reversing Momentary SPST switch, can I do it?

Thread Starter

BigMacguitar

Joined Jan 8, 2021
10
Hello!

I'm currently wiring the electronics on a guitar I'm building. It's the first time I've done it and it's going surprisingly well. I say that because I am completely and utterly clueless with any form of electrics. The one major flaw in my system is a kill switch I installed. Well it's meant to be a killswitch but it turns I bought an engage switch by accident. So the whole thing is de-activated until the switch is engaged. I've already drilled the hole for the switch in the body of the guitar so I want to keep it if I can. So what I'm wondering is can I reverse the function of the SPST switch? instead of finishing the circuit can I make it disconnect the circuit?

Any help would very much be appreciated.
Liam
 

scorbin1

Joined Dec 24, 2019
70
Is it a momentary switch or a toggle switch? What your looking for is a Normally Closed SPST switch. Depending on the switch you may be able to find an identical replacement with this configuration. With the switch you have now, not without other major modifications and considerable complexity added.
 

Ian0

Joined Aug 7, 2020
2,178
You should have two wires coming out of the pickup, that go to the jack. They probably go through some dreadful combination of capacitors and potentiometers that calls itself a tone control, then to the 6.3mm jack socket.
Connect the switch to either to the two wires from the pickup, or the two terminals of the jack socket. Either will work.
 

Thread Starter

BigMacguitar

Joined Jan 8, 2021
10
PXL_20210108_232918718.jpg


I don't know if this helps but here is a picture of the circuit. There is two pickups the red at the top and the yellow lead to the pickups.
I've got all the grounds going to the volume potentiometer, the red and yellow hot wires going to the three way switch. the red output is going straight to the output jack and then the black is wired to the output jack with momentary switch in the middle of it.

I'm still not sure how I would wire the switch to short the pickups
 

Thread Starter

BigMacguitar

Joined Jan 8, 2021
10
the switch itself is 16mm diameter
the nut it screws into is 19mm - and the hole in guitar accommodates the nut
It's about 24mm in height, I cant really go any bigger than that as it would leave the guitar too weak if I drilled any deeper

I'm based in Ireland so finding parts is a little more difficult here
 

eetech00

Joined Jun 8, 2013
2,349
View attachment 227214


I don't know if this helps but here is a picture of the circuit. There is two pickups the red at the top and the yellow lead to the pickups.
I've got all the grounds going to the volume potentiometer, the red and yellow hot wires going to the three way switch. the red output is going straight to the output jack and then the black is wired to the output jack with momentary switch in the middle of it.

I'm still not sure how I would wire the switch to short the pickups
You won't be able to open the output connection like you wanted using that button.
But you should be able wire the button so when pressed, it would connect the output to ground, thru a resistor (or capacitor) and "mute" the signal. Then button would act more like a "mute" button.
 

Thread Starter

BigMacguitar

Joined Jan 8, 2021
10
eetech00 I like the sound of this solution, I think it makes the most sense to me. Would this essentially be reducing the current to zero when the switch is engaged or do I have it all wrong?
 

eetech00

Joined Jun 8, 2013
2,349
eetech00 I like the sound of this solution, I think it makes the most sense to me. Would this essentially be reducing the current to zero when the switch is engaged or do I have it all wrong?
Does the guitar have active or passive pickups? (a give away is a required 9v battery in the guitar).
 

Ian0

Joined Aug 7, 2020
2,178
In that case the best choice (out of the two alternatives I suggested in Post #8) is across the two wires to the output socket, see photo.
As @eetech00 says, check whether it's active or passive. The active type won't like being shorted out - it bet it will make some loud clicks.
(I'd recommend Rapid Electronics for bits and bobs like switches, they'll deliver to Ireland - when everyone has sorted out the new VAT rules) https://www.rapidonline.com/37D69CA2-67FC-4DA3-9F97-4EECDD9423D1.jpeg5CA63FF6-7C74-471A-A0BF-9EA17B2EAF2C.jpeg
I'll just add - shorting the signal out will actually work better than inserting the switch in the wire, disconnecting the pickup from the output will leave it open circuit and it will hum. All microphones with on/off switches short out the capsule to mute it.
It doesn't work quite so well with the mains. . . .
 
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Thread Starter

BigMacguitar

Joined Jan 8, 2021
10
Ian0 got it wired up like you said, with the switch shorting the circuit, worked a charm thanks a million for the help!
now to figure out how I've messed up wiring the pickup selector!
 

Ian0

Joined Aug 7, 2020
2,178
Ian0 got it wired up like you said, with the switch shorting the circuit, worked a charm thanks a million for the help!
Now I'm intrigued how you are using it?
now to figure out how I've messed up wiring the pickup selector!
Generally all the screens are connected together, and connect to the screen on the jack socket.
The signal wires from the pickups go through a SPDT switch, and then to the "tone" control.
However, some allow you to put the two pickups in series, or in parallel, and they get quite complicated.
I had to sort out a Westone bass a while ago, and Google found me a wiring diagram so easily.
 

Thread Starter

BigMacguitar

Joined Jan 8, 2021
10
I made it for a friend he's always wanted a guitar with a killswitch, I think mainly for cutting up feedback, but just for doing weird stuff in general

Generally all the screens are connected together, and connect to the screen on the jack socket.
The signal wires from the pickups go through a SPDT switch, and then to the "tone" control.
However, some allow you to put the two pickups in series, or in parallel, and they get quite complicated.
I had to sort out a Westone bass a while ago, and Google found me a wiring diagram so easily.
I lost you at screens to be honest
:oops:

I have a wiring diagram, it's for a telecaster with a 3 way pick up selector.
I'm getting good clear signal but no matter what pickup it is set to I'm just getting both pickups together
 

Thread Starter

BigMacguitar

Joined Jan 8, 2021
10
eetech00 thank you and thanks for the suggestion as well

Ian0 figured out the selector it came with a wire that was bridging the the two pickups to each other so they couldn't be isolated (very weird). Removed the wire and we're golden now
 
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