In this circuit, the integrated amplifier used is uncommon today. The circuit is from an American documentation from the 70's making use of a power transistor for output. A TIP32 can be used.
In this circuit the capacitor under test is charged at switch position A and then discharged...
This is a common circuit in the 1990s, when experimental FM transmitters were in vogue. The...
Using a piezoelectric sensor of the time, this circuit was found in the February 1994 issue of...