Inconsistant Chance switches

[Doctor Bob]

I'm currently trying to bend a kid's toy keyboard, found in a charity shop but from the badge, it's originally from the Early Learning Centre. I've found a couple of cool pitch mods and something that sounds a bit like it's altering the pulse width, which can make some great noises!

On occasion, I manage to get one of those 'stream of glitchiness' chance sequences, but I'm having trouble getting it to do this consistently, and I've been trying things out all evening!

At the moment, I have one test lead connected to a resistor on the timer circuit, and sometimes the keyboard will go haywire in just the right way when I tap the other end on part of the control board that has all the keyboard controls on it. Most of the time though, it'll crash the circuit. I've tried using variable resistors to lower the current through the test lead to see how that affects it, but this just alters the sound a little, or crashes it.

On occasion, it'll go haywire just when I touch the same side of the timer resistor without anything on the other end of the lead, but this is quite rare. Very confusing....

Are there any tips for helping find and nail these chance triggers?

[iqoruvuc]

Hi - what values of resistance have you been using?  I have a keyboard that is so sensative just soldering a wire connected to nothing at all creates all kinds of changes and sounds a bit like a radio nearly tuned into something.  Whats the lowest possible resistor you can insert between the two leads that does not cause it crash?  Try adding a 1k pot in series to a resistor and have it set on maximum resistance - when you find the lowest possible resistor that will not cause it to crash then turn the pot down a little and see if it crashes.  If you can get this to work then on you final project you can have the resistor in series with the pot and also in series after the pot a push to make switch.  You can the use the pot to select the optimum resistance (as this changes a bit as battries run down) and then tap the switch and cause it to crash - that's of course if this eeven works at all : )

[Doctor Bob]

Cheers for that! Sorry about the delay, got caught up in another project, but will hopefully be on this one again this coming week. Will let you know what I found out