Synth-DIY Yahoo! Groups Archives

Thread

CGS 14 clean PSU Suitable transformer?

2007-10-02 by machvingtsun

Ive built a CGS 14 clean power supply. Can I use a 12v or 24v AC wall
wart to power it. These are the only reasonably priced transformers
here (Ireland).

Or does anyone know where I could salvage or buy for a reasonable
price a center tapped transformer?

Regards,
Michael.

Re: CGS 14 clean PSU Suitable transformer?

2007-10-03 by Andre Majorel

On 2007-10-02 15:52 -0000, machvingtsun wrote:

Show quoted textHide quoted text

> Ive built a CGS 14 clean power supply. Can I use a 12v or 24v AC wall
> wart to power it. These are the only reasonably priced transformers
> here (Ireland).
>
> Or does anyone know where I could salvage or buy for a reasonable
> price a center tapped transformer?

Farnell and RS Components have some. Last time I looked, it was
a lot cheaper to buy a large transformer and hang several PS off
it than buying one small transformer for each PS.

For bigger sizes, the toroidals are actually cheaper per VA.

I got a 300 VA 2 x 18 V toroidal (Farnell SKU 430-1742).

--
André Majorel <URL:http://www.teaser.fr/~amajorel/>
Do not use this account for regular correspondence.
See the URL above for contact information.

Re: CGS 14 clean PSU Suitable transformer?

2007-10-04 by machvingtsun

--- In cgs_synth@yahoogroups.com, Andre Majorel <aym-htnys@...>
wrote:

Show quoted textHide quoted text

>
> On 2007-10-02 15:52 -0000, machvingtsun wrote:
>
> > Ive built a CGS 14 clean power supply. Can I use a 12v or 24v AC

wall

> > wart to power it. These are the only reasonably priced

transformers

> > here (Ireland).
> >
> > Or does anyone know where I could salvage or buy for a reasonable
> > price a center tapped transformer?
>
> Farnell and RS Components have some. Last time I looked, it was
> a lot cheaper to buy a large transformer and hang several PS off
> it than buying one small transformer for each PS.
>
> For bigger sizes, the toroidals are actually cheaper per VA.
>
> I got a 300 VA 2 x 18 V toroidal (Farnell SKU 430-1742).
>
> --
> André Majorel <URL:http://www.teaser.fr/~amajorel/>
> Do not use this account for regular correspondence.
> See the URL above for contact information.
>

Thanks for the link Andre. One question though, in the
specifications its described as having two 115v primary, I assume
this is intended for a mains supply of 230V?

Re: CGS 14 clean PSU Suitable transformer?

2007-10-04 by Ove Ridé

On 04/10/2007, machvingtsun <machvingtsun@...> wrote:

Show quoted textHide quoted text

> Thanks for the link Andre. One question though, in the
> specifications its described as having two 115v primary, I assume
> this is intended for a mains supply of 230V?

If it says it has two 115v primaries, it most probably means the
transformer as designed that way to allow either 110~120 V and 220~240
V supplies by choosing different wires.

/Ove

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Re: CGS 14 clean PSU Suitable transformer?

2007-10-04 by Andre Majorel

On 2007-10-04 10:19 -0000, machvingtsun wrote:

Show quoted textHide quoted text

> --- In cgs_synth@yahoogroups.com, Andre Majorel <aym-htnys@...>
> wrote:
> > On 2007-10-02 15:52 -0000, machvingtsun wrote:
> >
> > > Ive built a CGS 14 clean power supply. Can I use a 12v or
> > > 24v AC wall wart to power it. These are the only reasonably
> > > priced transformers here (Ireland).
> > >
> > > Or does anyone know where I could salvage or buy for a
> > > reasonable price a center tapped transformer?
> >
> > I got a 300 VA 2 x 18 V toroidal (Farnell SKU 430-1742).
>
> Thanks for the link Andre. One question though, in the
> specifications its described as having two 115v primary, I assume
> this is intended for a mains supply of 230V?

As Ove said. Should you ever need to use your gear in a 115 V
locale, you would just have to rewire the primary.

A 300 VA transformer is quite heavy. The idea is to put it in a
box on the floor and run the secondaries to your power supplies
via 4-way connectors. Since the connectors and cable will be
pre-filtering caps and pre-regulator, voltage drop doesn't matter.
You could probably get away with something cheap like a 4-way DIN
if your PS doesn't draw more than about 2 A on each rail.

--
André Majorel <URL:http://www.teaser.fr/~amajorel/>
Do not use this account for regular correspondence.
See the URL above for contact information.

Bi N Tic question

2007-10-06 by Anthony Rolando

Hello, just finished building the Bi N Tic filter/ osc. and I have a couple of questions.

I was getting quite a bit of slop on the Frequency panel control. It basically only worked from about 12:00 on...

I traced this down to the 100n cap between pin 6 of the 3140 and the 100k that is connected to the base of the BC547`(of the collector is connected to the CD4024).

What was happening is that once the VCO went below a certain frequency, the Saw wave would all but disappear AFTER the 100n cap. It was a good signal at pin 6 of the 3140. The collect of the BC547 was just setting at 7V when the frequency was set to (or beyond) this low point.

I was able to rectify the situation (I think) by bridging the 100n. With the 100n out of circuit I get good strong oscillations for the entire range of the Freqency Panel control. The filter sonds really cool.

Any insight as to what might be happening would be greatly appreciate. I do not like the idea of removing something from the circit design in order to get it to work.

Thanx,

Tony
_________________________________________________________________
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Re: Bi N Tic question

2007-10-06 by sasami@hotkey.net.au

It sounds like the 100k pull-down resistor across the base/emitter of the
transistor may not be soldered in propperly or is or the wrong value, or
perhaps the 100n itself is bad, or the wrong value. Failing all else, if it
works with the 100n shorted out, just run it that way. There is enough other
protection circuitry there for there to be no problems.

Ken

Show quoted textHide quoted text

>
>Hello, just finished building the Bi N Tic filter/ osc. and I have a couple

of questions.

>
>I was getting quite a bit of slop on the Frequency panel control. It

basically only worked from about 12:00 on...

>
>I traced this down to the 100n cap between pin 6 of the 3140 and the 100k

that is connected to the base of the BC547`(of the collector is connected to
the CD4024).

>
>What was happening is that once the VCO went below a certain frequency, the

Saw wave would all but disappear AFTER the 100n cap. It was a good signal at
pin 6 of the 3140. The collect of the BC547 was just setting at 7V when the
frequency was set to (or beyond) this low point.

>
>I was able to rectify the situation (I think) by bridging the 100n. With

the 100n out of circuit I get good strong oscillations for the entire range
of the Freqency Panel control. The filter sonds really cool.

>
>Any insight as to what might be happening would be greatly appreciate. I do

not like the idea of removing something from the circit design in order to
get it to work.

>
>Thanx,
>
>Tony
>_________________________________________________________________
>Help yourself to FREE treats served up daily at the Messenger Café. Stop by

today.

>http://www.cafemessenger.com/info/info_sweetstuff2.html?ocid=TXT_TAGLM_OctW

Ltagline

>
>
>The CGS Modular Synth home page: http://www.cgs.synth.net/
>
>Yahoo! Groups Links
>
>
>
>

_______________________________________________________________________
Ken Stone sasami@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>

Re: Bi N Tic question

2007-10-06 by djbrow54

I had a similar problem. Basically I was loosing amplitude of the
signal through the capacitor at < 5 Hz. Eventually, it would fall
below the threshold of the transistor. There is plenty of signal to
clock the 4024, it's just at the wrong level. I replaced that circuit
with a two resistor and diode clamp to clock the 4024 directly.
Details are at
http://modularsynthesis.com/cgs/cgs.htm

Yours sounds similar, but different in that it stops at a higher
frequency.

Later, Richard Brewster posted a message for a similar problem: "I am
finishing mine, finally. I found an error in the clock coupling
circuit etch. The diode that is supposed to clamp the voltage on the
transistor base is not connected to the base of the transistor, but
rather to the opposite end of the 100K series input resistor. I fixed
this (cut the connection to the non-grounded end of the diode and put
a jumper to the correct spot). I also DC-coupled (omitted the 100nf
cap) that delivers the ramp out of the VCO."

That might have fixed mine but I never tried it. Richard also posted
another message about an error on the damping potentiometer wiring
diagram.

Dave

--- In cgs_synth@yahoogroups.com, Anthony Rolando <goldenechos@...>
wrote:

Show quoted textHide quoted text

>
>
> Hello, just finished building the Bi N Tic filter/ osc. and I have a

couple of questions.

>
> I was getting quite a bit of slop on the Frequency panel control. It

basically only worked from about 12:00 on...

>
> I traced this down to the 100n cap between pin 6 of the 3140 and the

100k that is connected to the base of the BC547`(of the collector is
connected to the CD4024).

>
> What was happening is that once the VCO went below a certain

frequency, the Saw wave would all but disappear AFTER the 100n cap. It
was a good signal at pin 6 of the 3140. The collect of the BC547 was
just setting at 7V when the frequency was set to (or beyond) this low
point.

>
> I was able to rectify the situation (I think) by bridging the 100n.

With the 100n out of circuit I get good strong oscillations for the
entire range of the Freqency Panel control. The filter sonds really
cool.

>
> Any insight as to what might be happening would be greatly

appreciate. I do not like the idea of removing something from the
circit design in order to get it to work.

>
> Thanx,
>
> Tony
> _________________________________________________________________
> Help yourself to FREE treats served up daily at the Messenger Café.

Stop by today.

> http://www.cafemessenger.com/info/info_sweetstuff2.html?

ocid=TXT_TAGLM_OctWLtagline

>

Re: Bi N Tic question

2007-10-06 by sasami@hotkey.net.au

Be aware the PCB should have been corrected since Richard found that error,
so depending on the age of the PCB you have, the diode may be in the correct
position.

Ken

Show quoted textHide quoted text

>I had a similar problem. Basically I was loosing amplitude of the
>signal through the capacitor at < 5 Hz. Eventually, it would fall
>below the threshold of the transistor. There is plenty of signal to
>clock the 4024, it's just at the wrong level. I replaced that circuit
>with a two resistor and diode clamp to clock the 4024 directly.
>Details are at
>http://modularsynthesis.com/cgs/cgs.htm
>
>Yours sounds similar, but different in that it stops at a higher
>frequency.
>
>Later, Richard Brewster posted a message for a similar problem: "I am
>finishing mine, finally. I found an error in the clock coupling
>circuit etch. The diode that is supposed to clamp the voltage on the
>transistor base is not connected to the base of the transistor, but
>rather to the opposite end of the 100K series input resistor. I fixed
>this (cut the connection to the non-grounded end of the diode and put
>a jumper to the correct spot). I also DC-coupled (omitted the 100nf
>cap) that delivers the ramp out of the VCO."
>
>That might have fixed mine but I never tried it. Richard also posted
>another message about an error on the damping potentiometer wiring
>diagram.
>
>Dave
>
>--- In cgs_synth@yahoogroups.com, Anthony Rolando <goldenechos@...>
>wrote:
>>
>>
>> Hello, just finished building the Bi N Tic filter/ osc. and I have a
>couple of questions.
>>
>> I was getting quite a bit of slop on the Frequency panel control. It
>basically only worked from about 12:00 on...
>>
>> I traced this down to the 100n cap between pin 6 of the 3140 and the
>100k that is connected to the base of the BC547`(of the collector is
>connected to the CD4024).
>>
>> What was happening is that once the VCO went below a certain
>frequency, the Saw wave would all but disappear AFTER the 100n cap. It
>was a good signal at pin 6 of the 3140. The collect of the BC547 was
>just setting at 7V when the frequency was set to (or beyond) this low
>point.
>>
>> I was able to rectify the situation (I think) by bridging the 100n.
>With the 100n out of circuit I get good strong oscillations for the
>entire range of the Freqency Panel control. The filter sonds really
>cool.
>>
>> Any insight as to what might be happening would be greatly
>appreciate. I do not like the idea of removing something from the
>circit design in order to get it to work.
>>
>> Thanx,
>>
>> Tony
>> _________________________________________________________________
>> Help yourself to FREE treats served up daily at the Messenger Café.
>Stop by today.
>> http://www.cafemessenger.com/info/info_sweetstuff2.html?
>ocid=TXT_TAGLM_OctWLtagline
>>
>
>
>
>
>The CGS Modular Synth home page: http://www.cgs.synth.net/
>
>Yahoo! Groups Links
>
>
>
>

Re: Bi N Tic question

2007-10-06 by Anthony Rolando

This is a revision 1.2 brd. Ken.

Tony

________________________________> To: cgs_synth@yahoogroups.com> From: sasami@...> Date: Sun, 7 Oct 2007 06:54:08 +1000> Subject: Re: [cgs_synth] Re: Bi N Tic question>> Be aware the PCB should have been corrected since Richard found that error,> so depending on the age of the PCB you have, the diode may be in the correct> position.> Ken>>I had a similar problem. Basically I was loosing amplitude of the>>signal through the capacitor at < 5 Hz. Eventually, it would fall>>below the threshold of the transistor. There is plenty of signal to>>clock the 4024, it's just at the wrong level. I replaced that circuit>>with a two resistor and diode clamp to clock the 4024 directly.>>Details are at>>http://modularsynthesis.com/cgs/cgs.htm>>>>Yours sounds similar, but different in that it stops at a higher>>frequency.>>>>Later, Richard Brewster posted a message for a similar problem: "I am>>finishing mine, finally. I found an error in the clock coupling>>circuit etch. The diode that is supposed to clamp the voltage on the>>transistor base is not connected to the base of the transistor, but>>rather to the opposite end of the 100K series input resistor. I fixed>>this (cut the connection to the non-grounded end of the diode and put>>a jumper to the correct spot). I also DC-coupled (omitted the 100nf>>cap) that delivers the ramp out of the VCO.">>>>That might have fixed mine but I never tried it. Richard also posted>>another message about an error on the damping potentiometer wiring>>diagram.>>>>Dave>>>>--- In cgs_synth@yahoogroups.com, Anthony Rolando>>wrote:>>>>>>>>> Hello, just finished building the Bi N Tic filter/ osc. and I have a>>couple of questions.>>>>>> I was getting quite a bit of slop on the Frequency panel control. It>>basically only worked from about 12:00 on...>>>>>> I traced this down to the 100n cap between pin 6 of the 3140 and the>>100k that is connected to the base of the BC547`(of the collector is>>connected to the CD4024).>>>>>> What was happening is that once the VCO went below a certain>>frequency, the Saw wave would all but disappear AFTER the 100n cap. It>>was a good signal at pin 6 of the 3140. The collect of the BC547 was>>just setting at 7V when the frequency was set to (or beyond) this low>>point.>>>>>> I was able to rectify the situation (I think) by bridging the 100n.>>With the 100n out of circuit I get good strong oscillations for the>>entire range of the Freqency Panel control. The filter sonds really>>cool.>>>>>> Any insight as to what might be happening would be greatly>>appreciate. I do not like the idea of removing something from the>>circit design in order to get it to work.>>>>>> Thanx,>>>>>> Tony>>> __________________________________________________________>>> Help yourself to FREE treats served up daily at the Messenger Café.>>Stop by today.>>> http://www.cafemessenger.com/info/info_sweetstuff2.html?>>ocid=TXT_TAGLM_OctWLtagline>>>>>>>>>>>>>The CGS Modular Synth home page: http://www.cgs.synth.net/>>>>Yahoo! Groups Links>>>>>>>>> __________________________________________________________> Ken Stone sasami@...> Modular Synth PCBs for sale> Australian Miniature Horses & Ponies>

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Re: Bi N Tic question

2007-10-06 by Anthony Rolando

>Basically I was loosing amplitude of the
> signal through the capacitor at < 5 Hz. Eventually, it would fall
> below the threshold of the transistor.

This is exactly the problem I am having. I did not measure the freqency at which it is occurring, but it is definitely at a low frequency (below 20hz).

I have the rev. 1.2 board, all the component vales have been checked and re-checked. The cap measures 100n out of circuit. Another 100n does the same thing.

Like Ken said, there should be plenty of protection for the 4024 (with the 100k, the diode, pull down R). STILL, I am very curious as to what could be causing this...

I was using a metal film cap, perhaps I should be using something else???

The unit is up and 'running without the cap AND IT IS FREAKING AWESOME.

I am just curious why this was happening.

Thanx for the replies,

Tony

________________________________> To: cgs_synth@yahoogroups.com> From: davebr@...> Date: Sat, 6 Oct 2007 14:15:46 +0000> Subject: [cgs_synth] Re: Bi N Tic question>> I had a similar problem. Basically I was loosing amplitude of the> signal through the capacitor at < 5 Hz. Eventually, it would fall> below the threshold of the transistor. There is plenty of signal to> clock the 4024, it's just at the wrong level. I replaced that circuit> with a two resistor and diode clamp to clock the 4024 directly.> Details are at> http://modularsynthesis.com/cgs/cgs.htm> Yours sounds similar, but different in that it stops at a higher> frequency.> Later, Richard Brewster posted a message for a similar problem: "I am> finishing mine, finally. I found an error in the clock coupling> circuit etch. The diode that is supposed to clamp the voltage on the> transistor base is not connected to the base of the transistor, but> rather to the opposite end of the 100K series input resistor. I fixed> this (cut the connection to the non-grounded end of the diode and put> a jumper to the correct spot). I also DC-coupled (omitted the 100nf> cap) that delivers the ramp out of the VCO."> That might have fixed mine but I never tried it. Richard also posted> another message about an error on the damping potentiometer wiring> diagram.> Dave> --- In cgs_synth@yahoogroups.com, Anthony Rolando> wrote:>>>>>> Hello, just finished building the Bi N Tic filter/ osc. and I have a> couple of questions.>>>> I was getting quite a bit of slop on the Frequency panel control. It> basically only worked from about 12:00 on...>>>> I traced this down to the 100n cap between pin 6 of the 3140 and the> 100k that is connected to the base of the BC547`(of the collector is> connected to the CD4024).>>>> What was happening is that once the VCO went below a certain> frequency, the Saw wave would all but disappear AFTER the 100n cap. It> was a good signal at pin 6 of the 3140. The collect of the BC547 was> just setting at 7V when the frequency was set to (or beyond) this low> point.>>>> I was able to rectify the situation (I think) by bridging the 100n.> With the 100n out of circuit I get good strong oscillations for the> entire range of the Freqency Panel control. The filter sonds really> cool.>>>> Any insight as to what might be happening would be greatly> appreciate. I do not like the idea of removing something from the> circit design in order to get it to work.>>>> Thanx,>>>> Tony>> __________________________________________________________>> Help yourself to FREE treats served up daily at the Messenger Café.> Stop by today.>> http://www.cafemessenger.com/info/info_sweetstuff2.html?> ocid=TXT_TAGLM_OctWLtagline>>>

_________________________________________________________________
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Re: Bi N Tic question

2007-10-07 by sasami@hotkey.net.au

>I am just curious why this was happening.

It probably comes down to the one significant variable in the area- the gain
of the transistor. Perhaps you have one with poor gain, where as I was
testing one with exceptional gain, the difference between the two extremes
thus not being allowed for in my design.

If the 100n is put back in circuit, and the resistor in series is reduced to
47k or 33k, what happens then?

Ken

>
>Thanx for the replies,
>
>Tony
>
>________________________________> To: cgs_synth@yahoogroups.com> From:

davebr@...> Date: Sat, 6 Oct 2007 14:15:46 +0000> Subject:
[cgs_synth] Re: Bi N Tic question>> I had a similar problem. Basically I was
loosing amplitude of the> signal through the capacitor at < 5 Hz.
Eventually, it would fall> below the threshold of the transistor. There is
plenty of signal to> clock the 4024, it's just at the wrong level. I
replaced that circuit> with a two resistor and diode clamp to clock the 4024
directly.> Details are at> http://modularsynthesis.com/cgs/cgs.htm> Yours
sounds similar, but different in that it stops at a higher> frequency.>
Later, Richard Brewster posted a message for a similar problem: "I am>
finishing mine, finally. I found an error in the clock coupling> circuit
etch. The diode that is supposed to clamp the voltage on the> transistor
base is not connected to the base of the transistor, but> rather to the
opposite end of the 100K series input resistor. I fixed> this (cut the
connection to the non-grounded end of the diode and put> a jumper to the
correct spot). I also DC-coupled (omitted the 100nf> cap) that delivers the
ramp out of the VCO."> That might have fixed mine but I never tried it.
Richard also posted> another message about an error on the damping
potentiometer wiring> diagram.> Dave> --- In cgs_synth@yahoogroups.com,
Anthony Rolando> wrote:>>>>>> Hello, just finished building the Bi N Tic
filter/ osc. and I have a> couple of questions.>>>> I was getting quite a
bit of slop on the Frequency panel control. It> basically only worked from
about 12:00 on...>>>> I traced this down to the 100n cap between pin 6 of
the 3140 and the> 100k that is connected to the base of the BC547`(of the
collector is> connected to the CD4024).>>>> What was happening is that once
the VCO went below a certain> frequency, the Saw wave would all but
disappear AFTER the 100n cap. It> was a good signal at pin 6 of the 3140.
The collect of the BC547 was> just setting at 7V when the frequency was set
to (or beyond) this low> point.>>>> I was able to rectify the situation (I
think) by bridging the 100n.> With the 100n out of circuit I get good strong
oscillations for the> entire range of the Freqency Panel control. The filter
sonds really> cool.>>>> Any insight as to what might be happening would be
greatly> appreciate. I do not like the idea of removing something from the>
circit design in order to get it to work.>>>> Thanx,>>>> Tony>>
__________________________________________________________>> Help yourself
to FREE treats served up daily at the Messenger Café.> Stop by today.>>
http://www.cafemessenger.com/info/info_sweetstuff2.html?>
ocid=TXT_TAGLM_OctWLtagline>>>

>
>_________________________________________________________________
>Climb to the top of the charts! Play Star Shuffle: the word scramble

challenge with star power.

>http://club.live.com/star_shuffle.aspx?icid=starshuffle_wlmailtextlink_oct
>
>The CGS Modular Synth home page: http://www.cgs.synth.net/
>
>Yahoo! Groups Links
>
>
>
>

Re: Bi N Tic question

2007-10-07 by contact@bridechamber.com

Just out of curiosity, what FET transistor are you using?

Scott

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

Show quoted textHide quoted text

From: Anthony Rolando
To: cgs_synth@yahoogroups.com
Sent: Saturday, October 06, 2007 8:32 PM
Subject: RE: [cgs_synth] Re: Bi N Tic question

>Basically I was loosing amplitude of the
> signal through the capacitor at < 5 Hz. Eventually, it would fall
> below the threshold of the transistor.

This is exactly the problem I am having. I did not measure the freqency at which it is occurring, but it is definitely at a low frequency (below 20hz).

I have the rev. 1.2 board, all the component vales have been checked and re-checked. The cap measures 100n out of circuit. Another 100n does the same thing.

Like Ken said, there should be plenty of protection for the 4024 (with the 100k, the diode, pull down R). STILL, I am very curious as to what could be causing this...

I was using a metal film cap, perhaps I should be using something else???

The unit is up and 'running without the cap AND IT IS FREAKING AWESOME.

I am just curious why this was happening.

Thanx for the replies,

Tony

________________________________> To: cgs_synth@yahoogroups.com> From: davebr@...> Date: Sat, 6 Oct 2007 14:15:46 +0000> Subject: [cgs_synth] Re: Bi N Tic question>> I had a similar problem. Basically I was loosing amplitude of the> signal through the capacitor at < 5 Hz. Eventually, it would fall> below the threshold of the transistor. There is plenty of signal to> clock the 4024, it's just at the wrong level. I replaced that circuit> with a two resistor and diode clamp to clock the 4024 directly.> Details are at> http://modularsynthesis.com/cgs/cgs.htm> Yours sounds similar, but different in that it stops at a higher> frequency.> Later, Richard Brewster posted a message for a similar problem: "I am> finishing mine, finally. I found an error in the clock coupling> circuit etch. The diode that is supposed to clamp the voltage on the> transistor base is not connected to the base of the transistor, but> rather to the opposite end of the 100K series input resistor. I fixed> this (cut the connection to the non-grounded end of the diode and put> a jumper to the correct spot). I also DC-coupled (omitted the 100nf> cap) that delivers the ramp out of the VCO."> That might have fixed mine but I never tried it. Richard also posted> another message about an error on the damping potentiometer wiring> diagram.> Dave> --- In cgs_synth@yahoogroups.com, Anthony Rolando> wrote:>>>>>> Hello, just finished building the Bi N Tic filter/ osc. and I have a> couple of questions.>>>> I was getting quite a bit of slop on the Frequency panel control. It> basically only worked from about 12:00 on...>>>> I traced this down to the 100n cap between pin 6 of the 3140 and the> 100k that is connected to the base of the BC547`(of the collector is> connected to the CD4024).>>>> What was happening is that once the VCO went below a certain> frequency, the Saw wave would all but disappear AFTER the 100n cap. It> was a good signal at pin 6 of the 3140. The collect of the BC547 was> just setting at 7V when the frequency was set to (or beyond) this low> point.>>>> I was able to rectify the situation (I think) by bridging the 100n.> With the 100n out of circuit I get good strong oscillations for the> entire range of the Freqency Panel control. The filter sonds really> cool.>>>> Any insight as to what might be happening would be greatly> appreciate. I do not like the idea of removing something from the> circit design in order to get it to work.>>>> Thanx,>>>> Tony>> __________________________________________________________>> Help yourself to FREE treats served up daily at the Messenger Café.> Stop by today.>> http://www.cafemessenger.com/info/info_sweetstuff2.html?> ocid=TXT_TAGLM_OctWLtagline>>>

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Re: Bi N Tic question

2007-10-07 by Anthony Rolando

4091. I do not think it is the FET. The signal maintains a pretty constant amplitude for the entire range of the the oscillator. It is onlt AFTER the 100n coupling cap that the amplitude is lost.

Tony

________________________________> To: cgs_synth@yahoogroups.com> From: contact@...> Date: Sun, 7 Oct 2007 11:08:07 -0400> Subject: Re: [cgs_synth] Re: Bi N Tic question>> Just out of curiosity, what FET transistor are you using?> Scott> ----- Original Message -----> From: Anthony Rolando> To: cgs_synth@yahoogroups.com> Sent: Saturday, October 06, 2007 8:32 PM> Subject: RE: [cgs_synth] Re: Bi N Tic question>>Basically I was loosing amplitude of the>> signal through the capacitor at < 5 Hz. Eventually, it would fall>> below the threshold of the transistor.> This is exactly the problem I am having. I did not measure the freqency at which it is occurring, but it is definitely at a low frequency (below 20hz).> I have the rev. 1.2 board, all the component vales have been checked and re-checked. The cap measures 100n out of circuit. Another 100n does the same thing.> Like Ken said, there should be plenty of protection for the 4024 (with the 100k, the diode, pull down R). STILL, I am very curious as to what could be causing this...> I was using a metal film cap, perhaps I should be using something else???> The unit is up and 'running without the cap AND IT IS FREAKING AWESOME.> I am just curious why this was happening.> Thanx for the replies,> Tony> ________________________________> To: cgs_synth@yahoogroups.com> From: davebr@...> Date: Sat, 6 Oct 2007 14:15:46 +0000> Subject: [cgs_synth] Re: Bi N Tic question>> I had a similar problem. Basically I was loosing amplitude of the> signal through the capacitor at < 5 Hz. Eventually, it would fall> below the threshold of the transistor. There is plenty of signal to> clock the 4024, it's just at the wrong level. I replaced that circuit> with a two resistor and diode clamp to clock the 4024 directly.> Details are at> http://modularsynthesis.com/cgs/cgs.htm> Yours sounds similar, but different in that it stops at a higher> frequency.> Later, Richard Brewster posted a message for a similar problem: "I am> finishing mine, finally. I found an error in the clock coupling> circuit etch. The diode that is supposed to clamp the voltage on the> transistor base is not connected to the base of the transistor, but> rather to the opposite end of the 100K series input resistor. I fixed> this (cut the connection to the non-grounded end of the diode and put> a jumper to the correct spot). I also DC-coupled (omitted the 100nf> cap) that delivers the ramp out of the VCO."> That might have fixed mine but I never tried it. Richard also posted> another message about an error on the damping potentiometer wiring> diagram.> Dave> --- In cgs_synth@yahoogroups.com, Anthony Rolando> wrote:>>>>>> Hello, just finished building the Bi N Tic filter/ osc. and I have a> couple of questions.>>>> I was getting quite a bit of slop on the Frequency panel control. It> basically only worked from about 12:00 on...>>>> I traced this down to the 100n cap between pin 6 of the 3140 and the> 100k that is connected to the base of the BC547`(of the collector is> connected to the CD4024).>>>> What was happening is that once the VCO went below a certain> frequency, the Saw wave would all but disappear AFTER the 100n cap. It> was a good signal at pin 6 of the 3140. The collect of the BC547 was> just setting at 7V when the frequency was set to (or beyond) this low> point.>>>> I was able to rectify the situation (I think) by bridging the 100n.> With the 100n out of circuit I get good strong oscillations for the> entire range of the Freqency Panel control. The filter sonds really> cool.>>>> Any insight as to what might be happening would be greatly> appreciate. I do not like the idea of removing something from the> circit design in order to get it to work.>>>> Thanx,>>>> Tony>> __________________________________________________________>> Help yourself to FREE treats served up daily at the Messenger Café.> Stop by today.>> http://www.cafemessenger.com/info/info_sweetstuff2.html?> ocid=TXT_TAGLM_OctWLtagline>>>> __________________________________________________________> Climb to the top of the charts! Play Star Shuffle: the word scramble challenge with star power.> http://club.live.com/star_shuffle.aspx?icid=starshuffle_wlmailtextlink_oct> [Non-text portions of this message have been removed]>

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Re: Bi N Tic question

2007-10-07 by Anthony Rolando

4091. I do not think it is the FET. The signal maintains a pretty constant amplitude for the entire range of the the oscillator. It is onlt AFTER the 100n coupling cap that the amplitude is lost.

Tony

________________________________> To: cgs_synth@yahoogroups.com> From: contact@...> Date: Sun, 7 Oct 2007 11:08:07 -0400> Subject: Re: [cgs_synth] Re: Bi N Tic question>> Just out of curiosity, what FET transistor are you using?> Scott> ----- Original Message -----> From: Anthony Rolando> To: cgs_synth@yahoogroups.com> Sent: Saturday, October 06, 2007 8:32 PM> Subject: RE: [cgs_synth] Re: Bi N Tic question>>Basically I was loosing amplitude of the>> signal through the capacitor at < 5 Hz. Eventually, it would fall>> below the threshold of the transistor.> This is exactly the problem I am having. I did not measure the freqency at which it is occurring, but it is definitely at a low frequency (below 20hz).> I have the rev. 1.2 board, all the component vales have been checked and re-checked. The cap measures 100n out of circuit. Another 100n does the same thing.> Like Ken said, there should be plenty of protection for the 4024 (with the 100k, the diode, pull down R). STILL, I am very curious as to what could be causing this...> I was using a metal film cap, perhaps I should be using something else???> The unit is up and 'running without the cap AND IT IS FREAKING AWESOME.> I am just curious why this was happening.> Thanx for the replies,> Tony> ________________________________> To: cgs_synth@yahoogroups.com> From: davebr@...> Date: Sat, 6 Oct 2007 14:15:46 +0000> Subject: [cgs_synth] Re: Bi N Tic question>> I had a similar problem. Basically I was loosing amplitude of the> signal through the capacitor at < 5 Hz. Eventually, it would fall> below the threshold of the transistor. There is plenty of signal to> clock the 4024, it's just at the wrong level. I replaced that circuit> with a two resistor and diode clamp to clock the 4024 directly.> Details are at> http://modularsynthesis.com/cgs/cgs.htm> Yours sounds similar, but different in that it stops at a higher> frequency.> Later, Richard Brewster posted a message for a similar problem: "I am> finishing mine, finally. I found an error in the clock coupling> circuit etch. The diode that is supposed to clamp the voltage on the> transistor base is not connected to the base of the transistor, but> rather to the opposite end of the 100K series input resistor. I fixed> this (cut the connection to the non-grounded end of the diode and put> a jumper to the correct spot). I also DC-coupled (omitted the 100nf> cap) that delivers the ramp out of the VCO."> That might have fixed mine but I never tried it. Richard also posted> another message about an error on the damping potentiometer wiring> diagram.> Dave> --- In cgs_synth@yahoogroups.com, Anthony Rolando> wrote:>>>>>> Hello, just finished building the Bi N Tic filter/ osc. and I have a> couple of questions.>>>> I was getting quite a bit of slop on the Frequency panel control. It> basically only worked from about 12:00 on...>>>> I traced this down to the 100n cap between pin 6 of the 3140 and the> 100k that is connected to the base of the BC547`(of the collector is> connected to the CD4024).>>>> What was happening is that once the VCO went below a certain> frequency, the Saw wave would all but disappear AFTER the 100n cap. It> was a good signal at pin 6 of the 3140. The collect of the BC547 was> just setting at 7V when the frequency was set to (or beyond) this low> point.>>>> I was able to rectify the situation (I think) by bridging the 100n.> With the 100n out of circuit I get good strong oscillations for the> entire range of the Freqency Panel control. The filter sonds really> cool.>>>> Any insight as to what might be happening would be greatly> appreciate. I do not like the idea of removing something from the> circit design in order to get it to work.>>>> Thanx,>>>> Tony>> __________________________________________________________>> Help yourself to FREE treats served up daily at the Messenger Café.> Stop by today.>> http://www.cafemessenger.com/info/info_sweetstuff2.html?> ocid=TXT_TAGLM_OctWLtagline>>>> __________________________________________________________> Climb to the top of the charts! Play Star Shuffle: the word scramble challenge with star power.> http://club.live.com/star_shuffle.aspx?icid=starshuffle_wlmailtextlink_oct> [Non-text portions of this message have been removed]>

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Re: Bi N Tic question

2007-10-08 by djbrow54

It'a a high pass filter and eventually it will roll off so that the
transistor is not ever biased on. Mine rolled off somewhere below 15
Hz. At 5 Hz the drive was 400 mV, well below Vbe required to bias the
transistor. That's why I changed to a level shifter by dividing the
signal and clamping it to ground. Fewer parts and works to 'DC'.

Dave

Re: Bi N Tic question

2007-10-08 by Anthony Rolando

Dave, your description makes alot of sense. When I look at what is happening on my scope I am seeing the VCO hi-pass filtered until there is almost no amplitude. I measured the frequency and mine really starts to lose amplitude at 20hz and is less than 500mv by 17hz.

The 100n cap and the 100k series R and 100k R to gnd form a high-pass filter, right.

Perhaps changing the value of the cap and or resistor(s) would also solve the problem. Dave I like your fix, it is simple, works.

Ken has suggested that the variation in gain on the transistor is the culprit. I am going to try changing the series R to 47k (as he suggested) tonight.

IN ANY CASE, THANK YOU everybody for your insight. I have the circuit working, but I am still just curious about how this was happening on my board. I have hard time believing that Dave and I are the only people that have had this issue... Maybe there is something about the way solder flows in North Carolina!

Tony
To: cgs_synth@yahoogroups.com
From: davebr@...
Date: Mon, 8 Oct 2007 04:23:37 +0000
Subject: [cgs_synth] Re: Bi N Tic question

It'a a high pass filter and eventually it will roll off so that the

transistor is not ever biased on. Mine rolled off somewhere below 15

Hz. At 5 Hz the drive was 400 mV, well below Vbe required to bias the

transistor. That's why I changed to a level shifter by dividing the

signal and clamping it to ground. Fewer parts and works to 'DC'.

Dave

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Re: Bi N Tic question

2007-10-09 by djbrow54

At 500 mV, no amount of gain is going to help your transistor. There
simply isn't enough voltage to bias the transistor on. You need to
change the rolloff frequency. Changing the value of the capacitor or
resistor will do that.

I couldn't figure out why I wanted a high pass filter or capacitive
coupling so I just simplified it with a level shifter. Maybe there is
a reason but no matter what, this is a great filter. It's one of my
favorites, and I get some really neat sounds with a very low
frequency.

Dave

--- In cgs_synth@yahoogroups.com, Anthony Rolando <goldenechos@...>
wrote:

Show quoted textHide quoted text

> Dave, your description makes alot of sense. When I look at what is

happening on my scope I am seeing the VCO hi-pass filtered until there
is almost no amplitude. I measured the frequency and mine really
starts to lose amplitude at 20hz and is less than 500mv by 17hz.

>
> The 100n cap and the 100k series R and 100k R to gnd form a high-

pass filter, right.

>
> Perhaps changing the value of the cap and or resistor(s) would also

solve the problem. Dave I like your fix, it is simple, works.

>
> Ken has suggested that the variation in gain on the transistor is

the culprit. I am going to try changing the series R to 47k (as he
suggested) tonight.

>
> IN ANY CASE, THANK YOU everybody for your insight. I have the

circuit working, but I am still just curious about how this was
happening on my board. I have hard time believing that Dave and I are
the only people that have had this issue... Maybe there is something
about the way solder flows in North Carolina!

>
> Tony
> To: cgs_synth@yahoogroups.com
> From: davebr@...
> Date: Mon, 8 Oct 2007 04:23:37 +0000
> Subject: [cgs_synth] Re: Bi N Tic question
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the

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> transistor. That's why I changed to a level shifter by dividing the
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> _________________________________________________________________
> Boo! Scare away worms, viruses and so much more! Try Windows Live

OneCare!

> http://onecare.live.com/standard/en-us/purchase/trial.aspx?

s_cid=wl_hotmailnews

>
> [Non-text portions of this message have been removed]
>

Cgs synth

CGS 14 clean PSU Suitable transformer?

CGS 14 clean PSU Suitable transformer?

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Re: CGS 14 clean PSU Suitable transformer?

Re: CGS 14 clean PSU Suitable transformer?

Re: CGS 14 clean PSU Suitable transformer?

Bi N Tic question

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