3PDT footswitch and true bypass wiring
Whenever I assemble a new effect pedal, I always end up confused about the wiring required for the 3PDT footswitch. More often than not, the wiring is the same, but presented differently or in a confusing manner in the assembly instructions of the different kits/PCBs and I always end up having to draw it out.
As well as the wiring, there's some theory about switches. You can go directly to the wiring diagram and explanations by clicking this link.
What are switches, really?
On-off, on-on, on-off-on, on-on-on, latching, momentary... Which one to choose?
How do you wire a 3PDT?
- The first two pins of the top row are going to be linked together. This will take you dry signal from the input jack are wire it directly to the output jack to bypass the PCB/circuit entirely. The last pin will stay not connected.
- The center row are your common pins:
- Left pin comes from the input jack
- Center pin goes to the output jack
- Right pin goes to the LED and its series resistor
- The resistor is important if you do not want to blow up the LEDs. For a 3V LED, a 270-390 ohms resistor should be enough depending on the color. You can use a higher resistance to control the intensity of the LED.
- AllAboutCircuits has a nice calculator to help you with that: https://www.allaboutcircuits.com/tools/led-resistor-calculator/
- The bottom row are going to/from the PCB:
- Left pin goes to the PCB/circuit input
- Center pin comes from the PCB/circuit output
- Right pin comes from the +9V of either the DC jack or PCB/circuit