[sdiy] WP LM3900 VCF

[Tim Parkhurst]

Check the schematics for the old PAIA Gnome. A fun effects synth / sound
box, and the whole thing was built around a single 3900.


Tim (getter older and more gnome-like everyday) Servo
--
"Imagination is more important than knowledge." - Albert Einstein


On 1/13/06, Johannes Öberg <johannes.oberg at gmail.com> wrote:
>
> Bringing up another old thread - what happened? And what about the 3900
> and norton amps in general? What are they really good for?
>
> I'm also considering the WP20 circuitry since it looks kinda "punk" :-)
> And I happen to have a bunch of LM3900's that I have no idea what to use
> for.
>
> /J
>
> On 3/1/05, anthony <aankrom at bluemarble.net> wrote:
> >
> > So I'm in the middle of building an effects synth from 2 XR2206's. I
> > came up
> > with a good VCO set-up on my own (even a mode where they're both used as
> > a
> > 100kHz beat oscillator).
> >
> > For the rest of it there were too many good ideas for me to easilly pick
> > the
> > circuits I wanted to use. But I decided on Ray Wilson's sound lab. (It's
> > a
> > really cool design. I may end up making another one for my daughter.)
> >
> > But after I decided this I looked at the older WP20 and I thought 'hey I
> >
> > have an LM3900...' So I could make the VCF, VCA and AR eg with one chip!
> > (Er
> > maybe there's a 555 in there too, but still...) This seemed cool to me.
> > Anyone think of a good reason not to? Or rather what is it about the
> > Norton
> > amp that makes it special? Or /is/ it special? It almost seems like a
> > backwards OTA...
> >
>
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