Enclosure not stated · 2 knobs
The Wahscillator
Based on the Run Off Groove Phozer· 1 other board clones it
- Category
- Wah / Envelope
- Price
- see vendor
From the vendor
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.
If you are looking for LDRs, I’ve had good luck with these LDRs , as well as part LDR-P9203 from StompBoxParts.com.
As always, some links might be affiliate links. Think of all the pennies I will make!
Schematic
The schematic is in the post. Open it at Eff Dub Audio. No KiCad fragment has been drawn for this circuit yet.
Parts list 44 rows
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ocr read from an image · sch paired from the schematic · fixed corrected by hand. Check marked values against the build document.
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 22 | ||||
| R1 | 2M2fixed | 2.2M | ||
| R2 | 2K2fixed | 2.2k | ||
| R3 | 470Kfixed | 470k | ||
| R4 | 1Mfixed | 1M | ||
| R5 | 1Mfixed | 1M | ||
| R6 | 1Mfixed | 1M | ||
| R7 | 10Kfixed | 10k | ||
| R8 | 10Kfixed | 10k | ||
| R9 | 470Kfixed | 470k | ||
| R10 | 2M2fixed | 2.2M | ||
| R11 | 220Kfixed | 220k | ||
| R12 | 220Kfixed | 220k | ||
| R13 | 220Kfixed | 220k | ||
| R14 | 220Kfixed | 220k | ||
| R15 | 2K2fixed | 2.2k | ||
| R16 | 1Kfixed | 1k | ||
| R17 | 1Kfixed | 1k | ||
| R18 | 470Rfixed | 470 | ||
| R19 | 100Rfixed | 100 | ||
| R20 | 100Rfixed | 100 | ||
| R21 | 100Kfixed | 100k | ||
| R22 | 100Kfixed | 100k | ||
| Capacitors 14 | ||||
| C1 | 100nfixed | 100n | ||
| C2 | 220pfixed | 220p | ||
| C3 | 1ufixed | 1u | ||
| C4 | 22ufixed | 22u | ||
| C5 | 680pfixed | 680p | ||
| C6 | 6n8fixed | 6.8n | ||
| C7 | 22ufixed | 22u | ||
| C8 | 100nfixed | 100n | ||
| C9 | 1ufixed | 1u | ||
| C10 | 10nfixed | 10n | ||
| C11 | 10ufixed | 10u | ||
| C12 | 47ufixed | 47u | ||
| C13 | 47ufixed | 47u | ||
| C14 | 47ufixed | 47u | ||
| Diodes 1 | ||||
| D1 | 1N4148fixed | 1N4148 | ||
| Transistors 1 | ||||
| Q1 | MPSA13fixed | MPSA13 | ||
| ICs 2 | ||||
| IC1 | TL072fixed | TL072 | ||
| IC2 | 4558fixed | 4558 | ||
| Opto 1 | ||||
| OK1 | H11F1Mfixed | H11F1M | ||
| Potentiometers 2 | ||||
| Speed | A250Kfixed | A250k | Potentiometer | |
| Depth | B2Kfixed | B2k | Potentiometer | |
| Trimmers 1 | ||||
| Bias | 1Mfixed | 1M | ||
Other boards based on the Run Off Groove Phozer
- Run Off Groove Phozer V1 Effects Layouts (blog)