Today this frequency corresponds to the end of the FM band. However, in December 1958, when the circuit was published in Radio Electronics magazine it was the frequency used by American satellites.
This circuit uses high voltage transistors to provide direct power from the 110 V power grid or a...
This circuit was designed to work with the previous one in triggering a relay by the sounds picked up...
This circuit was suggested by Signetics in 1980s documentation. The circuit makes use of the...