Automatic Inverter and Mains Supply Changeover Circuit

There are many types of Inverters to build. Once you build one inverter, you can light bulbs, or other electrical equipments by battery.

But, you had to do a boring thing that is manual changeover. That required you to plug in equipments in inverter when powercut and turn on inverter manually. And when mains came back you had to turn off inverter, and plug the equipment back to mains.

The following circuit will do that job automatically. It does the following,

When mains are on: Equipments are connected to mains

When mains are off: Equipments are connected to Inverter and inverter is turned on.

It requires a DPDT relay or 2C relay and a power adapter that can run the relay by mains.

Have a look on the image below to get an overview of the working process of this setup, automatic inverter and mains supply changeover.


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29 Responses

  1. Germain says:


    I have a machine that draws 200 watts, I want to buy a Seal Lead Battery of around 25 amps and a 300 watts inverter. I need to buy a DPDT relay, what kind or how big should it be. I live in Montreal and I don’t know where I can get a DPDT. Can you tell me where on the internet I can buy those.

    Thanks a million

  2. moore says:

    thank you for the automatic change over. I really appreciate it. Pls i need a cct of inverter, can u send it to my mail? Pls

  3. shiva says:

    I Design 12 volt online solar inverter , when battery voltage below 7 volt then how to protect failure during changeover (if battery too low and mains present but no output then during early morning solar will charge the battery and that time fault will come because main charger pulse full fire)

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