connecting a piezo topic

[Archangel]

These look like regular piezo transducers but are on a steel plate instead of the more usual brass plate. You can drive them with a square wave direct from one pin on any PIC to ground. For long life make sure the device idles with no DC across the transducer. Make the drive pin an output and set it low in the idle period.

HTH
BrianT

Or you might put a 10µF cap in series with that pin . . .