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 simple two-transistor receiver was found in Radio Electronics magazine from September 1960....
We found this circuit in an article in Radio Electronics magazine from November 1971. The circuit has...
This single trigger circuit has been indicated for photography applications. The circuit is from a...