We found this circuit in a 1968 Electronics World. It fires a buzzer if the ignition key is turned on and the headlight is off. The circuit uses an included oscillator buzzer like the Sonalert.
This 1960s Signalite circuit uses two SCRs to achieve full wave control. The trigger elements are...
This voltage controlled oscillator uses a varicap to change the frequency. Usin a 100 turns coil...
July 2017 - Mouser Electronics announced the availability of its new ISO771x digital isolators...