Circuit Breaker for Power Supply

When testing new circuits it's easy to damage electronic components on the process or even blow a fuse on the bench power supply produced by a short circuit.

To avoid changing the fuse all the time or even damage the power supply transformer i made a small circuit breaker that protects my power supply.

On this project i show you how to make one.

Watch the Video

Watch the video and see how the circuit performs in the event of a short circuit.

Gather the Material

You will need for this project:

- Relay with Double Pole Double Throw

- 5V Zener

- 22 Ohms Resistor

- 18K Ohms Resistor

- 2x 1N4001 Diodo

- Push Button

- Bi Color Led

Get Started

Follow the schematic of the circuit and make it on small circuit board.

How It Works

The relay to turn on was to have 12v apply to the coil, but to remain on the coil needs less voltage, around 5V this value may vary depending on the relay.

In the off position the relay will not give the 12v positive output, when you push the momentary button giving 12v to the relay coil this will turn on and remain on thanks to the constant 5v.

For the circuit breaker to cut the 12v positive output it only needs a 1v drop voltage to occur, like a short circuit event, making a reasonable fast reaction to protect your power supply and the circuit that you are testing.

The bi color led will give you the status of the circuit, red for open circuit and green for close circuit.

Final Thoughts

Check out the video there you can see my power supply made out of old VCR, inside a case that was repurpose from a tool case where a run this small circuit breaker protection.

This is my back backup power supply that I use for testing new circuits and it's really handy to have.