DIY Short Circuit (Overcurrent) Protection

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About: Awesome Electronics Tutorials, Projects and How To´s

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

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    29 Discussions

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    MarinoH1

    1 year ago

    hey scott, i want to adapt this circuit into my lm317 variable power supply, how do i keep the value the same while still being able to change the voltage of my supply??
    also how do yo make your circuit's? i tried eagle, fritzing and my head but i can't nice PCB's

    2 replies
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    MubashirS7MarinoH1

    Reply 20 days ago

    I know it has been some times but I will still try to give a reply. From the schematic, there shouldn't be alot of problems, as although the drop across the resistor changes, so does the reference voltage in the comparator(assuming you take the reference voltage from the supply), so the proportion should stay the same, however as I still haven't built this circuit, I maybe wrong, try it on a bread board using a battery and a voltage divider and see if it works at different voltages as well.

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    ThundertronicsMarinoH1

    Reply 1 year ago

    If you design a lab psu then you should add current limit feature which will serve you as short circuit limit as well.

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    ChaA3

    8 months ago

    Hello Sir
    Im a electronics engineering student from philippines. I am currently working on AC short circuit and overload protection circuit. Im looking for possible circuits that will suit for my applications.

    can i use this circuit?

    thanks in advance..

    1 reply
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    seanfoxen

    7 weeks ago

    I attempted to create a simulation model of this design in Tinkercad Circuits. I believe I have built the model per the schematic, however, it exhibits some unusual behavior. It is not clear to me if this is a limitation of the modeling software or a problem with the schematic. A review of the model and suggestions on how to fix it would be most welcome.

    The simulation can be found here: https://www.tinkercad.com/things/dFuMeg8GPku

    DC Overcurrent Protection.png
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    JorgeU15

    Question 8 months ago on Introduction

    .can i program it using arduino uno to set a maximum range of current it will trip?

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    dpkagr1112

    Question 9 months ago on Step 3

    What actually this project work. As i give 10v supply to it and my microcontroller required only 3.7 volt than what happen . And if i give 2v than what happen

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    MichałP9

    Question 9 months ago

    Hello,
    very nice tutorial. What is required to control reset logic (handling overcurrent error state) with 3.V programmable logic e.g. from an arduino? Is it necessary for the coil VCC to have the same level as load circuitry (12V)? If not, there could be a buffer at the comparator output converting 12V to 5V and driving Q2. Tactile switch could be replaced with just another transistor driven by the GPIO. What do you think?

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    asaneie

    11 months ago

    Hello

    If you guys made pcb for this circuit please share with us.

    Thank you

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    asaneie

    11 months ago

    hello
    I make this circuit but it's didn't work I don't know why Because everthing looks okay so please someone look at pictures and tell me why it's not working.
    thank you

    IMG_20171208_205104.jpgIMG_20171208_205056.jpgIMG_20171208_204948.jpgIMG_20171208_204839.jpg
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    camdogg00

    1 year ago

    Could you upload a higher res schematic or one were it is zoomed in a bit. The one up now is a bit hard to read due to pixelation

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    mak_paint

    1 year ago

    the differential amplifier circuit on the vcc side does not work with the lm358

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    asaneie

    1 year ago

    hello

    Thanks for sharing your awesome project.

    I didn't find 10 pin relay but I find this 8 pin.

    Could you please tell me how to use it on circuit or send me new schematic with this one?

    Thank you

    P_20171020_212418.jpgP_20171020_212410.jpgP_20171020_212558.jpg
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    meisl.sprax

    1 year ago

    Hi, I tried to adapt your circuit to 5V. The main problem is that the LM358 requires "head room" of 1.5V to Vcc on its output, which isn't of much concern with 12V but becomes a major issue at 5V.

    I ended up putting the 0R1 sense resistor between the load and GND rather than between Vcc and the load, and used a simple non-inverting amplifying configuration for the first op-amp instead of a differential amplifier. This approach should work equally well at higher Vcc, and it even saves a few parts.

    Have I missed something? What do you think?

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    Aristarco

    1 year ago

    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?

    2 replies
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    Camoman619Aristarco

    Reply 1 year ago

    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.

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    AristarcoCamoman619

    Reply 1 year ago

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

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    itsmescotty

    1 year ago

    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.

    1 reply