Found in Elektor Electronics from the 90s, this circuit produces the tone of 1 750 Hz for calling VHF relay stations used by radio amateurs.
This old circuit, from the 80s, was found in American documentation. The circuit uses dual gate...
This simple signal injector circuit was found in Radio Electronics magazine from June 1961. It...
This circuit trips, changing state, when the input voltage exceeds a value determined by R1 and...