Stops current flowing through the load (green resistor) when the supply voltage falls below a set value.
Can be used to stop batteries discharging past a set voltage, or to turn of a circuit when the supply voltage is too low for it to function properly.
Cut off limit can be adjusted using the potentiometer.
The mosfet can be replaced with a relay if required, but will draw more power (reduced battery life) and likely result in a bulkier circuit.
Works by using an op amp as a comparator comparing a fraction of the supply voltage (defined by the pot) to a reference voltage (defined by the zener diode). The amp will then only turn on the mosfet if the fraction of the supply voltage is greater than the reference voltage.
