Blog - Overview

Blog - Overview

Monday, February 2, 2015

Catch 22 / Timmy Overdrive


The Tim Overdrive is a pedal developed by Paul Cochrane. Although its only available on request (these pedals are still handmade only), its a very hyped and popular pedal.
The Timmy is a small version of the Tim, missing the Send/Return jacks and the boost section. So it only contains the OD section of the Tim.

The Timmy is an very transparent overdrive with 4 knobs for Volume, Drive, Bass and Treble.
Additionally it features a toggle switch to select different amounts of clipping diodes.

The Catch 22 is a project by Grind Customs FX (
It is a Timmy workalike, with some mods:
-) Internal Voltage pump charge from 9V to 18V for more volume and headroom
-) 3 different clipping options (on-off-on toggle switch)
-) Treble and bass control: Frequencies are increased when turning the pot up, not the either way round (no frequency cut controls as in the original, what is more logical)


Note theres a little mistake in this schematic:
The Volume pot is 10kA (and NOT 100k as shown below)

Be careful when building the Catch22 project:
  • If you want to put it in a 1590b enclosure, be very careful during drilling! The PCB fits exactly into an 1590b. Horizontally theres no space left!
  • The Pots are placed very close vertically. That can cause a short-circuit when mounting the pots to the enclosure. You can use tape for the Drive and Volume pots to prevent this!

Drill Plan

Download the Drill Template here

My Build

The Volume pot must be 10kA. For my build I used a 25kA pot and soldered a 18k resistor between Lug 2 and 3.



  1. Hi, I just saw this post from last year and wanted to address some points about the mods. The 3-way clipping selector is not a mod. The Timmy has had these 3 same settings of 2+2 diodes/2+1/1+1 on an external toggle switch (spdt on-off-on)since 2010. You only need 5 diodes to do this instead of the 7 shown. The jumper between the diodes is part of the switching. Also the tone controls are still cut style controls doing the same thing as before. They just turn the other way. I would recommend a 50kC for the bass control since a lin pot wired this way has a pretty large dead spot where nothing happens. I used audio tapers wired backwards to not have to deal with the large area of nothing happening with the linears because 16mm 50kc pots were not very common when I made the pedal in 2004. Take care, PaulC

  2. how cool is it that paul gave ya the lowdown on his circuit? respect!