Found in a Popular Electronics from the 1990s, this circuit monitors the voltage of a power supply or battery. The trigger voltage is adjusted with a potentiometer.
The output voltage depends on the zener diode. Zener in the range between 1.2 to 12 V rated to 1 W...
This shield with full-wave triggering was found in the Radio Electronics Experimenter magazine of 1989....
We obtained this circuit in a Maxim documentation from the 90s. The circuit is based on the...