Cgs synth

Anyone with the Bi N Tic VCO/VCF out there know, if it's easier to
tune the VCO portion to 1V/O by disconnecting the 4024 counter / 4051
multiplexers? When I was tuning the VCO last night, there were a fair
bit of jitter. I've gotten it tuned to under 1% over 4 octaves, but
the jitter makes it a little hard to get down below 0.25%. :(

Just curious - as I'm going to be modding both of mine, to buffer the
3140's +5 sawtooth, for +/- 5VAC Saw, as well as dual PW/PWM waveform
outputs, bringing the Counter input to a jack as well. So that the
VCO as well as an external input can both drive it. (Buffer / mixer,
for the two.)

Thanks for any help. :) I'm figuring the 4024 counting away, could be
introducing current jitter, to the VCO, for tuning to 1V/O. (I THINK -
I'm still lacking on theory to completely understand.)

Outside of that - Ken / Jan Hall - this is one of the most demonically
twisted modules I've ever heard in my 32 years of playing with modular
synths. :O Well, well done! :) :) :)

--
Take care,
Warmth and Peace,
Ryk

http://www.sdiy.org/damian/index.html - my modular synth's homepage :)

I removed (shorted out) the 100n capacitor between the CA3140 pin 6
output and the 100k input to the base of the transistor that drives the
4024. This works fine. I don't know if it would reduce the jitter, but
it's easy to try. Interesting idea you have to provide the counter
input, so it can be driven externally. Should be easy to do, and if you
make the sawtooth available as an output, normalized to the counter
input, that sounds like a good idea as well.

For general mods to the VCO, including the +/- 5V sawtooth output, see
my mods for the CGS VCO, which is the same circuit:

http://www.pugix.com/cgs-vco.htm
http://www.pugix.com/images/cgs-vco-11-5-05.pdf

Richard Brewster

Rykhaard D.A.M.I.A.N. wrote: