Taptation Trouble

[bkrawetz]

I have delay build (Sea Urchin) I'm adding tap tempo to with the Taptation (purchased here about a month ago), and I'm having issues with the tap circuit. The Tap is on an isolated board, and is essentially the "Typical Application Circuit" included in the application notes.

When I adjust the Time control pot on pin 13, the temp clock LED on pin 3 reflects roughly what I would expect.  As well, when I connect this tap circuit to pin 6 of the PT2399, I get the delay and modulation behaviour I expect -- including use of the tempo scale, double time, and PWM cycle speed switches.

The problem is when I try the tap clock on pin 2.  The Taptation "sees" the taps as far as I can tell -- the LED blinks whenever I tap -- but the Taptation does not lock into the tapped time. As soon as I stop tapping, the LED blinking (and the delay) reverts back to the time set by the pot on pin 13 -- even if I don't touch the pot.

I've been using a momentary SPST footswitch on pin 2, but the behaviour is the same even if I remove the switch and just tap pin 2 to ground manually with a loose wire.

Any ideas?

[bkrawetz]

Got it! The switch was not being debounced.  I missed the cap across the switch. With the cap in, all is good.

[PRR]

Ah! Thanks for the follow-up.

Un-de-bounced, a switch will make/break a dozen times in a fraction of a second. I guess the tap counter thought this was impossibly fast, and didn't try to obey.