relay DC Automatic switch

Short circuit autocut relay switch for DC

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Smart relay switch for DC


when a short circuit occurs, Automatic Switch OFF the supply and an indicator will also start to glow. This is just like an MCB used for AC. This switch is used for DC supply. This automatic Cut relay switch is very useful for damage protection to the circuit from the Short circuit. If you want to use a 6v load then you need to use 6v relay. and if you have to 12v load then use a 12v Relay. 

This is easy to build and very few components are used in this circuit and no ic is used in the. This is not a digital sensor circuit but this is based on the simple relay detection analog circuit.


Relay is an Electromechanical device that works on the principle of Electromagnetic. Relay has a coil to create a magnetic field and some movable pins are fixed with the help of a spring. When giving to supply into the coil of a relay, a strong magnetic field is created by it and pull the moving pins and touch the contacts pin each other and switch is then turn on to flowing the current. Generally, a relay coil connected with the DC supply but the connecting movable pins is used to ON or OFF either DC or AC. A relay has mainly 2 coil input pins and 3 other pins that are internally mechanically movable. COM- Common, NO- normally opened( this pin is connected after relay activate after coil get supply) and NC- Normally connected (Connected when the coil has no supply).

Working principle 

The working mechanism of this DC Autocut relay switch is simple. When the pushbutton SW1 pressed once, the current starts to pass to the relay coil and suddenly at the same time the relay will activate, then also current starts flowing to output through relay NO pin and starts to conducting the current continuously.

But if a short circuit occurs at the output portion then the potential difference will go to zero at the coil of the relay and then the relay will Deactivate. now the supply is automatically stopped to flowing the current.

You can understand the working mechanism of this circuit by flowing gif animation.

relay DC Automatic switch

DC relay switch with autocut 2

Schematic diagram

DC Relay switch circuit with short circuit protection


Relay 12v – 1

LED Blue or Green – 1

LED Red – 1

Resistor 1K- 2

pushbutton switch -1

Diode 1N4007 -1

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