> >
>> > > On Dec 25, 2018, at 11:13, cheater00 cheater00 <cheater00 at gmail.com> wrote:
>> > >
>> > > The objective is to be able to create a way for a single patch cord to
>> > > carry 16 voices. I'm not sure how an FPGA in itself will help me, have
>> > > you got any ideas?
>> > >
>> > > MADI interfaces are prohibitively expensive.
>> > >
>> > >> On Tue, Dec 25, 2018 at 9:19 PM oren levy <orenlevysticky at gmail.com> wrote:
>> > >>
>> > >> I think you?d be better off using FPGAs so you can mux the signals however you want along with data. Either a bunch of small ones or one big one per module.
>> > >> If you just want to share audio and don?t want to mess around with FPGAs, you can probably use a protocol like MADI. Not sure if MADI has a DC coupling requirement but if not, CV could also be passed.
>> > >> You?d probably want a very stable clock to sync all the modules to and optimize clock phase delays so everything can mux/demux in sync.
>> > >>
>> > >> Rock & Roll,
>> > >> Oren Levy
>> > >>
>> > >>> On Dec 25, 2018, at 10:01, Mike Beauchamp <list at mikebeauchamp.com> wrote:
>> > >>>
>> > >>>
>> > >>>> transmission. In a 16 voice system, at about 5 output functions per
>> > >>>> module, and 12 modules, you can easily use up ~1000 of those, which
>> > >>>> drops the price to $4. I was wondering what everyone thinks about this
>> > >>>> sort of scheme.
>> > >>>
>> > >>> So there's $4000 worth of just one IC in a single complete polysynth?
>> > >>>
>> > >>>
>> > >>>
>> > >>> _______________________________________________
>> > >>> Synth-diy mailing list
>> > >>> Synth-diy at synth-diy.org
>> > >>> http://synth-diy.org/mailman/listinfo/synth-diy
>> > >>
>> > >> _______________________________________________
>> > >> Synth-diy mailing list
>> > >> Synth-diy at synth-diy.org
>> > >> http://synth-diy.org/mailman/listinfo/synth-diy
>> >
>> > _______________________________________________
>> > Synth-diy mailing list
>> > Synth-diy at synth-diy.org
>> > http://synth-diy.org/mailman/listinfo/synth-diy
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>
>_______________________________________________
>Synth-diy mailing list
>Synth-diy at synth-diy.org
>http://synth-diy.org/mailman/listinfo/synth-diy



From tom at electricdruid.net  Wed Dec 26 17:16:28 2018
From: tom at electricdruid.net (Tom Wiltshire)
Date: Wed, 26 Dec 2018 16:16:28 +0000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
Message-ID: <710FACCB-AC30-41CB-A2F1-27E2C6D4E8DD@electricdruid.net>

Why not make a number of ?analog virtual patch cables? with analog switch ICs? Each cable has a switch at both ends, one selects between X sources, and the other selects between Y destinations. This is conceptually very similar to a genuine modular with hardware cables, but the control signals can be fanned out to however many voices you have.

Alternatively, you could have a ?mod buss? type system, where each module output could be sent to a particular destination buss, and each module input could be switch to tap signal from a given buss. Again, control signals for the switches in such a set-up can be fanned out to however many voices are required.

For any polyphonic system (except the early oberheims?), the control panel is separated from the voice generation, so you can think about the interface separately from the audio-producing part of the circuit.

Tom

==================
       Electric Druid
Synth & Stompbox DIY
==================

> On 25 Dec 2018, at 22:40, cheater00 cheater00 <cheater00 at gmail.com> wrote:
> 
> I want to make this work for an all-analog synthesizer, but rather
> than use crosspoint switches I want to use patch cables which makes
> things much less annoyingly complex and expensive. The thing is, where
> on a monosynth you have a single patch cable, on a patchable polysynth
> you have n patch cables, one for each voice. So I am currently trying
> to work out how to do this using a single patch cable, and frequency
> domain multiplexing came to mind. I'm 100% certain an FPGA cannot do
> FDM, since almost all of this is analog, so I'm looking at dedicated
> radio transmitter chips. At $4 per chip, it's not so bad. The question
> is how to make the chips talk to a single medium without fighting each
> other.
> 
> On Tue, Dec 25, 2018 at 11:24 PM Ben Bradley <ben.pi.bradley at gmail.com> wrote:
>> 
>> What you're describing sounds all-digital.
>> 
>> It seems to me a crosspoint switch would be the thing to have on each
>> (analog) voice, and have them controlled by the usual microcontroller
>> for a polyphonic analog-signal-path synthesizer. Of course, this is a
>> woefully incomplete description.
>> 
>> On Tue, Dec 25, 2018 at 4:58 PM oren levy <orenlevysticky at gmail.com> wrote:
>>> 
>>> You can use the FPGA to combine all the data you are trying to transmit into a single stream that you can transmit over a single cable.
>>> MADI interfaces are expensive as a unit. There are various ways to implement MADI at a board level with microcontrollers and FPGAs.
>>> Other options would be to make your own protocol. Using a TRRS cable should be able to provide enough bandwidth at more manageable speeds that won?t require you to think about transmission line theory.
>>> 
>>> 
>>> Rock & Roll,
>>> Oren Levy
>>> 
>>>> On Dec 25, 2018, at 11:13, cheater00 cheater00 <cheater00 at gmail.com> wrote:
>>>> 
>>>> The objective is to be able to create a way for a single patch cord to
>>>> carry 16 voices. I'm not sure how an FPGA in itself will help me, have
>>>> you got any ideas?
>>>> 
>>>> MADI interfaces are prohibitively expensive.
>>>> 
>>>>> On Tue, Dec 25, 2018 at 9:19 PM oren levy <orenlevysticky at gmail.com> wrote:
>>>>> 
>>>>> I think you?d be better off using FPGAs so you can mux the signals however you want along with data. Either a bunch of small ones or one big one per module.
>>>>> If you just want to share audio and don?t want to mess around with FPGAs, you can probably use a protocol like MADI. Not sure if MADI has a DC coupling requirement but if not, CV could also be passed.
>>>>> You?d probably want a very stable clock to sync all the modules to and optimize clock phase delays so everything can mux/demux in sync.
>>>>> 
>>>>> Rock & Roll,
>>>>> Oren Levy
>>>>> 
>>>>>> On Dec 25, 2018, at 10:01, Mike Beauchamp <list at mikebeauchamp.com> wrote:
>>>>>> 
>>>>>> 
>>>>>>> transmission. In a 16 voice system, at about 5 output functions per
>>>>>>> module, and 12 modules, you can easily use up ~1000 of those, which
>>>>>>> drops the price to $4. I was wondering what everyone thinks about this
>>>>>>> sort of scheme.
>>>>>> 
>>>>>> So there's $4000 worth of just one IC in a single complete polysynth?
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> _______________________________________________
>>>>>> Synth-diy mailing list
>>>>>> Synth-diy at synth-diy.org
>>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>>> 
>>>>> _______________________________________________
>>>>> Synth-diy mailing list
>>>>> Synth-diy at synth-diy.org
>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>> 
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy
>> 
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy




From cheater00 at gmail.com  Wed Dec 26 20:09:08 2018
From: cheater00 at gmail.com (cheater00 cheater00)
Date: Wed, 26 Dec 2018 20:09:08 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <710FACCB-AC30-41CB-A2F1-27E2C6D4E8DD@electricdruid.net>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
 <710FACCB-AC30-41CB-A2F1-27E2C6D4E8DD@electricdruid.net>
Message-ID: <CA+9GZUh_xi2dKBMNwQG3TjUN3yUAO52MEKg7QWg8R38FBA=v2Q@mail.gmail.com>

analog switch ICs are terrible, let's just skip them. You're not
making an analog switch ic based system anywhere near close a medium
sized modular, it's insanity and prone to shitloads of interference.
same with mod busses. the switch ICs are very proprietary. I haven't
found a digital multiplexer IC that was good, has anyone got any good
suggestions?

On Wed, Dec 26, 2018 at 5:16 PM Tom Wiltshire <tom at electricdruid.net> wrote:
>
> Why not make a number of ?analog virtual patch cables? with analog switch ICs? Each cable has a switch at both ends, one selects between X sources, and the other selects between Y destinations. This is conceptually very similar to a genuine modular with hardware cables, but the control signals can be fanned out to however many voices you have.
>
> Alternatively, you could have a ?mod buss? type system, where each module output could be sent to a particular destination buss, and each module input could be switch to tap signal from a given buss. Again, control signals for the switches in such a set-up can be fanned out to however many voices are required.
>
> For any polyphonic system (except the early oberheims?), the control panel is separated from the voice generation, so you can think about the interface separately from the audio-producing part of the circuit.
>
> Tom
>
> ==================
>        Electric Druid
> Synth & Stompbox DIY
> ==================
>
> > On 25 Dec 2018, at 22:40, cheater00 cheater00 <cheater00 at gmail.com> wrote:
> >
> > I want to make this work for an all-analog synthesizer, but rather
> > than use crosspoint switches I want to use patch cables which makes
> > things much less annoyingly complex and expensive. The thing is, where
> > on a monosynth you have a single patch cable, on a patchable polysynth
> > you have n patch cables, one for each voice. So I am currently trying
> > to work out how to do this using a single patch cable, and frequency
> > domain multiplexing came to mind. I'm 100% certain an FPGA cannot do
> > FDM, since almost all of this is analog, so I'm looking at dedicated
> > radio transmitter chips. At $4 per chip, it's not so bad. The question
> > is how to make the chips talk to a single medium without fighting each
> > other.
> >
> > On Tue, Dec 25, 2018 at 11:24 PM Ben Bradley <ben.pi.bradley at gmail.com> wrote:
> >>
> >> What you're describing sounds all-digital.
> >>
> >> It seems to me a crosspoint switch would be the thing to have on each
> >> (analog) voice, and have them controlled by the usual microcontroller
> >> for a polyphonic analog-signal-path synthesizer. Of course, this is a
> >> woefully incomplete description.
> >>
> >> On Tue, Dec 25, 2018 at 4:58 PM oren levy <orenlevysticky at gmail.com> wrote:
> >>>
> >>> You can use the FPGA to combine all the data you are trying to transmit into a single stream that you can transmit over a single cable.
> >>> MADI interfaces are expensive as a unit. There are various ways to implement MADI at a board level with microcontrollers and FPGAs.
> >>> Other options would be to make your own protocol. Using a TRRS cable should be able to provide enough bandwidth at more manageable speeds that won?t require you to think about transmission line theory.
> >>>
> >>>
> >>> Rock & Roll,
> >>> Oren Levy
> >>>
> >>>> On Dec 25, 2018, at 11:13, cheater00 cheater00 <cheater00 at gmail.com> wrote:
> >>>>
> >>>> The objective is to be able to create a way for a single patch cord to
> >>>> carry 16 voices. I'm not sure how an FPGA in itself will help me, have
> >>>> you got any ideas?
> >>>>
> >>>> MADI interfaces are prohibitively expensive.
> >>>>
> >>>>> On Tue, Dec 25, 2018 at 9:19 PM oren levy <orenlevysticky at gmail.com> wrote:
> >>>>>
> >>>>> I think you?d be better off using FPGAs so you can mux the signals however you want along with data. Either a bunch of small ones or one big one per module.
> >>>>> If you just want to share audio and don?t want to mess around with FPGAs, you can probably use a protocol like MADI. Not sure if MADI has a DC coupling requirement but if not, CV could also be passed.
> >>>>> You?d probably want a very stable clock to sync all the modules to and optimize clock phase delays so everything can mux/demux in sync.
> >>>>>
> >>>>> Rock & Roll,
> >>>>> Oren Levy
> >>>>>
> >>>>>> On Dec 25, 2018, at 10:01, Mike Beauchamp <list at mikebeauchamp.com> wrote:
> >>>>>>
> >>>>>>
> >>>>>>> transmission. In a 16 voice system, at about 5 output functions per
> >>>>>>> module, and 12 modules, you can easily use up ~1000 of those, which
> >>>>>>> drops the price to $4. I was wondering what everyone thinks about this
> >>>>>>> sort of scheme.
> >>>>>>
> >>>>>> So there's $4000 worth of just one IC in a single complete polysynth?
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> _______________________________________________
> >>>>>> Synth-diy mailing list
> >>>>>> Synth-diy at synth-diy.org
> >>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
> >>>>>
> >>>>> _______________________________________________
> >>>>> Synth-diy mailing list
> >>>>> Synth-diy at synth-diy.org
> >>>>> http://synth-diy.org/mailman/listinfo/synth-diy
> >>>
> >>> _______________________________________________
> >>> Synth-diy mailing list
> >>> Synth-diy at synth-diy.org
> >>> http://synth-diy.org/mailman/listinfo/synth-diy
> >>
> >> _______________________________________________
> >> Synth-diy mailing list
> >> Synth-diy at synth-diy.org
> >> http://synth-diy.org/mailman/listinfo/synth-diy
> >
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
>



From orenlevysticky at gmail.com  Wed Dec 26 20:29:53 2018
From: orenlevysticky at gmail.com (oren levy)
Date: Wed, 26 Dec 2018 09:29:53 -1000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+9GZUh_xi2dKBMNwQG3TjUN3yUAO52MEKg7QWg8R38FBA=v2Q@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
 <710FACCB-AC30-41CB-A2F1-27E2C6D4E8DD@electricdruid.net>
 <CA+9GZUh_xi2dKBMNwQG3TjUN3yUAO52MEKg7QWg8R38FBA=v2Q@mail.gmail.com>
Message-ID: <AC91E158-BBE4-4172-9BBD-70A2720CAF33@gmail.com>

Sorry about my earlier recommendations; didn?t realize you wanted all analog.

As far as switches go, I really like the Intersil (now Renesas) BiCMOS 16x8 crosspoint switch IC. Low ron and very very low crosstalk. I used it when designing the Music Man ?Game Changer? guitars for pickup switching, but, it maxes out at 15V.
https://www.renesas.com/us/en/products/audio-video/video-switching/unbuffered-crosspoint-switches/device/CD22M3494.html

Rock & Roll,
Oren Levy

> On Dec 26, 2018, at 09:09, cheater00 cheater00 <cheater00 at gmail.com> wrote:
> 
> analog switch ICs are terrible, let's just skip them. You're not
> making an analog switch ic based system anywhere near close a medium
> sized modular, it's insanity and prone to shitloads of interference.
> same with mod busses. the switch ICs are very proprietary. I haven't
> found a digital multiplexer IC that was good, has anyone got any good
> suggestions?
> 
>> On Wed, Dec 26, 2018 at 5:16 PM Tom Wiltshire <tom at electricdruid.net> wrote:
>> 
>> Why not make a number of ?analog virtual patch cables? with analog switch ICs? Each cable has a switch at both ends, one selects between X sources, and the other selects between Y destinations. This is conceptually very similar to a genuine modular with hardware cables, but the control signals can be fanned out to however many voices you have.
>> 
>> Alternatively, you could have a ?mod buss? type system, where each module output could be sent to a particular destination buss, and each module input could be switch to tap signal from a given buss. Again, control signals for the switches in such a set-up can be fanned out to however many voices are required.
>> 
>> For any polyphonic system (except the early oberheims?), the control panel is separated from the voice generation, so you can think about the interface separately from the audio-producing part of the circuit.
>> 
>> Tom
>> 
>> ==================
>>       Electric Druid
>> Synth & Stompbox DIY
>> ==================
>> 
>>> On 25 Dec 2018, at 22:40, cheater00 cheater00 <cheater00 at gmail.com> wrote:
>>> 
>>> I want to make this work for an all-analog synthesizer, but rather
>>> than use crosspoint switches I want to use patch cables which makes
>>> things much less annoyingly complex and expensive. The thing is, where
>>> on a monosynth you have a single patch cable, on a patchable polysynth
>>> you have n patch cables, one for each voice. So I am currently trying
>>> to work out how to do this using a single patch cable, and frequency
>>> domain multiplexing came to mind. I'm 100% certain an FPGA cannot do
>>> FDM, since almost all of this is analog, so I'm looking at dedicated
>>> radio transmitter chips. At $4 per chip, it's not so bad. The question
>>> is how to make the chips talk to a single medium without fighting each
>>> other.
>>> 
>>>> On Tue, Dec 25, 2018 at 11:24 PM Ben Bradley <ben.pi.bradley at gmail.com> wrote:
>>>> 
>>>> What you're describing sounds all-digital.
>>>> 
>>>> It seems to me a crosspoint switch would be the thing to have on each
>>>> (analog) voice, and have them controlled by the usual microcontroller
>>>> for a polyphonic analog-signal-path synthesizer. Of course, this is a
>>>> woefully incomplete description.
>>>> 
>>>>> On Tue, Dec 25, 2018 at 4:58 PM oren levy <orenlevysticky at gmail.com> wrote:
>>>>> 
>>>>> You can use the FPGA to combine all the data you are trying to transmit into a single stream that you can transmit over a single cable.
>>>>> MADI interfaces are expensive as a unit. There are various ways to implement MADI at a board level with microcontrollers and FPGAs.
>>>>> Other options would be to make your own protocol. Using a TRRS cable should be able to provide enough bandwidth at more manageable speeds that won?t require you to think about transmission line theory.
>>>>> 
>>>>> 
>>>>> Rock & Roll,
>>>>> Oren Levy
>>>>> 
>>>>>> On Dec 25, 2018, at 11:13, cheater00 cheater00 <cheater00 at gmail.com> wrote:
>>>>>> 
>>>>>> The objective is to be able to create a way for a single patch cord to
>>>>>> carry 16 voices. I'm not sure how an FPGA in itself will help me, have
>>>>>> you got any ideas?
>>>>>> 
>>>>>> MADI interfaces are prohibitively expensive.
>>>>>> 
>>>>>>> On Tue, Dec 25, 2018 at 9:19 PM oren levy <orenlevysticky at gmail.com> wrote:
>>>>>>> 
>>>>>>> I think you?d be better off using FPGAs so you can mux the signals however you want along with data. Either a bunch of small ones or one big one per module.
>>>>>>> If you just want to share audio and don?t want to mess around with FPGAs, you can probably use a protocol like MADI. Not sure if MADI has a DC coupling requirement but if not, CV could also be passed.
>>>>>>> You?d probably want a very stable clock to sync all the modules to and optimize clock phase delays so everything can mux/demux in sync.
>>>>>>> 
>>>>>>> Rock & Roll,
>>>>>>> Oren Levy
>>>>>>> 
>>>>>>>> On Dec 25, 2018, at 10:01, Mike Beauchamp <list at mikebeauchamp.com> wrote:
>>>>>>>> 
>>>>>>>> 
>>>>>>>>> transmission. In a 16 voice system, at about 5 output functions per
>>>>>>>>> module, and 12 modules, you can easily use up ~1000 of those, which
>>>>>>>>> drops the price to $4. I was wondering what everyone thinks about this
>>>>>>>>> sort of scheme.
>>>>>>>> 
>>>>>>>> So there's $4000 worth of just one IC in a single complete polysynth?
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>>> _______________________________________________
>>>>>>>> Synth-diy mailing list
>>>>>>>> Synth-diy at synth-diy.org
>>>>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>>>>> 
>>>>>>> _______________________________________________
>>>>>>> Synth-diy mailing list
>>>>>>> Synth-diy at synth-diy.org
>>>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>>> 
>>>>> _______________________________________________
>>>>> Synth-diy mailing list
>>>>> Synth-diy at synth-diy.org
>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>> 
>>>> _______________________________________________
>>>> Synth-diy mailing list
>>>> Synth-diy at synth-diy.org
>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>> 
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
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From obl64 at ix.netcom.com  Wed Dec 26 21:12:19 2018
From: obl64 at ix.netcom.com (Oren Leavitt)
Date: Wed, 26 Dec 2018 14:12:19 -0600
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <AC91E158-BBE4-4172-9BBD-70A2720CAF33@gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
 <710FACCB-AC30-41CB-A2F1-27E2C6D4E8DD@electricdruid.net>
 <CA+9GZUh_xi2dKBMNwQG3TjUN3yUAO52MEKg7QWg8R38FBA=v2Q@mail.gmail.com>
 <AC91E158-BBE4-4172-9BBD-70A2720CAF33@gmail.com>
Message-ID: <0b021375-9642-85c0-2043-508051e68b17@ix.netcom.com>

Some years ago, I had an idea of using 9 pin DB9 data connectors as 
patch cords for a polyphonic all-analog modular synth. Technically, you 
could patch up 8 voices + common ground.

- Oren (another Oren!)

On 12/26/18 1:29 PM, oren levy wrote:
> Sorry about my earlier recommendations; didn?t realize you wanted all 
> analog.
>
> As far as switches go, I really like the Intersil (now Renesas) BiCMOS 
> 16x8 crosspoint switch IC. Low ron and very very low crosstalk. I used 
> it when designing the Music Man ?Game Changer? guitars for pickup 
> switching, but, it maxes out at 15V.
> https://www.renesas.com/us/en/products/audio-video/video-switching/unbuffered-crosspoint-switches/device/CD22M3494.html
>
> Rock & Roll,
> Oren Levy
>
> On Dec 26, 2018, at 09:09, cheater00 cheater00 <cheater00 at gmail.com 
> <mailto:cheater00 at gmail.com>> wrote:
>
>> analog switch ICs are terrible, let's just skip them. You're not
>> making an analog switch ic based system anywhere near close a medium
>> sized modular, it's insanity and prone to shitloads of interference.
>> same with mod busses. the switch ICs are very proprietary. I haven't
>> found a digital multiplexer IC that was good, has anyone got any good
>> suggestions?
>>
>> On Wed, Dec 26, 2018 at 5:16 PM Tom Wiltshire <tom at electricdruid.net 
>> <mailto:tom at electricdruid.net>> wrote:
>>>
>>> Why not make a number of ?analog virtual patch cables? with analog 
>>> switch ICs? Each cable has a switch at both ends, one selects 
>>> between X sources, and the other selects between Y destinations. 
>>> This is conceptually very similar to a genuine modular with hardware 
>>> cables, but the control signals can be fanned out to however many 
>>> voices you have.
>>>
>>> Alternatively, you could have a ?mod buss? type system, where each 
>>> module output could be sent to a particular destination buss, and 
>>> each module input could be switch to tap signal from a given buss. 
>>> Again, control signals for the switches in such a set-up can be 
>>> fanned out to however many voices are required.
>>>
>>> For any polyphonic system (except the early oberheims?), the control 
>>> panel is separated from the voice generation, so you can think about 
>>> the interface separately from the audio-producing part of the circuit.
>>>
>>> Tom
>>>
>>> ==================
>>> ??????Electric Druid
>>> Synth & Stompbox DIY
>>> ==================
>>>
>>>> On 25 Dec 2018, at 22:40, cheater00 cheater00 <cheater00 at gmail.com 
>>>> <mailto:cheater00 at gmail.com>> wrote:
>>>>
>>>> I want to make this work for an all-analog synthesizer, but rather
>>>> than use crosspoint switches I want to use patch cables which makes
>>>> things much less annoyingly complex and expensive. The thing is, where
>>>> on a monosynth you have a single patch cable, on a patchable polysynth
>>>> you have n patch cables, one for each voice. So I am currently trying
>>>> to work out how to do this using a single patch cable, and frequency
>>>> domain multiplexing came to mind. I'm 100% certain an FPGA cannot do
>>>> FDM, since almost all of this is analog, so I'm looking at dedicated
>>>> radio transmitter chips. At $4 per chip, it's not so bad. The question
>>>> is how to make the chips talk to a single medium without fighting each
>>>> other.
>>>>
>>>> On Tue, Dec 25, 2018 at 11:24 PM Ben Bradley 
>>>> <ben.pi.bradley at gmail.com <mailto:ben.pi.bradley at gmail.com>> wrote:
>>>>>
>>>>> What you're describing sounds all-digital.
>>>>>
>>>>> It seems to me a crosspoint switch would be the thing to have on each
>>>>> (analog) voice, and have them controlled by the usual microcontroller
>>>>> for a polyphonic analog-signal-path synthesizer. Of course, this is a
>>>>> woefully incomplete description.
>>>>>
>>>>> On Tue, Dec 25, 2018 at 4:58 PM oren levy 
>>>>> <orenlevysticky at gmail.com <mailto:orenlevysticky at gmail.com>> wrote:
>>>>>>
>>>>>> You can use the FPGA to combine all the data you are trying to 
>>>>>> transmit into a single stream that you can transmit over a single 
>>>>>> cable.
>>>>>> MADI interfaces are expensive as a unit. There are various ways 
>>>>>> to implement MADI at a board level with microcontrollers and FPGAs.
>>>>>> Other options would be to make your own protocol. Using a TRRS 
>>>>>> cable should be able to provide enough bandwidth at more 
>>>>>> manageable speeds that won?t require you to think about 
>>>>>> transmission line theory.
>>>>>>
>>>>>>
>>>>>> Rock & Roll,
>>>>>> Oren Levy
>>>>>>
>>>>>>> On Dec 25, 2018, at 11:13, cheater00 cheater00 
>>>>>>> <cheater00 at gmail.com <mailto:cheater00 at gmail.com>> wrote:
>>>>>>>
>>>>>>> The objective is to be able to create a way for a single patch 
>>>>>>> cord to
>>>>>>> carry 16 voices. I'm not sure how an FPGA in itself will help 
>>>>>>> me, have
>>>>>>> you got any ideas?
>>>>>>>
>>>>>>> MADI interfaces are prohibitively expensive.
>>>>>>>
>>>>>>>> On Tue, Dec 25, 2018 at 9:19 PM oren levy 
>>>>>>>> <orenlevysticky at gmail.com <mailto:orenlevysticky at gmail.com>> wrote:
>>>>>>>>
>>>>>>>> I think you?d be better off using FPGAs so you can mux the 
>>>>>>>> signals however you want along with data. Either a bunch of 
>>>>>>>> small ones or one big one per module.
>>>>>>>> If you just want to share audio and don?t want to mess around 
>>>>>>>> with FPGAs, you can probably use a protocol like MADI. Not sure 
>>>>>>>> if MADI has a DC coupling requirement but if not, CV could also 
>>>>>>>> be passed.
>>>>>>>> You?d probably want a very stable clock to sync all the modules 
>>>>>>>> to and optimize clock phase delays so everything can mux/demux 
>>>>>>>> in sync.
>>>>>>>>
>>>>>>>> Rock & Roll,
>>>>>>>> Oren Levy
>>>>>>>>
>>>>>>>>> On Dec 25, 2018, at 10:01, Mike Beauchamp 
>>>>>>>>> <list at mikebeauchamp.com <mailto:list at mikebeauchamp.com>> wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> transmission. In a 16 voice system, at about 5 output 
>>>>>>>>>> functions per
>>>>>>>>>> module, and 12 modules, you can easily use up ~1000 of those, 
>>>>>>>>>> which
>>>>>>>>>> drops the price to $4. I was wondering what everyone thinks 
>>>>>>>>>> about this
>>>>>>>>>> sort of scheme.
>>>>>>>>>
>>>>>>>>> So there's $4000 worth of just one IC in a single complete 
>>>>>>>>> polysynth?
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> Synth-diy mailing list
>>>>>>>>> Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
>>>>>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> Synth-diy mailing list
>>>>>>>> Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
>>>>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>>>>
>>>>>> _______________________________________________
>>>>>> Synth-diy mailing list
>>>>>> Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
>>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>>>
>>>>> _______________________________________________
>>>>> Synth-diy mailing list
>>>>> Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>>
>>>> _______________________________________________
>>>> Synth-diy mailing list
>>>> Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
>> http://synth-diy.org/mailman/listinfo/synth-diy
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
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From don at till.com  Wed Dec 26 21:50:25 2018
From: don at till.com (Donald Tillman)
Date: Wed, 26 Dec 2018 12:50:25 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
Message-ID: <FB8E0B2F-9996-4027-B4E4-2CF1FA70A000@till.com>

On Dec 25, 2018, at 11:49 AM, cheater00 cheater00 <cheater00 at gmail.com> wrote:
> 
> I was thinking again about how you could do a modular polysynth well,
> and it occurred to me that you might be able to use frequency domain
> multiplexing (FDM) to put several signals over a single conductor
> pair. A quick search found the Si4710 which is a bit pricey at ~$12 on
> digikey but it's a tiny 3x3mm QFN device that performs complete FM
> transmission. In a 16 voice system, at about 5 output functions per
> module, and 12 modules, you can easily use up ~1000 of those, which
> drops the price to $4. I was wondering what everyone thinks about this
> sort of scheme.

The FDM approach will likely create a lot number of problems and nasty side effects.

Why not just use those 0.1 inch Molex board connectors with ribbon cable?  They've been readily available and dirt cheap for 30-something years.

But whatever solution is determined much more by the practical use cases.  Do you really have 16 VCOs?  And 16 VCFs?  And 16 EGs?  Why 16?  And once you have those, how many ways are there of wiring them up?

So it would be helpful if you described how you are planning on using this beast.

----

People my age might remember a 1973 album by Robert Mason's ensemble Stardrive called "Intergalactic Trot".  The story is that Robert Mason developed an early polyphonic synth out of parts of an ARP 2500 and his own electronics, and as a musician, could play the hell out of it, and was able to round up top talent to do an album.

    The Intergalactic Sonic Travels of Robert Mason and His Synth
    http://strangesoundsfrombeyond.com/magazineitem/intergalactic-sonic-travels-robert-mason-synth/

Check it out.

  -- Don
--
Donald Tillman, Palo Alto, California
http://www.till.com




From rsdio at audiobanshee.com  Wed Dec 26 21:58:55 2018
From: rsdio at audiobanshee.com (rsdio at audiobanshee.com)
Date: Wed, 26 Dec 2018 12:58:55 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <0b021375-9642-85c0-2043-508051e68b17@ix.netcom.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
 <710FACCB-AC30-41CB-A2F1-27E2C6D4E8DD@electricdruid.net>
 <CA+9GZUh_xi2dKBMNwQG3TjUN3yUAO52MEKg7QWg8R38FBA=v2Q@mail.gmail.com>
 <AC91E158-BBE4-4172-9BBD-70A2720CAF33@gmail.com>
 <0b021375-9642-85c0-2043-508051e68b17@ix.netcom.com>
Message-ID: <15AC5A05-1A48-479B-A6D4-197FE2BBA269@audiobanshee.com>

Bumping up from DB9 to 13-pin would allow such a design to be compatible with either the Akai S900 sampler to VX90/AX73 (6-voice) or the popular Roland synth guitar (technically 6-string, but with 7 audio channels). Unfortunately, despite sharing the 13-pin connector, the Akai and Roland cables are not compatible, because they put the voices on different pins. Also, another obvious disadvantage is that the 13-pin jacks and plugs are large.

Then again, DB9 (DE-9) is not exactly ?small? either. Unless you were talking about mini-DIN size connectors, where you can find 10-pin versions that fit in the 9.5 mm plug body.

Whether you want to standardize on 6-voice, 7-voice, or 8-voice would be an interesting choice.


As for cheater?s comment that analog switch ICs are terrible - wait until you try frequency domain multiplexing! It?s going to be way more of a design challenge to get good quality out of frequency domain multiplexing - unless you?re happy with telephone quality audio - than getting analog switches to work. There are some very high-end analog audio devices that use analog switch ICs, but they all use the more expensive chips that aren?t exactly replacements for the standard analog switch ICs found in vintage analog synths. These newer chips have expanded voltage ranges and much lower resistance, as Mr. Levy alluded. Intersil and Siliconix were the original high-end analog switch companies, and now Renasas and Vishay seem to share that market, having purchased the former leading companies, respectively.

Brian Willoughby


On Dec 26, 2018, at 12:12 PM, Oren Leavitt <obl64 at ix.netcom.com> wrote:
> Some years ago, I had an idea of using 9 pin DB9 data connectors as patch cords for a polyphonic all-analog modular synth. Technically, you could patch up 8 voices + common ground.
> 
> - Oren (another Oren!)
> On 12/26/18 1:29 PM, oren levy wrote:
>> Sorry about my earlier recommendations; didn?t realize you wanted all analog.
>> 
>> As far as switches go, I really like the Intersil (now Renesas) BiCMOS 16x8 crosspoint switch IC. Low ron and very very low crosstalk. I used it when designing the Music Man ?Game Changer? guitars for pickup switching, but, it maxes out at 15V.
>> https://www.renesas.com/us/en/products/audio-video/video-switching/unbuffered-crosspoint-switches/device/CD22M3494.html
>> 
>> Rock & Roll,
>> Oren Levy
>> 
>> On Dec 26, 2018, at 09:09, cheater00 wrote:
>>> analog switch ICs are terrible, let's just skip them. You're not
>>> making an analog switch ic based system anywhere near close a medium
>>> sized modular, it's insanity and prone to shitloads of interference.
>>> same with mod busses. the switch ICs are very proprietary. I haven't
>>> found a digital multiplexer IC that was good, has anyone got any good
>>> suggestions?
>>> 
>>> On Wed, Dec 26, 2018 at 5:16 PM Tom Wiltshire wrote:
>>>> 
>>>> Why not make a number of ?analog virtual patch cables? with analog switch ICs? Each cable has a switch at both ends, one selects between X sources, and the other selects between Y destinations. This is conceptually very similar to a genuine modular with hardware cables, but the control signals can be fanned out to however many voices you have.
>>>> 
>>>> Alternatively, you could have a ?mod buss? type system, where each module output could be sent to a particular destination buss, and each module input could be switch to tap signal from a given buss. Again, control signals for the switches in such a set-up can be fanned out to however many voices are required.
>>>> 
>>>> For any polyphonic system (except the early oberheims?), the control panel is separated from the voice generation, so you can think about the interface separately from the audio-producing part of the circuit.
>>>> 
>>>> Tom
>>>> 
>>>> On 25 Dec 2018, at 22:40, cheater00 wrote:
>>>>> I want to make this work for an all-analog synthesizer, but rather
>>>>> than use crosspoint switches I want to use patch cables which makes
>>>>> things much less annoyingly complex and expensive. The thing is, where
>>>>> on a monosynth you have a single patch cable, on a patchable polysynth
>>>>> you have n patch cables, one for each voice. So I am currently trying
>>>>> to work out how to do this using a single patch cable, and frequency
>>>>> domain multiplexing came to mind. I'm 100% certain an FPGA cannot do
>>>>> FDM, since almost all of this is analog, so I'm looking at dedicated
>>>>> radio transmitter chips. At $4 per chip, it's not so bad. The question
>>>>> is how to make the chips talk to a single medium without fighting each
>>>>> other.
>>>>> 
>>>>> On Tue, Dec 25, 2018 at 11:24 PM Ben Bradley wrote:
>>>>>> What you're describing sounds all-digital.
>>>>>> 
>>>>>> It seems to me a crosspoint switch would be the thing to have on each
>>>>>> (analog) voice, and have them controlled by the usual microcontroller
>>>>>> for a polyphonic analog-signal-path synthesizer. Of course, this is a
>>>>>> woefully incomplete description.
>>>>>> 
>>>>>> On Dec 25, 2018, at 11:13, cheater00 wrote:
>>>>>>> The objective is to be able to create a way for a single patch cord to
>>>>>>> carry 16 voices. I'm not sure how an FPGA in itself will help me, have
>>>>>>> you got any ideas?
>>>>>>> 
>>>>>>> MADI interfaces are prohibitively expensive.
>>>>>>> 
>>>>>>> On Dec 25, 2018, at 10:01, Mike Beauchamp wrote:
>>>>>>>>> transmission. In a 16 voice system, at about 5 output functions per
>>>>>>>>> module, and 12 modules, you can easily use up ~1000 of those, which
>>>>>>>>> drops the price to $4. I was wondering what everyone thinks about this
>>>>>>>>> sort of scheme.
>>>>>>>> 
>>>>>>>> So there's $4000 worth of just one IC in a single complete polysynth?




From rsdio at audiobanshee.com  Wed Dec 26 22:24:28 2018
From: rsdio at audiobanshee.com (rsdio at audiobanshee.com)
Date: Wed, 26 Dec 2018 13:24:28 -0800
Subject: [sdiy] rca female to male adaptor source?
In-Reply-To: <f1cd066c-e7f6-6627-b902-8de3da7cc1e1@sonic.net>
References: <f1cd066c-e7f6-6627-b902-8de3da7cc1e1@sonic.net>
Message-ID: <C80B36B2-4928-47F7-BC42-61E27F10CDB0@audiobanshee.com>

My standard preference is to build a custom cable and put the attenuating resistors at one end. I always build cables with plugs that have quality, metal, screw-on shields, and so that usually provides enough space for a couple of metal film (not metal oxide) resistors. Throw in some tiny diameter heat shrink tubing, and you have a very reliable construction.

Admittedly, the last time I did this was an adaptor cable from RCA to TRS, so I had a bit more room to work in, but I believe that RCA to RCA would still be feasible despite the small dimensions.

Another advantage of this approach, besides the cost savings and the ability to control quality to your custom standards, is that the cable fits anywhere a normal cable would fit. You don?t have to worry about the extra strain of an inline adaptor that might get caught or might be too large to fit in the tight spacing of rack mount back panels. In fact, I have an old power amplifier with RCA inputs where the RCA jack is bent from a time when I used those inline adaptors and the cable got caught and severely torqued. Ever since then, I?ve shunned those barrel adaptors!

Brian Willoughby


On Dec 25, 2018, at 1:53 PM, David Manley <dlmanley at sonic.net> wrote:
> 
> Hi All,
> 
> Anyone have a source for an RCA female-> RCA male adapter that would fit an attenuator (2 resistors)?
> 
> Something like this: https://www.canford.co.uk/Images/ItemImages/large/20-901_01.jpg
> 
> There are expensive products available (Harrison Labs, Roth, etc) that go for $25-40, that is triggering my cheepnis.  I could also kludge something together with separate male and female connectors held together with heat shrink, etc, but would prefer something like the image.
> 
> The closest I've found, and what I'll probably end up buying and modifying is linked below which unfortunately is only 1dB, when I'm looking for something like 6dB or 12dB:
> 
> https://www.w5swl.com/Line-Atennuator-MCM-1-dB-RCA-Male-to-RCA-Female-_p_499.html
> 
> 
> Thanks,
> 
> Dave





From mec.forumreader at gmail.com  Thu Dec 27 03:14:09 2018
From: mec.forumreader at gmail.com (Michael E Caloroso)
Date: Wed, 26 Dec 2018 21:14:09 -0500
Subject: [sdiy] Caution with DIY MIDI cabling
Message-ID: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>

I build my own I/O panels for my racks, and my own MIDI cables.  I
recently uncovered a nasty bug that has perplexed me for years:

If you use metal shell MIDI plugs on your DIY MIDI cables, DO NOT
ALLOW MIDI GROUND TO COME IN CONTACT WITH THE SHELL.

I was gigging my road system and was experiencing intermittent MIDI
errors.  After finally being able to reproduce it at home, I figured
out that the metal shell of the MIDI plug shorted to earth ground via
the metal DIN jacks I was using on my DIY I/O panels.  Stray shield
wires from the cable had contacted the cable clamp of the plug
(despite my best attempts at trimming the stray wires), completing the
short circuit of MIDI ground to earth ground.  MIDI gets very upset
under this condition.

I use an EBTech cable tester after I build all my DIY cables, and it
does not have the capacity to detect a short from the shell to any of
the pins - it's not supposed to.  Even with my diligent testing after
completing a cable, this bug had eluded me for YEARS in my studio
system.  Yes I was well aware that the MIDI specification grounding
system is designed that way FOR A REASON.

The only way to guarantee complete isolation of MIDI ground from earth
on the metal shell of the plug was to disassemble the plug and add
shrink tubing over the trimmed end of the cable.  This separates any
stray shield wires from the metal clamp of the plug.  Once I fixed my
cabling for the stage rig, it behaved MUCH better.

Nasty bug, this.

For years I had wondered why my SYSEX dumps were never 100% reliable,
now I know why.

That's just the STAGE rig.  Now I have to make the cable corrections
to my STUDIO system, which has easily over 30 DIY cables that I built.
Guess how I am spending my holiday break...

Sent from my iGroundingCanBiteYou,
MC


From rsdio at audiobanshee.com  Thu Dec 27 03:41:50 2018
From: rsdio at audiobanshee.com (rsdio at audiobanshee.com)
Date: Wed, 26 Dec 2018 18:41:50 -0800
Subject: [sdiy] Caution with DIY MIDI cabling
In-Reply-To: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>
References: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>
Message-ID: <D3D89875-13F2-41F5-9D73-2DE35922FBBE@audiobanshee.com>

Hmm, I think the reason that this is happening is that MIDI In and MIDI Out jacks should be wired differently. MIDI Out should connect the shield ground, while MIDI In should not. It?s easy to manage in a synth, where there is only one of each (well, two MIDI ?out? if you count MIDI Thru).

I assume that your DIY MIDI I/O panel was perhaps generic? ? so that the panel does not distinguish between In and Out, but depends upon which port you connect internally to the rack gear?

It might work if you had one row dedicated to MIDI In, with isolated ground, and another row dedicated to MIDI Out, where you wouldn?t need to worry about grounding issues. Seems like that would be the only way for a generic panel to work, although you would be limited by the dedicate Input versus Output/Thru designations.

Brian


On Dec 26, 2018, at 6:14 PM, Michael E Caloroso <mec.forumreader at gmail.com> wrote:
> I build my own I/O panels for my racks, and my own MIDI cables.  I
> recently uncovered a nasty bug that has perplexed me for years:
> 
> If you use metal shell MIDI plugs on your DIY MIDI cables, DO NOT
> ALLOW MIDI GROUND TO COME IN CONTACT WITH THE SHELL.
> 
> I was gigging my road system and was experiencing intermittent MIDI
> errors.  After finally being able to reproduce it at home, I figured
> out that the metal shell of the MIDI plug shorted to earth ground via
> the metal DIN jacks I was using on my DIY I/O panels.  Stray shield
> wires from the cable had contacted the cable clamp of the plug
> (despite my best attempts at trimming the stray wires), completing the
> short circuit of MIDI ground to earth ground.  MIDI gets very upset
> under this condition.
> 
> I use an EBTech cable tester after I build all my DIY cables, and it
> does not have the capacity to detect a short from the shell to any of
> the pins - it's not supposed to.  Even with my diligent testing after
> completing a cable, this bug had eluded me for YEARS in my studio
> system.  Yes I was well aware that the MIDI specification grounding
> system is designed that way FOR A REASON.
> 
> The only way to guarantee complete isolation of MIDI ground from earth
> on the metal shell of the plug was to disassemble the plug and add
> shrink tubing over the trimmed end of the cable.  This separates any
> stray shield wires from the metal clamp of the plug.  Once I fixed my
> cabling for the stage rig, it behaved MUCH better.
> 
> Nasty bug, this.
> 
> For years I had wondered why my SYSEX dumps were never 100% reliable,
> now I know why.
> 
> That's just the STAGE rig.  Now I have to make the cable corrections
> to my STUDIO system, which has easily over 30 DIY cables that I built.
> Guess how I am spending my holiday break...
> 
> Sent from my iGroundingCanBiteYou,
> MC




From mec.forumreader at gmail.com  Thu Dec 27 03:58:28 2018
From: mec.forumreader at gmail.com (Michael E Caloroso)
Date: Wed, 26 Dec 2018 21:58:28 -0500
Subject: [sdiy] Caution with DIY MIDI cabling
In-Reply-To: <D3D89875-13F2-41F5-9D73-2DE35922FBBE@audiobanshee.com>
References: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>
 <D3D89875-13F2-41F5-9D73-2DE35922FBBE@audiobanshee.com>
Message-ID: <CAAv6=UD9oTt75ESGYENtuWQeKfezDtvaV-oR-gk3-75NBDG6zA@mail.gmail.com>

Only true for the ports in the devices, not for the cabling.  If you
think about it, it makes sense.

I am not using a generic OTS MIDI panel, I built my own MIDI panel
using raw materials.

MC

On 12/26/18, rsdio at audiobanshee.com <rsdio at audiobanshee.com> wrote:
> Hmm, I think the reason that this is happening is that MIDI In and MIDI Out
> jacks should be wired differently. MIDI Out should connect the shield
> ground, while MIDI In should not. It?s easy to manage in a synth, where
> there is only one of each (well, two MIDI ?out? if you count MIDI Thru).
>
> I assume that your DIY MIDI I/O panel was perhaps generic? ? so that the
> panel does not distinguish between In and Out, but depends upon which port
> you connect internally to the rack gear?
>
> It might work if you had one row dedicated to MIDI In, with isolated ground,
> and another row dedicated to MIDI Out, where you wouldn?t need to worry
> about grounding issues. Seems like that would be the only way for a generic
> panel to work, although you would be limited by the dedicate Input versus
> Output/Thru designations.
>
> Brian
>
>
> On Dec 26, 2018, at 6:14 PM, Michael E Caloroso <mec.forumreader at gmail.com>
> wrote:
>> I build my own I/O panels for my racks, and my own MIDI cables.  I
>> recently uncovered a nasty bug that has perplexed me for years:
>>
>> If you use metal shell MIDI plugs on your DIY MIDI cables, DO NOT
>> ALLOW MIDI GROUND TO COME IN CONTACT WITH THE SHELL.
>>
>> I was gigging my road system and was experiencing intermittent MIDI
>> errors.  After finally being able to reproduce it at home, I figured
>> out that the metal shell of the MIDI plug shorted to earth ground via
>> the metal DIN jacks I was using on my DIY I/O panels.  Stray shield
>> wires from the cable had contacted the cable clamp of the plug
>> (despite my best attempts at trimming the stray wires), completing the
>> short circuit of MIDI ground to earth ground.  MIDI gets very upset
>> under this condition.
>>
>> I use an EBTech cable tester after I build all my DIY cables, and it
>> does not have the capacity to detect a short from the shell to any of
>> the pins - it's not supposed to.  Even with my diligent testing after
>> completing a cable, this bug had eluded me for YEARS in my studio
>> system.  Yes I was well aware that the MIDI specification grounding
>> system is designed that way FOR A REASON.
>>
>> The only way to guarantee complete isolation of MIDI ground from earth
>> on the metal shell of the plug was to disassemble the plug and add
>> shrink tubing over the trimmed end of the cable.  This separates any
>> stray shield wires from the metal clamp of the plug.  Once I fixed my
>> cabling for the stage rig, it behaved MUCH better.
>>
>> Nasty bug, this.
>>
>> For years I had wondered why my SYSEX dumps were never 100% reliable,
>> now I know why.
>>
>> That's just the STAGE rig.  Now I have to make the cable corrections
>> to my STUDIO system, which has easily over 30 DIY cables that I built.
>> Guess how I am spending my holiday break...
>>
>> Sent from my iGroundingCanBiteYou,
>> MC
>
>



From nitro2k01 at gmail.com  Thu Dec 27 04:54:23 2018
From: nitro2k01 at gmail.com (=?UTF-8?B?T3ZlIFJpZMOp?=)
Date: Thu, 27 Dec 2018 04:54:23 +0100
Subject: [sdiy] Caution with DIY MIDI cabling
In-Reply-To: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>
References: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>
Message-ID: <CABacs=CERkyQ5LuazRhqiyzgz42CjRjgTOYA+hqJVuZFYTFEWg@mail.gmail.com>

I'm trying to figure out what would have gone wrong in your case. MIDI
ground (pin 2, or the middle of the 5 pins due to DIN5 pin numbering*)
is not part of the signal circuit. You should be able to connect it to
other grounds without much effect to the MIDI signal integrity.
(Although that could on the other hand introduce hum to audio
signals.) If you were saying that either the +5V pin or the signal pin
were connected to the otherwise floating mains earth then, yes, that
could certainly cause some troubles because those lines are actually
transmitting data.

(*) The DIN5 pin numbering is based on the DIN3 pin numbering where
pins 1-3 are at 90 degree intervals. Then pins 4 and 5 are added
between those, at the 45 degree positions.

On Thu, 27 Dec 2018 at 03:16, Michael E Caloroso
<mec.forumreader at gmail.com> wrote:
>
> I build my own I/O panels for my racks, and my own MIDI cables.  I
> recently uncovered a nasty bug that has perplexed me for years:
>
> If you use metal shell MIDI plugs on your DIY MIDI cables, DO NOT
> ALLOW MIDI GROUND TO COME IN CONTACT WITH THE SHELL.
>
> I was gigging my road system and was experiencing intermittent MIDI
> errors.  After finally being able to reproduce it at home, I figured
> out that the metal shell of the MIDI plug shorted to earth ground via
> the metal DIN jacks I was using on my DIY I/O panels.  Stray shield
> wires from the cable had contacted the cable clamp of the plug
> (despite my best attempts at trimming the stray wires), completing the
> short circuit of MIDI ground to earth ground.  MIDI gets very upset
> under this condition.
>
> I use an EBTech cable tester after I build all my DIY cables, and it
> does not have the capacity to detect a short from the shell to any of
> the pins - it's not supposed to.  Even with my diligent testing after
> completing a cable, this bug had eluded me for YEARS in my studio
> system.  Yes I was well aware that the MIDI specification grounding
> system is designed that way FOR A REASON.
>
> The only way to guarantee complete isolation of MIDI ground from earth
> on the metal shell of the plug was to disassemble the plug and add
> shrink tubing over the trimmed end of the cable.  This separates any
> stray shield wires from the metal clamp of the plug.  Once I fixed my
> cabling for the stage rig, it behaved MUCH better.
>
> Nasty bug, this.
>
> For years I had wondered why my SYSEX dumps were never 100% reliable,
> now I know why.
>
> That's just the STAGE rig.  Now I have to make the cable corrections
> to my STUDIO system, which has easily over 30 DIY cables that I built.
> Guess how I am spending my holiday break...
>
> Sent from my iGroundingCanBiteYou,
> MC
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



-- 
/Ove

Blog: <http://blog.gg8.se/>

"Here is Evergreen City. Evergreen? is the color of green forever."



From ben.pi.bradley at gmail.com  Thu Dec 27 05:33:45 2018
From: ben.pi.bradley at gmail.com (Ben Bradley)
Date: Wed, 26 Dec 2018 23:33:45 -0500
Subject: [sdiy] Caution with DIY MIDI cabling
In-Reply-To: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>
References: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>
Message-ID: <CA+wjhVt2VchxJ02qaR6zd27BUFxyd5EyWfvnB6z5fDWb4q0XPQ@mail.gmail.com>

I recall the original MIDI cable spec (because I made my own cables
back then), it used ONLY the two signal wires, supposedly twisted in
the cable, with the idea that "it's a current loop, it doesn't need a
shield." It worked, but perhaps enough people had enough interference
to audio cables from their MIDI cables that the shield thing was added
to the spec. The original MIDI spec was fully isolated by the
optocoupler on the input. If the cable needs a shield it can be
telescoped (as in connected to ground, NOT one of the two MIDI
signals, at either end of the cable but NOT both).

On Wed, Dec 26, 2018 at 9:15 PM Michael E Caloroso
<mec.forumreader at gmail.com> wrote:
>
> I build my own I/O panels for my racks, and my own MIDI cables.  I
> recently uncovered a nasty bug that has perplexed me for years:
>
> If you use metal shell MIDI plugs on your DIY MIDI cables, DO NOT
> ALLOW MIDI GROUND TO COME IN CONTACT WITH THE SHELL.
>
> I was gigging my road system and was experiencing intermittent MIDI
> errors.  After finally being able to reproduce it at home, I figured
> out that the metal shell of the MIDI plug shorted to earth ground via
> the metal DIN jacks I was using on my DIY I/O panels.  Stray shield
> wires from the cable had contacted the cable clamp of the plug
> (despite my best attempts at trimming the stray wires), completing the
> short circuit of MIDI ground to earth ground.  MIDI gets very upset
> under this condition.
>
> I use an EBTech cable tester after I build all my DIY cables, and it
> does not have the capacity to detect a short from the shell to any of
> the pins - it's not supposed to.  Even with my diligent testing after
> completing a cable, this bug had eluded me for YEARS in my studio
> system.  Yes I was well aware that the MIDI specification grounding
> system is designed that way FOR A REASON.
>
> The only way to guarantee complete isolation of MIDI ground from earth
> on the metal shell of the plug was to disassemble the plug and add
> shrink tubing over the trimmed end of the cable.  This separates any
> stray shield wires from the metal clamp of the plug.  Once I fixed my
> cabling for the stage rig, it behaved MUCH better.
>
> Nasty bug, this.
>
> For years I had wondered why my SYSEX dumps were never 100% reliable,
> now I know why.
>
> That's just the STAGE rig.  Now I have to make the cable corrections
> to my STUDIO system, which has easily over 30 DIY cables that I built.
> Guess how I am spending my holiday break...
>
> Sent from my iGroundingCanBiteYou,
> MC
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy


From rsdio at audiobanshee.com  Thu Dec 27 05:59:50 2018
From: rsdio at audiobanshee.com (rsdio at audiobanshee.com)
Date: Wed, 26 Dec 2018 20:59:50 -0800
Subject: [sdiy] Caution with DIY MIDI cabling
In-Reply-To: <CAAv6=UD9oTt75ESGYENtuWQeKfezDtvaV-oR-gk3-75NBDG6zA@mail.gmail.com>
References: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>
 <D3D89875-13F2-41F5-9D73-2DE35922FBBE@audiobanshee.com>
 <CAAv6=UD9oTt75ESGYENtuWQeKfezDtvaV-oR-gk3-75NBDG6zA@mail.gmail.com>
Message-ID: <53F15517-7E6F-413F-9A07-F623574AB85C@audiobanshee.com>

You are correct that the cable ground and shield can be connected at both ends of a MIDI cable with no problems, but this assumes that each separate cable is kept separate from all other cables, as well as individual jacks being kept separate from each other.

In your patch panel, connections between shield and the metal plate would effectively connect all jacks together, meaning that In and Out could be grounded together. You have a point that each MIDI device in your rack would still have isolation on its own MIDI In port, but your physical construction could end up connecting the MIDI Out grounds together for potentially all of the MIDI Devices in your rack.

I?ve seen this happen when I accidentally connected MIDI Out from one device to MIDI Out of another device. Hum started immediately. There probably was no damage to the MIDI Out circuitry, but the devices were certainly not designed to deal with the mistake of connecting output MIDI grounds together.

So, I?ll revise my original suggestion. Instead of isolating just the MIDI In jacks, you?d actually have to isolate each of the MIDI Out jacks. At that point, you might as well just make sure that every MIDI jack is isolated, and then you wouldn?t have to designate them as ?In? or ?Out"

Ove has a very good point. Grounding errors should not normally cause MIDI data errors. However, at some point all digital signals have a ground reference, before the conversion to the current loop of MIDI is involved, and a significant ground loop in a rack of MIDI gear could actually cause bit errors.

I?ve also had problems with digital audio data glitches when power spikes causes two or more digital audio devices to see different ground references. In this case, there?s no optical isolation, but I still think that enough of a ground loop between two or more MIDI devices could actually affect the non-isolated digital signals. In other words, the optical isolation of MIDI is only effective if you maintain the ground isolation between units. As soon as you have a ground loop, there?s no longer any isolation. It?s just that the problem isn?t coming through the MIDI current loop - it?s coming through the MIDI shield ground.

Anyway, sorry if this is way too much analysis. I happen to be always on the lookout for potential problems with designing musical electronics, so this is a particularly interesting scenario to consider. Thanks for sharing, M.E.C.

Brian Willoughby


On Dec 26, 2018, at 6:58 PM, Michael E Caloroso wrote:
> Only true for the ports in the devices, not for the cabling.  If you
> think about it, it makes sense.
> 
> I am not using a generic OTS MIDI panel, I built my own MIDI panel
> using raw materials.
> 
> MC
> 
> On 12/26/18, rsdio wrote:
>> Hmm, I think the reason that this is happening is that MIDI In and MIDI Out
>> jacks should be wired differently. MIDI Out should connect the shield
>> ground, while MIDI In should not. It?s easy to manage in a synth, where
>> there is only one of each (well, two MIDI ?out? if you count MIDI Thru).
>> 
>> I assume that your DIY MIDI I/O panel was perhaps generic? ? so that the
>> panel does not distinguish between In and Out, but depends upon which port
>> you connect internally to the rack gear?
>> 
>> It might work if you had one row dedicated to MIDI In, with isolated ground,
>> and another row dedicated to MIDI Out, where you wouldn?t need to worry
>> about grounding issues. Seems like that would be the only way for a generic
>> panel to work, although you would be limited by the dedicate Input versus
>> Output/Thru designations.
>> 
>> Brian
>> 
>> 
>> On Dec 26, 2018, at 6:14 PM, Michael E Caloroso wrote:
>>> I build my own I/O panels for my racks, and my own MIDI cables.  I
>>> recently uncovered a nasty bug that has perplexed me for years:
>>> 
>>> If you use metal shell MIDI plugs on your DIY MIDI cables, DO NOT
>>> ALLOW MIDI GROUND TO COME IN CONTACT WITH THE SHELL.
>>> 
>>> I was gigging my road system and was experiencing intermittent MIDI
>>> errors.  After finally being able to reproduce it at home, I figured
>>> out that the metal shell of the MIDI plug shorted to earth ground via
>>> the metal DIN jacks I was using on my DIY I/O panels.  Stray shield
>>> wires from the cable had contacted the cable clamp of the plug
>>> (despite my best attempts at trimming the stray wires), completing the
>>> short circuit of MIDI ground to earth ground.  MIDI gets very upset
>>> under this condition.
>>> 
>>> I use an EBTech cable tester after I build all my DIY cables, and it
>>> does not have the capacity to detect a short from the shell to any of
>>> the pins - it's not supposed to.  Even with my diligent testing after
>>> completing a cable, this bug had eluded me for YEARS in my studio
>>> system.  Yes I was well aware that the MIDI specification grounding
>>> system is designed that way FOR A REASON.
>>> 
>>> The only way to guarantee complete isolation of MIDI ground from earth
>>> on the metal shell of the plug was to disassemble the plug and add
>>> shrink tubing over the trimmed end of the cable.  This separates any
>>> stray shield wires from the metal clamp of the plug.  Once I fixed my
>>> cabling for the stage rig, it behaved MUCH better.
>>> 
>>> Nasty bug, this.
>>> 
>>> For years I had wondered why my SYSEX dumps were never 100% reliable,
>>> now I know why.




From mec.forumreader at gmail.com  Thu Dec 27 08:11:55 2018
From: mec.forumreader at gmail.com (Michael E Caloroso)
Date: Thu, 27 Dec 2018 02:11:55 -0500
Subject: [sdiy] Caution with DIY MIDI cabling
In-Reply-To: <53F15517-7E6F-413F-9A07-F623574AB85C@audiobanshee.com>
References: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>
 <D3D89875-13F2-41F5-9D73-2DE35922FBBE@audiobanshee.com>
 <CAAv6=UD9oTt75ESGYENtuWQeKfezDtvaV-oR-gk3-75NBDG6zA@mail.gmail.com>
 <53F15517-7E6F-413F-9A07-F623574AB85C@audiobanshee.com>
Message-ID: <CAAv6=UCdifq6dBsiWhyDTwHJpq06UwPjRfq-BcBJwCAgf=7sDQ@mail.gmail.com>

I neglected to mention that my system consists of not a single rack
(which would had been too bulky and heavy for gigging) but multiple
racks which are cabled together.  I am aware of the attention that has
to be paid to power distribution to multiple racks, and the earth and
power are a star based distribution not daisy chain.  I have been
building rack systems for 30+ years.

Early in the development of this system I found an audible buzz in the
short audio cables between racks (ground loop) and I had to lift
ground at one end of those cables.  That would indicate that earth
potential between racks is not the same, despite all precautions.

The current loop used in MIDI transmissions is impervious to EMI, but
it is not foolproof.  It is not differential like the balanced audio
system that cancels common mode signals.  Interference can still make
its way in the MIDI current loop.  While the MIDI pin 2 shield is not
intended to be a ground reference, my error condition created one and
if the audible buzz from my audio cables were any indication, that
created a ground loop that interfered with the MIDI signal.

Why hadn't I encountered the ground loop in audio cables in my
previous systems?  Because the 1/4" panel jacks were the isolated
type, with a plastic barrel surrounding the sleeve.  Fine for studio,
but not rugged enough for stage.

I had confirmed the AC wiring in my racks, but maybe it is time I
check the power cables between them...

MC

On 12/26/18, rsdio at audiobanshee.com <rsdio at audiobanshee.com> wrote:
> You are correct that the cable ground and shield can be connected at both
> ends of a MIDI cable with no problems, but this assumes that each separate
> cable is kept separate from all other cables, as well as individual jacks
> being kept separate from each other.
>
> In your patch panel, connections between shield and the metal plate would
> effectively connect all jacks together, meaning that In and Out could be
> grounded together. You have a point that each MIDI device in your rack would
> still have isolation on its own MIDI In port, but your physical construction
> could end up connecting the MIDI Out grounds together for potentially all of
> the MIDI Devices in your rack.
>
> I?ve seen this happen when I accidentally connected MIDI Out from one device
> to MIDI Out of another device. Hum started immediately. There probably was
> no damage to the MIDI Out circuitry, but the devices were certainly not
> designed to deal with the mistake of connecting output MIDI grounds
> together.
>
> So, I?ll revise my original suggestion. Instead of isolating just the MIDI
> In jacks, you?d actually have to isolate each of the MIDI Out jacks. At that
> point, you might as well just make sure that every MIDI jack is isolated,
> and then you wouldn?t have to designate them as ?In? or ?Out"
>
> Ove has a very good point. Grounding errors should not normally cause MIDI
> data errors. However, at some point all digital signals have a ground
> reference, before the conversion to the current loop of MIDI is involved,
> and a significant ground loop in a rack of MIDI gear could actually cause
> bit errors.
>
> I?ve also had problems with digital audio data glitches when power spikes
> causes two or more digital audio devices to see different ground references.
> In this case, there?s no optical isolation, but I still think that enough of
> a ground loop between two or more MIDI devices could actually affect the
> non-isolated digital signals. In other words, the optical isolation of MIDI
> is only effective if you maintain the ground isolation between units. As
> soon as you have a ground loop, there?s no longer any isolation. It?s just
> that the problem isn?t coming through the MIDI current loop - it?s coming
> through the MIDI shield ground.
>
> Anyway, sorry if this is way too much analysis. I happen to be always on the
> lookout for potential problems with designing musical electronics, so this
> is a particularly interesting scenario to consider. Thanks for sharing,
> M.E.C.
>
> Brian Willoughby
>
>
> On Dec 26, 2018, at 6:58 PM, Michael E Caloroso wrote:
>> Only true for the ports in the devices, not for the cabling.  If you
>> think about it, it makes sense.
>>
>> I am not using a generic OTS MIDI panel, I built my own MIDI panel
>> using raw materials.
>>
>> MC
>>
>> On 12/26/18, rsdio wrote:
>>> Hmm, I think the reason that this is happening is that MIDI In and MIDI
>>> Out
>>> jacks should be wired differently. MIDI Out should connect the shield
>>> ground, while MIDI In should not. It?s easy to manage in a synth, where
>>> there is only one of each (well, two MIDI ?out? if you count MIDI Thru).
>>>
>>> I assume that your DIY MIDI I/O panel was perhaps generic? ? so that the
>>> panel does not distinguish between In and Out, but depends upon which
>>> port
>>> you connect internally to the rack gear?
>>>
>>> It might work if you had one row dedicated to MIDI In, with isolated
>>> ground,
>>> and another row dedicated to MIDI Out, where you wouldn?t need to worry
>>> about grounding issues. Seems like that would be the only way for a
>>> generic
>>> panel to work, although you would be limited by the dedicate Input
>>> versus
>>> Output/Thru designations.
>>>
>>> Brian
>>>
>>>
>>> On Dec 26, 2018, at 6:14 PM, Michael E Caloroso wrote:
>>>> I build my own I/O panels for my racks, and my own MIDI cables.  I
>>>> recently uncovered a nasty bug that has perplexed me for years:
>>>>
>>>> If you use metal shell MIDI plugs on your DIY MIDI cables, DO NOT
>>>> ALLOW MIDI GROUND TO COME IN CONTACT WITH THE SHELL.
>>>>
>>>> I was gigging my road system and was experiencing intermittent MIDI
>>>> errors.  After finally being able to reproduce it at home, I figured
>>>> out that the metal shell of the MIDI plug shorted to earth ground via
>>>> the metal DIN jacks I was using on my DIY I/O panels.  Stray shield
>>>> wires from the cable had contacted the cable clamp of the plug
>>>> (despite my best attempts at trimming the stray wires), completing the
>>>> short circuit of MIDI ground to earth ground.  MIDI gets very upset
>>>> under this condition.
>>>>
>>>> I use an EBTech cable tester after I build all my DIY cables, and it
>>>> does not have the capacity to detect a short from the shell to any of
>>>> the pins - it's not supposed to.  Even with my diligent testing after
>>>> completing a cable, this bug had eluded me for YEARS in my studio
>>>> system.  Yes I was well aware that the MIDI specification grounding
>>>> system is designed that way FOR A REASON.
>>>>
>>>> The only way to guarantee complete isolation of MIDI ground from earth
>>>> on the metal shell of the plug was to disassemble the plug and add
>>>> shrink tubing over the trimmed end of the cable.  This separates any
>>>> stray shield wires from the metal clamp of the plug.  Once I fixed my
>>>> cabling for the stage rig, it behaved MUCH better.
>>>>
>>>> Nasty bug, this.
>>>>
>>>> For years I had wondered why my SYSEX dumps were never 100% reliable,
>>>> now I know why.
>
>



From Stromeko at NexGo.DE  Thu Dec 27 10:10:12 2018
From: Stromeko at NexGo.DE (ASSI)
Date: Thu, 27 Dec 2018 10:10:12 +0100
Subject: [sdiy] Caution with DIY MIDI cabling
In-Reply-To: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>
References: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>
Message-ID: <09c4d2fe-2377-eedb-329a-6769ba92c383@NexGo.DE>

Am 27.12.2018 um 03:14 schrieb Michael E Caloroso:
> I build my own I/O panels for my racks, and my own MIDI cables.  I
> recently uncovered a nasty bug that has perplexed me for years:
> 
> If you use metal shell MIDI plugs on your DIY MIDI cables, DO NOT
> ALLOW MIDI GROUND TO COME IN CONTACT WITH THE SHELL.

Well, that is actually explicitly specified in the MIDI electrical spec. 
  MIDI is a 5mA current loop optically isolated at the MIDI input 
(receiver end), and the cable shield must not be part of it.  There is 
no "MIDI ground", as the loop is isolated and actually referenced to +V 
for the current source.  The reference voltage used to be 5V in MIDI1.0, 
but there probably is equipment by now that provides 5mA through pin4, 
but not necessarily 5V, so you'd best not rely on any specific voltage.

MIDI cables: Pin 2 (cable shield) and pins 4 & 5 (current loop) are 
wired straight through, pins 3 & 4 are left unconnected.

-- 
Achim.

(on the road :-)


From neil.johnson71 at gmail.com  Thu Dec 27 11:05:42 2018
From: neil.johnson71 at gmail.com (Neil Johnson)
Date: Thu, 27 Dec 2018 10:05:42 +0000
Subject: [sdiy] Caution with DIY MIDI cabling
In-Reply-To: <09c4d2fe-2377-eedb-329a-6769ba92c383@NexGo.DE>
References: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>
 <09c4d2fe-2377-eedb-329a-6769ba92c383@NexGo.DE>
Message-ID: <CACZGMxJJAkNMSysM0zpWekAx=tR0ESu4Uus=WEzb65_oag7PpA@mail.gmail.com>

The actual MIDI electrical specification can be downloaded for FREE from
the MMA website (you might need to register if you've not already done so).
The latest electrical spec - document ca33.pdf - describes in clear terms
and diagrams the shield connections on IN/OUT/THRU sockets and in the cable.

https://www.midi.org/specifications-old/item/the-midi-1-0-specification

Cheers,
Neil
-- 
http://www.njohnson.co.uk
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From modular at go2.pl  Thu Dec 27 14:55:06 2018
From: modular at go2.pl (Roman Sowa)
Date: Thu, 27 Dec 2018 14:55:06 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
Message-ID: <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>

Frequency domain multiplexing was used long time ago in telephony.
How nice and easy solution this was can be simply put in two questions:
- why nobody remembers that?
- why it was abandonned so quickly?

I mean you have ready to use multichannel digital standards and 
multichannel ADc and DACs, why bother using an ancient idea that was so 
troublesome to manage that even 0.3-3.4kHz bandwith audio was a challenge.
And if you want full analog, I'd go with multipin connectors, there are 
lots to choose from. OK expensive patch cable then, but still a tiny 
fraction of the price of any 16-voice module.

Polysynths are hardwired for a reason.

Roman

W dniu 2018-12-25 o?20:49, cheater00 cheater00 pisze:
> Hi everyone,
> I was thinking again about how you could do a modular polysynth well,
> and it occurred to me that you might be able to use frequency domain
> multiplexing (FDM) to put several signals over a single conductor
> pair. A quick search found the Si4710 which is a bit pricey at ~$12 on
> digikey but it's a tiny 3x3mm QFN device that performs complete FM
> transmission. In a 16 voice system, at about 5 output functions per
> module, and 12 modules, you can easily use up ~1000 of those, which
> drops the price to $4. I was wondering what everyone thinks about this
> sort of scheme.
> 
> Given that metal patch cables could function as antennas and cause
> both cross talk and external signal pick up, one could also use
> multimode glass fiber and transmit signals this way. The question is,
> does anyone know whether support electronics could be found that are
> integrated enough (small in footprint) and inexpensive? The idea would
> be to build an electronics module that takes 16 analog audio channels
> and outputs a signal that can be then converted to glass media
> signalling.
> 
> Merry Christmas everyone!
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> 


From frey at radioles.com  Thu Dec 27 16:21:10 2018
From: frey at radioles.com (Joe Frey)
Date: Thu, 27 Dec 2018 10:21:10 -0500
Subject: [sdiy] clock pulse to vtrig
In-Reply-To: <5068ebfe-7c4d-4bcb-a606-e61465a39eb9@radioles.com>
References: <5068ebfe-7c4d-4bcb-a606-e61465a39eb9@radioles.com>
Message-ID: <678db06c-8163-4023-a4e6-6b1240b72e79@radioles.com>

Thanks for the help. I am wondering if I wanted to limit the output of the yusynth pulse delay to 5V would I make a voltage divider by adding a 5k resistor after R7 and change R8 to 5k from 10k?
If I wanted to vary the gate size could I do the above and change R8 to a 5k pot?
Please refer to
http://www.yusynth.net/Modular/Commun/PULSEDELAY/pulsedelay-sch.gif

at

http://www.yusynth.net/Modular/EN/PULSEDELAY/index.html

Thanks. JoeF.

?Sent from TypeApp ?

On Dec 17, 2018, 2:03 PM, at 2:03 PM, Joe Frey <frey at radioles.com> wrote:
>Hello all, this is a follow-up to an email from 2 weeks ago some may
>remember. Anyway, I am using a clock out from my EHX 8-step sequencer
>to trigger my Lyra-8. The Lyra-8 plays for as long as the clock pulse.
>I want to be able to create a longer and variable pulse using a
>circuit. I am not interested in tackling programming a microcontroller,
>yet.
>Can anyone point me in the direction of some circuitry that can do
>this? Thanks. JoeF.
>
>?Sent from TypeApp ?
>
>------------------------------------------------------------------------
>
>_______________________________________________
>Synth-diy mailing list
>Synth-diy at synth-diy.org
>http://synth-diy.org/mailman/listinfo/synth-diy
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From gordonjcp at gjcp.net  Thu Dec 27 20:06:45 2018
From: gordonjcp at gjcp.net (Gordonjcp)
Date: Thu, 27 Dec 2018 19:06:45 +0000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+9GZUh_xi2dKBMNwQG3TjUN3yUAO52MEKg7QWg8R38FBA=v2Q@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
 <710FACCB-AC30-41CB-A2F1-27E2C6D4E8DD@electricdruid.net>
 <CA+9GZUh_xi2dKBMNwQG3TjUN3yUAO52MEKg7QWg8R38FBA=v2Q@mail.gmail.com>
Message-ID: <20181227190645.GA13860@ilyushin>

On Wed, Dec 26, 2018 at 08:09:08PM +0100, cheater00 cheater00 wrote:
> analog switch ICs are terrible, let's just skip them. You're not
> making an analog switch ic based system anywhere near close a medium
> sized modular, it's insanity and prone to shitloads of interference.

The Elka Synthex would beg to differ.

Actually, so would damn near any practical polysynth.

-- 
Gordonjcp



From gordonjcp at gjcp.net  Thu Dec 27 20:07:53 2018
From: gordonjcp at gjcp.net (Gordonjcp)
Date: Thu, 27 Dec 2018 19:07:53 +0000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
Message-ID: <20181227190753.GB13860@ilyushin>

On Thu, Dec 27, 2018 at 02:55:06PM +0100, Roman Sowa wrote:
> Frequency domain multiplexing was used long time ago in telephony.
> How nice and easy solution this was can be simply put in two questions:
> - why nobody remembers that?
> - why it was abandonned so quickly?

As a further hint, speaking as someone who does wired and wireless
telecoms as his day job, let me just say:

Fuck DACS boxes
Fuck DACS2 boxes
Fuck anyone who ever fitted them
Fuck anyone who ever thought they were a good idea

-- 
Gordonjcp



From rsdio at audiobanshee.com  Fri Dec 28 02:16:26 2018
From: rsdio at audiobanshee.com (rsdio at audiobanshee.com)
Date: Thu, 27 Dec 2018 17:16:26 -0800
Subject: [sdiy] clock pulse to vtrig
In-Reply-To: <678db06c-8163-4023-a4e6-6b1240b72e79@radioles.com>
References: <5068ebfe-7c4d-4bcb-a606-e61465a39eb9@radioles.com>
 <678db06c-8163-4023-a4e6-6b1240b72e79@radioles.com>
Message-ID: <83C180E3-1B1F-472D-B98F-148BF1B0E960@audiobanshee.com>

R7 & R8 already form a voltage divider, making the output 68% of the CD4538?s V(OL). Looks like +Vcc is up to 15V. The CD4538 will output at least 14.95V when using a 15V supply, so that makes OUT around 10V or just slightly above that.

If you want to limit the OUT to 5V, you could take advantage of the fact that the CD4538 will run on any Vcc from 3V to 15V. Targeting exactly 5.0V OUT, you could probably just run +Vcc at 7.4V without changing anything in the circuit at all. There might be some component values that are tuned for 15V, but I assume they?ll all work fine on reduced voltage. There?s no harm in trying, especially not if you start by confirming proper operations at 15V and proceed from there.

Option 1) Build the circuit and try running it on 7.5V or less. If it works fine, and your OUT doesn?t exceed 5V, then you?re done.

Option 2) If there is trouble above, then just change R7 & R8 values without adding any resistors.

As far as varying the Gate size, it looks like there are already controls for Pulse Delay and Pulse Width. I don?t see how R8 as a pot would change the ?size? of anything. If you?re talking about changing the Gate Voltage with a pot, I?d be more inclined to vary Vcc and leave the circuit alone, especially since the CD4000 series is so flexible about power supply voltages.

Brian


On Dec 27, 2018, at 7:21 AM, Joe Frey <frey at radioles.com> wrote:
> Thanks for the help. I am wondering if I wanted to limit the output of the yusynth pulse delay to 5V would I make a voltage divider by adding a 5k resistor after R7 and change R8 to 5k from 10k?
> If I wanted to vary the gate size could I do the above and change R8 to a 5k pot?
> Please refer to
> http://www.yusynth.net/Modular/Commun/PULSEDELAY/pulsedelay-sch.gif
> 
> at
> 
> http://www.yusynth.net/Modular/EN/PULSEDELAY/index.html
> 
> Thanks. JoeF.
> 
> Sent from TypeApp
> On Dec 17, 2018, at 2:03 PM, Joe Frey <frey at radioles.com> wrote:
> Hello all, this is a follow-up to an email from 2 weeks ago some may remember. Anyway, I am using a clock out from my EHX 8-step sequencer to trigger my Lyra-8. The Lyra-8 plays for as long as the clock pulse. I want to be able to create a longer and variable pulse using a circuit. I am not interested in tackling programming a microcontroller, yet.
> Can anyone point me in the direction of some circuitry that can do this? Thanks. JoeF.




From onephatcat at earthlink.net  Fri Dec 28 05:14:42 2018
From: onephatcat at earthlink.net (Joel B)
Date: Thu, 27 Dec 2018 20:14:42 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
Message-ID: <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>

Cat5 cable might be a nice small footprint way to send multiple signals from module to module with easy connect/disconnect-ability. 8 wires per cable, nice little phone-jack...

Joel

Sent from my iPhone 

> On Dec 27, 2018, at 5:55 AM, Roman Sowa <modular at go2.pl> wrote:
> 
> Frequency domain multiplexing was used long time ago in telephony.
> How nice and easy solution this was can be simply put in two questions:
> - why nobody remembers that?
> - why it was abandonned so quickly?
> 
> I mean you have ready to use multichannel digital standards and multichannel ADc and DACs, why bother using an ancient idea that was so troublesome to manage that even 0.3-3.4kHz bandwith audio was a challenge.
> And if you want full analog, I'd go with multipin connectors, there are lots to choose from. OK expensive patch cable then, but still a tiny fraction of the price of any 16-voice module.
> 
> Polysynths are hardwired for a reason.
> 
> Roman
> 
> W dniu 2018-12-25 o 20:49, cheater00 cheater00 pisze:
>> Hi everyone,
>> I was thinking again about how you could do a modular polysynth well,
>> and it occurred to me that you might be able to use frequency domain
>> multiplexing (FDM) to put several signals over a single conductor
>> pair. A quick search found the Si4710 which is a bit pricey at ~$12 on
>> digikey but it's a tiny 3x3mm QFN device that performs complete FM
>> transmission. In a 16 voice system, at about 5 output functions per
>> module, and 12 modules, you can easily use up ~1000 of those, which
>> drops the price to $4. I was wondering what everyone thinks about this
>> sort of scheme.
>> Given that metal patch cables could function as antennas and cause
>> both cross talk and external signal pick up, one could also use
>> multimode glass fiber and transmit signals this way. The question is,
>> does anyone know whether support electronics could be found that are
>> integrated enough (small in footprint) and inexpensive? The idea would
>> be to build an electronics module that takes 16 analog audio channels
>> and outputs a signal that can be then converted to glass media
>> signalling.
>> Merry Christmas everyone!
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy




From indigoid at oldcorollas.org  Fri Dec 28 05:43:19 2018
From: indigoid at oldcorollas.org (john slee)
Date: Fri, 28 Dec 2018 15:43:19 +1100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
Message-ID: <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>

In a large-format system, perhaps. Large tangles of Cat5 patch leads can be
pretty inflexible and annoying to manage

To the OP, I would ask: have you tried building something like what you
want with pre-existing hardware or, possibly, with virtual hardware? eg. in
Max? It would be unfortunate to go through all that analog hardware
engineering pain (and it does sound like pain!) only to find that any or
all of the below are true:

- the result is musically uninteresting
- you rarely or never go beyond patches that are essentially a
fixed-architecture polysynth
- the user interface required to manage it all is horrible

It's a very hazy memory now but didn't Creamware/Sonic Core's DSP modular
have polyphonic capability?

John

On Fri, 28 Dec 2018 at 15:18, Joel B <onephatcat at earthlink.net> wrote:

> Cat5 cable might be a nice small footprint way to send multiple signals
> from module to module with easy connect/disconnect-ability. 8 wires per
> cable, nice little phone-jack...
>
> Joel
>
> Sent from my iPhone
>
> > On Dec 27, 2018, at 5:55 AM, Roman Sowa <modular at go2.pl> wrote:
> >
> > Frequency domain multiplexing was used long time ago in telephony.
> > How nice and easy solution this was can be simply put in two questions:
> > - why nobody remembers that?
> > - why it was abandonned so quickly?
> >
> > I mean you have ready to use multichannel digital standards and
> multichannel ADc and DACs, why bother using an ancient idea that was so
> troublesome to manage that even 0.3-3.4kHz bandwith audio was a challenge.
> > And if you want full analog, I'd go with multipin connectors, there are
> lots to choose from. OK expensive patch cable then, but still a tiny
> fraction of the price of any 16-voice module.
> >
> > Polysynths are hardwired for a reason.
> >
> > Roman
> >
> > W dniu 2018-12-25 o 20:49, cheater00 cheater00 pisze:
> >> Hi everyone,
> >> I was thinking again about how you could do a modular polysynth well,
> >> and it occurred to me that you might be able to use frequency domain
> >> multiplexing (FDM) to put several signals over a single conductor
> >> pair. A quick search found the Si4710 which is a bit pricey at ~$12 on
> >> digikey but it's a tiny 3x3mm QFN device that performs complete FM
> >> transmission. In a 16 voice system, at about 5 output functions per
> >> module, and 12 modules, you can easily use up ~1000 of those, which
> >> drops the price to $4. I was wondering what everyone thinks about this
> >> sort of scheme.
> >> Given that metal patch cables could function as antennas and cause
> >> both cross talk and external signal pick up, one could also use
> >> multimode glass fiber and transmit signals this way. The question is,
> >> does anyone know whether support electronics could be found that are
> >> integrated enough (small in footprint) and inexpensive? The idea would
> >> be to build an electronics module that takes 16 analog audio channels
> >> and outputs a signal that can be then converted to glass media
> >> signalling.
> >> Merry Christmas everyone!
> >> _______________________________________________
> >> Synth-diy mailing list
> >> Synth-diy at synth-diy.org
> >> http://synth-diy.org/mailman/listinfo/synth-diy
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
>
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From mec.forumreader at gmail.com  Fri Dec 28 07:11:39 2018
From: mec.forumreader at gmail.com (Michael E Caloroso)
Date: Fri, 28 Dec 2018 01:11:39 -0500
Subject: [sdiy] Caution with DIY MIDI cabling
In-Reply-To: <CACZGMxJJAkNMSysM0zpWekAx=tR0ESu4Uus=WEzb65_oag7PpA@mail.gmail.com>
References: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>
 <09c4d2fe-2377-eedb-329a-6769ba92c383@NexGo.DE>
 <CACZGMxJJAkNMSysM0zpWekAx=tR0ESu4Uus=WEzb65_oag7PpA@mail.gmail.com>
Message-ID: <CAAv6=UCNO407aUeLopF_fhzp+w1BEN3mATqVAewPD-ZZ4f5y2A@mail.gmail.com>

I have the 1983 and the 1988 edition of the MIDI spec.  Not
downloaded, originals from the MMA.

MC

On 12/27/18, Neil Johnson <neil.johnson71 at gmail.com> wrote:
> The actual MIDI electrical specification can be downloaded for FREE from
> the MMA website (you might need to register if you've not already done so).
> The latest electrical spec - document ca33.pdf - describes in clear terms
> and diagrams the shield connections on IN/OUT/THRU sockets and in the
> cable.
>
> https://www.midi.org/specifications-old/item/the-midi-1-0-specification
>
> Cheers,
> Neil
> --
> http://www.njohnson.co.uk
>


From onephatcat at earthlink.net  Fri Dec 28 07:16:19 2018
From: onephatcat at earthlink.net (Joel B)
Date: Thu, 27 Dec 2018 22:16:19 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
Message-ID: <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>

Weeeell... tangles happen if you allow them to - have you ever wired up an office building and server room with Ethernet? Lots and lots of cables in a very tiny area. Typically 32 cables per 1 rack unit high device...

I?m not aware of a smaller form factor cable with equal or higher wire count, but perhaps one exists.

Joel





Sent from my iPhone 

> On Dec 27, 2018, at 8:43 PM, john slee <indigoid at oldcorollas.org> wrote:
> 
> In a large-format system, perhaps. Large tangles of Cat5 patch leads can be pretty inflexible and annoying to manage
> 
> To the OP, I would ask: have you tried building something like what you want with pre-existing hardware or, possibly, with virtual hardware? eg. in Max? It would be unfortunate to go through all that analog hardware engineering pain (and it does sound like pain!) only to find that any or all of the below are true:
> 
> - the result is musically uninteresting
> - you rarely or never go beyond patches that are essentially a fixed-architecture polysynth
> - the user interface required to manage it all is horrible
> 
> It's a very hazy memory now but didn't Creamware/Sonic Core's DSP modular have polyphonic capability?
> 
> John
> 
>> On Fri, 28 Dec 2018 at 15:18, Joel B <onephatcat at earthlink.net> wrote:
>> Cat5 cable might be a nice small footprint way to send multiple signals from module to module with easy connect/disconnect-ability. 8 wires per cable, nice little phone-jack...
>> 
>> Joel
>> 
>> Sent from my iPhone 
>> 
>> > On Dec 27, 2018, at 5:55 AM, Roman Sowa <modular at go2.pl> wrote:
>> > 
>> > Frequency domain multiplexing was used long time ago in telephony.
>> > How nice and easy solution this was can be simply put in two questions:
>> > - why nobody remembers that?
>> > - why it was abandonned so quickly?
>> > 
>> > I mean you have ready to use multichannel digital standards and multichannel ADc and DACs, why bother using an ancient idea that was so troublesome to manage that even 0.3-3.4kHz bandwith audio was a challenge.
>> > And if you want full analog, I'd go with multipin connectors, there are lots to choose from. OK expensive patch cable then, but still a tiny fraction of the price of any 16-voice module.
>> > 
>> > Polysynths are hardwired for a reason.
>> > 
>> > Roman
>> > 
>> > W dniu 2018-12-25 o 20:49, cheater00 cheater00 pisze:
>> >> Hi everyone,
>> >> I was thinking again about how you could do a modular polysynth well,
>> >> and it occurred to me that you might be able to use frequency domain
>> >> multiplexing (FDM) to put several signals over a single conductor
>> >> pair. A quick search found the Si4710 which is a bit pricey at ~$12 on
>> >> digikey but it's a tiny 3x3mm QFN device that performs complete FM
>> >> transmission. In a 16 voice system, at about 5 output functions per
>> >> module, and 12 modules, you can easily use up ~1000 of those, which
>> >> drops the price to $4. I was wondering what everyone thinks about this
>> >> sort of scheme.
>> >> Given that metal patch cables could function as antennas and cause
>> >> both cross talk and external signal pick up, one could also use
>> >> multimode glass fiber and transmit signals this way. The question is,
>> >> does anyone know whether support electronics could be found that are
>> >> integrated enough (small in footprint) and inexpensive? The idea would
>> >> be to build an electronics module that takes 16 analog audio channels
>> >> and outputs a signal that can be then converted to glass media
>> >> signalling.
>> >> Merry Christmas everyone!
>> >> _______________________________________________
>> >> Synth-diy mailing list
>> >> Synth-diy at synth-diy.org
>> >> http://synth-diy.org/mailman/listinfo/synth-diy
>> > _______________________________________________
>> > Synth-diy mailing list
>> > Synth-diy at synth-diy.org
>> > http://synth-diy.org/mailman/listinfo/synth-diy
>> 
>> 
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
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From indigoid at oldcorollas.org  Fri Dec 28 07:47:39 2018
From: indigoid at oldcorollas.org (john slee)
Date: Fri, 28 Dec 2018 17:47:39 +1100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
Message-ID: <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>

Yup, done plenty of that. I'm not sure it's a good example to look at
because datacentre cabling isn't designed with frequent repatching in mind.
I've worked in places that had "patch once then throw it in the trash"
policies for Cat5e/etc cables ? you don't have to waste many hours on
troubleshooting problems that turn out to be caused by damaged cables
before it's cheaper to operate that way. Wasteful, perhaps, but typical
Cat5/etc cables, regardless of how much you pay for them, aren't really
that resilient. Not good for modular patching.

John

On Fri, 28 Dec 2018 at 17:16, Joel B <onephatcat at earthlink.net> wrote:

> Weeeell... tangles happen if you allow them to - have you ever wired up an
> office building and server room with Ethernet? Lots and lots of cables in a
> very tiny area. Typically 32 cables per 1 rack unit high device...
>
> I?m not aware of a smaller form factor cable with equal or higher wire
> count, but perhaps one exists.
>
> Joel
>
>
>
>
>
> Sent from my iPhone
>
> On Dec 27, 2018, at 8:43 PM, john slee <indigoid at oldcorollas.org> wrote:
>
> In a large-format system, perhaps. Large tangles of Cat5 patch leads can
> be pretty inflexible and annoying to manage
>
> To the OP, I would ask: have you tried building something like what you
> want with pre-existing hardware or, possibly, with virtual hardware? eg. in
> Max? It would be unfortunate to go through all that analog hardware
> engineering pain (and it does sound like pain!) only to find that any or
> all of the below are true:
>
> - the result is musically uninteresting
> - you rarely or never go beyond patches that are essentially a
> fixed-architecture polysynth
> - the user interface required to manage it all is horrible
>
> It's a very hazy memory now but didn't Creamware/Sonic Core's DSP modular
> have polyphonic capability?
>
> John
>
> On Fri, 28 Dec 2018 at 15:18, Joel B <onephatcat at earthlink.net> wrote:
>
>> Cat5 cable might be a nice small footprint way to send multiple signals
>> from module to module with easy connect/disconnect-ability. 8 wires per
>> cable, nice little phone-jack...
>>
>> Joel
>>
>> Sent from my iPhone
>>
>> > On Dec 27, 2018, at 5:55 AM, Roman Sowa <modular at go2.pl> wrote:
>> >
>> > Frequency domain multiplexing was used long time ago in telephony.
>> > How nice and easy solution this was can be simply put in two questions:
>> > - why nobody remembers that?
>> > - why it was abandonned so quickly?
>> >
>> > I mean you have ready to use multichannel digital standards and
>> multichannel ADc and DACs, why bother using an ancient idea that was so
>> troublesome to manage that even 0.3-3.4kHz bandwith audio was a challenge.
>> > And if you want full analog, I'd go with multipin connectors, there are
>> lots to choose from. OK expensive patch cable then, but still a tiny
>> fraction of the price of any 16-voice module.
>> >
>> > Polysynths are hardwired for a reason.
>> >
>> > Roman
>> >
>> > W dniu 2018-12-25 o 20:49, cheater00 cheater00 pisze:
>> >> Hi everyone,
>> >> I was thinking again about how you could do a modular polysynth well,
>> >> and it occurred to me that you might be able to use frequency domain
>> >> multiplexing (FDM) to put several signals over a single conductor
>> >> pair. A quick search found the Si4710 which is a bit pricey at ~$12 on
>> >> digikey but it's a tiny 3x3mm QFN device that performs complete FM
>> >> transmission. In a 16 voice system, at about 5 output functions per
>> >> module, and 12 modules, you can easily use up ~1000 of those, which
>> >> drops the price to $4. I was wondering what everyone thinks about this
>> >> sort of scheme.
>> >> Given that metal patch cables could function as antennas and cause
>> >> both cross talk and external signal pick up, one could also use
>> >> multimode glass fiber and transmit signals this way. The question is,
>> >> does anyone know whether support electronics could be found that are
>> >> integrated enough (small in footprint) and inexpensive? The idea would
>> >> be to build an electronics module that takes 16 analog audio channels
>> >> and outputs a signal that can be then converted to glass media
>> >> signalling.
>> >> Merry Christmas everyone!
>> >> _______________________________________________
>> >> Synth-diy mailing list
>> >> Synth-diy at synth-diy.org
>> >> http://synth-diy.org/mailman/listinfo/synth-diy
>> > _______________________________________________
>> > Synth-diy mailing list
>> > Synth-diy at synth-diy.org
>> > http://synth-diy.org/mailman/listinfo/synth-diy
>>
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>>
>
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From cheater00 at gmail.com  Fri Dec 28 23:09:16 2018
From: cheater00 at gmail.com (cheater00 cheater00)
Date: Fri, 28 Dec 2018 23:09:16 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <15AC5A05-1A48-479B-A6D4-197FE2BBA269@audiobanshee.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
 <710FACCB-AC30-41CB-A2F1-27E2C6D4E8DD@electricdruid.net>
 <CA+9GZUh_xi2dKBMNwQG3TjUN3yUAO52MEKg7QWg8R38FBA=v2Q@mail.gmail.com>
 <AC91E158-BBE4-4172-9BBD-70A2720CAF33@gmail.com>
 <0b021375-9642-85c0-2043-508051e68b17@ix.netcom.com>
 <15AC5A05-1A48-479B-A6D4-197FE2BBA269@audiobanshee.com>
Message-ID: <CA+9GZUg1kdEpGNcrH+cZFf9+20VOL50i75mL0u-QgomAL-S79w@mail.gmail.com>

We only need 70 dB or so dynamic range for a single voice, so a
(modern) phone conversation will do.

D connectors are not patchable, have only few cycles, and the cables
are thick and have a lot of heft to them. There's no way you're
running a complex patch with monitor cables :)

On Wed, Dec 26, 2018 at 10:00 PM <rsdio at audiobanshee.com> wrote:
>
> Bumping up from DB9 to 13-pin would allow such a design to be compatible with either the Akai S900 sampler to VX90/AX73 (6-voice) or the popular Roland synth guitar (technically 6-string, but with 7 audio channels). Unfortunately, despite sharing the 13-pin connector, the Akai and Roland cables are not compatible, because they put the voices on different pins. Also, another obvious disadvantage is that the 13-pin jacks and plugs are large.
>
> Then again, DB9 (DE-9) is not exactly ?small? either. Unless you were talking about mini-DIN size connectors, where you can find 10-pin versions that fit in the 9.5 mm plug body.
>
> Whether you want to standardize on 6-voice, 7-voice, or 8-voice would be an interesting choice.
>
>
> As for cheater?s comment that analog switch ICs are terrible - wait until you try frequency domain multiplexing! It?s going to be way more of a design challenge to get good quality out of frequency domain multiplexing - unless you?re happy with telephone quality audio - than getting analog switches to work. There are some very high-end analog audio devices that use analog switch ICs, but they all use the more expensive chips that aren?t exactly replacements for the standard analog switch ICs found in vintage analog synths. These newer chips have expanded voltage ranges and much lower resistance, as Mr. Levy alluded. Intersil and Siliconix were the original high-end analog switch companies, and now Renasas and Vishay seem to share that market, having purchased the former leading companies, respectively.
>
> Brian Willoughby
>
>
> On Dec 26, 2018, at 12:12 PM, Oren Leavitt <obl64 at ix.netcom.com> wrote:
> > Some years ago, I had an idea of using 9 pin DB9 data connectors as patch cords for a polyphonic all-analog modular synth. Technically, you could patch up 8 voices + common ground.
> >
> > - Oren (another Oren!)
> > On 12/26/18 1:29 PM, oren levy wrote:
> >> Sorry about my earlier recommendations; didn?t realize you wanted all analog.
> >>
> >> As far as switches go, I really like the Intersil (now Renesas) BiCMOS 16x8 crosspoint switch IC. Low ron and very very low crosstalk. I used it when designing the Music Man ?Game Changer? guitars for pickup switching, but, it maxes out at 15V.
> >> https://www.renesas.com/us/en/products/audio-video/video-switching/unbuffered-crosspoint-switches/device/CD22M3494.html
> >>
> >> Rock & Roll,
> >> Oren Levy
> >>
> >> On Dec 26, 2018, at 09:09, cheater00 wrote:
> >>> analog switch ICs are terrible, let's just skip them. You're not
> >>> making an analog switch ic based system anywhere near close a medium
> >>> sized modular, it's insanity and prone to shitloads of interference.
> >>> same with mod busses. the switch ICs are very proprietary. I haven't
> >>> found a digital multiplexer IC that was good, has anyone got any good
> >>> suggestions?
> >>>
> >>> On Wed, Dec 26, 2018 at 5:16 PM Tom Wiltshire wrote:
> >>>>
> >>>> Why not make a number of ?analog virtual patch cables? with analog switch ICs? Each cable has a switch at both ends, one selects between X sources, and the other selects between Y destinations. This is conceptually very similar to a genuine modular with hardware cables, but the control signals can be fanned out to however many voices you have.
> >>>>
> >>>> Alternatively, you could have a ?mod buss? type system, where each module output could be sent to a particular destination buss, and each module input could be switch to tap signal from a given buss. Again, control signals for the switches in such a set-up can be fanned out to however many voices are required.
> >>>>
> >>>> For any polyphonic system (except the early oberheims?), the control panel is separated from the voice generation, so you can think about the interface separately from the audio-producing part of the circuit.
> >>>>
> >>>> Tom
> >>>>
> >>>> On 25 Dec 2018, at 22:40, cheater00 wrote:
> >>>>> I want to make this work for an all-analog synthesizer, but rather
> >>>>> than use crosspoint switches I want to use patch cables which makes
> >>>>> things much less annoyingly complex and expensive. The thing is, where
> >>>>> on a monosynth you have a single patch cable, on a patchable polysynth
> >>>>> you have n patch cables, one for each voice. So I am currently trying
> >>>>> to work out how to do this using a single patch cable, and frequency
> >>>>> domain multiplexing came to mind. I'm 100% certain an FPGA cannot do
> >>>>> FDM, since almost all of this is analog, so I'm looking at dedicated
> >>>>> radio transmitter chips. At $4 per chip, it's not so bad. The question
> >>>>> is how to make the chips talk to a single medium without fighting each
> >>>>> other.
> >>>>>
> >>>>> On Tue, Dec 25, 2018 at 11:24 PM Ben Bradley wrote:
> >>>>>> What you're describing sounds all-digital.
> >>>>>>
> >>>>>> It seems to me a crosspoint switch would be the thing to have on each
> >>>>>> (analog) voice, and have them controlled by the usual microcontroller
> >>>>>> for a polyphonic analog-signal-path synthesizer. Of course, this is a
> >>>>>> woefully incomplete description.
> >>>>>>
> >>>>>> On Dec 25, 2018, at 11:13, cheater00 wrote:
> >>>>>>> The objective is to be able to create a way for a single patch cord to
> >>>>>>> carry 16 voices. I'm not sure how an FPGA in itself will help me, have
> >>>>>>> you got any ideas?
> >>>>>>>
> >>>>>>> MADI interfaces are prohibitively expensive.
> >>>>>>>
> >>>>>>> On Dec 25, 2018, at 10:01, Mike Beauchamp wrote:
> >>>>>>>>> transmission. In a 16 voice system, at about 5 output functions per
> >>>>>>>>> module, and 12 modules, you can easily use up ~1000 of those, which
> >>>>>>>>> drops the price to $4. I was wondering what everyone thinks about this
> >>>>>>>>> sort of scheme.
> >>>>>>>>
> >>>>>>>> So there's $4000 worth of just one IC in a single complete polysynth?
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From cheater00 at gmail.com  Fri Dec 28 23:10:11 2018
From: cheater00 at gmail.com (cheater00 cheater00)
Date: Fri, 28 Dec 2018 23:10:11 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
Message-ID: <CA+9GZUjC6+6sqMjjVoxdqEjFoV0yABYifiAWW769WN+9MnF+2Q@mail.gmail.com>

I don't know Roman, I can receive more than 16 FM stations over the
air and they're all pretty listenable and have more than 3.4 kHz
bandwidth.

On Thu, Dec 27, 2018 at 2:55 PM Roman Sowa <modular at go2.pl> wrote:
>
> Frequency domain multiplexing was used long time ago in telephony.
> How nice and easy solution this was can be simply put in two questions:
> - why nobody remembers that?
> - why it was abandonned so quickly?
>
> I mean you have ready to use multichannel digital standards and
> multichannel ADc and DACs, why bother using an ancient idea that was so
> troublesome to manage that even 0.3-3.4kHz bandwith audio was a challenge.
> And if you want full analog, I'd go with multipin connectors, there are
> lots to choose from. OK expensive patch cable then, but still a tiny
> fraction of the price of any 16-voice module.
>
> Polysynths are hardwired for a reason.
>
> Roman
>
> W dniu 2018-12-25 o 20:49, cheater00 cheater00 pisze:
> > Hi everyone,
> > I was thinking again about how you could do a modular polysynth well,
> > and it occurred to me that you might be able to use frequency domain
> > multiplexing (FDM) to put several signals over a single conductor
> > pair. A quick search found the Si4710 which is a bit pricey at ~$12 on
> > digikey but it's a tiny 3x3mm QFN device that performs complete FM
> > transmission. In a 16 voice system, at about 5 output functions per
> > module, and 12 modules, you can easily use up ~1000 of those, which
> > drops the price to $4. I was wondering what everyone thinks about this
> > sort of scheme.
> >
> > Given that metal patch cables could function as antennas and cause
> > both cross talk and external signal pick up, one could also use
> > multimode glass fiber and transmit signals this way. The question is,
> > does anyone know whether support electronics could be found that are
> > integrated enough (small in footprint) and inexpensive? The idea would
> > be to build an electronics module that takes 16 analog audio channels
> > and outputs a signal that can be then converted to glass media
> > signalling.
> >
> > Merry Christmas everyone!
> > _______________________________________________
> > Synth-diy mailing list
> > Synth-diy at synth-diy.org
> > http://synth-diy.org/mailman/listinfo/synth-diy
> >


From cheater00 at gmail.com  Fri Dec 28 23:11:59 2018
From: cheater00 at gmail.com (cheater00 cheater00)
Date: Fri, 28 Dec 2018 23:11:59 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
Message-ID: <CA+9GZUi3MQv4UATc1bxSgPH0HPNwFWgiHF-VKmnx=Tb51A48GQ@mail.gmail.com>

I've used lots of virtual modulars with high polyphony and they were
very useful.

On Fri, Dec 28, 2018 at 5:43 AM john slee <indigoid at oldcorollas.org> wrote:
>
> In a large-format system, perhaps. Large tangles of Cat5 patch leads can be pretty inflexible and annoying to manage
>
> To the OP, I would ask: have you tried building something like what you want with pre-existing hardware or, possibly, with virtual hardware? eg. in Max? It would be unfortunate to go through all that analog hardware engineering pain (and it does sound like pain!) only to find that any or all of the below are true:
>
> - the result is musically uninteresting
> - you rarely or never go beyond patches that are essentially a fixed-architecture polysynth
> - the user interface required to manage it all is horrible
>
> It's a very hazy memory now but didn't Creamware/Sonic Core's DSP modular have polyphonic capability?
>
> John
>
> On Fri, 28 Dec 2018 at 15:18, Joel B <onephatcat at earthlink.net> wrote:
>>
>> Cat5 cable might be a nice small footprint way to send multiple signals from module to module with easy connect/disconnect-ability. 8 wires per cable, nice little phone-jack...
>>
>> Joel
>>
>> Sent from my iPhone
>>
>> > On Dec 27, 2018, at 5:55 AM, Roman Sowa <modular at go2.pl> wrote:
>> >
>> > Frequency domain multiplexing was used long time ago in telephony.
>> > How nice and easy solution this was can be simply put in two questions:
>> > - why nobody remembers that?
>> > - why it was abandonned so quickly?
>> >
>> > I mean you have ready to use multichannel digital standards and multichannel ADc and DACs, why bother using an ancient idea that was so troublesome to manage that even 0.3-3.4kHz bandwith audio was a challenge.
>> > And if you want full analog, I'd go with multipin connectors, there are lots to choose from. OK expensive patch cable then, but still a tiny fraction of the price of any 16-voice module.
>> >
>> > Polysynths are hardwired for a reason.
>> >
>> > Roman
>> >
>> > W dniu 2018-12-25 o 20:49, cheater00 cheater00 pisze:
>> >> Hi everyone,
>> >> I was thinking again about how you could do a modular polysynth well,
>> >> and it occurred to me that you might be able to use frequency domain
>> >> multiplexing (FDM) to put several signals over a single conductor
>> >> pair. A quick search found the Si4710 which is a bit pricey at ~$12 on
>> >> digikey but it's a tiny 3x3mm QFN device that performs complete FM
>> >> transmission. In a 16 voice system, at about 5 output functions per
>> >> module, and 12 modules, you can easily use up ~1000 of those, which
>> >> drops the price to $4. I was wondering what everyone thinks about this
>> >> sort of scheme.
>> >> Given that metal patch cables could function as antennas and cause
>> >> both cross talk and external signal pick up, one could also use
>> >> multimode glass fiber and transmit signals this way. The question is,
>> >> does anyone know whether support electronics could be found that are
>> >> integrated enough (small in footprint) and inexpensive? The idea would
>> >> be to build an electronics module that takes 16 analog audio channels
>> >> and outputs a signal that can be then converted to glass media
>> >> signalling.
>> >> Merry Christmas everyone!
>> >> _______________________________________________
>> >> Synth-diy mailing list
>> >> Synth-diy at synth-diy.org
>> >> http://synth-diy.org/mailman/listinfo/synth-diy
>> > _______________________________________________
>> > Synth-diy mailing list
>> > Synth-diy at synth-diy.org
>> > http://synth-diy.org/mailman/listinfo/synth-diy
>>
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy



From cheater00 at gmail.com  Fri Dec 28 23:17:59 2018
From: cheater00 at gmail.com (cheater00 cheater00)
Date: Fri, 28 Dec 2018 23:17:59 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
Message-ID: <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>

cat5 cables are pretty terrible for repatching, as are the jacks.

In case someone wants to mention some other more or less obscure type
of cable, PLEASE DON'T, I really considered them all.

Can we please have the thread return to the original question, which is below:

How to use multiple FM transmitter ICs to succesfully transmit
multiple FM stations over a single copper cable? What are suitable ICs
to use? Is there an inexpensive IC that will transmit multiple bands
at once?

Can we please NOT talk about whether this is feasible, provide good
results, or be cheap. Can we please not talk about crossbar ICs,
digital transmission, or multi-conductor cables. If you want, you can
start your own thread, thanks. We've had those exact conversations on
this mailing list a dozen times over the last 20 years at least,
please look in the archives. There's absolutely nothing new to be said
here.

On Fri, Dec 28, 2018 at 7:48 AM john slee <indigoid at oldcorollas.org> wrote:
>
> Yup, done plenty of that. I'm not sure it's a good example to look at because datacentre cabling isn't designed with frequent repatching in mind. I've worked in places that had "patch once then throw it in the trash" policies for Cat5e/etc cables ? you don't have to waste many hours on troubleshooting problems that turn out to be caused by damaged cables before it's cheaper to operate that way. Wasteful, perhaps, but typical Cat5/etc cables, regardless of how much you pay for them, aren't really that resilient. Not good for modular patching.
>
> John
>
> On Fri, 28 Dec 2018 at 17:16, Joel B <onephatcat at earthlink.net> wrote:
>>
>> Weeeell... tangles happen if you allow them to - have you ever wired up an office building and server room with Ethernet? Lots and lots of cables in a very tiny area. Typically 32 cables per 1 rack unit high device...
>>
>> I?m not aware of a smaller form factor cable with equal or higher wire count, but perhaps one exists.
>>
>> Joel
>>
>>
>>
>>
>>
>> Sent from my iPhone
>>
>> On Dec 27, 2018, at 8:43 PM, john slee <indigoid at oldcorollas.org> wrote:
>>
>> In a large-format system, perhaps. Large tangles of Cat5 patch leads can be pretty inflexible and annoying to manage
>>
>> To the OP, I would ask: have you tried building something like what you want with pre-existing hardware or, possibly, with virtual hardware? eg. in Max? It would be unfortunate to go through all that analog hardware engineering pain (and it does sound like pain!) only to find that any or all of the below are true:
>>
>> - the result is musically uninteresting
>> - you rarely or never go beyond patches that are essentially a fixed-architecture polysynth
>> - the user interface required to manage it all is horrible
>>
>> It's a very hazy memory now but didn't Creamware/Sonic Core's DSP modular have polyphonic capability?
>>
>> John
>>
>> On Fri, 28 Dec 2018 at 15:18, Joel B <onephatcat at earthlink.net> wrote:
>>>
>>> Cat5 cable might be a nice small footprint way to send multiple signals from module to module with easy connect/disconnect-ability. 8 wires per cable, nice little phone-jack...
>>>
>>> Joel
>>>
>>> Sent from my iPhone
>>>
>>> > On Dec 27, 2018, at 5:55 AM, Roman Sowa <modular at go2.pl> wrote:
>>> >
>>> > Frequency domain multiplexing was used long time ago in telephony.
>>> > How nice and easy solution this was can be simply put in two questions:
>>> > - why nobody remembers that?
>>> > - why it was abandonned so quickly?
>>> >
>>> > I mean you have ready to use multichannel digital standards and multichannel ADc and DACs, why bother using an ancient idea that was so troublesome to manage that even 0.3-3.4kHz bandwith audio was a challenge.
>>> > And if you want full analog, I'd go with multipin connectors, there are lots to choose from. OK expensive patch cable then, but still a tiny fraction of the price of any 16-voice module.
>>> >
>>> > Polysynths are hardwired for a reason.
>>> >
>>> > Roman
>>> >
>>> > W dniu 2018-12-25 o 20:49, cheater00 cheater00 pisze:
>>> >> Hi everyone,
>>> >> I was thinking again about how you could do a modular polysynth well,
>>> >> and it occurred to me that you might be able to use frequency domain
>>> >> multiplexing (FDM) to put several signals over a single conductor
>>> >> pair. A quick search found the Si4710 which is a bit pricey at ~$12 on
>>> >> digikey but it's a tiny 3x3mm QFN device that performs complete FM
>>> >> transmission. In a 16 voice system, at about 5 output functions per
>>> >> module, and 12 modules, you can easily use up ~1000 of those, which
>>> >> drops the price to $4. I was wondering what everyone thinks about this
>>> >> sort of scheme.
>>> >> Given that metal patch cables could function as antennas and cause
>>> >> both cross talk and external signal pick up, one could also use
>>> >> multimode glass fiber and transmit signals this way. The question is,
>>> >> does anyone know whether support electronics could be found that are
>>> >> integrated enough (small in footprint) and inexpensive? The idea would
>>> >> be to build an electronics module that takes 16 analog audio channels
>>> >> and outputs a signal that can be then converted to glass media
>>> >> signalling.
>>> >> Merry Christmas everyone!
>>> >> _______________________________________________
>>> >> Synth-diy mailing list
>>> >> Synth-diy at synth-diy.org
>>> >> http://synth-diy.org/mailman/listinfo/synth-diy
>>> > _______________________________________________
>>> > Synth-diy mailing list
>>> > Synth-diy at synth-diy.org
>>> > http://synth-diy.org/mailman/listinfo/synth-diy
>>>
>>>
>>> _______________________________________________
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy



From vladoman at gmail.com  Fri Dec 28 23:24:46 2018
From: vladoman at gmail.com (Vladimir Pantelic)
Date: Fri, 28 Dec 2018 23:24:46 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
Message-ID: <89392ba6-25f5-4459-9293-9bef0685d9b6@gmail.com>

let's not forget why these solutions were developed in the first place, it was 
because the actual transmission channel was an expensive and scarce resource, be 
it a long distance phone cable crossing the Atlantic or a satellite link, in 
each case the added cost for mux/demux at the ends was still way less than 
adding more separate "wires".

in the use case here, having to mux/demux at every patch point will add way more 
cost and overhead than just running N lines in parallel, copper is still 
relatively cheap for short lengths...

On 27/12/18 14:55, Roman Sowa wrote:
> Frequency domain multiplexing was used long time ago in telephony.
> How nice and easy solution this was can be simply put in two questions:
> - why nobody remembers that?
> - why it was abandonned so quickly?
> 
> I mean you have ready to use multichannel digital standards and multichannel ADc 
> and DACs, why bother using an ancient idea that was so troublesome to manage 
> that even 0.3-3.4kHz bandwith audio was a challenge.
> And if you want full analog, I'd go with multipin connectors, there are lots to 
> choose from. OK expensive patch cable then, but still a tiny fraction of the 
> price of any 16-voice module.
> 
> Polysynths are hardwired for a reason.
> 
> Roman
> 
> W dniu 2018-12-25 o?20:49, cheater00 cheater00 pisze:
>> Hi everyone,
>> I was thinking again about how you could do a modular polysynth well,
>> and it occurred to me that you might be able to use frequency domain
>> multiplexing (FDM) to put several signals over a single conductor
>> pair. A quick search found the Si4710 which is a bit pricey at ~$12 on
>> digikey but it's a tiny 3x3mm QFN device that performs complete FM
>> transmission. In a 16 voice system, at about 5 output functions per
>> module, and 12 modules, you can easily use up ~1000 of those, which
>> drops the price to $4. I was wondering what everyone thinks about this
>> sort of scheme.
>>
>> Given that metal patch cables could function as antennas and cause
>> both cross talk and external signal pick up, one could also use
>> multimode glass fiber and transmit signals this way. The question is,
>> does anyone know whether support electronics could be found that are
>> integrated enough (small in footprint) and inexpensive? The idea would
>> be to build an electronics module that takes 16 analog audio channels
>> and outputs a signal that can be then converted to glass media
>> signalling.
>>
>> Merry Christmas everyone!
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
>>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From gordonjcp at gjcp.net  Fri Dec 28 23:59:45 2018
From: gordonjcp at gjcp.net (Gordonjcp)
Date: Fri, 28 Dec 2018 22:59:45 +0000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
 <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
Message-ID: <20181228225945.GA20264@ilyushin>

On Fri, Dec 28, 2018 at 11:17:59PM +0100, cheater00 cheater00 wrote:
> 
> How to use multiple FM transmitter ICs to succesfully transmit
> multiple FM stations over a single copper cable? What are suitable ICs
> to use? Is there an inexpensive IC that will transmit multiple bands
> at once?

No.  There is not.  There isn't even an expensive IC that can do it.

Analogue FDMA is not a thing.

-- 
Gordonjcp



From gordonjcp at gjcp.net  Sat Dec 29 00:00:26 2018
From: gordonjcp at gjcp.net (Gordonjcp)
Date: Fri, 28 Dec 2018 23:00:26 +0000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+9GZUjC6+6sqMjjVoxdqEjFoV0yABYifiAWW769WN+9MnF+2Q@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <CA+9GZUjC6+6sqMjjVoxdqEjFoV0yABYifiAWW769WN+9MnF+2Q@mail.gmail.com>
Message-ID: <20181228230026.GB20264@ilyushin>

On Fri, Dec 28, 2018 at 11:10:11PM +0100, cheater00 cheater00 wrote:
> I don't know Roman, I can receive more than 16 FM stations over the
> air and they're all pretty listenable and have more than 3.4 kHz
> bandwidth.

Do you understand how radios work?

-- 
Gordonjcp



From music.maker at gte.net  Sat Dec 29 00:07:15 2018
From: music.maker at gte.net (Scott Gravenhorst)
Date: Fri, 28 Dec 2018 15:07:15 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
Message-ID: <20181228230715.7AA58980055@pi3c.lan>


cheater00 cheater00 <cheater00 at gmail.com> wrote:
>I don't know Roman, I can receive more than 16 FM stations over the
>air and they're all pretty listenable and have more than 3.4 kHz
>bandwidth.

And those radio stations have advanced transmitter systems that by law cannot emit energy
outside of their bandwidth.  The radio you receive it on is an advanced circuit called a
superheterodyne receiver which has critical layout, power and shielding requirements.  It
is the superheterodyne circuit that allows the receiver to be so incredibly selective
that there's never interference even with it's full hearing range audio bandwidth.  There
is a big difference between the radio transmitter and receiver systems for FM music and
something for FDM and be sure to check those FDM chips for a spec on usable bandwidth. 
3.4 kHz is pretty much crap for full range music.  Almost any modular can make
fundamental pitches well above 3.4 kHz and then add harmonics on top of that..  Sure, you
can do superhet, but (and I'm sorry, but it's necessary to mention cost) imagine the
price tag of 16 superhet receivers and 16 advanced transmitters per module (for the 16
voice system you imagined).

You also write of "complex patches".  I have no idea what you mean by that, but I'm sure
we're talking more than 2 VCOs, a VCF, an EG and VCA for each voice - and obviously
there's not much point in making that patchable, but (using your own voice count of 16)
just that is 32 VCOs, 16 VCFs, 16 EGs and 16 VCAs.  Have you done pricing checks on just
those analog components?  And just that small system would need 80 receivers and 80
transmitters.  Now start talking about a truly patchable system that does more than a
Fatman and I think you'll see that without lotto winnings, it won't happen.

You asked a question, you're hearing the answers based in reality and cost and
feasibility is part of reality.  But you're also invited to prove us all wrong - do the
research on how to use those FDM chips and build up a simple system of say, just 4 or
even just 2 voices - and make it work with quality full audio range output.


>On Thu, Dec 27, 2018 at 2:55 PM Roman Sowa <modular at go2.pl> wrote:
>>
>> Frequency domain multiplexing was used long time ago in telephony.
>> How nice and easy solution this was can be simply put in two questions:
>> - why nobody remembers that?
>> - why it was abandonned so quickly?
>>
>> I mean you have ready to use multichannel digital standards and
>> multichannel ADc and DACs, why bother using an ancient idea that was so
>> troublesome to manage that even 0.3-3.4kHz bandwith audio was a challenge.
>> And if you want full analog, I'd go with multipin connectors, there are
>> lots to choose from. OK expensive patch cable then, but still a tiny
>> fraction of the price of any 16-voice module.
>>
>> Polysynths are hardwired for a reason.
>>
>> Roman
>>
>> W dniu 2018-12-25 o 20:49, cheater00 cheater00 pisze:
>> > Hi everyone,
>> > I was thinking again about how you could do a modular polysynth well,
>> > and it occurred to me that you might be able to use frequency domain
>> > multiplexing (FDM) to put several signals over a single conductor
>> > pair. A quick search found the Si4710 which is a bit pricey at ~$12 on
>> > digikey but it's a tiny 3x3mm QFN device that performs complete FM
>> > transmission. In a 16 voice system, at about 5 output functions per
>> > module, and 12 modules, you can easily use up ~1000 of those, which
>> > drops the price to $4. I was wondering what everyone thinks about this
>> > sort of scheme.
>> >
>> > Given that metal patch cables could function as antennas and cause
>> > both cross talk and external signal pick up, one could also use
>> > multimode glass fiber and transmit signals this way. The question is,
>> > does anyone know whether support electronics could be found that are
>> > integrated enough (small in footprint) and inexpensive? The idea would
>> > be to build an electronics module that takes 16 analog audio channels
>> > and outputs a signal that can be then converted to glass media
>> > signalling.
>> >
>> > Merry Christmas everyone!
>> > _______________________________________________
>> > Synth-diy mailing list
>> > Synth-diy at synth-diy.org
>> > http://synth-diy.org/mailman/listinfo/synth-diy
>> >
>_______________________________________________
>Synth-diy mailing list
>Synth-diy at synth-diy.org
>http://synth-diy.org/mailman/listinfo/synth-diy
>

-- ScottG
________________________________________________________________________
-- Scott Gravenhorst
-- http://scott.joviansynth.com/
-- When the going gets tough, the tough use the command line.
-- Matt 21:22



From neil.johnson71 at gmail.com  Sat Dec 29 00:32:17 2018
From: neil.johnson71 at gmail.com (Neil Johnson)
Date: Fri, 28 Dec 2018 23:32:17 +0000
Subject: [sdiy] Caution with DIY MIDI cabling
In-Reply-To: <CAAv6=UCNO407aUeLopF_fhzp+w1BEN3mATqVAewPD-ZZ4f5y2A@mail.gmail.com>
References: <CAAv6=UCEJA-=q+xjoCdqZyfGJgaazGQzLihQ7xO4Kp3=wKfTVA@mail.gmail.com>
 <09c4d2fe-2377-eedb-329a-6769ba92c383@NexGo.DE>
 <CACZGMxJJAkNMSysM0zpWekAx=tR0ESu4Uus=WEzb65_oag7PpA@mail.gmail.com>
 <CAAv6=UCNO407aUeLopF_fhzp+w1BEN3mATqVAewPD-ZZ4f5y2A@mail.gmail.com>
Message-ID: <CACZGMxKfG8P0be9bLXfiEnCSeedOCG1fwxKwf+W7ccJfuKcxeg@mail.gmail.com>

Hi,

Michael E Caloroso wrote:
> I have the 1983 and the 1988 edition of the MIDI spec.  Not
> downloaded, originals from the MMA.

Excellent!  I bought a copy of the 1996 edition of the standard, way
back when the only option was to phone up the MMA with a credit card
and swallow the international phone call and postage.  This is the
same edition as that now published on the MMA website.

Looking at the detailed specification, Hardware section, 4th paragraph
in its entirety states:
"The grounding shield connector on the MIDI jacks should not be
connected to any circuit or chassis ground."

The 2014 update to the electrical specification does consider the jack
shield connection, showing that for OUT/THRU connectors the shield can
be connected to chassis, but for IN the shield must, if connected, go
through a small capacitor (e.g., 100n) to improve EMI/EMC performance.
A direct connection is not permitted.

Neil
-- 
http://www.njohnson.co.uk


From indigoid at oldcorollas.org  Sat Dec 29 01:06:42 2018
From: indigoid at oldcorollas.org (john slee)
Date: Sat, 29 Dec 2018 11:06:42 +1100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
Message-ID: <CAK+JDy2n95vOM5PUP++z6aQqfTgNU++EBOFdKaDvSSF_m+kkPw@mail.gmail.com>

On Wed, 26 Dec 2018 at 06:52, cheater00 cheater00 <cheater00 at gmail.com>
wrote:
> Given that metal patch cables could function as antennas and cause
> both cross talk and external signal pick up, one could also use
> multimode glass fiber and transmit signals this way.

Multimode fibre has a lower bound on the cable length. I haven't found a
solid reference
for what that actually is, and I expect it differs across transceiver
parts, but I've found a
LOT of stories of people being unable to get short runs to work and the
solution being
longer fibres. One thread mentioned a Cisco recommendation of 2 metres ?
something
about needing a certain amount of attenuation to avoid damaging the
hardware at the
receive end ? which would be irritatingly long even in something the size
of Keith
Emerson's Moog

Also glass fibre patch leads are pretty fragile. If you were filling a 48U
rack with polysynth
modules and were only rarely going to change the patching it might be
feasible, I suppose,
but a traditional "electronics+keys" polysynth format is not going to work
well with fragile
2m patch cables dangling everywhere!

This thread reeks of https://en.wikipedia.org/wiki/XY_problem

John
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From 21pointy at tpg.com.au  Sat Dec 29 01:26:21 2018
From: 21pointy at tpg.com.au (Adam Inglis)
Date: Sat, 29 Dec 2018 10:26:21 +1000
Subject: [sdiy] clock pulse to vtrig
In-Reply-To: <678db06c-8163-4023-a4e6-6b1240b72e79@radioles.com>
References: <5068ebfe-7c4d-4bcb-a606-e61465a39eb9@radioles.com>
 <678db06c-8163-4023-a4e6-6b1240b72e79@radioles.com>
Message-ID: <C8800987-D0C5-4A5F-B274-CF5599CC2D77@tpg.com.au>

That?s a useful little circuit.
And I like Brian?s quick and dirty approach to modify it to specific needs.
I assume Joe is talking about adding an adjustable gate voltage - I think that would be a very useful addition here. Why wouldn?t adding a pot in there work?

Adam
> On 28 Dec 2018, at 1:21 AM, Joe Frey <frey at radioles.com> wrote:
> 
> Thanks for the help. I am wondering if I wanted to limit the output of the yusynth pulse delay to 5V would I make a voltage divider by adding a 5k resistor after R7 and change R8 to 5k from 10k?
> If I wanted to vary the gate size could I do the above and change R8 to a 5k pot?
> Please refer to
> http://www.yusynth.net/Modular/Commun/PULSEDELAY/pulsedelay-sch.gif <http://www.yusynth.net/Modular/Commun/PULSEDELAY/pulsedelay-sch.gif>
> 
> at
> 
> http://www.yusynth.net/Modular/EN/PULSEDELAY/index.html <http://www.yusynth.net/Modular/EN/PULSEDELAY/index.html>
> 
> Thanks. JoeF.
> 
> Sent from TypeApp <http://www.typeapp.com/r?b=14068>
> On Dec 17, 2018, at 2:03 PM, Joe Frey <frey at radioles.com <mailto:frey at radioles.com>> wrote:
> Hello all, this is a follow-up to an email from 2 weeks ago some may remember. Anyway, I am using a clock out from my EHX 8-step sequencer to trigger my Lyra-8. The Lyra-8 plays for as long as the clock pulse. I want to be able to create a longer and variable pulse using a circuit. I am not interested in tackling programming a microcontroller, yet.
> Can anyone point me in the direction of some circuitry that can do this? Thanks. JoeF.
> 
> Sent from TypeApp <http://www.typeapp.com/r?b=14068>
> 
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy <http://synth-diy.org/mailman/listinfo/synth-diy>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy

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From 21pointy at tpg.com.au  Sat Dec 29 01:30:33 2018
From: 21pointy at tpg.com.au (Adam Inglis)
Date: Sat, 29 Dec 2018 10:30:33 +1000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CAK+JDy2n95vOM5PUP++z6aQqfTgNU++EBOFdKaDvSSF_m+kkPw@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <CAK+JDy2n95vOM5PUP++z6aQqfTgNU++EBOFdKaDvSSF_m+kkPw@mail.gmail.com>
Message-ID: <17BEF3BA-7DD1-4798-9A4C-38AB3DA0748B@tpg.com.au>


> On 29 Dec 2018, at 10:06 AM, john slee <indigoid at oldcorollas.org> wrote:
> 
> This thread reeks of https://en.wikipedia.org/wiki/XY_problem <https://en.wikipedia.org/wiki/XY_problem>
Perhaps it is a post-post-post modern phenomenon. A world full of solutions looking for problems?

A
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From blincoln at eventualdecline.com  Sat Dec 29 01:46:02 2018
From: blincoln at eventualdecline.com (Ben Lincoln)
Date: Fri, 28 Dec 2018 16:46:02 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
 <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
Message-ID: <279BA7C0-F32E-4904-BB68-04BD45C1F993@eventualdecline.com>

Your original post included a suggestion of using fiber-optic connections, which - unless I'm greatly mistaken - inherently means converting between analogue and digital at every patch point.

I think you're getting the sort of responses you're getting because your overall goal is unclear. I.e. trying to somehow multiplex a bunch of analogue signals onto a single pair of wires is going to result in poor audio quality. If you're OK with reducing the quality, why aren't you OK with using digital connections, or doing the whole thing in software? If you're not OK with reducing the quality _and_ want to stay entirely analogue, you're basically stuck with two wires per signal. If you're just curious from a theoretical perspective of what's physically possible, why are you pricing out parts? Etc.

Someone else mentioned the "XY problem", and I tend to agree. You're asking for help with a very specific part of an overall approach that doesn't seem to be practical, so people are trying to guide you toward an overall approach that makes more sense based on what you've described so far.

Maybe it would make more sense, and maybe you'd get answers you were happier with, if you explicitly stated what you were hoping to end up with. A working analogue modular polysynth that you built yourself? A design to have someone else build? A theoretical design that you want to patent and hope to license? Etc. 


On 28 December 2018 14:17:59 GMT-08:00, cheater00 cheater00 <cheater00 at gmail.com> wrote:
>cat5 cables are pretty terrible for repatching, as are the jacks.
>
>In case someone wants to mention some other more or less obscure type
>of cable, PLEASE DON'T, I really considered them all.
>
>Can we please have the thread return to the original question, which is
>below:
>
>How to use multiple FM transmitter ICs to succesfully transmit
>multiple FM stations over a single copper cable? What are suitable ICs
>to use? Is there an inexpensive IC that will transmit multiple bands
>at once?
>
>Can we please NOT talk about whether this is feasible, provide good
>results, or be cheap. Can we please not talk about crossbar ICs,
>digital transmission, or multi-conductor cables. If you want, you can
>start your own thread, thanks. We've had those exact conversations on
>this mailing list a dozen times over the last 20 years at least,
>please look in the archives. There's absolutely nothing new to be said
>here.
>
>On Fri, Dec 28, 2018 at 7:48 AM john slee <indigoid at oldcorollas.org>
>wrote:
>>
>> Yup, done plenty of that. I'm not sure it's a good example to look at
>because datacentre cabling isn't designed with frequent repatching in
>mind. I've worked in places that had "patch once then throw it in the
>trash" policies for Cat5e/etc cables ? you don't have to waste many
>hours on troubleshooting problems that turn out to be caused by damaged
>cables before it's cheaper to operate that way. Wasteful, perhaps, but
>typical Cat5/etc cables, regardless of how much you pay for them,
>aren't really that resilient. Not good for modular patching.
>>
>> John
>>
>> On Fri, 28 Dec 2018 at 17:16, Joel B <onephatcat at earthlink.net>
>wrote:
>>>
>>> Weeeell... tangles happen if you allow them to - have you ever wired
>up an office building and server room with Ethernet? Lots and lots of
>cables in a very tiny area. Typically 32 cables per 1 rack unit high
>device...
>>>
>>> I?m not aware of a smaller form factor cable with equal or higher
>wire count, but perhaps one exists.
>>>
>>> Joel
>>>
>>>
>>>
>>>
>>>
>>> Sent from my iPhone
>>>
>>> On Dec 27, 2018, at 8:43 PM, john slee <indigoid at oldcorollas.org>
>wrote:
>>>
>>> In a large-format system, perhaps. Large tangles of Cat5 patch leads
>can be pretty inflexible and annoying to manage
>>>
>>> To the OP, I would ask: have you tried building something like what
>you want with pre-existing hardware or, possibly, with virtual
>hardware? eg. in Max? It would be unfortunate to go through all that
>analog hardware engineering pain (and it does sound like pain!) only to
>find that any or all of the below are true:
>>>
>>> - the result is musically uninteresting
>>> - you rarely or never go beyond patches that are essentially a
>fixed-architecture polysynth
>>> - the user interface required to manage it all is horrible
>>>
>>> It's a very hazy memory now but didn't Creamware/Sonic Core's DSP
>modular have polyphonic capability?
>>>
>>> John
>>>
>>> On Fri, 28 Dec 2018 at 15:18, Joel B <onephatcat at earthlink.net>
>wrote:
>>>>
>>>> Cat5 cable might be a nice small footprint way to send multiple
>signals from module to module with easy connect/disconnect-ability. 8
>wires per cable, nice little phone-jack...
>>>>
>>>> Joel
>>>>
>>>> Sent from my iPhone
>>>>
>>>> > On Dec 27, 2018, at 5:55 AM, Roman Sowa <modular at go2.pl> wrote:
>>>> >
>>>> > Frequency domain multiplexing was used long time ago in
>telephony.
>>>> > How nice and easy solution this was can be simply put in two
>questions:
>>>> > - why nobody remembers that?
>>>> > - why it was abandonned so quickly?
>>>> >
>>>> > I mean you have ready to use multichannel digital standards and
>multichannel ADc and DACs, why bother using an ancient idea that was so
>troublesome to manage that even 0.3-3.4kHz bandwith audio was a
>challenge.
>>>> > And if you want full analog, I'd go with multipin connectors,
>there are lots to choose from. OK expensive patch cable then, but still
>a tiny fraction of the price of any 16-voice module.
>>>> >
>>>> > Polysynths are hardwired for a reason.
>>>> >
>>>> > Roman
>>>> >
>>>> > W dniu 2018-12-25 o 20:49, cheater00 cheater00 pisze:
>>>> >> Hi everyone,
>>>> >> I was thinking again about how you could do a modular polysynth
>well,
>>>> >> and it occurred to me that you might be able to use frequency
>domain
>>>> >> multiplexing (FDM) to put several signals over a single
>conductor
>>>> >> pair. A quick search found the Si4710 which is a bit pricey at
>~$12 on
>>>> >> digikey but it's a tiny 3x3mm QFN device that performs complete
>FM
>>>> >> transmission. In a 16 voice system, at about 5 output functions
>per
>>>> >> module, and 12 modules, you can easily use up ~1000 of those,
>which
>>>> >> drops the price to $4. I was wondering what everyone thinks
>about this
>>>> >> sort of scheme.
>>>> >> Given that metal patch cables could function as antennas and
>cause
>>>> >> both cross talk and external signal pick up, one could also use
>>>> >> multimode glass fiber and transmit signals this way. The
>question is,
>>>> >> does anyone know whether support electronics could be found that
>are
>>>> >> integrated enough (small in footprint) and inexpensive? The idea
>would
>>>> >> be to build an electronics module that takes 16 analog audio
>channels
>>>> >> and outputs a signal that can be then converted to glass media
>>>> >> signalling.
>>>> >> Merry Christmas everyone!
>>>> >> _______________________________________________
>>>> >> Synth-diy mailing list
>>>> >> Synth-diy at synth-diy.org
>>>> >> http://synth-diy.org/mailman/listinfo/synth-diy
>>>> > _______________________________________________
>>>> > Synth-diy mailing list
>>>> > Synth-diy at synth-diy.org
>>>> > http://synth-diy.org/mailman/listinfo/synth-diy
>>>>
>>>>
>>>> _______________________________________________
>>>> Synth-diy mailing list
>>>> Synth-diy at synth-diy.org
>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>
>_______________________________________________
>Synth-diy mailing list
>Synth-diy at synth-diy.org
>http://synth-diy.org/mailman/listinfo/synth-diy
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From onephatcat at earthlink.net  Sat Dec 29 02:16:33 2018
From: onephatcat at earthlink.net (Joel B)
Date: Fri, 28 Dec 2018 17:16:33 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <279BA7C0-F32E-4904-BB68-04BD45C1F993@eventualdecline.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
 <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
 <279BA7C0-F32E-4904-BB68-04BD45C1F993@eventualdecline.com>
Message-ID: <959BE6ED-9BF4-4F6D-80F0-DE6058F9E4FF@earthlink.net>

Not sure why you couldn?t send analog signals via fiber - probably use the wave angle to multiplex over the same cable just like networking signals do, and convert the amplitude or frequency back to an electrical signal.

Joel

Sent from my iPhone 

> On Dec 28, 2018, at 4:46 PM, Ben Lincoln <blincoln at eventualdecline.com> wrote:
> 
> Your original post included a suggestion of using fiber-optic connections, which - unless I'm greatly mistaken - inherently means converting between analogue and digital at every patch point.
> 
> I think you're getting the sort of responses you're getting because your overall goal is unclear. I.e. trying to somehow multiplex a bunch of analogue signals onto a single pair of wires is going to result in poor audio quality. If you're OK with reducing the quality, why aren't you OK with using digital connections, or doing the whole thing in software? If you're not OK with reducing the quality _and_ want to stay entirely analogue, you're basically stuck with two wires per signal. If you're just curious from a theoretical perspective of what's physically possible, why are you pricing out parts? Etc.
> 
> Someone else mentioned the "XY problem", and I tend to agree. You're asking for help with a very specific part of an overall approach that doesn't seem to be practical, so people are trying to guide you toward an overall approach that makes more sense based on what you've described so far.
> 
> Maybe it would make more sense, and maybe you'd get answers you were happier with, if you explicitly stated what you were hoping to end up with. A working analogue modular polysynth that you built yourself? A design to have someone else build? A theoretical design that you want to patent and hope to license? Etc. 
> 
> 
>> On 28 December 2018 14:17:59 GMT-08:00, cheater00 cheater00 <cheater00 at gmail.com> wrote:
>> cat5 cables are pretty terrible for repatching, as are the jacks.
>> 
>> In case someone wants to mention some other more or less obscure type
>> of cable, PLEASE DON'T, I really considered them all.
>> 
>> Can we please have the thread return to the original question, which is below:
>> 
>> How to use multiple FM transmitter ICs to succesfully transmit
>> multiple FM stations over a single copper cable? What are suitable ICs
>> to use? Is there an inexpensive IC that will transmit multiple bands
>> at once?
>> 
>> Can we please NOT talk about whether this is feasible, provide good
>> results, or be cheap. Can we please not talk about crossbar ICs,
>> digital transmission, or multi-conductor cables. If you want, you can
>> start your own thread, thanks. We've had those exact conversations on
>> this mailing list a dozen times over the last 20 years at least,
>> please look in the archives. There's absolutely nothing new to be said
>> here.
>> 
>>> On Fri, Dec 28, 2018 at 7:48 AM john slee <indigoid at oldcorollas.org> wrote:
>>> >
>>>  Yup, done plenty of that. I'm not sure it's a good example to look at because datacentre cabling isn't designed with frequent repatching in mind. I've worked in places that had "patch once then throw it in the trash" policies for Cat5e/etc cables ? you don't have to waste many hours on troubleshooting problems that turn out to be caused by damaged cables before it's cheaper to operate that way. Wasteful, perhaps, but typical Cat5/etc cables, regardless of how much you pay for them, aren't really that resilient. Not good for modular patching.
>>> 
>>>  John
>>> 
>>>>  On Fri, 28 Dec 2018 at 17:16, Joel B <onephatcat at earthlink.net> wrote:
>>>>  Weeeell... tangles happen if you allow them to - have you ever wired up an office building and server room with Ethernet? Lots and lots of cables in a very tiny area. Typically 32 cables per 1 rack unit high device...
>>>> 
>>>>  I?m not aware of a smaller form factor cable with equal or higher wire count, but perhaps one exists.
>>>> 
>>>>  Joel
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>>  Sent from my iPhone
>>>> 
>>>>  On Dec 27, 2018, at 8:43 PM, john slee <indigoid at oldcorollas.org> wrote:
>>>> 
>>>>  In a large-format system, perhaps. Large tangles of Cat5 patch leads can be pretty inflexible and annoying to manage
>>>> 
>>>>  To the OP, I would ask: have you tried building something like what you want with pre-existing hardware or, possibly, with virtual hardware? eg. in Max? It would be unfortunate to go through all that analog hardware engineering pain (and it does sound like pain!) only to find that any or all of the below are true:
>>>> 
>>>>  - the result is musically uninteresting
>>>>  - you rarely or never go beyond patches that are essentially a fixed-architecture polysynth
>>>>  - the user interface required to manage it all is horrible
>>>> 
>>>>  It's a very hazy memory now but didn't Creamware/Sonic Core's DSP modular have polyphonic capability?
>>>> 
>>>>  John
>>>> 
>>>>>  On Fri, 28 Dec 2018 at 15:18, Joel B <onephatcat at earthlink.net> wrote:
>>>>>  Cat5 cable might be a nice small footprint way to send multiple signals from module to module with easy connect/disconnect-ability. 8 wires per cable, nice little phone-jack...
>>>>> 
>>>>>  Joel
>>>>> 
>>>>>  Sent from my iPhone
>>>>> 
>>>>>>  On Dec 27, 2018, at 5:55 AM, Roman Sowa <modular at go2.pl> wrote:
>>>>>> 
>>>>>>  Frequency domain multiplexing was used long time ago in telephony.
>>>>>>  How nice and easy solution this was can be simply put in two questions:
>>>>>>  - why nobody remembers that?
>>>>>>  - why it was abandonned so quickly?
>>>>>> 
>>>>>>  I mean you have ready to use multichannel digital standards and multichannel ADc and DACs, why bother using an ancient idea that was so troublesome to manage that even 0.3-3.4kHz bandwith audio was a challenge.
>>>>>>  And if you want full analog, I'd go with multipin connectors, there are lots to choose from. OK expensive patch cable then, but still a tiny fraction of the price of any 16-voice module.
>>>>>> 
>>>>>>  Polysynths are hardwired for a reason.
>>>>>> 
>>>>>>  Roman
>>>>>> 
>>>>>>  W dniu 2018-12-25 o 20:49, cheater00 cheater00 pisze:
>>>>>>> Hi everyone,
>>>>>>> I was thinking again about how you could do a modular polysynth well,
>>>>>>> and it occurred to me that you might be able to use frequency domain
>>>>>>> multiplexing (FDM) to put several signals over a single conductor
>>>>>>> pair. A quick search found the Si4710 which is a bit pricey at ~$12 on
>>>>>>> digikey but it's a tiny 3x3mm QFN device that performs complete FM
>>>>>>> transmission. In a 16 voice system, at about 5 output functions per
>>>>>>> module, and 12 modules, you can easily use up ~1000 of those, which
>>>>>>> drops the price to $4. I was wondering what everyone thinks about this
>>>>>>> sort of scheme.
>>>>>>> Given that metal patch cables could function as antennas and cause
>>>>>>> both cross talk and external signal pick up, one could also use
>>>>>>> multimode glass fiber and transmit signals this way. The question is,
>>>>>>> does anyone know whether support electronics could be found that are
>>>>>>> integrated enough (small in footprint) and inexpensive? The idea would
>>>>>>> be to build an electronics module that takes 16 analog audio channels
>>>>>>> and outputs a signal that can be then converted to glass media
>>>>>>> signalling.
>>>>>>> Merry Christmas everyone!
>>>>>>> Synth-diy mailing list
>>>>>>> Synth-diy at synth-diy.org
>>>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>>>> Synth-diy mailing list
>>>>>> Synth-diy at synth-diy.org
>>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>>>  Synth-diy mailing list
>>>>>  Synth-diy at synth-diy.org
>>>>>  http://synth-diy.org/mailman/listinfo/synth-diy
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
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From blincoln at eventualdecline.com  Sat Dec 29 02:51:04 2018
From: blincoln at eventualdecline.com (Ben Lincoln)
Date: Fri, 28 Dec 2018 17:51:04 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <959BE6ED-9BF4-4F6D-80F0-DE6058F9E4FF@earthlink.net>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
 <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
 <279BA7C0-F32E-4904-BB68-04BD45C1F993@eventualdecline.com>
 <959BE6ED-9BF4-4F6D-80F0-DE6058F9E4FF@earthlink.net>
Message-ID: <DE2BE875-560F-462B-9D48-56717E67CD2C@eventualdecline.com>

You could, but is there any hardware that does that, or would it involve designing and building  custom fiber-optic communication circuitry? 

Even if one did that, it seems like it would still involve appreciable losses bouncing between electrical analogue and optical analogue at every patch point, but that's not my area of expertise, so I could be wrong. 


On 28 December 2018 17:16:33 GMT-08:00, Joel B <onephatcat at earthlink.net> wrote:
>Not sure why you couldn?t send analog signals via fiber - probably use
>the wave angle to multiplex over the same cable just like networking
>signals do, and convert the amplitude or frequency back to an
>electrical signal.
>
>Joel
>
>Sent from my iPhone 
>
>> On Dec 28, 2018, at 4:46 PM, Ben Lincoln
><blincoln at eventualdecline.com> wrote:
>> 
>> Your original post included a suggestion of using fiber-optic
>connections, which - unless I'm greatly mistaken - inherently means
>converting between analogue and digital at every patch point.
>> 
>> I think you're getting the sort of responses you're getting because
>your overall goal is unclear. I.e. trying to somehow multiplex a bunch
>of analogue signals onto a single pair of wires is going to result in
>poor audio quality. If you're OK with reducing the quality, why aren't
>you OK with using digital connections, or doing the whole thing in
>software? If you're not OK with reducing the quality _and_ want to stay
>entirely analogue, you're basically stuck with two wires per signal. If
>you're just curious from a theoretical perspective of what's physically
>possible, why are you pricing out parts? Etc.
>> 
>> Someone else mentioned the "XY problem", and I tend to agree. You're
>asking for help with a very specific part of an overall approach that
>doesn't seem to be practical, so people are trying to guide you toward
>an overall approach that makes more sense based on what you've
>described so far.
>> 
>> Maybe it would make more sense, and maybe you'd get answers you were
>happier with, if you explicitly stated what you were hoping to end up
>with. A working analogue modular polysynth that you built yourself? A
>design to have someone else build? A theoretical design that you want
>to patent and hope to license? Etc. 
>> 
>> 
>>> On 28 December 2018 14:17:59 GMT-08:00, cheater00 cheater00
><cheater00 at gmail.com> wrote:
>>> cat5 cables are pretty terrible for repatching, as are the jacks.
>>> 
>>> In case someone wants to mention some other more or less obscure
>type
>>> of cable, PLEASE DON'T, I really considered them all.
>>> 
>>> Can we please have the thread return to the original question, which
>is below:
>>> 
>>> How to use multiple FM transmitter ICs to succesfully transmit
>>> multiple FM stations over a single copper cable? What are suitable
>ICs
>>> to use? Is there an inexpensive IC that will transmit multiple bands
>>> at once?
>>> 
>>> Can we please NOT talk about whether this is feasible, provide good
>>> results, or be cheap. Can we please not talk about crossbar ICs,
>>> digital transmission, or multi-conductor cables. If you want, you
>can
>>> start your own thread, thanks. We've had those exact conversations
>on
>>> this mailing list a dozen times over the last 20 years at least,
>>> please look in the archives. There's absolutely nothing new to be
>said
>>> here.
>>> 
>>>> On Fri, Dec 28, 2018 at 7:48 AM john slee
><indigoid at oldcorollas.org> wrote:
>>>> >
>>>>  Yup, done plenty of that. I'm not sure it's a good example to look
>at because datacentre cabling isn't designed with frequent repatching
>in mind. I've worked in places that had "patch once then throw it in
>the trash" policies for Cat5e/etc cables ? you don't have to waste many
>hours on troubleshooting problems that turn out to be caused by damaged
>cables before it's cheaper to operate that way. Wasteful, perhaps, but
>typical Cat5/etc cables, regardless of how much you pay for them,
>aren't really that resilient. Not good for modular patching.
>>>> 
>>>>  John
>>>> 
>>>>>  On Fri, 28 Dec 2018 at 17:16, Joel B <onephatcat at earthlink.net>
>wrote:
>>>>>  Weeeell... tangles happen if you allow them to - have you ever
>wired up an office building and server room with Ethernet? Lots and
>lots of cables in a very tiny area. Typically 32 cables per 1 rack unit
>high device...
>>>>> 
>>>>>  I?m not aware of a smaller form factor cable with equal or higher
>wire count, but perhaps one exists.
>>>>> 
>>>>>  Joel
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>>  Sent from my iPhone
>>>>> 
>>>>>  On Dec 27, 2018, at 8:43 PM, john slee <indigoid at oldcorollas.org>
>wrote:
>>>>> 
>>>>>  In a large-format system, perhaps. Large tangles of Cat5 patch
>leads can be pretty inflexible and annoying to manage
>>>>> 
>>>>>  To the OP, I would ask: have you tried building something like
>what you want with pre-existing hardware or, possibly, with virtual
>hardware? eg. in Max? It would be unfortunate to go through all that
>analog hardware engineering pain (and it does sound like pain!) only to
>find that any or all of the below are true:
>>>>> 
>>>>>  - the result is musically uninteresting
>>>>>  - you rarely or never go beyond patches that are essentially a
>fixed-architecture polysynth
>>>>>  - the user interface required to manage it all is horrible
>>>>> 
>>>>>  It's a very hazy memory now but didn't Creamware/Sonic Core's DSP
>modular have polyphonic capability?
>>>>> 
>>>>>  John
>>>>> 
>>>>>>  On Fri, 28 Dec 2018 at 15:18, Joel B <onephatcat at earthlink.net>
>wrote:
>>>>>>  Cat5 cable might be a nice small footprint way to send multiple
>signals from module to module with easy connect/disconnect-ability. 8
>wires per cable, nice little phone-jack...
>>>>>> 
>>>>>>  Joel
>>>>>> 
>>>>>>  Sent from my iPhone
>>>>>> 
>>>>>>>  On Dec 27, 2018, at 5:55 AM, Roman Sowa <modular at go2.pl> wrote:
>>>>>>> 
>>>>>>>  Frequency domain multiplexing was used long time ago in
>telephony.
>>>>>>>  How nice and easy solution this was can be simply put in two
>questions:
>>>>>>>  - why nobody remembers that?
>>>>>>>  - why it was abandonned so quickly?
>>>>>>> 
>>>>>>>  I mean you have ready to use multichannel digital standards and
>multichannel ADc and DACs, why bother using an ancient idea that was so
>troublesome to manage that even 0.3-3.4kHz bandwith audio was a
>challenge.
>>>>>>>  And if you want full analog, I'd go with multipin connectors,
>there are lots to choose from. OK expensive patch cable then, but still
>a tiny fraction of the price of any 16-voice module.
>>>>>>> 
>>>>>>>  Polysynths are hardwired for a reason.
>>>>>>> 
>>>>>>>  Roman
>>>>>>> 
>>>>>>>  W dniu 2018-12-25 o 20:49, cheater00 cheater00 pisze:
>>>>>>>> Hi everyone,
>>>>>>>> I was thinking again about how you could do a modular polysynth
>well,
>>>>>>>> and it occurred to me that you might be able to use frequency
>domain
>>>>>>>> multiplexing (FDM) to put several signals over a single
>conductor
>>>>>>>> pair. A quick search found the Si4710 which is a bit pricey at
>~$12 on
>>>>>>>> digikey but it's a tiny 3x3mm QFN device that performs complete
>FM
>>>>>>>> transmission. In a 16 voice system, at about 5 output functions
>per
>>>>>>>> module, and 12 modules, you can easily use up ~1000 of those,
>which
>>>>>>>> drops the price to $4. I was wondering what everyone thinks
>about this
>>>>>>>> sort of scheme.
>>>>>>>> Given that metal patch cables could function as antennas and
>cause
>>>>>>>> both cross talk and external signal pick up, one could also use
>>>>>>>> multimode glass fiber and transmit signals this way. The
>question is,
>>>>>>>> does anyone know whether support electronics could be found
>that are
>>>>>>>> integrated enough (small in footprint) and inexpensive? The
>idea would
>>>>>>>> be to build an electronics module that takes 16 analog audio
>channels
>>>>>>>> and outputs a signal that can be then converted to glass media
>>>>>>>> signalling.
>>>>>>>> Merry Christmas everyone!
>>>>>>>> Synth-diy mailing list
>>>>>>>> Synth-diy at synth-diy.org
>>>>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>>>>> Synth-diy mailing list
>>>>>>> Synth-diy at synth-diy.org
>>>>>>> http://synth-diy.org/mailman/listinfo/synth-diy
>>>>>>  Synth-diy mailing list
>>>>>>  Synth-diy at synth-diy.org
>>>>>>  http://synth-diy.org/mailman/listinfo/synth-diy
>>> Synth-diy mailing list
>>> Synth-diy at synth-diy.org
>>> http://synth-diy.org/mailman/listinfo/synth-diy
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
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From 21pointy at tpg.com.au  Sat Dec 29 02:54:27 2018
From: 21pointy at tpg.com.au (Adam Inglis)
Date: Sat, 29 Dec 2018 11:54:27 +1000
Subject: [sdiy] clock pulse to vtrig
In-Reply-To: <C8800987-D0C5-4A5F-B274-CF5599CC2D77@tpg.com.au>
References: <5068ebfe-7c4d-4bcb-a606-e61465a39eb9@radioles.com>
 <678db06c-8163-4023-a4e6-6b1240b72e79@radioles.com>
 <C8800987-D0C5-4A5F-B274-CF5599CC2D77@tpg.com.au>
Message-ID: <27664616-21F7-4F41-BBEF-20BEBE82A911@tpg.com.au>


> On 29 Dec 2018, at 10:26 AM, Adam Inglis <21pointy at tpg.com.au> wrote:
> 
> That?s a useful little circuit.
> And I like Brian?s quick and dirty approach to modify it to specific needs.
> I assume Joe is talking about adding an adjustable gate voltage - I think that would be a very useful addition here. Why wouldn?t adding a pot in there work?
> 
> Adam

Sorry, that should be ?pulse amplitude? not "gate voltage"








>> On 28 Dec 2018, at 1:21 AM, Joe Frey <frey at radioles.com <mailto:frey at radioles.com>> wrote:
>> 
>> Thanks for the help. I am wondering if I wanted to limit the output of the yusynth pulse delay to 5V would I make a voltage divider by adding a 5k resistor after R7 and change R8 to 5k from 10k?
>> If I wanted to vary the gate size could I do the above and change R8 to a 5k pot?
>> Please refer to
>> http://www.yusynth.net/Modular/Commun/PULSEDELAY/pulsedelay-sch.gif <http://www.yusynth.net/Modular/Commun/PULSEDELAY/pulsedelay-sch.gif>
>> 
>> at
>> 
>> http://www.yusynth.net/Modular/EN/PULSEDELAY/index.html <http://www.yusynth.net/Modular/EN/PULSEDELAY/index.html>
>> 
>> Thanks. JoeF.
>> 
>> Sent from TypeApp <http://www.typeapp.com/r?b=14068>
>> On Dec 17, 2018, at 2:03 PM, Joe Frey <frey at radioles.com <mailto:frey at radioles.com>> wrote:
>> Hello all, this is a follow-up to an email from 2 weeks ago some may remember. Anyway, I am using a clock out from my EHX 8-step sequencer to trigger my Lyra-8. The Lyra-8 plays for as long as the clock pulse. I want to be able to create a longer and variable pulse using a circuit. I am not interested in tackling programming a microcontroller, yet.
>> Can anyone point me in the direction of some circuitry that can do this? Thanks. JoeF.
>> 
>> Sent from TypeApp <http://www.typeapp.com/r?b=14068>
>> 
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
>> http://synth-diy.org/mailman/listinfo/synth-diy <http://synth-diy.org/mailman/listinfo/synth-diy>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org <mailto:Synth-diy at synth-diy.org>
>> http://synth-diy.org/mailman/listinfo/synth-diy
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy

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From rsdio at audiobanshee.com  Sat Dec 29 03:05:56 2018
From: rsdio at audiobanshee.com (rsdio at audiobanshee.com)
Date: Fri, 28 Dec 2018 18:05:56 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <DE2BE875-560F-462B-9D48-56717E67CD2C@eventualdecline.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
 <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
 <279BA7C0-F32E-4904-BB68-04BD45C1F993@eventualdecline.com>
 <959BE6ED-9BF4-4F6D-80F0-DE6058F9E4FF@earthlink.net>
 <DE2BE875-560F-462B-9D48-56717E67CD2C@eventualdecline.com>
Message-ID: <2D305CCC-5495-4CFC-A95C-89A28CE6E596@audiobanshee.com>

Fiber-optic cable will attenuate signals significantly in proportion to bending of the cable, among other causes. That?s why digital signals are used, since an attenuated ?1" is still distinct from a ?0.? This sort of thing doesn?t happen with copper cables.

I doubt that you could get analog signals to work properly over fiber without using frequency modulation to remove the amplitude sensitivity.


On Dec 28, 2018, at 5:51 PM, Ben Lincoln <blincoln at eventualdecline.com> wrote:
> You could, but is there any hardware that does that, or would it involve designing and building custom fiber-optic communication circuitry? 
> 
> Even if one did that, it seems like it would still involve appreciable losses bouncing between electrical analogue and optical analogue at every patch point, but that's not my area of expertise, so I could be wrong. 
> 
> On 28 December 2018 17:16:33 GMT-08:00, Joel B <onephatcat at earthlink.net> wrote:
>> Not sure why you couldn?t send analog signals via fiber - probably use the wave angle to multiplex over the same cable just like networking signals do, and convert the amplitude or frequency back to an electrical signal.
>> 
>> Joel
>> 
>> Sent from my iPhone 
>> 
>> On Dec 28, 2018, at 4:46 PM, Ben Lincoln <blincoln at eventualdecline.com> wrote:
>>> Your original post included a suggestion of using fiber-optic connections, which - unless I'm greatly mistaken - inherently means converting between analogue and digital at every patch point.
>>> 
>>> Maybe it would make more sense, and maybe you'd get answers you were happier with, if you explicitly stated what you were hoping to end up with. A working analogue modular polysynth that you built yourself? A design to have someone else build? A theoretical design that you want to patent and hope to license? Etc. 
>>> 
>>> 
>>> On 28 December 2018 14:17:59 GMT-08:00, cheater00 wrote:
>>>> In case someone wants to mention some other more or less obscure type
>>>> of cable, PLEASE DON'T, I really considered them all.

I?ve you?re already considered all of the options, why are you asking questions? It?s not very convincing when you claim to know everything about an aspect of the problem, but still need help.


>>>> Can we please have the thread return to the original question, which is below:
>>>> 
>>>> Can we please NOT talk about whether this is feasible, provide good
>>>> results, or be cheap. Can we please not talk about crossbar ICs,
>>>> digital transmission, or multi-conductor cables. If you want, you can
>>>> start your own thread, thanks. We've had those exact conversations on
>>>> this mailing list a dozen times over the last 20 years at least,
>>>> please look in the archives. There's absolutely nothing new to be said
>>>> here.
>>>> 
>>>>  W dniu 2018-12-25 o 20:49, cheater00 pisze:
>>>>> Given that metal patch cables could function as antennas and cause
>>>>> both cross talk and external signal pick up, one could also use
>>>>> multimode glass fiber and transmit signals this way. The question is,
>>>>> does anyone know whether support electronics could be found that are
>>>>> integrated enough (small in footprint) and inexpensive? The idea would
>>>>> be to build an electronics module that takes 16 analog audio channels
>>>>> and outputs a signal that can be then converted to glass media
>>>>> signalling.
>>>>> Merry Christmas everyone!



From sdiy-mz01 at blauwurf.info  Sat Dec 29 04:08:26 2018
From: sdiy-mz01 at blauwurf.info (Michael Zacherl)
Date: Sat, 29 Dec 2018 04:08:26 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CAK+JDy2n95vOM5PUP++z6aQqfTgNU++EBOFdKaDvSSF_m+kkPw@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <CAK+JDy2n95vOM5PUP++z6aQqfTgNU++EBOFdKaDvSSF_m+kkPw@mail.gmail.com>
Message-ID: <375D939F-CDF6-4E26-BB60-F2932E6CCB3D@blauwurf.info>


> On 29 Dec 2018, at 01:06, john slee <indigoid at oldcorollas.org> wrote:
> 
> Multimode fibre has a lower bound on the cable length. I haven't found a solid reference
> for what that actually is, and I expect it differs across transceiver parts, but I've found a
> LOT of stories of people being unable to get short runs to work and the solution being
> longer fibres. One thread mentioned a Cisco recommendation of 2 metres ? something
> about needing a certain amount of attenuation to avoid damaging the hardware at the
> receive end ? which would be irritatingly long even in something the size of Keith
> Emerson's Moog

[OT]
that?s entirely correct: the sensitivity of the receiver is designed to deal with a certain amount of light being received. Good multimode fibres have a typical attenuation of 0.5dB/km (@1310nm).
So the receiver?s just getting ?blinded? if you shorten the cable. 
And then you either still use patching fibres with attenuators or add separate attenuators (choose between 5dB and 15dB).
The shortest (networking!) patch cable I found in the catalogue here is 1m, BTW.
[/OT]
And that?s going to be expensive anyway.
Then again, it?s moot because either I don?t understand the idea or ?multimode? is just a misconception:
It?s still just one optical fibre with delicate joining technology involved, designed to carry digital signals.
And without appropriate back and forth conversion of the originally analogue signal for each and every connection?
(the rest has been said numerous times here, already)

> Also glass fibre patch leads are pretty fragile.






From dixon at mail.ubc.ca  Sat Dec 29 09:41:31 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Sat, 29 Dec 2018 00:41:31 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <20181228225945.GA20264@ilyushin>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
 <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
 <20181228225945.GA20264@ilyushin>
Message-ID: <FEA63EE7B8364520839BC54C8B899973@galvanox01>

> Analogue FDMA is not a thing.
> Gordonjcp

>From Wikipedia:

"FDMA can be used with both analog and digital signal but it generally used
with analog signal."

???

Is FDMA related to the thing that Hedy Lamarr invented?



From orenlevysticky at gmail.com  Sat Dec 29 10:25:24 2018
From: orenlevysticky at gmail.com (oren levy)
Date: Fri, 28 Dec 2018 23:25:24 -1000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <FEA63EE7B8364520839BC54C8B899973@galvanox01>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
 <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
 <20181228225945.GA20264@ilyushin>
 <FEA63EE7B8364520839BC54C8B899973@galvanox01>
Message-ID: <0AF47184-3DC8-49F6-87F7-D51BD8EB75EB@gmail.com>

Most of the possible solutions for passing the multiple channels of audio won?t pass DC. Do you need to route the control voltages or will the same voltage be used for each element in a module? You?d also need some protocol for handling your gates/triggers in a single cable. 

For the audio, you modulate the audio on a frequency, say 200k. You?d modulate all your audio on spaced out frequencies then modulate all those on a much higher frequency; 10s of MHz. On the other end, you?d demodulate twice to get the audio for each channel and pick up your audio again. 
If you do this, you could have the carrier frequencies shared across all the modules to keep everything tight. 
I think that?s how it works? 

Oren Levy

On Dec 28, 2018, at 22:41, David G Dixon <dixon at mail.ubc.ca> wrote:

>> Analogue FDMA is not a thing.
>> Gordonjcp
> 
> From Wikipedia:
> 
> "FDMA can be used with both analog and digital signal but it generally used
> with analog signal."
> 
> ???
> 
> Is FDMA related to the thing that Hedy Lamarr invented?
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From vladoman at gmail.com  Sat Dec 29 15:21:56 2018
From: vladoman at gmail.com (Vladimir Pantelic)
Date: Sat, 29 Dec 2018 15:21:56 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <FEA63EE7B8364520839BC54C8B899973@galvanox01>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
 <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
 <20181228225945.GA20264@ilyushin>
 <FEA63EE7B8364520839BC54C8B899973@galvanox01>
Message-ID: <59b3f7ae-2b1e-55d6-fc22-042f23e6f4e5@gmail.com>

Hedy Lamarr invented Spread Spectrum Technology which you can combine with FDMA 
but not necessarily. FDMA means that you divide your available spectrum / 
bandwidth into multiple "channels" and each participant gets assigned one 
channel to transmit data through.
spread spectrum means that you constantly (randomly) change the actual channel, 
initially in order to prevent somebody else to listen to your communication.



On 29/12/18 09:41, David G Dixon wrote:
>> Analogue FDMA is not a thing.
>> Gordonjcp
> 
>  From Wikipedia:
> 
> "FDMA can be used with both analog and digital signal but it generally used
> with analog signal."
> 
> ???
> 
> Is FDMA related to the thing that Hedy Lamarr invented?
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> 



From igg.debus at gmail.com  Sat Dec 29 16:00:00 2018
From: igg.debus at gmail.com (Ingo Debus)
Date: Sat, 29 Dec 2018 16:00:00 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <279BA7C0-F32E-4904-BB68-04BD45C1F993@eventualdecline.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
 <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
 <279BA7C0-F32E-4904-BB68-04BD45C1F993@eventualdecline.com>
Message-ID: <F5177EF4-351F-4ABA-B961-343632EF1045@gmail.com>


> Am 29.12.2018 um 01:46 schrieb Ben Lincoln <blincoln at eventualdecline.com>:
> 
> trying to somehow multiplex a bunch of analogue signals onto a single pair of wires is going to result in poor audio quality.

Not necessarily. As someone said, FM radio has decent audio quality. But we?re talking carrier frequencies in the range of 100 MHz here. At these frequencies we don?t even need wires at all :-)
Receiver chips can?t be that expensive either. FM radios are dirt cheap these days. A quick search turned up the Sanyo LA1260 for instance.

I think this all is just a thought experiment. But an interesting one :-)

Ingo


From mskala at ansuz.sooke.bc.ca  Sat Dec 29 16:12:22 2018
From: mskala at ansuz.sooke.bc.ca (mskala at ansuz.sooke.bc.ca)
Date: Sat, 29 Dec 2018 10:12:22 -0500 (EST)
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <F5177EF4-351F-4ABA-B961-343632EF1045@gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
 <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
 <279BA7C0-F32E-4904-BB68-04BD45C1F993@eventualdecline.com>
 <F5177EF4-351F-4ABA-B961-343632EF1045@gmail.com>
Message-ID: <alpine.LNX.2.20.1812291006520.26135@localhost.localdomain>

On Sat, 29 Dec 2018, Ingo Debus wrote:
> > Am 29.12.2018 um 01:46 schrieb Ben Lincoln <blincoln at eventualdecline.com>:
> > trying to somehow multiplex a bunch of analogue signals onto a single pair of wires is going to result in poor audio quality.
>
> Not necessarily. As someone said, FM radio has decent audio quality. But we?re talking carrier frequencies in the range of 100 MHz here. At these frequencies we don?t even need wires at all :-)
> Receiver chips can?t be that expensive either. FM radios are dirt cheap these days. A quick search turned up the Sanyo LA1260 for instance.

Still looking at using thousands of transistors to multiplex and
demultiplex the signals for each hundred-transistor analog module.  It's a
ridiculous way to do things, artificially created by the original poster's
insistence on forbidding better classes of solution (and on not specifying
what problem is being solved).

If cheater00 has the digitalitis so bad, it would be more interesting to
build a non-computerized telephone exchange and route signals through that
instead of messing around with multiplexed patch cables.

-- 
Matthew Skala
mskala at ansuz.sooke.bc.ca                 People before tribes.
http://ansuz.sooke.bc.ca/


From rburnett at richieburnett.co.uk  Sat Dec 29 16:17:23 2018
From: rburnett at richieburnett.co.uk (Richie Burnett)
Date: Sat, 29 Dec 2018 15:17:23 -0000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <59b3f7ae-2b1e-55d6-fc22-042f23e6f4e5@gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
 <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
 <20181228225945.GA20264@ilyushin>
 <FEA63EE7B8364520839BC54C8B899973@galvanox01>
 <59b3f7ae-2b1e-55d6-fc22-042f23e6f4e5@gmail.com>
Message-ID: <3E8D2B47863D4A80A692AB830D0B9941@RICHIEPC>

Cheater, if I was doing this, I would be looking at 
Time-Division-Multiplexing rather than FDM.  (Yes you can pick up many 
different STEREO! FM radio stations on your radio, but these are generated 
by thousands of pounds worth of technology to achieve broadcast audio 
quality and ensure that they don't interfere with each other.  An "audio 
sender" FM transmitter chip is not going to get you anywhere near broadcast 
quality in terms of THD, noise, interference, etc.  And "FM broadcast 
quality" isn't actually THAT good by modern standards at all.)

*In my opinion* TDM would be much less hassle.

So if you want to send a sawtooth oscillator output for 8 voices down one 
patch cable I would time-division-multiplex them on to one cable, and then 
use sample-and-hold circuits at the receiving end to split the signals apart 
again.  Think how drum machines and early digital synths used to put more 
than one audio signal or control signal through a single decent-spec DAC 
because the cost of multiple DACs would have been prohibitive.

For synchronisation, you could have a global synchronisation pulse at the 
start of each frame, that every module gets fed from a backplane.  Or 
alternatively, you could embed synchronisation pulses into the TDM stream.

-Richie, 



From rburnett at richieburnett.co.uk  Sat Dec 29 16:22:30 2018
From: rburnett at richieburnett.co.uk (Richie Burnett)
Date: Sat, 29 Dec 2018 15:22:30 -0000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <F5177EF4-351F-4ABA-B961-343632EF1045@gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
 <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
 <279BA7C0-F32E-4904-BB68-04BD45C1F993@eventualdecline.com>
 <F5177EF4-351F-4ABA-B961-343632EF1045@gmail.com>
Message-ID: <7B2C4F0850CF448C8A87143307411FB0@RICHIEPC>

> Not necessarily. As someone said, FM radio has decent audio quality...

It's reasonable.  Not great THD, SNR and Dynamic Range by today's standards 
though.  And there is literally a shit ton of processing applied to audio 
before it's broadcast on modern FM transmitters, in order to get it to sound 
decent and minimise noise/interference to neighbouring channels, etc.

Don't think that you are going to get near to broadcast quality audio with 
an "audio-sender" FM-transmitter in a chip!

-Richie, 



From gordonjcp at gjcp.net  Sun Dec 30 12:50:02 2018
From: gordonjcp at gjcp.net (Gordonjcp)
Date: Sun, 30 Dec 2018 11:50:02 +0000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
Message-ID: <20181230115002.GA30783@ilyushin>

On Tue, Dec 25, 2018 at 11:40:24PM +0100, cheater00 cheater00 wrote:
> I want to make this work for an all-analog synthesizer, but rather

Can you show an example of an all-analogue polyphonic synthesizer?
Like, no digital control at all?

-- 
Gordonjcp



From modular at go2.pl  Sun Dec 30 13:44:53 2018
From: modular at go2.pl (Roman)
Date: Sun, 30 Dec 2018 13:44:53 +0100
Subject: [sdiy]
 =?utf-8?q?Patchable_polyphonic_synth_with_FM_or_AM_transm?=
 =?utf-8?q?ission_idea?=
In-Reply-To: <<CA+9GZUjC6+6sqMjjVoxdqEjFoV0yABYifiAWW769WN+9MnF+2Q@mail.gmail.com>>
References: <ca+9gzugirfkgsvyphe8olmz=3moyk3n1njxr1czut9va5fx+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <CA+9GZUjC6+6sqMjjVoxdqEjFoV0yABYifiAWW769WN+9MnF+2Q@mail.gmail.com>
Message-ID: <6f0815a46fbc4bd597c0a91d88c27f16@grupawp.pl>

Telephony was only one real-life example of this technology being used. BTW, it was AM. Or SSB to be precise.  You talk FM broadcast. Well, as many has pointed already, what you hear on the radio is not $12 sinfgle chip, but a ton of advanced digital stuff on both ends. And besides, analog FM radio is fading out already, as digital broadcast is taking over because you can squeeze more channels in the same area with less cost and higher audio quality.  One may say there are FM radio transmitters and receivers available on Ali for $2 (just guessing price range). But do they provide quality expected in a modular? And is it possible to combine at least 2 of them on the same medium, even if they alow to be trimmed 1MHz apart?   You wanted multichannel FM over regular $0.10 patchcord - do it. You asked for solutions, instead got a bunch of voices saying it&#39;s a wrong way. Too bad. Do your own R&amp;D and proove us wrong. Then patent it and get rich.   One more thought about optical fibre: how about using wavelength multiplication over single fiber? You can modulate each light source separately then mix them in optical mixer to put in one singlemode fiber, then split at the receiver so each wavelenght is output to its own receiver like if it was on separate fiber. The trouble is, equipment to do this is at the price range of big vintage modular. At least it was 10 years ago. And yes, all high thruput transmission in optical fiber IS analog. I mean modern stuff, not ancient RZ/NRZ.   Roman   Dnia 28 grudnia 2018 23:10 cheater00 cheater00 &lt;cheater00 at gmail.com&gt; napisa?(a):  I don&#39;t know Roman, I can receive more than 16 FM stations over the  air and they&#39;re all pretty listenable and have more than 3.4 kHz  bandwidth.   On Thu, Dec 27, 2018 at 2:55 PM Roman Sowa &lt;modular at go2.pl&gt; wrote:   Frequency domain multiplexing was used long time ago in telephony.  How nice and easy solution this was can be simply put in two questions:  - why nobody remembers that?  - why it was abandonned so quickly?   I mean you have ready to use multichannel digital standards and  multichannel ADc and DACs, why bother using an ancient idea that was so  troublesome to manage that even 0.3-3.4kHz bandwith audio was a challenge.  And if you want full analog, I&#39;d go with multipin connectors, there are  lots to choose from. OK expensive patch cable then, but still a tiny  fraction of the price of any 16-voice module.   Polysynths are hardwired for a reason.   Roman
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From modular at go2.pl  Sun Dec 30 13:59:23 2018
From: modular at go2.pl (Roman)
Date: Sun, 30 Dec 2018 13:59:23 +0100
Subject: [sdiy]
 =?utf-8?q?Patchable_polyphonic_synth_with_FM_or_AM_transm?=
 =?utf-8?q?ission_idea?=
In-Reply-To: <<959BE6ED-9BF4-4F6D-80F0-DE6058F9E4FF@earthlink.net>>
References: <ca+9gzugirfkgsvyphe8olmz=3moyk3n1njxr1czut9va5fx+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <bc319314-deea-47d6-b81a-8ba9b70b8baa@earthlink.net>
 <cak+jdy1mb9amcvnpd-yelfgzpzwr1joozas_qalvzkfbeuu-xq@mail.gmail.com>
 <e6daf410-f23d-4288-b77a-0e8bd5574dfb@earthlink.net>
 <cak+jdy0plp_8qaiaexyauv5x_pjd7chiy0be_sdqrw95guflca@mail.gmail.com>
 <ca+9gzuitey7gfxp0rhd2ws-=6nrw8q_vignysv2tebopvrkvla@mail.gmail.com>
 <279ba7c0-f32e-4904-bb68-04bd45c1f993@eventualdecline.com>
 <959BE6ED-9BF4-4F6D-80F0-DE6058F9E4FF@earthlink.net>
Message-ID: <02f777fd94cd46a8a5843a452546c230@grupawp.pl>

Oh yes, you could. For example widely used QAM256 modulation is actually analog signal that is transmitted over fiber.  Someone said that bending fiber brings a lot of attenuation. Yes, if you bend it around your finger, which is not the typical angle of laying out fiber patchcords.  Nevertheless, because of the price point, we&#39;re limited here at synth-DIY to the optical components used in S/PDIF and they are digital only.   Roman   Dnia 29 grudnia 2018 02:21 Joel B &lt;  onephatcat at earthlink.net &gt; napisa?(a):  Not sure why you couldn?t send analog signals via fiber - probably use the wave angle to multiplex over the same cable just like networking signals do, and convert the amplitude or frequency back to an electrical signal.   Joel   Sent from my iPhone
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From sdiy-mz01 at blauwurf.info  Sun Dec 30 16:27:27 2018
From: sdiy-mz01 at blauwurf.info (Michael Zacherl)
Date: Sun, 30 Dec 2018 16:27:27 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <3E8D2B47863D4A80A692AB830D0B9941@RICHIEPC>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
 <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
 <20181228225945.GA20264@ilyushin>
 <FEA63EE7B8364520839BC54C8B899973@galvanox01>
 <59b3f7ae-2b1e-55d6-fc22-042f23e6f4e5@gmail.com>
 <3E8D2B47863D4A80A692AB830D0B9941@RICHIEPC>
Message-ID: <B195C0D3-51B1-4E20-B00C-AA887B66CA5D@blauwurf.info>


> On 29 Dec 2018, at 16:17, Richie Burnett <rburnett at richieburnett.co.uk> wrote:
> 
> *In my opinion* TDM would be much less hassle.
> 
> So if you want to send a sawtooth oscillator output for 8 voices down one patch cable I would time-division-multiplex them on to one cable, and then use sample-and-hold circuits at the receiving end to split the signals apart again.

So, there?s no A/D-D/A involved but everything else including S&Hs and filters on both sides.

IMHO still the cheapest and least challenging way. 
Then again, with, say, two to twelve jacks on each module still quite some extra hardware!

m.


From sdiy-mz01 at blauwurf.info  Sun Dec 30 17:29:49 2018
From: sdiy-mz01 at blauwurf.info (Michael Zacherl)
Date: Sun, 30 Dec 2018 17:29:49 +0100
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <6f0815a46fbc4bd597c0a91d88c27f16@grupawp.pl>
References: <ca+9gzugirfkgsvyphe8olmz=3moyk3n1njxr1czut9va5fx+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <CA+9GZUjC6+6sqMjjVoxdqEjFoV0yABYifiAWW769WN+9MnF+2Q@mail.gmail.com>
 <6f0815a46fbc4bd597c0a91d88c27f16@grupawp.pl>
Message-ID: <A9BC53CF-B8CD-483B-A836-32D992A8012D@blauwurf.info>


> On 30 Dec 2018, at 13:44, Roman <modular at go2.pl> wrote:
> 
> One more thought about optical fibre: how about using wavelength multiplication over single fiber? You can modulate each light source separately then mix them in optical mixer to put in one singlemode fiber, then split at the receiver so each wavelenght is output to its own receiver like if it was on separate fiber. The trouble is, equipment to do this is at the price range of big vintage modular. At least it was 10 years ago. And yes, all high thruput transmission in optical fiber IS analog. I mean modern stuff, not ancient RZ/NRZ.

LOL, now you?re getting really ambitious, Roman! :)
WDM systems are really big, and .. well, and I?d rather buy a couple of new-old Moog 55s and hire somebody to patch them up polyphonically for me instead and there?s still some money left, I?d say. ;)
(not saying that I?d prefer the Moogs, that?s just to give a sense of the money involved)

Did the original poster specify the format he?d like to have his creation built? Hopefully not Euro in a skiff?  ;)
m.




From oakleysound at btinternet.com  Sun Dec 30 19:45:49 2018
From: oakleysound at btinternet.com (Tony Allgood)
Date: Sun, 30 Dec 2018 18:45:49 +0000 (GMT)
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <20181230115002.GA30783@ilyushin>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
 <20181230115002.GA30783@ilyushin>
Message-ID: <23640203.20038.1546195549325.JavaMail.defaultUser@defaultHost>

> Can you show an example of an all-analogue polyphonic synthesizer? 
> Like, no digital control at all? 
Korg PS-3100, PE-2000, PE-1000
:-)
Tony
www.oakleysound.com 
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From dlmanley at sonic.net  Sun Dec 30 20:34:16 2018
From: dlmanley at sonic.net (Dave)
Date: Sun, 30 Dec 2018 11:34:16 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <2D305CCC-5495-4CFC-A95C-89A28CE6E596@audiobanshee.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <BC319314-DEEA-47D6-B81A-8BA9B70B8BAA@earthlink.net>
 <CAK+JDy1mb9AmcvNPD-YELFgzpZWR1JOozas_qALVzKFBEuU-XQ@mail.gmail.com>
 <E6DAF410-F23D-4288-B77A-0E8BD5574DFB@earthlink.net>
 <CAK+JDy0pLP_8QAiAexYauV5X_pjD7chiY0bE_SDqrW95gUfLcA@mail.gmail.com>
 <CA+9GZUiteY7gfxP0rHd2wS-=6nRw8q_vigNySv2tEBoPVrkvLA@mail.gmail.com>
 <279BA7C0-F32E-4904-BB68-04BD45C1F993@eventualdecline.com>
 <959BE6ED-9BF4-4F6D-80F0-DE6058F9E4FF@earthlink.net>
 <DE2BE875-560F-462B-9D48-56717E67CD2C@eventualdecline.com>
 <2D305CCC-5495-4CFC-A95C-89A28CE6E596@audiobanshee.com>
Message-ID: <DC2C0C57-0C92-49B7-8F64-1C4389CB89AB@sonic.net>



On December 28, 2018 6:05:56 PM PST, rsdio at audiobanshee.com wrote:
>I doubt that you could get analog signals to work properly over fiber
>without using frequency modulation to remove the amplitude sensitivity.

Old school analog cable TV modulates hundreds of analog RF channels for transmission over coax.  Today, single mode digital fiber is often used for delivery of digital bandwidth to homes (FTTH, GPON, EPON, etc) at distances reaching 10 to 40 kft.  In some networks they overlay the analog RF on the same fiber with the digital so everything is done over fiber, getting rid of the copper.   This technology is called RFoG, or RF over  Glass. This is done because it is a cheap way to transport the broadcast channels, leaving the digital bw for voice, data,  and video on demand. 

So yes, analog is transmitted over fiber. 

The head-end equipment is not cheap, but it is shared across 100s of houses and they're paying $$ per month for the service so there is a viable business model in urban areas. 

Not that any of this makes any senses for a synth. 

These same telecom markets are also looking at WDM, for use in distributing multiple 10Gbps streams over different lambdas (XGPON).  The optic transceivers required are expensive and only make sense when amortized across hundred of homes over years of payments. 

FDM was used for multiplexing 24, 48, 96, etc+ telephone channels over long-distance microwave links (some of this may still be deployed,  haven't looked at this in years).

Perhaps you could look at PAM. Older telephone switches would use this on the backplane to route between line cards in the pre-PCM/TDM days when ADC/DAC was expensive. 

-Dave



From gordonjcp at gjcp.net  Sun Dec 30 23:50:45 2018
From: gordonjcp at gjcp.net (Gordonjcp)
Date: Sun, 30 Dec 2018 22:50:45 +0000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <23640203.20038.1546195549325.JavaMail.defaultUser@defaultHost>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
 <20181230115002.GA30783@ilyushin>
 <23640203.20038.1546195549325.JavaMail.defaultUser@defaultHost>
Message-ID: <20181230225045.GA1172@ilyushin>

On Sun, Dec 30, 2018 at 06:45:49PM +0000, Tony Allgood wrote:
> > Can you show an example of an all-analogue polyphonic synthesizer? 
> > Like, no digital control at all? 
> Korg PS-3100, PE-2000, PE-1000
> :-)
> Tony

Synthesizers, not divider organs... ;-)

-- 
Gordonjcp



From richard at wentk.com  Mon Dec 31 00:23:12 2018
From: richard at wentk.com (Richard Wentk)
Date: Sun, 30 Dec 2018 23:23:12 +0000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <02f777fd94cd46a8a5843a452546c230@grupawp.pl>
References: <ca+9gzugirfkgsvyphe8olmz=3moyk3n1njxr1czut9va5fx+zg@mail.gmail.com>
 <517a6723-806c-7523-11cf-b8d458751b25@go2.pl>
 <bc319314-deea-47d6-b81a-8ba9b70b8baa@earthlink.net>
 <cak+jdy1mb9amcvnpd-yelfgzpzwr1joozas_qalvzkfbeuu-xq@mail.gmail.com>
 <e6daf410-f23d-4288-b77a-0e8bd5574dfb@earthlink.net>
 <cak+jdy0plp_8qaiaexyauv5x_pjd7chiy0be_sdqrw95guflca@mail.gmail.com>
 <ca+9gzuitey7gfxp0rhd2ws-=6nrw8q_vignysv2tebopvrkvla@mail.gmail.com>
 <279ba7c0-f32e-4904-bb68-04bd45c1f993@eventualdecline.com>
 <959BE6ED-9BF4-4F6D-80F0-DE6058F9E4FF@earthlink.net>
 <02f777fd94cd46a8a5843a452546c230@grupawp.pl>
Message-ID: <9C899B7B-3819-49E9-9549-FB2F7A09A036@wentk.com>

Might need something more advanced.

https://en.m.wikipedia.org/wiki/Orbital_angular_momentum_of_light

But TBH, IMO a patchable poly is a dumb idea anyway...

Richard

> On 30 Dec 2018, at 12:59, Roman <modular at go2.pl> wrote:
> 
> Oh yes, you could. For example widely used QAM256 modulation is actually analog signal that is transmitted over fiber.
> Someone said that bending fiber brings a lot of attenuation. Yes, if you bend it around your finger, which is not the typical angle of laying out fiber patchcords.
> Nevertheless, because of the price point, we're limited here at synth-DIY to the optical components used in S/PDIF and they are digital only.
> 
> Roman
> 
> Dnia 29 grudnia 2018 02:21 Joel B <onephatcat at earthlink.net> napisa?(a):
> 
> Not sure why you couldn?t send analog signals via fiber - probably use the wave angle to multiplex over the same cable just like networking signals do, and convert the amplitude or frequency back to an electrical signal.
> 
> Joel
> 
> Sent from my iPhone 
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
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From rsdio at audiobanshee.com  Mon Dec 31 00:59:04 2018
From: rsdio at audiobanshee.com (rsdio at audiobanshee.com)
Date: Sun, 30 Dec 2018 15:59:04 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <20181230115002.GA30783@ilyushin>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
 <20181230115002.GA30783@ilyushin>
Message-ID: <672DFB04-49B9-4E47-988C-C900FEB65174@audiobanshee.com>


On Dec 30, 2018, at 3:50 AM, Gordonjcp wrote:
> On Tue, Dec 25, 2018 at 11:40:24PM +0100, cheater00 wrote:
>> I want to make this work for an all-analog synthesizer, but rather
> 
> Can you show an example of an all-analogue polyphonic synthesizer?
> Like, no digital control at all?

Technically, Gate is a digital signal. There are no all-analog synthesizers.

Brian Willoughby



From dixon at mail.ubc.ca  Mon Dec 31 02:55:30 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Sun, 30 Dec 2018 17:55:30 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <20181230115002.GA30783@ilyushin>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
 <20181230115002.GA30783@ilyushin>
Message-ID: <D8B1A110E257459180CA93E5041BBBF4@galvanox01>

Korg PS3100 

> -----Original Message-----
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On 
> Behalf Of Gordonjcp
> Sent: Sunday, December 30, 2018 3:50 AM
> To: synth-diy at synth-diy.org
> Subject: Re: [sdiy] Patchable polyphonic synth with FM or AM 
> transmission idea
> 
> On Tue, Dec 25, 2018 at 11:40:24PM +0100, cheater00 cheater00 wrote:
> > I want to make this work for an all-analog synthesizer, but rather
> 
> Can you show an example of an all-analogue polyphonic synthesizer?
> Like, no digital control at all?
> 
> --
> Gordonjcp
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From dixon at mail.ubc.ca  Mon Dec 31 03:11:14 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Sun, 30 Dec 2018 18:11:14 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <672DFB04-49B9-4E47-988C-C900FEB65174@audiobanshee.com>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
 <20181230115002.GA30783@ilyushin>
 <672DFB04-49B9-4E47-988C-C900FEB65174@audiobanshee.com>
Message-ID: <42E03BF8EA2C4EDC9F50696832E69646@galvanox01>

That's ridiculous.  By that standard, every electronic (or just electric)
device with an On-Off switch is digital.

> -----Original Message-----
> From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On 
> Behalf Of rsdio at audiobanshee.com
> Sent: Sunday, December 30, 2018 3:59 PM
> To: Gordonjcp
> Cc: synth-diy at synth-diy.org
> Subject: Re: [sdiy] Patchable polyphonic synth with FM or AM 
> transmission idea
> 
> 
> On Dec 30, 2018, at 3:50 AM, Gordonjcp wrote:
> > On Tue, Dec 25, 2018 at 11:40:24PM +0100, cheater00 wrote:
> >> I want to make this work for an all-analog synthesizer, but rather
> > 
> > Can you show an example of an all-analogue polyphonic synthesizer?
> > Like, no digital control at all?
> 
> Technically, Gate is a digital signal. There are no 
> all-analog synthesizers.
> 
> Brian Willoughby
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From tim.parkhurst at gmail.com  Mon Dec 31 03:53:56 2018
From: tim.parkhurst at gmail.com (Tim Parkhurst)
Date: Sun, 30 Dec 2018 18:53:56 -0800
Subject: [sdiy] Why do LCDs die?
Message-ID: <CACDGQT89j7B798bE3SprSORT6ZOrwVk+4rWA+JWc1QRQY=x3eQ@mail.gmail.com>

So, I have an old Roland U-220 that I haven't used in a few years, but I
keep it around because I do love the piano and string samples. The fretless
bass and the drums are pretty good too. Also, I'd be lucky to get $50 for
it these days. Long story short, I turned it on the other day and the LCD
was barely visible, getting dimmer to the point after a few hours where it
is completely unreadable. The backlight is okay, but the digits themselves
can't be seen. I see there are replacements on the market, so I should be
able to resurrect it, but this begs my original point:

What causes LCDs to die in the first place? Are the crystals themselves
unstable? Is it the high-frequency excitation required that causes an
eventual breakdown? Or is it mechanical, with small connections or wire
bonds breaking down with time? Do we replace them because they are
unrepairable, or is it simply a matter of replacement being quicker and
cheaper than repair? Is there an internal adjustment to crank up the
contrast on this old beast (can't change the contrast from the front panel
settings since I can't see the display to navigate)?

Awaiting the collective enlightenment from the SDIY hive mind...

Tim (do Borgs get hive mind hives?) Servo
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From weplar at gmail.com  Mon Dec 31 04:34:07 2018
From: weplar at gmail.com (Tony K)
Date: Sun, 30 Dec 2018 22:34:07 -0500
Subject: [sdiy] Why do LCDs die?
In-Reply-To: <CACDGQT89j7B798bE3SprSORT6ZOrwVk+4rWA+JWc1QRQY=x3eQ@mail.gmail.com>
References: <CACDGQT89j7B798bE3SprSORT6ZOrwVk+4rWA+JWc1QRQY=x3eQ@mail.gmail.com>
Message-ID: <73283994-C665-4C31-B8B2-AF9E619F097F@gmail.com>

Hi Tim, I can't answer your question as to why lcds die, as you put it, but I have several older units that are getting harder to read, such as the Lexicon MRC, and Korg Wavestation A/D rack( now sold partly for aformentioned display issues) . I have a contrast control on the former unit but at some point ai will have to switch to a modern OLED? , or VFD ( Noritake , old school solution) . 

I think MTG has something about it on his site , at least the MRC.  I have been putting this off. Come to think of it the Novation X-Station contrast is getting weaker as time goes on, but that one is meant to be on all yhe time - I use it as my audio interface. So it's a safe bet to say these displays do have a MTBF. The old Hitachi 16x2 is not a problem to get lcd replacements ( ie MMT-8 etc.) I know Noritake VFDa make drop in replacements for those, or used to anyway. But then there is the high voltage filament voltage to worry about and the fragility.

Anyway I love those VFD's on the Xpander. 

Tony K

> On Dec 30, 2018, at 9:53 PM, Tim Parkhurst <tim.parkhurst at gmail.com> wrote:
> 
> So, I have an old Roland U-220 that I haven't used in a few years, but I keep it around because I do love the piano and string samples. The fretless bass and the drums are pretty good too. Also, I'd be lucky to get $50 for it these days. Long story short, I turned it on the other day and the LCD was barely visible, getting dimmer to the point after a few hours where it is completely unreadable. The backlight is okay, but the digits themselves can't be seen. I see there are replacements on the market, so I should be able to resurrect it, but this begs my original point: 
> 
> What causes LCDs to die in the first place? Are the crystals themselves unstable? Is it the high-frequency excitation required that causes an eventual breakdown? Or is it mechanical, with small connections or wire bonds breaking down with time? Do we replace them because they are unrepairable, or is it simply a matter of replacement being quicker and cheaper than repair? Is there an internal adjustment to crank up the contrast on this old beast (can't change the contrast from the front panel settings since I can't see the display to navigate)?
> 
> Awaiting the collective enlightenment from the SDIY hive mind...
> 
> Tim (do Borgs get hive mind hives?) Servo
> 
> 
> 
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy



From grant at musictechnologiesgroup.com  Mon Dec 31 05:17:20 2018
From: grant at musictechnologiesgroup.com (MTG)
Date: Sun, 30 Dec 2018 20:17:20 -0800
Subject: [sdiy] Why do LCDs die?
In-Reply-To: <73283994-C665-4C31-B8B2-AF9E619F097F@gmail.com>
References: <CACDGQT89j7B798bE3SprSORT6ZOrwVk+4rWA+JWc1QRQY=x3eQ@mail.gmail.com>
 <73283994-C665-4C31-B8B2-AF9E619F097F@gmail.com>
Message-ID: <253af55d-2ef7-3f3c-4e83-0ed34f82c089@musictechnologiesgroup.com>

To the OP, probably all of the above as being reasons for failure.

A lot of the Z80 machines really push the timing to memory map those 
LCDs. I don't know what it is exactly since I've never really studied 
the Z80. There is one guy doing a bunch of Z80 upgrade work these days, 
but I can't recall who. Anyway the MRC .. U118 is a 74HCTLS on the ones 
I fixed. I had to replace it with a 74LS00. Then it was fine. Don't ask 
me how I came to that conclusion but maybe with a schematic in front of 
me I could say better.

The Yamaha TX7 is another odd beast to fix and it's not even a Z80 (it's 
a 6303 which is a 6801 more or less).

Not sure I would pop an OLED or VFD in these two machines as they are 
finicky enough with LCDs.

On 12/30/2018 7:34 PM, Tony K wrote:
> Hi Tim, I can't answer your question as to why lcds die, as you put it, but I have several older units that are getting harder to read, such as the Lexicon MRC, and Korg Wavestation A/D rack( now sold partly for aformentioned display issues) . I have a contrast control on the former unit but at some point ai will have to switch to a modern OLED? , or VFD ( Noritake , old school solution) .
> 
> I think MTG has something about it on his site , at least the MRC.  I have been putting this off. Come to think of it the Novation X-Station contrast is getting weaker as time goes on, but that one is meant to be on all yhe time - I use it as my audio interface. So it's a safe bet to say these displays do have a MTBF. The old Hitachi 16x2 is not a problem to get lcd replacements ( ie MMT-8 etc.) I know Noritake VFDa make drop in replacements for those, or used to anyway. But then there is the high voltage filament voltage to worry about and the fragility.
> 
> Anyway I love those VFD's on the Xpander.
> 
> Tony K
> 
>> On Dec 30, 2018, at 9:53 PM, Tim Parkhurst <tim.parkhurst at gmail.com> wrote:
>>
>> So, I have an old Roland U-220 that I haven't used in a few years, but I keep it around because I do love the piano and string samples. The fretless bass and the drums are pretty good too. Also, I'd be lucky to get $50 for it these days. Long story short, I turned it on the other day and the LCD was barely visible, getting dimmer to the point after a few hours where it is completely unreadable. The backlight is okay, but the digits themselves can't be seen. I see there are replacements on the market, so I should be able to resurrect it, but this begs my original point:
>>
>> What causes LCDs to die in the first place? Are the crystals themselves unstable? Is it the high-frequency excitation required that causes an eventual breakdown? Or is it mechanical, with small connections or wire bonds breaking down with time? Do we replace them because they are unrepairable, or is it simply a matter of replacement being quicker and cheaper than repair? Is there an internal adjustment to crank up the contrast on this old beast (can't change the contrast from the front panel settings since I can't see the display to navigate)?
>>
>> Awaiting the collective enlightenment from the SDIY hive mind...
>>
>> Tim (do Borgs get hive mind hives?) Servo
>>
>>
>>
>>
>> _______________________________________________
>> Synth-diy mailing list
>> Synth-diy at synth-diy.org
>> http://synth-diy.org/mailman/listinfo/synth-diy
> 
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at synth-diy.org
> http://synth-diy.org/mailman/listinfo/synth-diy
> 
> 


From kenny at beatkamp.com  Mon Dec 31 05:29:38 2018
From: kenny at beatkamp.com (Kenny Balys)
Date: Mon, 31 Dec 2018 04:29:38 +0000
Subject: [sdiy] Why do LCDs die?
In-Reply-To: <253af55d-2ef7-3f3c-4e83-0ed34f82c089@musictechnologiesgroup.com>
References: <CACDGQT89j7B798bE3SprSORT6ZOrwVk+4rWA+JWc1QRQY=x3eQ@mail.gmail.com>
 <73283994-C665-4C31-B8B2-AF9E619F097F@gmail.com>
 <253af55d-2ef7-3f3c-4e83-0ed34f82c089@musictechnologiesgroup.com>
Message-ID: <5C299B32.6080605@beatkamp.com>


I have (possibly) the first Timex LCD wrist watch and its
display has gradually faded over time and is now unreadable.

My guess is that the liquid has dried out / been lost and this
renders the display non functional.

Would love to hear more opinions on this. The LCD in my Emax
appeared to do the same thing. I put in a new red on black OLED
and that just looks fantastic now.

The only Z80 person I know of in the synth world is Tauntek.
http://tauntek.com/

On 31.12.18 04:17 , MTG wrote:
> To the OP, probably all of the above as being reasons for failure.
>
> A lot of the Z80 machines really push the timing to memory map those LCDs. I
> don't know what it is exactly since I've never really studied the Z80. There is
> one guy doing a bunch of Z80 upgrade work these days, but I can't recall who.
> Anyway the MRC .. U118 is a 74HCTLS on the ones I fixed. I had to replace it
> with a 74LS00. Then it was fine. Don't ask me how I came to that conclusion but
> maybe with a schematic in front of me I could say better.
>
> The Yamaha TX7 is another odd beast to fix and it's not even a Z80 (it's a 6303
> which is a 6801 more or less).
>
> Not sure I would pop an OLED or VFD in these two machines as they are finicky
> enough with LCDs.
>
> On 12/30/2018 7:34 PM, Tony K wrote:
>> Hi Tim, I can't answer your question as to why lcds die, as you put it, but I
>> have several older units that are getting harder to read, such as the Lexicon
>> MRC, and Korg Wavestation A/D rack( now sold partly for aformentioned display
>> issues) . I have a contrast control on the former unit but at some point ai
>> will have to switch to a modern OLED? , or VFD ( Noritake , old school
>> solution) .
>>
>> I think MTG has something about it on his site , at least the MRC.  I have
>> been putting this off. Come to think of it the Novation X-Station contrast is
>> getting weaker as time goes on, but that one is meant to be on all yhe time -
>> I use it as my audio interface. So it's a safe bet to say these displays do
>> have a MTBF. The old Hitachi 16x2 is not a problem to get lcd replacements (
>> ie MMT-8 etc.) I know Noritake VFDa make drop in replacements for those, or
>> used to anyway. But then there is the high voltage filament voltage to worry
>> about and the fragility.
>>
>> Anyway I love those VFD's on the Xpander.
>>
>> Tony K
>>
>>> On Dec 30, 2018, at 9:53 PM, Tim Parkhurst <tim.parkhurst at gmail.com> wrote:
>>>
>>> So, I have an old Roland U-220 that I haven't used in a few years, but I keep
>>> it around because I do love the piano and string samples. The fretless bass
>>> and the drums are pretty good too. Also, I'd be lucky to get $50 for it these
>>> days. Long story short, I turned it on the other day and the LCD was barely
>>> visible, getting dimmer to the point after a few hours where it is completely
>>> unreadable. The backlight is okay, but the digits themselves can't be seen. I
>>> see there are replacements on the market, so I should be able to resurrect
>>> it, but this begs my original point:
>>>
>>> What causes LCDs to die in the first place? Are the crystals themselves
>>> unstable? Is it the high-frequency excitation required that causes an
>>> eventual breakdown? Or is it mechanical, with small connections or wire bonds
>>> breaking down with time? Do we replace them because they are unrepairable, or
>>> is it simply a matter of replacement being quicker and cheaper than repair?
>>> Is there an internal adjustment to crank up the contrast on this old beast
>>> (can't change the contrast from the front panel settings since I can't see
>>> the display to navigate)?
>>>
>>> Awaiting the collective enlightenment from the SDIY hive mind...
>>>
>>> Tim (do Borgs get hive mind hives?) Servo
>>>


From weplar at gmail.com  Mon Dec 31 06:04:01 2018
From: weplar at gmail.com (Tony K)
Date: Mon, 31 Dec 2018 00:04:01 -0500
Subject: [sdiy] Why do LCDs die?
In-Reply-To: <5C299B32.6080605@beatkamp.com>
References: <CACDGQT89j7B798bE3SprSORT6ZOrwVk+4rWA+JWc1QRQY=x3eQ@mail.gmail.com>
 <73283994-C665-4C31-B8B2-AF9E619F097F@gmail.com>
 <253af55d-2ef7-3f3c-4e83-0ed34f82c089@musictechnologiesgroup.com>
 <5C299B32.6080605@beatkamp.com>
Message-ID: <D71E6FD0-DDBF-4618-8E81-36EBE3976148@gmail.com>

Meant to say anode , not heater, high voltage.

Thanks for that info Grant. Didn't think it was that simple a fix for the MRC. Will have to give that one a whirl. 






From onephatcat at earthlink.net  Mon Dec 31 07:36:54 2018
From: onephatcat at earthlink.net (Joel B)
Date: Sun, 30 Dec 2018 22:36:54 -0800
Subject: [sdiy] Mini-Din cable woes
Message-ID: <7548DF1A-4CF0-4F95-93A7-26BD53175238@earthlink.net>

I have a couple of Pearl fightman analog drum modules (circa 1979/80) and one came with the complete drum kit and cables, the other without.

 I?ve been attempting to create a second set of cables, with only partial success. The cables are each a 5 pin mini-din (https://goo.gl/images/pDHvsP) that split to a fan of 4 and 5 RCA Male jacks - proprietary cables that nobody seems to make. (crash/ride/oh/ch)/(kick/snare/toms). First problem is how to solder tiny wires to tiny posts. Took a while to get that right, and I?m pretty sure there is a better way, like wires with some kind of clip already attached...

Second problem was that I think the outside ring on the mini-din is the ground (or at least the ?common? wire) as far as I can tell from my amature multimetering. 

So I built a couple cables, and the second try sort of worked but a little intermittently. Thinking I understood how to do this now I built a third one that works even less and a fourth one that doesn?t work at all. I can?t find a short. The pins all have good connectivity. 

I was trying to adapt to 3.5mm jacks so I wired to 3.5mm female sockets instead of RCA male, to use with beatstep pro or other trigger (Original cables with an rca/3.5mm adapter do work with beatstep pro). I could only find TRS 3.5mm sockets online when I wanted TS but I?m pretty sure I soldered that part the same way on all my attempts... 

I?m wondering, are the pins on the newer mini-din male just maybe not long enough? What am I doing wrong? Certainly they seem not designed for the sleeve of the mini-din to be a soldier point but It seems to be so in the original cables, so I made that connection.

Joel
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From rsdio at audiobanshee.com  Mon Dec 31 08:01:04 2018
From: rsdio at audiobanshee.com (rsdio at audiobanshee.com)
Date: Sun, 30 Dec 2018 23:01:04 -0800
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <42E03BF8EA2C4EDC9F50696832E69646@galvanox01>
References: <CA+9GZUgiRfkgsVyphE8OLMz=3mOyk3n1NJxr1CZut9vA5fX+zg@mail.gmail.com>
 <63223c87-7691-86ea-bc50-012d37811792@mikebeauchamp.com>
 <69A6422A-B7A6-40E6-842A-D75A4B373C24@gmail.com>
 <CA+9GZUjfsoy3pH=PwwFtOQBXEYk7WHPaJ76+rXsPccd8iqxrow@mail.gmail.com>
 <7E4779AA-97D0-479F-B51D-456ECA3ED9EB@gmail.com>
 <CA+wjhVtO31p5SOrURk8G37Jm1YamKSAao2L+3JA7U8rk_jnMew@mail.gmail.com>
 <CA+9GZUhHzcqPHazAvWX8bP04U+COfsPkx2CEqoSEKMaWGHGEbg@mail.gmail.com>
 <20181230115002.GA30783@ilyushin>
 <672DFB04-49B9-4E47-988C-C900FEB65174@audiobanshee.com>
 <42E03BF8EA2C4EDC9F50696832E69646@galvanox01>
Message-ID: <FB4AA101-4F54-492E-A29B-976106B33FE9@audiobanshee.com>

To be fair, I?m not counting any simple switch as digital, because there?s no control signal in the broadest examples within that category. Switches were used in electronics long before the concept of digital signals was envisioned.

A Gate, however, is a signal that?s separate from the physical switches, and it?s a digital signal. In fact, a Gate signal may come from a switch (keyboard), or it may come from some other source such as a sequencer, a clock, or some other module. In that sense, Gate is a pure digital signal, as pure as any definition of digital could be.

The Moog S-Trigger is a little difficult to categorize, however, because it is basically equivalent to a switch closure. I?m not sure that it would be valid to count S-Trigger as a digital ?signal,? per se. You?d have to get into the realm of current loop signaling before you could begin to consider S-Trigger as a digital signal, and even still it would be an outlier.

Brian Willoughby


On Dec 30, 2018, at 6:11 PM, David G Dixon <dixon at mail.ubc.ca> wrote:
> That's ridiculous.  By that standard, every electronic (or just electric)
> device with an On-Off switch is digital.
> 
>> -----Original Message-----
>> Sent: Sunday, December 30, 2018 3:59 PM
>> Cc: synth-diy at synth-diy.org
>> 
>> On Dec 30, 2018, at 3:50 AM, Gordonjcp wrote:
>>> On Tue, Dec 25, 2018 at 11:40:24PM +0100, cheater00 wrote:
>>>> I want to make this work for an all-analog synthesizer, but rather
>>> 
>>> Can you show an example of an all-analogue polyphonic synthesizer?
>>> Like, no digital control at all?
>> 
>> Technically, Gate is a digital signal. There are no 
>> all-analog synthesizers.
>> 
>> Brian Willoughby
> 



From weplar at gmail.com  Mon Dec 31 08:03:26 2018
From: weplar at gmail.com (Tony Kalomiris)
Date: Mon, 31 Dec 2018 02:03:26 -0500
Subject: [sdiy] Why do LCDs die?
In-Reply-To: <253af55d-2ef7-3f3c-4e83-0ed34f82c089@musictechnologiesgroup.com>
Message-ID: <D84F2761.ACB6%weplar@gmail.com>

>From the MRC service manual:

"A DC to AC converter, T101, converts +5VDC to approximately 100 VAC which
supplies power to the fluorescent lighting on the LCD display via J110 and
is self-adjusting as the LCD ages."

That last part surprised me, self-adjusting backlight? It's not shown on
the schematic but that 14 pin connector, J110, looks familiar (Hitachi
44780).
I don't see how the chip select, CS6, from that NAND gate, could make a
difference in brightness, but hey if you say so, who am I to question why.

Tony

On 18-12-30 11:17 PM, "MTG" <grant at musictechnologiesgroup.com> wrote:

>Anyway the MRC .. U118 is a 74HCTLS on the ones
>I fixed. I had to replace it with a 74LS00. Then it was fine. Don't ask
>me how I came to that conclusion but maybe with a schematic in front of
>me I could say better.




From rsdio at audiobanshee.com  Mon Dec 31 08:32:24 2018
From: rsdio at audiobanshee.com (rsdio at audiobanshee.com)
Date: Sun, 30 Dec 2018 23:32:24 -0800
Subject: [sdiy] Why do LCDs die?
In-Reply-To: <CACDGQT89j7B798bE3SprSORT6ZOrwVk+4rWA+JWc1QRQY=x3eQ@mail.gmail.com>
References: <CACDGQT89j7B798bE3SprSORT6ZOrwVk+4rWA+JWc1QRQY=x3eQ@mail.gmail.com>
Message-ID: <D24FEE9E-3B08-4D69-91F3-E10C7CD76CB0@audiobanshee.com>

As with anything electronic, there is more than one circuit design possible, and therefore more than one way for things to go bad.

As a remotely related example, I have a Fluke 87 meter with an LCD display. That thing started getting dim after about 15 or 20 years of use, so I took it apart to take a look at how it was put together. Turns out that they used rubber impregnated with carbon for the contacts between the PCB and the LCD. On a hunch, I purchased some deionized water and carefully cleaned both the carbonized rubber contacts and the PCB contacts on both sides. After thoroughly drying the pieces, I reassembled it and the display was just as sharp in contrast as when it was new. What?s really interesting is that my makeshift repair was done more than 20 years ago, and it?s still just as readable. Perhaps I lived in more humid conditions before?

Based on this one experience, I?d recommend checking the contacts for excess resistance. It seems doubtful that a Roland U-220 would have the same kind of carbonized rubber contacts, but maybe there are some 100-mil headers and ribbon cables that have oxidized over the years.

in other words, increased resistance could be one explanation for dim LCD, or low-contrast performance. I?m sure there are other ways for an LCD to fail, but oxidization is at least something you might be able to fix.

Brian Willoughby

p.s. Be careful about cranking up the contrast if there is a resistance problem, because that might just accelerate the decay.

p.p.s. If you can?t see the display, maybe there is a MIDI System Exclusive implementation that would allow you to change the contrast setting remotely, even though you can?t see the display now.


On Dec 30, 2018, at 6:53 PM, Tim Parkhurst <tim.parkhurst at gmail.com> wrote:
> So, I have an old Roland U-220 that I haven't used in a few years, but I keep it around because I do love the piano and string samples. The fretless bass and the drums are pretty good too. Also, I'd be lucky to get $50 for it these days. Long story short, I turned it on the other day and the LCD was barely visible, getting dimmer to the point after a few hours where it is completely unreadable. The backlight is okay, but the digits themselves can't be seen. I see there are replacements on the market, so I should be able to resurrect it, but this begs my original point: 
> 
> What causes LCDs to die in the first place? Are the crystals themselves unstable? Is it the high-frequency excitation required that causes an eventual breakdown? Or is it mechanical, with small connections or wire bonds breaking down with time? Do we replace them because they are unrepairable, or is it simply a matter of replacement being quicker and cheaper than repair? Is there an internal adjustment to crank up the contrast on this old beast (can't change the contrast from the front panel settings since I can't see the display to navigate)?
> 



From rsdio at audiobanshee.com  Mon Dec 31 08:43:57 2018
From: rsdio at audiobanshee.com (rsdio at audiobanshee.com)
Date: Sun, 30 Dec 2018 23:43:57 -0800
Subject: [sdiy] Why do LCDs die?
In-Reply-To: <253af55d-2ef7-3f3c-4e83-0ed34f82c089@musictechnologiesgroup.com>
References: <CACDGQT89j7B798bE3SprSORT6ZOrwVk+4rWA+JWc1QRQY=x3eQ@mail.gmail.com>
 <73283994-C665-4C31-B8B2-AF9E619F097F@gmail.com>
 <253af55d-2ef7-3f3c-4e83-0ed34f82c089@musictechnologiesgroup.com>
Message-ID: <B89869CF-DA50-476F-9F2A-D129215C82F0@audiobanshee.com>


On Dec 30, 2018, at 8:17 PM, MTG <grant at musictechnologiesgroup.com> wrote:
> A lot of the Z80 machines really push the timing to memory map those LCDs. I don't know what it is exactly since I've never really studied the Z80. There is one guy doing a bunch of Z80 upgrade work these days, but I can't recall who. Anyway the MRC .. U118 is a 74HCTLS on the ones I fixed. I had to replace it with a 74LS00. Then it was fine. Don't ask me how I came to that conclusion but maybe with a schematic in front of me I could say better.

None of the problems with LCDs are specific to the Z80 or the 74LS00. Yes, they were pushing the timing, but the thing about digital is that once you work out the timing successfully, it?s not going to change. Sure, parts can go bad, and you can replace them with faster parts, but you can?t change the timing of a system that was designed as an integrated whole. You probably just got lucky, finding a marginal part and replacing it with one that actually met or exceeded the original timing requirements.


> The Yamaha TX7 is another odd beast to fix and it's not even a Z80 (it's a 6303 which is a 6801 more or less).

This era of machines were all designed around 8-bit chips that ran around 1 MHz or 2 MHz, or maybe 4 MHz with 4 clocks per instruction - same difference.


> Not sure I would pop an OLED or VFD in these two machines as they are finicky enough with LCDs.

Agreed.

I have no experience with OLED, but my understanding is that an LCD lasts 25 times as long as an OLED, so you?re not doing yourself any favors by replacing an aging LCD with a new OLED.

"The light that burns twice as bright burns half as long."

Brian Willoughby




From weplar at gmail.com  Mon Dec 31 09:23:46 2018
From: weplar at gmail.com (Tony Kalomiris)
Date: Mon, 31 Dec 2018 03:23:46 -0500
Subject: [sdiy] Why do LCDs die?
In-Reply-To: <D24FEE9E-3B08-4D69-91F3-E10C7CD76CB0@audiobanshee.com>
Message-ID: <D84F3B0F.AD9B%weplar@gmail.com>

I don't recommend messing with Zebra strips. I have messed up my Timex
Indiglo watch, a Timer, and a great HP calculator "cleaning" those.
I was never able to get the dead characters back. And yes I used distilled
water and allowed to dry thoroughly.

Brian, could it be you are referring to the ghosting on that meter, from
poor contact? The OP was referring to dying LCD (weak contrast).
I can't recall off hand but I remember an excellent article on how LCDs
work in a magazine> PE, R&EW, can't recall.

Tony

On 18-12-31 2:32 AM, "rsdio at audiobanshee.com" <rsdio at audiobanshee.com>
wrote:

>I have a Fluke 87 meter with an LCD display. That thing started getting
>dim after about 15 or 20 years of use, so I took it apart to take a look
>at how it was put together. Turns out that they used rubber impregnated
>with carbon for the contacts between the PCB and the LCD. On a hunch, I
>purchased some deionized water and carefully cleaned both the carbonized
>rubber contacts and the PCB contacts on both sides. After thoroughly
>drying the pieces, I reassembled it and the display was just as sharp in
>contrast as when it was new. What?s really interesting is that my
>makeshift repair was done more than 20 years ago, and it?s still just as
>readable. Perhaps I lived in more humid conditions before?





From dixon at mail.ubc.ca  Mon Dec 31 09:24:07 2018
From: dixon at mail.ubc.ca (David G Dixon)
Date: Mon, 31 Dec 2018 00:24:07 -0800
Subject: [sdiy] Help, I'm Desperate! (Charge Injection with DG408)
In-Reply-To: <8A1202FEEFD441D794564DD4394DAA3F@galvanox01>
References: <6f6f6d21-3435-f06f-7e43-0adf79e5e983@bendentech.co.uk>
 <7ed8bf9c-5a8f-5cc0-400c-21118a775e5d@bendentech.co.uk>
 <5b40ab00390062a6a2c3d33598dcdc11@richieburnett.co.uk>
 <99e8daac539343c9be2c166f95e7d675@galvanox01>
 <1c9ee46b-8823-690d-2846-41a367f55da4@go2.pl>
 <46480845c1d149c4bc4b869921c52f57@galvanox01>
 <c6f29668-5ea0-a291-7ef2-fcae03b426e8@go2.pl>
 <dda338da412d4a62930ab5980ef49255@galvanox01>
 <38c3fafaa9e4486e98933dddc7d7ded2@galvanox01>
 <2EFDC1DB-86C1-4EBE-B3FF-5736B62BA790@gmail.com>
 <87047a284558469ca7b973d8be4d423a@grupawp.pl>
 <141F2ED141084CCAB3AB3A5FDC2C8783@galvanox01>
 <CAJ2Txe22UbyMLvY3ziat=XcFHcJ9AvfWuj65=brJFayr4aFL3A@mail.gmail.com>
 <9040F25BCE0D4A408056B2024B7DEBB3@galvanox01>
 <6e07c18c-5ce0-5d0c-fa24-06268c70d8fa@bugbrand.co.uk>
 <71333af6-9c7a-53ee-616c-4eacd0a8db98@btinternet.com>
 <8A1202FEEFD441D794564DD4394DAA3F@galvanox01>
Message-ID: <64f526dd-bce2-41a1-bead-4aa5d21bf064@S-ITSV-HUB03P.ead.ubc.ca>

Hi All,

Remember this thread?  Well, I have some progress to report...

I took Roman's advice and used SPST analog switches instead of multiplexers
for my scanner.  I just panelized the prototype board, and it all works
perfectly!  The switching is completely noise-free, as expected.  Also, the
board worked the first time with no layout corrections needed, which is a
bit of a surprise given that this is a 4" x 6" one-sided PCB which is
completely stuffed (12 ICs and a pile of resistors and diodes).

This was not a terribly straightforward redesign.  First of all, the CV
circuit was originally designed to convert a -5V to +5V ramp to four
truncated triangles from 5V to 0V (5-0-5-0-5-0-5-0-5).  This was perfect for
9 channels, which my original multiplexing scanner did.  However, with the
SPST scanner, each channel requires its own switch, and the switches come
four to a chip (DG444), so this means only 8 channels.  Hence, I want my
triangles to only go 5-0-5-0-5-0-5-0 (no final 5).  This means that I want
to convert the ramp to 3.5 truncated triangles instead of 4.  This took some
serious thinking, but was ultimately pretty easy to achieve, with only a
couple of additional opamps.  I designed it so that if the incoming CV
signal is lower than -5V, the scanner will output Channel 1, and if it is
higher than +5V, the scanner will output Channel 8.

As for the switching circuit, it required 6 comparators (LM339 + LM393), 8
XNOR gates (2 4077), and 8 SPST switches (2 DG444).  I used hysteresis on
the comparators, and wired things up using Roman's "Fat Dot" concept.
Actually, the channels fall on two CV busses -- A and B (A is on when the
2164 CV is 0V and B is on when the 2164 CV is 5V).  Channels 1357 are on the
B bus (5V), and channels 2468 are on the A bus (0V).  Rather than thinking
of the XNORs as providing fat dots, if one simply sees channels 1357 as one
circuit, and 2468 as another circuit, with the XNORs alternating between
them, the one has two 4-channel logic circuits with regular skinny dots.
Either way, it works.  Also, to clarify Roman's schematic, the top and
bottom comparators are not necessary.  The top one can be replaced with
Ground, and the bottom one with 5V.  Hence, only 6 comparators are needed.

Also, I opted for "negative logic" in this circuit, and thus used XNOR gates
(4077) and DG444.  However, it would work just as well with "positive
logic", which would use XOR gates (4070) and DG445.  These are
pin-compatible with the others, so either could be used on the same board.

Finally, the "client" had originally wanted LEDs to indicate the channels.
I had deemed this impossible with my original circuit.  However, it is very
straightforward with this new circuit.  The XNOR outputs provide "ground"
for the LEDs, and the truncated triangle CV signal drives the LEDs.  Since
only one XNOR output from either the 1357 or the 2468 side is on (at ground)
at any given time, only one LED from each bus will shine.  The "inactive"
LEDs have 5V instead of ground at their negative end, and therefore cannot
conduct.  The triangles cause these two active LEDs to fade one to the other
in exactly the same fashion as the audio signals themselves.  Really, this
works better than I could have hoped, and it was very easy to do.  I just
had to invert and level shift the truncated triangle CV signal so that one
goes 5-0-5-0-5-0-5-0 while the other goes 0-5-0-5-0-5-0-5, and use these two
different signals to drive the 1357 and 2468 LEDs, respectively.  If
"positive logic" were used instead (with 4070 and DG445), then one would
simply have to swap the CV signals around and wire up the LEDs the other
way.

I'm going to make some kind of video to show how this works, and I'll put up
a link here for it.  It will probably be tomorrow.  I also plan to create a
big long thread on Muff Wiggler explaining the entire circuit in detail with
schematics and stuff, as a sort of tutorial on how I approach design.  I
think that might be pretty useful for other DIYers.

Thanks again for all your help, especially Roman!!

Cheers,
Dave



From oakleysound at btinternet.com  Mon Dec 31 11:59:40 2018
From: oakleysound at btinternet.com (Oakley Sound)
Date: Mon, 31 Dec 2018 10:59:40 +0000
Subject: [sdiy] Patchable polyphonic synth with FM or AM transmission
 idea
In-Reply-To: <20181230225045.GA1172@ilyushin>
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Message-ID: <3d3be39b-f18f-23bf-0fd3-deb7ffd1da8d@btinternet.com>

 > Synthesizers, not divider organs...

The Korg series approach polyphony with a brute force method of 
providing an oscillator, filter, amplifier and EG per note. The PE-1000 
even goes as far as making the oscillator a VCO, so there's no divide 
down there.

The PS3100 does use divide down by only for the octaves with the top 
octave being generated by twelve individual VCOs. It's probably as close 
to a polyphonic MS-10 as you can get with using any digital note assigners.

The filters are voltage controlled, only one pole on the PE series but 
two pole with resonance on the PS series.

The PE2000 is probably the most organy with a TOG and divider chain 
(albeit three of them) but even that has the separate filter, envelope 
and amplifier per note.

There's also the Polymoog. TOG and divide down (this time just two of 
them) but independent filters, envelopes and amplifiers per note.

They're all synths but if anything they are good examples why one should 
be using digital in a polyphonic synth if only to bring the cost and 
complexity down. However, the cleverness in all those designs to avoid 
using digital note assignment is something to behold.

Tony

www.oakleysound.com


From weplar at gmail.com  Mon Dec 31 13:10:19 2018
From: weplar at gmail.com (Tony Kalomiris)
Date: Mon, 31 Dec 2018 07:10:19 -0500
Subject: [sdiy] Why do LCDs die?
In-Reply-To: <D84F3B0F.AD9B%weplar@gmail.com>
Message-ID: <D84F6FB4.ADAE%weplar@gmail.com>

The MRC uses an OKI MSM6222B-XX LCD controller, equivalent to Hitachi
HD44780 except for slight differences.
In 8-bit mode. So my suspicions were confirmed by that 14 pin IDC header.




>




From modular at go2.pl  Mon Dec 31 13:22:59 2018
From: modular at go2.pl (Roman Sowa)
Date: Mon, 31 Dec 2018 13:22:59 +0100
Subject: [sdiy] Why do LCDs die?
In-Reply-To: <CACDGQT89j7B798bE3SprSORT6ZOrwVk+4rWA+JWc1QRQY=x3eQ@mail.gmail.com>
References: <CACDGQT89j7B798bE3SprSORT6ZOrwVk+4rWA+JWc1QRQY=x3eQ@mail.gmail.com>
Message-ID: <626c5b62-8b17-4ae6-cb84-a0c92c73a635@go2.pl>

It may be that driving signals were not precise enough. Bad 
non-symetrical levels and bad timing might have caused DC component to 
appear over glass. Mean value of the voltage actross any part of crystal 
must be 0V, otherwise it will be damaged over time.

Roman

W dniu 2018-12-31 o?03:53, Tim Parkhurst pisze:
> So, I have an old Roland U-220 that I haven't used in a few years, but I 
> keep it around because I do love the piano and string samples. The 
> fretless bass and the drums are pretty good too. Also, I'd be lucky to 
> get $50 for it these days. Long story short, I turned it on the other 
> day and the LCD was barely visible, getting dimmer to the point after a 
> few hours where it is completely unreadable. The backlight is okay, but 
> the digits themselves can't be seen. I see there are replacements on the 
> market, so I should be able to resurrect it, but this begs my original 
> point:
> 
> What causes LCDs to die in the first place? Are the crystals themselves 
> unstable? Is it the high-frequency excitation required that causes an 
> eventual breakdown? Or is it mechanical, with small connections or wire 
> bonds breaking down with time? Do we replace them because they are 
> unrepairable, or is it simply a matter of replacement being quicker and 
> cheaper than repair? Is there an internal adjustment to crank up the 
> contrast on this old beast (can't change the contrast from the front 
> panel settings since I can't see the display to navigate)?
> 
> Awaiting the collective enlightenment from the SDIY hive mind...
> 
> Tim (do Borgs get hive mind hives?) Servo
> 
> 
> 
> 
> 
> 
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> Synth-diy mailing list
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From gordonjcp at gjcp.net  Mon Dec 31 13:48:49 2018
From: gordonjcp at gjcp.net (Gordonjcp)
Date: Mon, 31 Dec 2018 12:48:49 +0000
Subject: [sdiy] Why do LCDs die?
In-Reply-To: <D24FEE9E-3B08-4D69-91F3-E10C7CD76CB0@audiobanshee.com>
References: <CACDGQT89j7B798bE3SprSORT6ZOrwVk+4rWA+JWc1QRQY=x3eQ@mail.gmail.com>
 <D24FEE9E-3B08-4D69-91F3-E10C7CD76CB0@audiobanshee.com>
Message-ID: <20181231124849.GA5323@ilyushin>

On Sun, Dec 30, 2018 at 11:32:24PM -0800, rsdio at audiobanshee.com wrote:
> As a remotely related example, I have a Fluke 87 meter with an LCD display. That thing started getting dim after about 15 or 20 years of use, so I took it apart to take a look at how it was put together. Turns out that they used rubber impregnated with carbon for the contacts between the PCB and the LCD. On a hunch, I purchased some deionized water and carefully cleaned both the carbonized rubber contacts and the PCB contacts on both sides. After thoroughly drying the pieces, I reassembled it and the display was just as sharp in contrast as when it was new. What?s really interesting is that my makeshift repair was done more than 20 years ago, and it?s still just as readable. Perhaps I lived in more humid conditions before?

A guy on the Range Rover forum I run had a huge batch of zebra strip
made for the heater LCD panels, which lose segments over time.  Once
you've taken out all 426 screws holding the heater controller together,
it's a quick and easy cure.

-- 
Gordonjcp



From grant at musictechnologiesgroup.com  Mon Dec 31 17:07:56 2018
From: grant at musictechnologiesgroup.com (MTG)
Date: Mon, 31 Dec 2018 08:07:56 -0800
Subject: [sdiy] Why do LCDs die?
In-Reply-To: <D84F2761.ACB6%weplar@gmail.com>
References: <D84F2761.ACB6%weplar@gmail.com>
Message-ID: <186c09bd-395e-d55c-f228-9813b65ad284@musictechnologiesgroup.com>

It's just a standard EL circuit as far as I know. Maybe there is some 
natural artifact of the EL "foil" that as it ages it also changes 
resistance or something. The self-adjusting does not appear to work in 
favor of readability. :)

Lets start at the issue. LCD not readable. Person changes old LCD with 
new LED backlit version and removes the EL circuit. New LCD shows 
garbage. I probably didn't make that last bit clear.

So, the gate doesn't have anything to do with brightness. When you pop a 
new LCD in, the timing (from the Z80 memory mapped LCD circuit) causes 
the new LCD to mess up in a variety of ways.  Changing the gate clears 
it up. Imagine grandiose hand-waving. I don't have any other notes handy 
but a photo of a repair showing before and after and that's what the fix 
was. If someone worked out the Z80 and logic timing on E, RS, R/W* and 
data I'm sure you'd see some parameter is pretty iffy regarding setup or 
hold time.

Aside: the new LCD will probably be of type HD44780A00 (Hitachi 500ns 
controller) versus the old HD447800 (which is the legacy 1us 
controller). You'd think that would make things better, not worse.

Anyway the timing issue is solved by replacing said gate(s). You have to 
unsolder the original gate. There may be other fixes that accomplish the 
same thing but I don't know for sure.


On 12/30/2018 11:03 PM, Tony Kalomiris wrote:
>>From the MRC service manual:
> 
> "A DC to AC converter, T101, converts +5VDC to approximately 100 VAC which
> supplies power to the fluorescent lighting on the LCD display via J110 and
> is self-adjusting as the LCD ages."
> 
> That last part surprised me, self-adjusting backlight? It's not shown on
> the schematic but that 14 pin connector, J110, looks familiar (Hitachi
> 44780).
> I don't see how the chip select, CS6, from that NAND gate, could make a
> difference in brightness, but hey if you say so, who am I to question why.
> 
> Tony
> 
> On 18-12-30 11:17 PM, "MTG" <grant at musictechnologiesgroup.com> wrote:
> 
>> Anyway the MRC .. U118 is a 74HCTLS on the ones
>> I fixed. I had to replace it with a 74LS00. Then it was fine. Don't ask
>> me how I came to that conclusion but maybe with a schematic in front of
>> me I could say better.
> 
> 
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