This circuit was found in specialized microwave documentation from the 1960s. The circuit makes use of a varicap, and the transistor is a microwave type.
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...