This circuit was found in the July 1986 issue of Radio Electronics magazine. The circuit has a loudspeaker warning system. The sensor is the ceramic capacitor C1 which acts as a transmission line.
This useful inductance bridge was found in a Radio Electronics from September 1963. The...
This circuit uses a 7-segment display to indicate the logic level of a test circuit. The power...
Powered by voltages from 6 to 12 V, this circuit from a Popular Electronics from the 90s,...