This circuit activates a horn from an audio signal. This can be used for remote control via audio signals. The circuit is from a Radio Electronics from October 1965.
In a modern version this circuit can use an LED in series with a resistor in place of the lamp. The...
This bistable circuit with SCR for direct current was found in the Radio Electronics magazine of...
The configuration shown in the figure uses two NPN transistors activating the load when the input...