[sdiy] RE: WP20 VCA

[Grant Richter]

Hi Ray,

> I just went and did some breadboarding to see what I was thinking 20 years
> ago. The answer... not much. At best the circuit is very non-linear. In
> other words if you start with a triangle wave in you get a severely
> distorted triangle wave out. While experimenting I had to double the gain
> (200K instead of 100K feedback resistor) so that the signal was a little
> more above the noise level of the chip. I recommend that you find another
> VCA circuit. I have a couple of pretty low parts count VCAs on my site but
> the WP20 stuff was the misguided effort of a much younger and not very
> electronically savvy man (me). I can't even remember if I had an
> oscilloscope back then.

Somebody used the term "anti-synth" a while back. That go me thinking about
a synth deliberately designed from nasty, distorted, non-conforming and
imperfect modules. (kind of like a PAIA Gnome, only deliberately this time,
just razzing you John!!!)

So let's call this circuit, part of the "anti-synth" collection. <grin> I
found a VC waveshaper that sounds like a train wreck (not literally), I will
post an "anti-synth" design at some point.

Like that CA3096 based VCO with 10K of DeFranco compensation. While still a
VCO, it has the most waveform shift with frequency. Bad in the traditional
sense, but a design win for an "anti-synth".

No offense intended here. The brilliant people on this list who are
dedicated to producing ever improved designs, have my complete admiration.
But it is kind of fun to reverse your perspective, and see how BAD you can
design, while still making a module function.