This circuit was obtained from a Radio Electronics issue from January 1989. The indicator is a ceramic transducer, and the frequency of the emitted sound is given by C3.
The components used in this 80's circuit are not common today. The circuit is very sensitive and must...
The circuit shown is for testing both signal diodes (low current) and rectifiers (high current). The...
Connected to the output of an audio amplifier or radio this circuit indicates the level of the...