This circuit was found in the July 1992 Radio Electronics magazine. Sensitivity adjustment is made at R6. Supply voltage is matched to that of the relay.
This circuit was originally designed to monitor the temperature of a vehicle. The integrated...
This circuit was obtained in a Popular Electronics of the 90s. It warns when the indicator lamp is...
This amplifier circuit with two transistors was found in a Mullard transistor manual from 1960. The...