This circuit is a very useful auto-cut off circuit to the safety of any electric or electronics equipment from high voltage. This is very simple and easy circuit. This circuit automatically cuts the current supply to any appliance from the input circuit. And when the voltage decreased at a normal level then automatic on the supply. 

Over Voltage Protection Circuit Diagram

This is very easy circuit I used only a few components for this like BC547 transistor, Relay and some other components check circuit below

over voltage protection circuit diagram
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Parts List

  1. Transistor BC547 ( Any NPN Transistor )
  2. Relay 12 volt or 6 V as Per Your Input Transformer
  3. Diode 1N4007 2pc
  4. Capacitor C1 100uf/25V C2 10uf/25V
  5. Variable Resistor (Preset) 10K
  6. Led 5mm any color
  7. Resistor R1 1k, R2 1k Both 1/4watt, R3 47K To 100K any 1 watt
  8. Connector 2pin 3pc
  9. Small Vero Board PCB

Even this project can be made with scrap electronic-components available at your own home. Inverters are used to convert DC current(the word DC stands for direct current) into AC current¬† Read More…

Circuit Working

At first, when the voltage under or below the maximum limit ( at which it adjusted) the maximum voltage dropped through the VR to the ground and the Base of Transistor does not get enough power to switch on the transistor. At this stage, the transistor in OFF state and Relay not get supply and it is not activated.

when the Input voltage of this circuit is increasing and cross a level than the input voltage through resistor R1 and preset also increased  enough amount of voltage is at the Base of Transistor Turned On it and Supply passed Between Emitter and collector. Now Relay is activated and supply is Disconnected to the appliance . And that is protected from high voltage supply.

Before using it should be adjusted by preset and tested the input voltage and set required the auto cut level according to suitable.

PCB Layout For Over Voltage Protection Circuit Diagram

Just Download Below Image and Print it on a normal A4 Paper or you can download gerber file from link below

over voltage protection pcb layout

Watch Video For Details