Cgs synth

Yes, I have 4 suboctave outputs so I needed them to always operate
correctly.

If the volume sounds just as loud, your fet is probably working
fine. It was worth a try. Hard to debug without a scope.

Dave

--- In cgs_synth@yahoogroups.com, "andrewlistmayer"
<andrewlistmayer@...> wrote:

>
> Hmm, I read on your site that you wanted to clock the 4024 at 5hz or
> less. I guess this would do nothing for the filter and you wanted to
> use the suboctave outputs as logic, right?
>
> I don't have a scope, so I can't measure the amplitude of the 3140
> output, but it seems to be almost as loud as a 5Vpp osc, just a

little

> less. When I measure it with my DVM it reads a steady 2.18. I guess

if

> the osc frequency is too high and the amplitude is low then it means
> that the FET or the 311 is switching prematurely, before the cap is
> fully charged? I'll try a different 4391. The only other fet I have

is

> MPF-102 and everyone seems to have problems with those.
>
>
>
> --- In cgs_synth@yahoogroups.com, "djbrow54" <davebr@> wrote:
> >
> > My VCO didn't run correctly the first time either. With a scope

I

> > could see that the ramp output of the VCO (pin 6 of the CA3140)

was

> > very low amplitude. I replaced the MPF102 with a different FET

and

> > it worked fine. I have no idea why the original FET didn't work.
> >
> > The clock mod is for very low frequency response. The clock is
> > capacitive coupled and there just isn't enough voltage swing to
> > trigger the clock input of the 4024 at VERY low frequencies. I

DC

> > coupled mine so it wouldn't be an issue.
> >
> > Richard Brewster later posted something with the PCB trace not
> > matching the schematic in this area. I don't know if he had an

early

> > PCB or what the issue was. Search for message 2164. This only
> > affects the output of the 4024, not the VCO output.
> >
> > Check the VCO output on pin 6 of the CA3140. You can just

connect

> > this to an amplifier through a suitable capacitor to remove the

DC

> > bias. This needs to be working correctly before verifying the

4024.

> > If it was like mine and only had 1V pk-pk - then the low

frequency

> > range is quite limited. It also could be an issue with the LM311
> > voltage comparator.
> >
> > Dave
> >
> > --- In cgs_synth@yahoogroups.com, Tom Adam <tom.adam@> wrote:
> > >
> > > I'm about to build my bi-n-tic and I came across this link.
> > > Check the clock driver mod. Is this what you're seeing?
> > >
> > > http://modularsynthesis.com/cgs/bi-n-tic/bi-n-tic.htm
> > >
> > > Cheers,
> > > ToAd
> > >
> >
>