On 23 Sep 97 at 8:08, Leon Heller wrote:

>
> I just put my 'scope across a piezo sounder, and found that I could
> get several volts out of it when I tapped it, with it resting on a
> hard surface. A 1n ceramic capacitor just produced a few mV, I
> couldn't measure it, but something was there, because it was
> triggering the 'scope.

It depends what kind of ceramic you use.  One, I think its Z5U,
(Barium Strontium Titanate, I think - dialectric constant of 7500 ) -
was very bad (good for you) at this.
These are the tiny very large capacity ceramics you might consider
for supply bypassing.
MikeS
<mikesmith_ozNOSP*M.relaymail.net>
(remove the you know what before replying)