Cgs synth

Hey,
thanks for the response! I discovered a huge problem. Somehow one of
the traces on the board was cut and there was no ground connection to
the 4051s or the 4024. Connecting fixed a few issues but had no
noticeable effect on the VCO leak through problem.
I checked the outs of the 4024 and I'm getting 3 clean square waves.
One strange issue is that the VCO cuts off, just stops running at a
high frequency ALMOST out of the audible range.
When you turn it up to a certain point it cuts very noisy then just
cuts off.
Plus As I mentioned a bunch of times, I'm still getting strong bleed
through.
I've replaced every chip except the CA3140. I don't have a
replacement for that. Could that be responsible for my cutoff problem?
-pete

On Dec 1, 2008, at 4:07 AM, andrewlistmayer wrote:

> Mine isn`t working properly either, but based on what you said I`m
> 99.9999% sure your isn`t either. The VCO is supposed to clock the
> filter, so the frequency of the filter changes with it. When the
> filter receives no clock from the VCO, it seems to lock to a fixed
> frequency which is below the audible range. Mine did this before I
> fixed the VCO. The reason you get a filter sweep in the last 20% of
> the bandwidth knob is because you are simply increasing the band large
> enough to let some audio through, while the center point still sits in
> the sub audio range, so it`s acting like a normal lowpass filter. At
> least that`s how I interpreted it when my VCO wasn`t working.
>
> Now, the VCO leaking through into the audio without clocking the
> filter, that`s a new one to me. I`m no expert at this, so all I can
> say is that it`s clear your filter and VCO are working, so your
> problem mostly likely lies in the circuitry that is supposed to make
> them work together. The filter is clocked by 3 outputs of the 4024, so
> I`d check around there. Good luck.
>
> --- In cgs_synth@yahoogroups.com, casperelectronics <pete@...> wrote:
> >
> > Hello everyone.
> > Sorry to continue the Bi-N-Tic questions. I know there have been a
> > lot and I've read them all and I still have a few more.
> > I think I got the whole thing working right but I'm not sure, it's a
> > weird module (as I'm sure you'll all agree)
> > The way it is working now it is really two modules, a filter and a
> > VCO, but I don't see (or hear) much connection between the two.
> >
> > If I turn the coarse and fine tune knobs all the way down, there is
> > no oscillator.
> > Then if I feed a signal in the IN jack i can get some really nice
> > filter cut sweeps using the BANDWIDTH knob and resonance using the
> > DAMPER knob. The whole filter sweep is in the last 20% of turn of
> > the bandwidth knob.
> > As I turn UP the coarse tune, a square osc, mixes into the signal.
> > It doesn't effect the filter, it just mixes into the audio path.
> > When I turn it up almost beyond the audio range, the osc suddenly
> > cuts off.
> > Anyway.. maybe this is just how it works? I'd like to talk to
> > someone who has built one or two of these so that I know if I should
> > work on it some more.
> > I really wish there was some kind of CV for filter cut. Am I missing
> > something?
> > Thanks!!!!
> > -pete
> >
> >
> >
> >
> >
> > On Nov 28, 2008, at 9:54 PM, casperelectronics wrote:
> >
> > > Hey Scott,
> > > I want to add the wave outputs on my bintic filter but I can't
> find
> > > the info.
> > > Do you sell daughter boards/ host schematics for that on your
> site??
> > > Thanks!
> > > -pete
> > >
> > >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
>



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