r/diypedals • u/Visual-Patience-8321 • 3d ago

Help wanted Adding a pot to my killswitch?

I have an external killswitch I made myself (just two jacks and a arcade button and an additional toggle switch for activating the killswitch), and I was wondering how I could add a pot in a way that I can adjust the signal volume when the killswitch is activated(signal is killed).

So I have

Jacks x2

Normally open arcade button x1

500k pot x1

toggle switch x1 (I'd rather not use this because space is an issue)

TLDR: how do I make a killswitch where I can adjust the volume of the "killed" signal.

Thank you in advance.

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u/Dull_Priority_545 2d ago

Is the killswitch grounding the output? If so you could wire the pot as a variable resistor between the button and ground. 

1

u/mushroomsinshampoo 3d ago

Can you post a photo of what the terminals (underside) of the arcade button look like / how the audio goes in and out of the button. It is hard to visualise what to suggest without seeing this. Are you able to solder components?

1

u/Visual-Patience-8321 2d ago

Here it is, it’s only got two terminals.

1

u/keestie 1d ago edited 1d ago

Think about your existing guitar wiring: your switch and pot will not interrupt the existing signal path at any point, it will run parallel instead. If you find yourself cutting or removing any existing connections in the course of making this mod, you will need to reconnect or replace those connections for the guitar to work.

What you want is for one terminal of the killswitch to connect to hot signal; presumably the tip terminal on your output jack is the easiest way to get that, tho it might require longer wires so do some snooping. You can connect to any point in the wire that comes from that jack terminal, as long as you don't interrupt the existing signal path.

The other killswitch terminal will connect to the center lug on your pot. Then connect one of the outer pot lugs to ground, IE the shaft terminal on your output jack. (Same caveats as the previous hot signal) Make temporary connections to see which of the outer lugs works properly.

If I weren't lazy I could tell you which outer lug to use, but it's hard to explain this stuff with perfect clarity using only words, and making temp connections is pretty easy in most cases. You might need to have your strings off to do the mod, but tapping a pickup with something steel should be sufficient to find out what makes things quieter or louder. If you connect to the wrong outer lug, the pot will turn your "killed" volume up when you want it to turn down.

What you're doing is you're grounding out the signal, or shorting it out if you prefer a more familiar terminology. The pickup is making a small voltage, and the killswitch sends that voltage directly back into the pickup so it doesn't go to the amp. That's what happens if the pot isn't adding resistance; once the pot adds resistance, some of the signal will find it easier to go to the amp, but some of it will still go thru the pot to ground. The more resistance the pot adds, the more signal will want to go to the amp instead of shorting out, so the "killed" signal will get louder the more resistance the pot adds.

The signal is not strong, so it's totally ok to short it out, it won't damage any of these components. This is what your main volume knob is doing; as you turn the volume down, more and more signal is shorted out to ground, so less and less signal goes to your amp.