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Re: OT: Kill switch for el guitar - design ideas?

Hi Per,
Many years ago I worked on a circuit which will work for your app. Using a Wien-bridge oscillator circuit and an op-amp, use RC of 150 pF and 1MOhm on on leg, on second leg match that with 1MOhm resistor to ground, and output to a metal plate(say 3 inch by 3 inch). The human body has a capacitance of 100-150pF, so when touching the plate the circuit is completed and you have oscillation(or not, depending on tuning). You can use simple Op-amp with the known RC above in the feedback loop, maybe make the 1MOhm adjustable. Take the output to a digital switch which switches gutiar output on/off.
This will provide real-time control of your drumming. Note that lifting your feet changes capacitance so the circuit may need to be tuned but it is do-able (I actually spent a lot of time tuning this in the lab and got a product to market, but got ripped-off for the patent  :(  one more learning experience of a rookie engineer)
If I have time I'll try to breadboard this to see if I can get something going....
If you want to experiment, the touch-sensitive light switches that are available work on the same principle. Here is an example, not sure what is really required, may need 120VAC for this:
alternatively, this is expensive but looks like something you could use with your laptop setup: