This circuit turns off when switch S1 is opened. The circuit is from the 1989 Radio Electronics Experimenter edition; The triac must be controlled according to the load.
This Japanese radio is from the 60s, presenting excellent sensitivity and an output power of 100mW...
Found in a Popular Electronics from the 90s, this circuit uses components that are still current....
This circuit consists of a simple capacitance bridge. The handset can be high impedance from 500...