This circuit was found in the October 1983 Radio Electronics issue. It is applicable to old analog telephones. The circuit uses common components.
This circuit allows the activation of a remote telephone bell made with a common piezoelectric capsule. The...
This circuit for analog VHF televisions was found in the 1989 Radio Electronics Experimenter...
The assembly of this circuit with 3 transistors was described in an article in Radio Electronics magazine...