Effect Pedal Build, Rat Build Your Own Effect Pedals – Rat (Part 1) Schematic 23Jan202020Jan2021 | Mark This time I show how I make a classic Distortion guitar effect pedal based on the ProCo Rat. In this video we lay out the basic schematic for this circuit. Here is a copy of the schematic for the unmodded circuit: Rat Schematic (unmodded) Share