Make Simple 555 Inverter circuit using MOSFET

Do you want to learn a simple inverter circuit? The output is about 50 watts. And using a few parts and a small circuit.

Here is an IC 555 inverter circuit. Because of using 555 timer and MOSFET as main.  I experiment it to work well.

When use source is 12V battery will have the output of 220V AC 50Hz.

555 Inverter circuit using MOSFET

The principle of the circuit

I think many peoples do not like to read many words or long reading.
So please read at simple principle inverter

inverter working principle

Firstly, DC voltage from a battery gets into square wave oscillator circuit. It produces AC voltage, 50Hz frequency.  But this is too low current.

Recommended: 555 Astable pulse oscillator

What can you do? Use the power switchings such as the power transistors or MOSFETs.

But AC voltage still is 12V.   Next, Transformer inductance voltage to rises into 220V AC 50Hz to apply load.

How 555 inverter circuit works

In the circuit above is completely circuit diagram of this project. I use IC-NE555 timer is a square wave frequency generator output of 50Hz.

555 inverter circuit diagram with MOSFET

The frequency is determined with R2-resistor and C1-capacitor.

Output 555 Frequency Calculation

If you use R2 is 150K. It is 47HZ output. You may use a potentiometer-50K in series with R2. To adjust a frequency is 50HZ

MF4Me said:
“By calculation (results will vary depending on component tolerances) a good combo of common parts would be:

  • 0.2 uf (2 x 0.1 in parallel)
  • 100 Ohm for R1
  • 72K (39K and 33K in series) for R2.
Calculation of 50HZ frequency of 555

That calculates to 50.069 Hz with a 50.03 duty cycle.

That is smart accuracy. If your tolerances work out.

What is more?

Then, we use both N-type MOSFET, IRF540 (Q2, Q3) to drive a transformer coil (primary winding).

The output current at Pin 3 of IC1 will flow two ways.

  • First, through R3 to a gate of Q2.
  • Second, flows to Q1-transistor BC549 as inverter logic form to reverse signal difference first ways.

Next, the current flows to the gate of Q3 to also drive the transformer. 

It inductance low AC voltage to high volts, about 220V to 250V.  According to the condition of the battery, 12V to 14.4V.

The circuit diagram of MOSFET Inverter

The transformer I use 2A current and 12V input at output power more than 100 watts.

Here are a few related posts you may find helpful, too:

Why use MOSFET?

In circuit use IRF540 MOSFET. There are many reasons to use them.

  1.  It is easy to use.  They do not need the pre-drive transistor in Darlington is the same as normal transistors, such as TIP41, 2SC1061 etc.
  2. It can drive high current to load, 27A max.  While the transistor (TIP41) can drive load 4A max.
  3.  It is inexpensive just 0.5US only.
  4. The body is TO-220 looks like TIP41 transistor so easy to mount on a heatsink.
  5. They can use smaller heatsink than a transistor, they are not too heat.

The component list

IC1: NE555 timer IC = 1 pcs.
Q1: BC549-NPN 40V 0.5A transistors = 1 pcs.
Q2, Q3: IRF540-N CHANNEL POWER MOSFET, 100V, 27A, TO-220; 2 pcs.
C1,C2: 0.1uF 100V mylar capacitors = 2 pcs.
0.5W resistor
R1: 4.7K = 1 pcs.
R2: 120K = 1 pcs.
R3,R4: 1K = 2 pcs.
R5: 5.6K = 1 pcs.
T1: 2A 12V__CT__12V transformer = 1 pcs.

Building and testing of 555 inverter circuit using MOSFET

This projects I assemble components on a universal PCB board. As Figure 2, while it operated will get little hot. So use enough heatsink.

555 inverter on universal PCB board

Figure 2

Then, check the circuit for error. Please watch the video below.

When checking all no error

We will test it with 100 watts lamp at the output. Then, apply 12V battery source. You will see that. The lamp glows. But the battery voltage is slightly low. Also, the AC voltage output is 190V.

After that, We check waveform is a square wave as shown on the scope.

Some people wonder about something. I will share with you.

The electrolytic capacitors are 470uF 50V. I put it to filter a smooth current. It does not need. If you use a 12V battery, 10Ah. Because it is a stable power current source.

Ideally, if you need full 100 watts output. You need to use 8A transformer. Because of input watts = output watts = 100 watts.

When the primary coil voltage of the transformer is 12V at 100 watts.
The output current input = 100W/12V = 8A (approximately)

555 Inverter circuit project

If it not working
I feel uneasy if you build this project It does not work.

First, you need to review well, the pin of the IC, resistors, capacitors. And the important is connecting the MOSFET.

View using IRF540 legs.

Second, should do not connect the power cord to the transformer and MOSFET.

Third, check the 555 timers working, frequency generators at pin 3 first. You may use a voltmeter to measure a voltage across pin 3 and ground. You use surely oscilloscope to watch waveform.

Check out these related articles, too:

Related Posts


I always try to make Electronics Learning Easy.

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