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DIY Stompboxes => Building your own stompbox => Topic started by: SamT89 on January 27, 2023, 05:26:32 PM

Title: SPST troubles
Post by: SamT89 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.
Title: Re: SPST troubles
Post by: antonis 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..)
Title: Re: SPST troubles
Post by: SamT89 on January 27, 2023, 05:36:30 PM
Hi. I followed this plan exactly.

https://diyeffectspedals.com/builds/diy-guitar-killswitch-stutter-pedal/
Title: Re: SPST troubles
Post by: bluebunny 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).
Title: Re: SPST troubles
Post by: SamT89 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.
Title: Re: SPST troubles
Post by: SamT89 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  :)
Title: Re: SPST troubles
Post by: PRR 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.
Title: Re: SPST troubles
Post by: bluebunny on January 28, 2023, 05:27:46 AM
Quote from: SamT89 on January 27, 2023, 05:52:18 PM
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.