I always liked the original ROG Phozer's base sound, but the LFO wasn't really that useful at lower speeds. So I took the basic idea, which is the Idiot Wah + LFO, and kicked it up a notch. Instead of the Phozer's input JFET buffer, I went with an op amp buffer, and since there's an extra amp in the package, I also added an output buffer. The LFO is the same one I've been tacking on to everything the past couple years (from the STM). For the variable resistor element, I went with the H11F1 opto IC. But a vactrol or LED/LDR would also work very similarly (and actually they sound better).
It's not a phaser. It's not a vibe. It's not a tremolo. I suppose it's most like a phaser with a dash of trem, but it's really not all that much like any commercially available modulation. Which is probably a good thing.
This was something I drew up and hoped worked when I ordered the proto board. And it does work quite well. Surely there are many mods and tweaks to be made to improve, extend, or expand the tones available. I offer this working, fun, useful circuit to the community to experiment with and renovate.
Sound clip of the circuit with the H11F1 opto is below. I recommend going with a vactrol or LED/LDR pair instead. The sound is more intense and with a wider sweep.
[soundcloud]http://soundcloud.com/effdub/wahscillator-quick-demo[/soundcloud]
Populated board (some parts are surface-mount to save space).
And here's the schematic if anybody wants to play around with the circuit:
