Proper wiring for adding an expression jack to a pedal.

[Andon]

Howdy! I'm building a pedal that I'd like to add an expression jack to in order to externally control an internal B50K pot, and I'd like it to be a stereo switching jack (Neutrik NMJ6HCD2) so that you can adjust it using either the knob or the expression pedal. I did a bunch of reading before making this thread, so this is hopefully more so just confirming that all of it was correct, or that I'm at least on the right track. Here is what I've surmised:



Assuming that most (but not all) conventional expression pedals connect the wiper to tip in a TRS setup, does this seem correct? The "TO POTENTIOMETER" side connecting to the potentiometer itself, and the "TO PCB" side going to where the potentiometer would "normally" connect on the PCB. Thanks for any input on this!

[antonis]

[GGBB]

Assuming that most (but not all) conventional expression pedals connect the wiper to tip in a TRS setup, does this seem correct? The "TO POTENTIOMETER" side connecting to the potentiometer itself, and the "TO PCB" side going to where the potentiometer would "normally" connect on the PCB. Thanks for any input on this!

Assuming: the "N" connections on the jack are the permanent connections and the others are switched.

If it were me I'd use pin1-sleeve, pin2-wiper, pin3-tip. It's much simpler. Explanation:

In expression pedals (e.g. Antonis's diagram), both wiper and pin3 are "tip" - on their respective mono jacks. So it doesn't matter which mono tip connects to your stereo tip - either way is dependent on the circuit wiring.

Sleeves are usually associated with ground or CCW and that is often lug 1 of pots (e.g. volume controls). Keeping sleeve/pin1/ground together will be less confusing and might avoid problems if you are actually connecting to ground.