I built Dean Hazelwanter’s Holtek HT8950 Pitch Shifter / Robot Voice / Vibrato from the build notes at General Guitar Gadgets.
For fun, I used an optoisolator (VTL5C3) to control the 250K freq pot (P3).
I connected the LED leads of the optoisolator to the LED pads on the PCB, and the LDR leads of the optoisolator to the pads for P3.
Here’s what it sounded like. . .
Hi (im french, sorry for the language)
I built this ggg stompbox but, of course, there’s a bug …
The unit seems powered, modulation led flashes, but no sound out 🙁
Pots seems to work and change the effect (led flash) and 7pst is affects it too.
Have you an idea of what could be the source of this ?
Really a great thanks !!!!
Could be a short somewhere, or a wiring mistake. I suggest using an audio probe to find the problem, the point in the circuit where the signal disappears. If you need more info, do a Google search for “audio probe”, or check out this page…
Any idea on when you might have more PCB’s for the flanger projects?
Sorry. No plans at this time.