MOTM

hello all,

powering through my DIY module backlog as i am, the following idea hit me -
how easy is it to make a swiitching module that uses a gate to switch a
relay
the relay is attached to tip & sleeve of a jack, and can be used for example
to switch in bypass mode on the MOTM850, but more importantly, various modes
on my roland vocoder, the bypass on my space echo etc etc

i assume the trick is to select the correct relay, then gate it via a buffer
circuit, and attach the switch section of the relay direct to the jacks -
any other idea anyone..?
also i asked this before, and lost the reply - does anyone have any stand
alone buffer circuit designs they can share..?

cheers
paul b

There is a chip (been around 20 years) called a UN2003 that is made for this. Cheap, too!

Paul S.

----- Original Message ----- 

From: "Sikorsky" <vulture.squadron@...>
To: "MOTM List" <motm@yahoogroups.com>
Sent: Wednesday, October 30, 2002 5:53 AM
Subject: [motm] daft circuit idea time


> hello all,
> 
> powering through my DIY module backlog as i am, the following idea hit me -
> how easy is it to make a swiitching module that uses a gate to switch a
> relay
> the relay is attached to tip & sleeve of a jack, and can be used for example
> to switch in bypass mode on the MOTM850, but more importantly, various modes
> on my roland vocoder, the bypass on my space echo etc etc
> 
> i assume the trick is to select the correct relay, then gate it via a buffer
> circuit, and attach the switch section of the relay direct to the jacks -
> any other idea anyone..?
> also i asked this before, and lost the reply - does anyone have any stand
> alone buffer circuit designs they can share..?
> 
> cheers
> paul b
> 
> 
> 
> 
> 
>  
> 
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
> 
>

----- Original Message -----

From: "Paul Schreiber" <synth1@...>


> There is a chip (been around 20 years) called a UN2003 that is made for
this. Cheap, too!

you mean ULN2003 - six buffers in a 16 pin dil..?

cheers
paul

Yep.

Paul S.

----- Original Message ----- 

From: "Sikorsky" <vulture.squadron@...>
To: "MOTM List" <motm@yahoogroups.com>
Sent: Wednesday, October 30, 2002 7:30 AM
Subject: Re: [motm] daft circuit idea time


> ----- Original Message -----
> From: "Paul Schreiber" <synth1@...>
> 
> 
> > There is a chip (been around 20 years) called a UN2003 that is made for
> this. Cheap, too!
> 
> you mean ULN2003 - six buffers in a 16 pin dil..?
> 
> cheers
> paul
> 
> 
> 
>  
> 
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ 
> 
>

>> There is a chip (been around 20 years) called a UN2003 that is made for
>this. Cheap, too!
>
>you mean ULN2003 - six buffers in a 16 pin dil..?

I don't care what it's called as long it's not about digital audio!!


Anyway, you can build a simple circuit using a transistor:


                                                         Bypass
                                          ----------------
      Gate        10k                    /                    |
	  -------/\/\/\---------+-------| 2N3904             ---
        |                       |        \                   ///
        |                       -        |
        |              1N4148   ^        |
        |                       |        |
       ---                     ---      ---
       ///                     ///      ///



The resistor value isn't critical.  Neither are the transistor specs.
And the diode is a safety feature :)

Keep in mind that compared to electronics, human feet are slow, so many
bypass inputs are heavily "debounced".  These might require the addition of
an RC pulse strecher between the input and the base of the transistor.  I
had to add one to clock my Vortex from 808 drum triggers.

hello all,

well i downloaded the ULN2003 specs - so i'm going to give that a try since
it seems a simple solution (just too simple for my suspicious mind)

cheers
paul b

On Wed, 30 Oct 2002, Sikorsky wrote:

> ----- Original Message -----
> From: "Paul Schreiber" <synth1@...>
> 
> 
> > There is a chip (been around 20 years) called a UN2003 that is made for
> this. Cheap, too!
> 
> you mean ULN2003 - six buffers in a 16 pin dil..?

  Seven darlington buffers in a dil16.  I've used thousands of these as
common-cathode LED display selectors.  For the segment side, I use either
a UDN2981 (eight current-sourcing drivers in a dil18) plus an rdip, or for
BCD I use the CA3161, a legacy part with constant-current outputs which
has the fun feature of being able to display the numerals 0~9, a negative
sign, a blank, and the letters 'H','E','L','P'.

Crow
/**/

WOW! 
http://www.prodikeys.com/
(I love how they have a strap for it and are wearing it like a guitar)

Yes, and unlike a relay, it doesn't double as a radio transmitter  
<grin>


--- In motm@y..., "Paul Schreiber" <synth1@a...> wrote:
> There is a chip (been around 20 years) called a UN2003 that is made 
for this. Cheap, too!
> 
> Paul S.
> 
> ----- Original Message ----- 
> From: "Sikorsky" <vulture.squadron@s...>
> To: "MOTM List" <motm@y...>
> Sent: Wednesday, October 30, 2002 5:53 AM
> Subject: [motm] daft circuit idea time
> 
> 
> > hello all,
> > 
> > powering through my DIY module backlog as i am, the following 
idea hit me -
> > how easy is it to make a swiitching module that uses a gate to 
switch a
> > relay
> > the relay is attached to tip & sleeve of a jack, and can be used 
for example
> > to switch in bypass mode on the MOTM850, but more importantly, 
various modes
> > on my roland vocoder, the bypass on my space echo etc etc
> > 
> > i assume the trick is to select the correct relay, then gate it 
via a buffer
> > circuit, and attach the switch section of the relay direct to the 
jacks -
> > any other idea anyone..?
> > also i asked this before, and lost the reply - does anyone have 
any stand
> > alone buffer circuit designs they can share..?
> > 
> > cheers
> > paul b
> > 
> > 
> > 
> > 
> > 
> >  
> > 
> > Your use of Yahoo! Groups is subject to 
http://docs.yahoo.com/info/terms/ 
> > 
> >