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 circuit consists of a voltage regulator for 6 V batteries with a very low voltage drop. The...
This BFO or OFB for listening to SSB (Single Sideband) signals was found in the January 1996 issue...
We found this circuit in a European publication from the 1990s. Transistors are still common types...