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How to Make a Simplest 150 watt MOSFET Inverter Circuit

Last Updated on by 60 Comments

The article explains a very simple yet powerful 150 watt inverter circuit design which can be built by any electronic enthusiast and used for powering most of the household electrical appliances (resistive).

The use a couple of mosfets influences a powerful response from the circuit involving very few components, however the square wave configuration does limit the unit from quite a few useful applications.



Introduction

Calculating MOSFET parameters may seem to involve a few difficult steps, however by following the standard design enforcing these wonderful devices into action is definitely easy.

When we talk about inverter circuits involving power outputs, MOSFETs imperatively become a part of the design and also the main component of the configuration, especially at the driving output ends of the circuit.

Inverter circuits being the favorites with these devices, we would be discussing one such design incorporating MOSFETs for powering the output stage of the circuit.

Referring to the diagram, we see a very basic inverter design involving a square wave oscillator stage, a buffer stage and the power output stage.

The use of a single IC for generating the required square waves and for buffering the pulses particularly makes the design easy to make, especially for the new electronic enthusiast.

Using IC 4093 NAND Gates for the Oscillator Circuit

The IC 4093 is a quad NAND gate Schmidt Trigger IC, a single NAND is wired up as an astable multivibrator for generating the base square pulses. The value of the resistor or the capacitor may be adjusted for acquiring either a 50 Hz or 60 Hz pulses. For 220 V applications 50 Hz option needs to be selected and a 60 Hz for the 120 V versions.

The output from the above oscillator stage is tied with a couple of more NAND gates used as buffers, whose outputs are ultimately terminated with the gate of the respective MOSFETs.

The two NAND gates are connected in series such that the two mosfets receive opposite logic levels alternately from the oscillator stage and switch the MOSFETs alternately for making the desired inductions in the input winding of the transformer.

 

Mosfet Switching

The above switching of the MOSFETs stuffs the entire battery current inside the relevant windings of the transformer, inducing an instant stepping up of the power at the opposite winding of the transformer where the output to the load is ultimately derived.

The MOSFETs are capable of handling more than 25 Amps of current and the range is pretty huge and therefore becomes suitable driving transformers of different power specs.

It’s just a matter of modifying the transformer and the battery for making inverters of different ranges with different power outputs.

Parts List for the above explained 150 watt inverter circuit diagram:

R1 = 220K pot, needs to be set for acquiring the desired frequency output.

R2, R3, R4, R5 = 1K,

T1, T2 = IRF540

N1—N4 = IC 4093

C1 = 0.01uF,

C3 = 0.1uF

TR1 = 0-12V input winding, current = 15 Amp, output voltage as per the required specs

Reader Interactions

Comments

  2. Thanks for ur answer sir, pls tell me how to calculate current which is going through mosfet ? if I want to make 200w inverter means how to calculate the VA value of the output transformer?

    Reply

    • simply connect an ammeter in series with the battery positive…that will provide you with an instant indication regarding the amount current being used (delivered) by the inverter (load)

      Battery (+)———-( A )—————->inverter

      Reply

  3. Dear Sir , please say me how to connect mosfet in the inverter, for other switching application and all I am connecting the load at. drain side and also I need to know how to calculate the how much current which is flowing through mosfet?

    Reply

    • Dear jayam, It may be done as shown in the explained diagram above….gate goes to the signal source via a low value resistor……..drain to the transformer taps, and the source to the ground or the negative of the battery.
      this set up is for all N channel mosfets which is the standard recommended type for inverter application.

      Reply

    • if the output of the trafo is rated at 220V and if the input supply is a little higher than the 12-0-12 or 24-0-24 spec then the output will be adequately above 220V

      Reply

  5. hi swatagam, can this schematics be used as a 1000 watt inverter with the right transformer and super battery and adequate cooling of the transistor without changing the schematics?

    Reply

    • Hi Fidel, yes it can be done!

      and the unused gate can be further modified to generate PWMs for transforming the design into a pure sine wave inverter.

      Reply

  6. can we add a battery charger to charge the battery along with the inverter circuit? so that when the inverter is not in use the battery can be charged up. if it's possible, can you please provide the circuit diagram ? thanks

    Reply

  8. dear sir. i also tried this circuit personally same would happend to me.the mosfet gets super hot and burns out but the another mosfet is stay cool. i checked the burned mosfet drain pin is fully blacked….and also i have one doubt how to check the gate, drain and source value

    Reply

  10. Dear sir,i have tried this circuit personally and trust me,one of the mosfets gets super hot while the other one still cool (dunno why?) but the sad thing is that my output I only got 193.4V instead of 230V and when i connected it another way I only get 96.5V instead of 150V….any chance why the output voltage quite low or any way of improving the efficiency of the circuit? Thanks in advance sir…..

    Reply

    • Dear Misterkibz,

      there could be something wrong in your circuit, check the voltages at the gates of the mosfets, they should be nearly equal, if the difference is more than 2V, then certainly either the IC or your mosfet could be faulty. Once you rectify this issue, the output voltage will automatically get corrected.

      Reply

  12. am a electronics and communication engineering student……..now am going to work for an major project….can u suggest me circuit for my main project?

    Reply

  15. sir will you please kindly give a rough sketch of the prices of the items used here !!
    please sir i am asking it so that i wont get cheated when i go to the electronics shop ,….

    Reply

  17. hi
    iam thinking of designing an inverter that runs one ceiling fan and one light……how can i do that and how much load the fan takes? do ceiling fan and table fan takes differnt load

    Reply

  18. Dear Swagatam Majumdar Saab

    Namashkaar

    Please provide me the details of the ordinary Step-Down Transformer ( as used for Audio Amplifier Circuit ) and that of Inverter Step-Up Transformer ; I mean – I wish to ask / clarify – that – whether the following is correct : Step-Down Transformer : Primary is for 220VAC and the winding is thin gauge copper wire – say 36 gauge – with more number of turns – say approx 1500 and Secondary is for say 12VAC with Center Tap – and the winding is thick gauge copper wire – say 18 gauge – with lesser number of turns – say approx 200 to 250 or so ; ; Step-Up Inverter Transformer : Primary is for 12VAC with Center Tap and the winding is thin gauge copper wire – say 24 gauge – with lesser number of turns – say approx 600 and Secondary is for – say 220VAC and the winding is thick gauge copper wire – say 12 gauge – with more number of turns – say approx 1800 to 2000 or so ; please correct me if i am wrong ; looking eagerly for your reply ; also mention the core / lamination Diameter / size and the total number of lamination plates that should be used ; GOD Bless You – in Advance – for your valuable information. My Blessings and wishes too ;-D

    Reply

    • Helio, Thanks!

      An ordinary step down transformer can be used for inverter application by connecting the low voltage side to the inverter circuit.

      Special designing may not be required as they are readily available in the market.

      I you are looking for a customized design, you may consult a qualified transformer designer/maker because I do not have much experience with transformer designing.

      Reply

    • The Nchannel mosfets in the above circuit switch ON in response to positive triggers which are applied alternately from the respective NAND gates.

      The two mosfets thus trigger alternately and load the respective winding of the transformer with the battery voltage/current, generating the required actions across the output winding of the transformer.

      Reply

    • Sir, if I would not like to connect the diodes so both the mosfet's Source will be short circuit to each other while each end of the transformer input will be connected to the Drain directly respectively?

      Reply

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