We found this circuit in the magazine Eletcronics Now of July 1994. The power supply is according to the relay and the transistor can be any general purpose one.
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...