How to Make a Homemade Power Inverter

Making an inverter at home may seem difficult, but it isn’t! A few simple (and affordable) things, about an hour of your time, and your inverter is ready.

A small 150-200 watt inverter can be connected to your car battery and power or charge your laptop, smartphones, LED lights and other small appliances. Inverters are expensive devices, but it is quite easy and inexpensive to build one at home.

If this is your first time making a homemade inverter, don’t worry, the circuit design is very simple and you don’t need more than three components to make it.

Are you ready to make your own power inverter?

In this post, we will discuss the step-by-step process of making a homemade inverter using only three components, a relay, a transformer, and an input battery. It is a 220 volt 50 Hz square wave converter that powers an LED lamp or charges small devices such as smartphones.

How Does a Power Inverter Work?

Inverters convert direct current (direct current) from an input power source (usually a car battery) into alternating current (alternating current) used to power electronic devices.

Power converters provide a great alternative to typical power generators. They require no fuel to generate power and are a great source of backup power.

Components Needed to Make a Power Inverter:

The circuit design used in our inverter is very simple. It only requires a few components and even someone with no previous electronics experience can do it easily.

  1. 12 volt rechargeable battery x1
  2. Cables to connect components
  3. 5 terminal 12 volt relay x1
  4. Transformer 12-0-12 (240-12 volts and 5 amps) x1
  5. LED lamp (220 volts) for load test x1

Circuit Design for the Homemade Power Inverter

How to Make a Homemade Power Inverter

How to Build a Power Inverter:

Making an inverter is not easy. It usually involves complex circuit design and multiple components. If you want to make a cost-effective home inverter for your home needs, you’ve come to the right place.

WARNING: The circuit uses hazardous alternating current, use extreme caution when handling.

We will make a homemade inverter with three components, that is, a relay, a transformer and an input power supply.

Step 1: Understanding Components 

Understanding the components used in our inverter is the key to understanding how inverters work.


We will use a simple 5 pole relay to make this inverter. The relay acts as an oscillator to produce a stable AC output when turned on.

The relay acts as a switch to open and close a circuit electromagnetically or electronically. The relay is used in circuits to control current by closing the contact in one circuit and opening the other.

Only four of the five terminals are used on the 5 pole relay. One of the terminals remains disconnected from the circuits as it is not needed. We will use the other four terminals of the relay to connect to the transformer and battery (two terminals each).

A relay contact is normally open (NO) or normally closed (NC). When a relay contact is normally open it means the coil is energized and normally closed means it is de-energized. Applying an electric current to a relay changes its state.

You may be wondering why we use a 5 terminal relay when only four terminals are used. The difference between a 4 terminal relay and a 5 terminal relay is that a 4 terminal relay is used to control a single circuit while a 5 terminal relay switches the current between two circuits.

The transformer is connected in parallel with the battery and relay. It works on the principle of magnetic induction and converts alternating current from one voltage to another. It actually ups the voltage game (12 volts DC – 240 volts AC)!

Step 2: Designing the Circuit 

Circuit design is the most difficult and crucial step. Pay close attention to the schedule and instructions.

  1. Start building your inverter by connecting all components according to the wiring diagram.
  2. The next step is to cut two pins out of the relay. Solder the normally closed (NC) pin of the relay to the coil 1 pin of the relay.
  3. Solder the 0 wire from the transformer to the coil 2 pin of the relay.
  4. Solder the first 12 wires from the transformer to the normally open (NO) pin of the relay and the other 12 wires from the transformer to the NC coil of the relay.
  5. Solder the LED lamp to the output wires of the transformer.
  6. The last step is to connect the input power to the circuit, connect the input power wire +ve to the common pin of the relay and the -ve input to the NO pin of the relay.
Step 3: Testing the Power Inverter

Once you have connected the positive and negative wires from the power supply, the LED should begin to glow. It means your inverter is ready! You can use it to power the LED lamp or to charge small appliances.

If the LED is not lit, repeat the sequence of steps again to make sure you are doing it right.

What is the Maximum Power Output of the Inverter?

The maximum output power of our homemade inverter depends on the size of the transformer and the input power supply. It is a square wave converter with a frequency of around 70 Hz and an efficiency of almost 65%.

And last but not least!
Caution is better than cure. Handle your electrical equipment with extreme care to avoid unpleasant accidents.

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