[sdiy] Found the Piezo Manufacturer!

[Peter Grenader]

Oh, one other thing - the pressure out in this diagram is simplified.  I've
put a bit of amplification and offset in there.  Done as shown, the
effective range of the pressure out is crappy.  A Gnat would find it
perfect, but I had a problem getting useful results, again due to the
deflection.  You see, there's a bit of pressure required to get the switch
to actuate, and I tended to press down more than required to do that so the
pressure out would immediately go up to it's high rail.

The key difference with 'real' touchplates is the capacitance changes with
the amount of finger which lays on the key, not necessarily the amount of
pressure (although of course increasing the pressure flattens your finger
out).  But when deflectin is required, it's hard to back it down fast enough
once you've got the key active.

- P