Annoying foot switch behavior

[FootSolder]

I'm using a OneSpot supply connected only to this one pedal. If I use a battery, the buzz is less pronounced but still occurs. The voltage reading across both LED pads is 1.84V.

I tried disconnecting C22, which didn't help, but I still tried connecting both LEDs before D7 (still buzzed) then added a 3K9 resistor and 1u (in series) across each LED (in parallel) but still get a nasty buzz.

The only thing that I noticed when I tried a waterclear LED was it stayed on very dimly even with the octave switch bypassed

Even if you use a mechanical switch, two diode drops at 1.4 volts can be almost equivalent to the 1.88 volts of the LED.  This would still limit the difference in current between the on and off state, thus limiting the noise

This is a mechanical switch - would the 2 diodes go between the LED and +ve supply? And what type of diodes?

[FootSolder]

measuring the DC voltage at the source pin to see if it rose or dipped when the static was heard

It only dipped 0.01V when the switch was activated

I did just notice that the problematic LED is very dimly glowing even with the switch off, feel like that can't be a coincidence?

[R.G.]

LED glows when the switch is off??

Are you sure your switch is working and that you have the right wires to the right places on the switch? What does your ohmmeter say about which switch pin is which and what they do when the switch is flipped?

[amptramp]

I'm using a OneSpot supply connected only to this one pedal. If I use a battery, the buzz is less pronounced but still occurs. The voltage reading across both LED pads is 1.84V.

I tried disconnecting C22, which didn't help, but I still tried connecting both LEDs before D7 (still buzzed) then added a 3K9 resistor and 1u (in series) across each LED (in parallel) but still get a nasty buzz.

The only thing that I noticed when I tried a waterclear LED was it stayed on very dimly even with the octave switch bypassed

Even if you use a mechanical switch, two diode drops at 1.4 volts can be almost equivalent to the 1.88 volts of the LED.  This would still limit the difference in current between the on and off state, thus limiting the noise

This is a mechanical switch - would the 2 diodes go between the LED and +ve supply? And what type of diodes?

I was suggesting parallel switching with the switch operating in the opposite sense to a series switch.  When the switch is closed, the LED is shorted out.  When it is open, current goes through the LED.  The key to minimizing noise is to make the shorted "off" condition nearly the same voltage as the "on" condition.  In this case, the switch is across the LED and the diodes in series with the switch serve to keep the "off" state voltage as close to the "on" state voltage as possible so the voltage across the dropping resistor changes as little as possible.