I have designed two simple Polarity Reverse Protection Switches that will find many uses in the field of electronics from the dangers of reverse polarity.


  This version has no LED Indicator.                                                       This version has a LED Indicator as well.              

Now if you would like to see it working then visit my You Tube page here.

Please note both versions are on this page.

What is Reverse Polarity?

This type of fault typically occur while installing new high capacity batteries the wrong way around or if you connect your power supply the wrong way around. Now even if you left your power adapter in the wrong polarity setting while these are the result of accidents their damaging effect can be devastating to electronic devises.


1). I designed this simple 12 volt reverse polarity protection devise to add more protection to a project I was working on I know this idea will be useful to a lot of people that want to protect there sensitive circuits from the dangers of reverse polarity damage.

2). The unit can be designed to use lower voltage relays if required I just needed to add some extra protection as I wanted to use my circuit with a car battery.

3). Now if you have ever connected your electronic devise to a high current devise the wrong way around then you know the damage the currents can do to sensitive circuits like ICs and more.

4). This simple protection devise I have designed can be used any where you have a 12 volt supply and want to add extra protection from High capacity battery's to mains adapter being left switched with the wrong polarity.

5). The unit is very simple to build even for beginners you will see the Schematic diagram for the project below.

6). The input is 12 volts and the output is 12 volts the unit works fine when you connect the input to the right connecters it will switch the relay on and supply a negative return path.

7). Now if you connect the wires the wrong way or you for got you left your power adapter in a reverse setting the unit will not switch the relay on and will not supply a negative return path so protecting your electronic devise from damage.

8). I used 1N4007 Diodes in both designs. 

9). I used a SPST Relay for this design with a 12 volt coil contact current 10 Amps max voltage 240 Volts.

10). Resister 1K Ohms.

11). Red 5mm LED