Guitar Pedal Switching – Part 1

by | Apr 17, 2023 | Audio Electronics, Circuit Design, Effects Pedals, Electronics

This is the first in a series of videos where we look at the processes involved in making a Guitar FX Pedals.

Here we explore some of the more common types of bypass switching found in Guitar FX pedals. Starting with a look at basic switches, switching circuits and L.E.D. indicators. We also reverse engineer the switching in an EHX Small Stone from 1976 and, later on, a small switching board that mounts directly onto the foot switch.

SPDT, DPDT, 3PDT, True Bypass, grounded inputs, and L.E.D. indicators are all covered here

Drawing of the 3PDT Grounded Input Switch

The approach taken by the PCB that we reverse engineer in the video is also achievable without using a specific printed circuit board, below is a drawing I created using DIY Layout Creator. The diagram below also includes the two hidden switches, there is one on the barrel power jack (top left) that disconnects the positive side of the battery when a 2.1mm genre negative power supply is used, and the second is on the input jack (left) that uses a TRS jack to connect the battery or power supply negative to ground, powering up the circuit, i.e the input has to be plugged in to power up the pedal.  I will discuss this further in Guitar Pedal Switching – Part 2, coming soon.

Also coming soon – In Part 3 will explore Buffered Bypass such as Ibanez and Boss, and Part 4 will look at how to add LEDs to older pedal circuits using Millenium Bypass. Finally, Part 5 will be a deep dive microcontroller (ATTiny) & relay switching found in many modern FX pedals such as Earthquaker and Walrus Audio.