Cgs synth

Thanks for the feedback. The VCO square wave output becomes distorted
for one half of a degree of a turn then just cuts off if I turn it up
any further.
The board is REV 1.2.
I'm using a 2N4091 and 2n2 styrene cap. I had used an MPF102 tran
before, but that didn't work at all.
-pete

On Dec 3, 2008, at 3:11 AM, sasami@... wrote:

> Any clocking issue usually relates to the transistor/capacitor
> coupling
> between the VCO and the counter. If the VCO continues up after the
> filter
> stops, look there. Make sure you are not using one of the ancient
> prototype
> boards! I made the mistake of giving a few away, and they keep on
> coming
> back to haunt me.
>
> >I'm not too sure if the 3140 would be causing your problem, but I
> >wouldn't expect so. If you are getting 3 clean square waves from the
> >4024, but they are not clocking the filter, I'd check the 4051's.
> >About the bleeding problem, maybe try removing the 4051's and 4024
> and
> >see if it persists? just to try to get a better idea of where it's
> >coming from.
> >
> >Just curious, how low does the pitch of the VCO go then fully CCW? I
> >have much the same problem on mine, where it goes up to the high
> audio
> >range then cuts out, however it DOES clock the filter and doesn't
> >bleed through. The minimum pitch I can get is fairly high, too.
> >
> >
> >--- In cgs_synth@yahoogroups.com, casperelectronics <pete@...> wrote:
> >>
> >> 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]
> >> > >
> >> >
> >> >
> >> >
> >>
> >>
> >>
> >> [Non-text portions of this message have been removed]
> >>
> >
> >
> >
> >------------------------------------
> >
> >The CGS Modular Synth home page: http://www.cgs.synth.net/
> >Yahoo! Groups Links
> >
> >
> >
> >
> __________________________________________________________
> Ken Stone sasami@... otherunicorn@...
> Modular Synth PCBs for sale <http://www.cgs.synth.net/>
> Australian Miniature Horses & Ponies <http://www.blaze.net.au/
> ~sasami/>
>
>
>



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