This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Friday, July 1, 2016

Harmonic Percolator

Here's the mythical Interfax Harmonic Percolator for Fuzz Friday. It's a pretty unique circuit design and uses germanium and silicon transistors. Here's the schematic for reference.


  1. I have 2 bagged NOS 2N404, motorola. I bought them to make a fuzz factory, cause zvex uses them in addition to AC128s. It occured to me that they might be the exact same thing, and according to several cross reference guides, they are.
    I still haven´t used them, cause I pulled 2 404s from an old PCB I found at a friend´s, so, if any of you want, I can measure them in any way you need.

  2. Hi! I make this Harmonic Percolator. It's a fucking great sound. A lot of fun. You can mess with the timbre using the guitar volume. It's a really peculiar fuzz. Great! Now you can put him on tested section! Thanks for this PCB.

  3. Built it, fuzz sounds great~ thanks for the layout~
    here's some shot share:

  4. That 10k resistor is has a big effect on how fuzzy the effect gets. 10k is pretty low, you'll get a very messy inarticulate sound. I suggest wiring pot in as a variable resistor to go up to 100k.

  5. i dont know why. but i built this pedal 6 times in a day because i tested a lot of transistor and diodes and i found the best sound with 2n3904 and 2n3906 all silicon. and a 10M instead of 750k but the output vol is very very very high .... in that way you can hear the germanium diode clipping.
    if i use a ac128 germanium transistor on the original schematic i must leave out the diode clipping from the schematic because the drive is ridicolusly low and there is a lot of noise. i dont know...

  6. anyone know the travel length for the OG slide pots?
    Thank you!