This circuit triggers by choosing the higher of two voltages. The circuit is from a 1964 Electronic Design. The transistors are of the time and can be replaced by current equivalents.
This circuit triggers the LED when the monitored battery voltage drops below 9 V for 12 V...
Suggested by National Semiconductor, this circuit can be applied to almost any operational...
This circuit was found in Radio Electronics from the 90s. The circuit can generate signals up to...