other controls aka capacitive plates

cyborg0 at GlobalEyes.net cyborg0 at GlobalEyes.net
Fri Jul 17 06:17:07 CEST 1998


Frank Lemieux wrote:

> Has anyone here worked on capacitance sensors?  I'm trying to figure out
> how those star-trek like panels worked :) Inductance, maybe? hmm...

Well, yeah.. a Theremin works on this principal..
Basically, you have a waveform traveling through the touch pad
(capacitance)..The output of this goes into a phase comparator.Your body
parts invoke a change in capacitance .If the "after" wave (the one going
through the plate) is too far out of phase with the "before", or input
wave, then you can have the resultant correction voltage trigger
something. Heck, you prolly could use a PLL to do the whole little
deal..
What would be REALLY cool is to have it so that it knows exactly how FAR
out of phase it is..I know with a PLL, it generates a correction voltage
in response to exactly how far out of phase it is as long as the phase
difference is within the capture range..it would be cool if you could
have the capture range large enough to give a big enough voltage
difference to generate other types of control data.
Maybe put a piezo under each plate to simulate pressure or impact and
route this to a VCA..

John Simonton at paia loves these things, or so it seems...
go to the paia website, he seems really into this sort of control..
rob



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