This is a shunt regulator diode.
Over voltage cutoff circuit.
The only way to destroy a regulator is to apply reverse voltage to its input.
Build a crowbar circuit with a scr that shorts the output if it goes over voltage.
When the voltage will exceed 8.4 v then the circuit will cut off the battery from charger.
So it helps to protect the circuit damage by the high voltage.
If any device needs 12v to work properly then this can be damaged by increasing the voltage.
As a result, the reset pin of the timer 2 is high which causes to output at pin 3 is high, so the transistor 2 conducts, and then the relay coil gets energized.
Be u sed directly as a standalone circuit between the mains sup ply.
Automatic equipment disconnect when the power cross the level of a fixed voltage.
Vr3 can be used to vary the volume of buzzer.
The scr will act much faster than a relay and stay shorted until the power is cycled.
The ultimate high/low voltage protector circuit.
Enjoy the video and eat the sweets.
The article describes 3 accurate automatic over and under voltage cut out circuits can be made at home for protecting the domestic appliances from sudden dangerous high and low voltage influxes.
230v ac mains over voltage protection circuit.
You will need a current limiting or foldback circuit to make the crowbar work.
Adjust variable resistor vr 1 in such a way that led 1 start to glow when the mains voltage is lower than 160v ac.
Adjust variable resistor vr 2 in such a way that led 2 start to glow when the.
If input voltage goes above 440v input power should cut off , once input voltage is back to normal 230v then switch (mosfet) should be conducting and when supply voltage is greater than 440v mosfet should not conduct**).