SPST vs SPDT switch

[chris.knudson]

Okay so this is probably a dumb question that I think I know the answer to, but I'm going to ask it to see if anybody has a unique perspective that I haven't thought about...

I have a tube pedal that I want to add an on/off switch to. I generally leave my pedal board plug in, and I don't worry too much about the solid state pedals, but I do worry about the lifecycle of my tube pedals.

I currently don't have a SPST in my inventory, but I have a ton of SPDT switches. Is there any reason why I shouldn't use an SPDT switch in lieu of an SPST switch?

 

[benny_profane]

No reason not to. Just leave the third lug empty if all you’re trying to do is interrupt the supply.

 

[bean]

Like benny said there is no switching problem that exclusively requires an SPST. For power on a tube pedal you can even do one better with an SPDT. Use a 1M resistor to ground on the extra lug to quickly drain the voltage off B+ on the tube pedal when powered down.

However, there is one important thing to consider: typical electrolytic caps usually have a lifespan around 1k - 2k hours before failure. That's good enough reason to disconnect your pedalboard power supply when not in use.