Author Topic: SPST troubles  (Read 943 times)

SamT89

SPST troubles
« on: January 27, 2023, 05:26:32 PM »
Finally building my first pedal but I've run into what I assume is probably a noob problem.
I've build a simple passive killswitch, just two 1/4 mono jacks and a NC SPST momentary foot switch. The plan was for the signal to only be cut while my foot is on the switch, however, it's working the wrong way around. I initially thought maybe the switch was NO but when I hooked it up to a battery and an LED it worked correctly as NC.
I'm completely out of ideas as to what the problem could be or how it's even possible for the switch to behave in this way.
Any help would be greatly appreciated.

antonis

Re: SPST troubles
« Reply #1 on: January 27, 2023, 05:31:24 PM »
Hi & Welcome.. :icon_wink:

A schematic should be enlightening..
(mainly from series/shunt connection point of view..)
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

SamT89

Re: SPST troubles
« Reply #2 on: January 27, 2023, 05:36:30 PM »

bluebunny

Re: SPST troubles
« Reply #3 on: January 27, 2023, 05:42:17 PM »
If your switch really is NC, then it's always grounding the input and output jacks, until you stand on it.  It needs to be NO for that circuit to work (open means there's no in/out-->ground short).
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Ohm's Law - much like Coles Law, but with less cabbage...

SamT89

Re: SPST troubles
« Reply #4 on: January 27, 2023, 05:52:18 PM »
Ahh ok. I guess I misunderstood how the switch works. Thank you very much for the help.

SamT89

Re: SPST troubles
« Reply #5 on: January 27, 2023, 06:31:15 PM »
I managed to find a work around. I connected the two jack sleeves together, and the two jack tips to either end of the switch  :)

PRR

Re: SPST troubles
« Reply #6 on: January 27, 2023, 10:41:10 PM »
> two jack tips to either end of the switch

That way allows more stray hum and buzz when "mute". But if it is OK for you, great.
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bluebunny

Re: SPST troubles
« Reply #7 on: January 28, 2023, 05:27:46 AM »
I guess I misunderstood how the switch works.

It wasn't your misunderstanding.  It was a mistake in the article.  Their BOM says NC, but should say NO.
  • SUPPORTER
Ohm's Law - much like Coles Law, but with less cabbage...