This 4-transistor timer was found in the April 1975 issue of Radio Electronics magazine. It uses both single-ended and single-junction transistors to provide a dual audio output.
This circuit was found in a Radio Electronics from May 1965. FETs are from the time, but the...
This circuit can generate signals from 80 to 800 Hz with an amplitude of 0.3 V. We find it in a...
Because it uses TTL integrated circuits, this siren must be powered by 5 V or as indicated with D1 to...