Making a killswitch pedal out of telegraph key

[SeneX225]

Hi!

Having decided that there's not enough killswitches in my life, I've set out to make me another one. I remembered seeing a converted telegraph key, so I bought one to have a go at it myself.


Principle and mechanics seemed simple enough and the key I received had two clear connection points, so I wired everything up and, of course, it didn't work.

Checking the wiring, as much as there is, yielded no results, for everything was in order. Then, I grabbed my multimeter and tested the connection on the key, which was fruitful if confusing: instead of expected signal and zeroes on the display, it made exactly no sound and showed a value of about 115-130.

Why is that and is there a way to recover this sorry mess?

[amptramp]

The key switches on when you press it.  This is the opposite of a burst box, which is the subject of a very long thread that will be what you want.

[SeneX225]

The key switches on when you press it.  This is the opposite of a burst box, which is the subject of a very long thread that will be what you want.

Well, yes, but that's exactly what I was counting on. According to this schematic , the switch should be of Normally Open type, which the key is.

The thing is, when pressed, it's not closing fully, as if there's still too much resistance, unless I miss my guess.

[ElectricDruid]

So do you get proper guitar signal when the key isn't pressed?

And then when you press it, the same?

What exactly is happening with the guitar signal? You only say "it didn't work" which doesn't tell us much about the problem.

100-130R is a fairly big resistance for switch contacts, but I can just about believe it for two exposed bits of metal banging together loosely. At least you can get at them to clean them up a bit.

What I'm not getting is why 100R to ground doesn't pretty effectively kill your signal.

[amptramp]

This sounds a bit like the keyboard action in my Minshall Model E organ where the keys are normally closed and they open to allow the signal to go through.  Over time, you get the chorus of demons in the background caused by contacts that didn't clean up and this is with series resistors from the sound generator in the megohm range.  Hearing has a large dynamic range and cutting a signal by 10,000 does not render it inaudible.

[SeneX225]

So do you get proper guitar signal when the key isn't pressed?

And then when you press it, the same?

What exactly is happening with the guitar signal? You only say "it didn't work" which doesn't tell us much about the problem.

My bad, should've specified it. Yes, when not pressed the signal goes through all nice and clean, but when pressed it just gets a litte dirtier, like it adds a bit of hum.

[PRR]

Clean the contacts.

[ElectricDruid]

Clean the contacts.

+1 agree. Definitely the first step.

[Fancy Lime]

The key switches on when you press it.  This is the opposite of a burst box, which is the subject of a very long thread that will be what you want.

The Burst Box thread is not so much simply *a* thread. More like *THE* thread. I thought that one was mandatory reading, no? Pretty sure you're not allowed to buy a soldering iron before you read the entire Burst Box thread and passed the quiz.