DIY Short Circuit (Overcurrent) Protection

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Introduction: DIY Short Circuit (Overcurrent) Protection

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 (affiliate links):

Aliexpress:

1x Relay (12V one with 2 changeover contacts): https://s.click.aliexpress.com/e/_dXytThh

2x PCB Terminal: https://s.click.aliexpress.com/e/_dYbstfZ

1x LM358 OpAmp: https://s.click.aliexpress.com/e/_d6VP6J1

2x BC547 NPN Transistor: https://s.click.aliexpress.com/e/_dU81lmT

1x 5mm green LED: https://s.click.aliexpress.com/e/_dV63r7D

1x 1N4007 Diode: https://s.click.aliexpress.com/e/_dYR45Bh

1x Tactile Switch (NC): https://s.click.aliexpress.com/e/_dXIIMcP

6x 1kΩ, 2x 20kΩ Resistor: https://s.click.aliexpress.com/e/_dTPpXjt

1x 10kΩ Trimmer: https://s.click.aliexpress.com/e/_dTFyPv5

1x 0.1Ω Resistor: https://s.click.aliexpress.com/e/_dZKdSGL

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

1 Person Made This Project!

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38 Discussions

0
RandyL11
RandyL11

2 months ago

Hi. Just wondering if you have an email address for me to send PM. I am 64y.o. and really struggle with electronics. I am embarrassed to post in open forums. I would like to ask questions about protecting 12v dc PWM controllers for my model train layout. So far I have 'blown up' for modules bought on ebay and I'd like to try and protect the last two I have. Thanks

0
UserInstru
UserInstru

4 months ago on Step 4

My compliments, really my compliments. No news, non discovery, but a very good way to design a project, to test it, to create good documentation and teach to the novice how it works, how we must work. Very good instructables. No one doubt remains, all is so clear. You have blessed hands!

0
erygion
erygion

5 months ago

Great circuit! Works perfectly, I love it! Thank you Great Scott, I've built many of your circuits and they're all great.

0
meisl.sprax
meisl.sprax

3 years 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?

0
prabhatk13
prabhatk13

Reply 1 year ago

Try using mcp602 opamp as it is rail to rail so its output voltage will be very close to input. It is expensive but will save you from the hassle.

0
shubhammorale6767
shubhammorale6767

1 year ago

I want to do this project ,but in this project here using relay which is costly as compare to regular relay ,can I use here two regular relay. if yes ...then plz let me know how it I use

0
Abhisek012
Abhisek012

1 year ago on Step 3

What if we don't use 0.1ohm resistance ?

0
ZulRoxx
ZulRoxx

Question 1 year ago

Notworking for me,

1
MrityunjayS3
MrityunjayS3

Question 1 year ago

I didn't get the use of the tactile switch. How is it making the relay kinda permanent as OFF when the first error signal comes.

0
JorgeU15
JorgeU15

Question 2 years ago on Introduction

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

0
kartik__07
kartik__07

Answer 1 year ago

yes u can , but u cannot sense the current ,u can sense voltage using analog.Read,
but still youll need current sensing resistor , only things u can eleminate using arduino are comparator and push button.......

0
MarinoH1
MarinoH1

3 years 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

0
MubashirS7
MubashirS7

Reply 1 year 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.

0
Thundertronics
Thundertronics

Reply 2 years ago

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

0
ChaA3
ChaA3

2 years 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..

0
seanfoxen
seanfoxen

2 years 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
0
dpkagr1112
dpkagr1112

Question 2 years 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

0
MichałP9
MichałP9

Question 2 years 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?