This pedal came to me severely hacked, with a few suspect or missing parts – of course, it wasn’t working … the re-build involved the following changes : replacing two electrolytic caps by modern equivalents or larger (100uF same, 330uF -> 470uF), replacing all 0.68uF film caps by 1uF Panasonic ECQ-C film, replacing the BC148 oscillator device by a 2n5210, and the missing jFET by a 2n5457, and also receiving a new dual-100k anti-log pot – as used in my Shin-Ei Univibe clones …
the actual circuit had resistor values that aren’t that common nowadays … NOTE: according to how the circuit is drawn and designed the DC voltages that are posted below are measured referenced to the negative rail, while the middle oscillator cap is temporarily shorted to kill the oscillator …
the first 2n5457 I picked had no trouble biasing from the stock 6.4vdc Zener …
finally, the schematic with my mods – which extend the slow-speed range a little …
the noiseless (passive) signal path is quite spectacular sounding if I may say – and obviously a basis for other noise-less style effector circuits: a noise-less Limiter anyone ?!
not that hard to do in reality // … consider the following:
almost reminds me of this patent by Mieda …
Hi JC, I’m curious if you can tell me the name of that Mieda paper you ref’d (but the link has gone dead)? Many thanks!
HI BRIE, THANKS FOR ASKING AND LETTING ME KNOW … HERE’S THE LINK: https://patents.google.com/patent/US20030016831
What are you using as an oscilloscope on that picture?
HI talisk3r, THE SCOPE IS AN EARLY VERSION DSO “NANO” … VERSION 3 CAN BE OBTAINED HERE (WHEN IN STOCK): http://www.seeedstudio.com/DSO-Nano-v3.html