Effects Projects

The Wahscillator – An LFO-driven Filter

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 Tim Escobedo’s 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 Shoot The Moon tremolo. For the variable resistor element, just about any of the usual suspects will work: LED/LDR combo, vactrol, or even one of those optical ICs such as the H11F1. And that’s how the Wahscillator came to be.

It’s not a phaser. It’s not a vibe. It’s not a tremolo. It is…..sort of just like a smooth wah (no inductor) with a mildly choppy LFO. 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. Changing the variable resistive element type and LED color/intensity varies the tone quite a bit, from watery pseudo-phaser to straight-up wah.  Can’t wait to see what you guys do with the Wahscillator.


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