When the voltage supplying the circuit falls below the zener value, the LED lights up, and if a low current buzzer is used, it is activated. The circuit is from a 1999 American publication.
This circuit was found in documentation from the 1980s. The transistor depends on the desired...
We found this circuit in a 1985 technical publication. The circuit uses PUTs to drive lamps....
This type of circuit, found in American documentation from the 1980s, triggers producing output...