The Bintic is a VCF that has its frequency driven by an internal VCO. External CVs control the filter by affecting the VCO's frequency.
It's easiest to think of it in three chunks -- the VCF which changes the audio signal input, the VCO which handles the frequency, and the logic section of divider and switches which "translate" from VCO to VCF in a way. Once you start seeing schematics as chunks of building blocks, it gets easier to see what's going on.
Now, Ken used a very good VCO core to drive the divider. He brought 4 divisions out to use as "Excite" signals. These are just squarewave divisions that are in sync with the filter's frequency and can do some interesting things -- interesting because the filter can be precisely tuned to 1v/oct.
Using a bit of extra circuitry you can use the VCO core to get sawtooth and squarewave at 1v/oct, as per the Electronotes link on Ken's page. That's what I did for my Bridechamber module. Using a bit more circuitry you can get pulse width -- Tellun's MUUB-4 would be a able to do that. Using a good bit more than that, you should use Ken's dedicated VCO :)
Hope that helps,
Scott
It's easiest to think of it in three chunks -- the VCF which changes the audio signal input, the VCO which handles the frequency, and the logic section of divider and switches which "translate" from VCO to VCF in a way. Once you start seeing schematics as chunks of building blocks, it gets easier to see what's going on.
Now, Ken used a very good VCO core to drive the divider. He brought 4 divisions out to use as "Excite" signals. These are just squarewave divisions that are in sync with the filter's frequency and can do some interesting things -- interesting because the filter can be precisely tuned to 1v/oct.
Using a bit of extra circuitry you can use the VCO core to get sawtooth and squarewave at 1v/oct, as per the Electronotes link on Ken's page. That's what I did for my Bridechamber module. Using a bit more circuitry you can get pulse width -- Tellun's MUUB-4 would be a able to do that. Using a good bit more than that, you should use Ken's dedicated VCO :)
Hope that helps,
Scott
----- Original Message -----
From: casperelectronics
To: cgs_synth@yahoogroups.com
Sent: Saturday, April 07, 2007 5:30 PM
Subject: Re: [cgs_synth] bi-n-tic filter...help!
I just realized I've been using the PN4391 too. But I don't think it
should make any difference.
I'm still confused....
Is this module supposed to function as a VCF> and< VCO or is it just
a VCF? Is the VCO only possible with added circuitry?
I'm confused because from Ken Stone's web site it sounds like you
should be able to use this module as a VCO.
This is an excerpt from the bi-n-tic page where he describes the
"excitation" rotary switch.
"Positions 2 to 5 of the rotary switch now provide four signals, one
octave apart, to "excite" the the filter when it is adjusted to be
near resonant, or if the filter is backed off, four octaves of square
wave VCO output."
Thanks!
-pete
www.casperelectronics.com
On Apr 5, 2007, at 3:01 PM, Scott Deyo wrote:
> I've been using the PN4391, not 2N4391. Sorry. Same pinout as the FET
> on the PCB.
> Didn't get to play w/ it last night...
>
> Scott Deyo
> The Bridechamber
> contact@...
> www.bridechamber.com
>
> On Apr 3, 2007, at 3:19 PM, casperelectronics wrote:
>
> > Hey scott,
> > Here are all of the part substitutions. I think these should all
> work
> > no prob.
> > LF356 > TL071s,
> > LM394>ssm2010 (Ray Wilson lists this as a good replacement for the
> > LM394)
> > 1Ktempco>standard 1K resistor
> > 1N4148>1N914
> > input "beads">10ohm resistors
> > I used a 2N4091 for my FET (which is what he says he uses in the
> > circuit description).
> > I checked all of the polarities, jumpers and other connections...no
> > prob. Before I wrote I noticed that my diode was in backwards. I was
> > excited thinking
> > that this must be the source of the problem,,,, I flipped it around
> > and their was absolutely no noticeable change in performance :(
> > How do you switch between filter and osc. when this is working
> > correctly?
> > -pete
> >
> > On Apr 3, 2007, at 9:14 AM, <contact@...>
> > <contact@...> wrote:
> >
> > > Any component substitutions?
> > > 99% of the time it's a polarity, wiring or trace problem, at least
> > > with me :)
> > >
> > > Cheers,
> > > Scott
> > >
> > > ----- Original Message -----
> > > From: casperelectronics
> > > To: cgs_synth@yahoogroups.com
> > > Sent: Tuesday, April 03, 2007 12:54 AM
> > > Subject: [cgs_synth] bi-n-tic filter...help!
> > >
> > > I just finished building the bi-n-tic filter and I don't seem
> to be
> > > getting any osc. output. The filter works great, bandwidth and
> > damper
> > > do what they are supposed to do but the frequency controls
> don't do
> > > anything. Anyone have much experience with this circuit?
> > >
> > > [Non-text portions of this message have been removed]
> > >
> > >
> > >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
>
> [Non-text portions of this message have been removed]
>
>
>
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