This two-tone alarm siren was found in the January 1975 issue of Radio Electronics magazine. The power transistor can be changed and with it, Rx has values from 10 to 47-ohm.
Suggested by Siliconix in documentation from the 90's, this circuit supports current equivalent...
This circuit decodes a 1800 Hz tone used in communications. The circuit is from an American...
This circuit was obtained in 1981 documentation. It is an FM transmitter that can serve to emit...