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DIY Stompboxes => Building your own stompbox => Topic started by: ianmgull on March 16, 2021, 07:50:14 PM

Title: Is it worth debouncing an external tap tempo switch?
Post by: ianmgull on March 16, 2021, 07:50:14 PM
I have a Boss ES-8 switching system. I'm building a simple external foot switch with a normally closed momentary stomp switch. 90% of the time, it will act as a tap tempo switch.

Is it worth adding a debouncing circuit to a switch like this? Or would you consider it good enough as is?

FWIW, the control voltage is just a 3.5v DC signal.
Title: Re: Is it worth debouncing an external tap tempo switch?
Post by: iainpunk on March 16, 2021, 08:11:58 PM
if its a momentary switch instead of a latching switch, its only one cap and resistor, its totally worth doing!
if its a latching switch, don't bother
Title: Re: Is it worth debouncing an external tap tempo switch?
Post by: ianmgull on March 16, 2021, 08:25:15 PM
Hey thanks.

I was under the impression that it was much more complicated than that. Do you know of a schematic that shows how this is put together?
Title: Re: Is it worth debouncing an external tap tempo switch?
Post by: iainpunk on March 16, 2021, 08:38:32 PM

(https://i.postimg.cc/R30cqG9X/debounced.jpg) (https://postimg.cc/R30cqG9X)
Title: Re: Is it worth debouncing an external tap tempo switch?
Post by: ianmgull on March 16, 2021, 08:42:27 PM
Easy enough. Thanks!!
Title: Re: Is it worth debouncing an external tap tempo switch?
Post by: iainpunk on March 16, 2021, 09:02:14 PM
if it still jitters or has problems, just increase the resistor tenfold, try the same trick if it still has problems after that.

cheers
Title: Re: Is it worth debouncing an external tap tempo switch?
Post by: ianmgull on March 16, 2021, 09:39:59 PM
Ok, so I just realized that I don't understand this schematic.

The signal is on a TS cable. So there's a 3.5v source and a ground. This means the what is labeled 'output' in the schem is actually ground. So does that mean the grounded end of the resistor and cap are actually connected to the output?
Title: Re: Is it worth debouncing an external tap tempo switch?
Post by: 11-90-an on March 16, 2021, 09:52:26 PM
perhaps try something like this then...

(https://i.postimg.cc/sBqwV9km/Screen-Shot-2021-03-17-at-9-52-10-AM.png) (https://postimg.cc/sBqwV9km)



Title: Re: Is it worth debouncing an external tap tempo switch?
Post by: composition4 on March 16, 2021, 10:50:34 PM
That won't work, the cap need some series resistance to have any debouncing effect
Title: Re: Is it worth debouncing an external tap tempo switch?
Post by: ianmgull on March 17, 2021, 08:22:46 AM
My understanding was that a simple debounce circuit is just an RC Lowpass filter? If that's the case, I wonder what series resistance to use without causing too much of a drop for the logic switching to do its job.
Title: Re: Is it worth debouncing an external tap tempo switch?
Post by: ElectricDruid on March 17, 2021, 09:36:32 AM
I suspect the normally-closed switch will be more of a problem that the debouncing. Most tap-tempo switches and similar are normally-open, and if I was designing an input for such a thing, I'd make sure to include debouncing either in my input socket hardware or in firmware after that.

I'd try it and see. Don't fix it if it isn't broken.