Introduction: DIY Short Circuit (Overcurrent) Protection

In this project I will show you how to create a simple circuit that can interrupt the current flow to a load when the adjusted current limit is reached. That means the circuit can act as an overcurrent or short circuit protection. Let's get started!

Step 1: Watch the Video!

The video gives you all the information you need to recreate the protection circuit. In the next steps though I will give you some additional information.

Step 2: Order Your Components!

Here you can find a parts list with example seller:

Amazon.com:

1x Relay (12V one with 2 changeover contacts): http://amzn.to/2v8vHyT

2x PCB Terminal: http://amzn.to/2uKP6VG

1x LM358 OpAmp: http://amzn.to/2v8RfLx

2x BC547 NPN Transistor: http://amzn.to/2u9yW4y

1x 5mm green LED: http://amzn.to/2hdv4OQ

1x 1N4007 Diode: http://amzn.to/2hdAAAU

1x Tactile Switch (NC): http://amzn.to/2uNZBpm

6x 1kΩ, 2x 20kΩ Resistor: http://amzn.to/2eYvgAA

1x 10kΩ Trimmer: http://amzn.to/2eYBArS

1x 0.1Ω Resistor: http://amzn.to/2eYRsdK

Ebay:

1x Relay (12V one with 2 changeover contacts):http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

2x PCB Terminal: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x LM358 OpAmp: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

2x BC547 NPN Transistor:http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 5mm green LED:http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 1N4007 Diode:http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x Tactile Switch (NC):http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

6x 1kΩ, 2x 20kΩ Resistor:http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 10kΩ Trimmer: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 0.1Ω Resistor: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

Amazon.de:

1x Relay (12V one with 2 changeover contacts): http://amzn.to/2uK2t8g

2x PCB Terminal: http://amzn.to/2viTnkl

1x LM358 OpAmp: http://amzn.to/2uNMsN6

2x BC547 NPN Transistor: http://amzn.to/2vj6qCy

1x 5mm green LED: http://amzn.to/2vbPfSn

1x 1N4007 Diode:http://amzn.to/2uO2kiL

1x Tactile Switch (NC): -

6x 1kΩ, 2x 20kΩ Resistor: http://amzn.to/2uNJ4BH

1x 10kΩ Trimmer: http://amzn.to/2uKc9j5

1x 0.1Ω Resistor: http://amzn.to/2eY98qa

Step 3: Build the Circuit!

Here you can find the schematic of the circuit along with pictures of my finished perfboard layout. Feel free to use them as a reference for your own circuit.

Step 4: Success!

You did it! You just created your own short circuit (overcurrent) protection circuit!


Feel free to check out my YouTube channel for more awesome projects:

http://www.youtube.com/user/greatscottlab

You can also follow me on Facebook, Twitter and Google+ for news about upcoming projects and behind the scenes information:

https://twitter.com/GreatScottLab
https://www.facebook.com/greatscottlab

Comments

author
Aristarco (author)2017-08-03

Excellent!! I'm putting this in the To Do list. One question: why do you push the reset button twice? I've been watching the video and still don't understand why you push it twice. Isn't it supposed to be a one-touch reset?

author
Camoman619 (author)Aristarco2017-08-04

It's because he is using a switch that acts as a toggle switch but as a button so when he presses it once it breaks the connection and stays that way so he has to hit it again to reset the switch back to the closed state which it will keep until he touches it again.

author
Aristarco (author)Camoman6192017-08-07

Heheh, you're right. I see now it's a push-on/push-off button. Thanks!

author
itsmescotty (author)2017-08-01

not beyond my capability to make but...

Is this limited to 12vdc? Is it capable of being scaled for use with a 30vdc LED for example.

author

Yes, that is possible. You just need another relay.

author
madhavdivya (author)2017-08-01

Great video and educational too. Keep up the good work, God bless.

author
DenM3 (author)2017-08-01

You make the best videos, and your circuit drawings are text book perfect. Judging from your accent and penmanship, I would say German. I spent 7 years in Germany. Mannheim, Baden Wuerttemberg to be exact. Best time of my life. Whenever I hear the German language or accent, I'm reminded of that beautiful country. Great work as always.

author
chingada (author)2017-08-01

neat project , coll willbe on my list to do , please some specs for voltage , amps safe ratings

author
hernytan (author)2017-07-31

I've been working on something similar, it uses an NE555 timer and a P-channel MOSFET instead of a relay to break and latch the circuit. Thought it might be another way to solve this circuit breaking problem (other than the fixed solution of using a resettable fuse). What do you think?

NE555 auto turn off.PNG
author
JULIOC136 (author)2017-07-31

Thanks.

author
tytower (author)2017-07-30

Im wondering if you can explain the circuit board connections in more detail please. The circuit is fine but where does it all fit on the board?

author
RafaelC179 (author)2017-07-30

As always, perfect. Useful and practical circuits. Now we just need to put an Arduino and an LCD to display the current limit and have an adjustable source. Scott congratulations from Spain.

author
EdwardF2005 (author)2017-07-30

Great Scott ,I have a sugestion for you , could you make a CNC drawing machine!

About This Instructable

11,576views

189favorites

License:

Bio: Awesome Electronics Tutorials, Projects and How To´s
More by GreatScottLab:Make Your Own ESCDIY Short Circuit (Overcurrent) ProtectionMake Your Own Photovoltaic Off-Grid System
Add instructable to: