Making a Simple Inverter Circuit

This super simple design of an inverter circuit does not limit it in any way from providing a high output power and an efficiency of a good 75%. Learn how to build an inverter that will satisfy most of your power requirement at quite an affordable cost.

The article deals with the construction details of a mini inverter. Read to know how to build an inverter which can provide reasonably good power output and yet is very affordable and sleek.

There may be a huge number of inverter circuits available over the internet and electronic magazines. But these circuits are often very complicated and hi-end type of inverters.

Thus we are left with no choice but just to wonder how to build an inverter that can be not only easy to build but also low cost and highly efficient in its working.

Well your search for such a circuit ends here. The circuit of an inverter described here is perhaps the smallest as far its component count goes yet is powerful enough to fulfill most of your requirements.

Construction Procedure

This simple mini inverter circuit can be completed through the following easy steps:

Cut two sheets of aluminum of 6/4 inches each.

Bend one end of the sheet as shown in the diagram. Drill appropriate sized holes on to the bends so that it can be clamped firmly to the metal cabinet.

Also drill holes for fitting of the power transistors. The holes are 3mm in diameter, TO-3 type of package size.

Fix the transistors tightly on to the heatsinks with the help of nuts and bolts.

Connect the resistors in a cross-coupled manner directly to the leads of the transistors as per the circuit diagram.

Now join the heatsink, transistor, resistor assembly to the secondary winding of the transformer.

Fix the whole circuit assembly along with the transformer inside a sturdy, well ventilated metal enclosure.

Fit the output and input sockets, fuse holder etc. externally to the cabinet and connect them appropriately to the circuit assembly.

Parts Required for the simple inverter circuit diagram

You will require just the following few components for the construction:

R1, R2= 100 OHMS./ 10 WATTS WIRE WOUND

R3, R4= 15 OHMS/ 10 WATTS WIRE WOUND

T1, T2 = 2N3055 POWER TRANSISTORS (MOTOROLA).

TRANSFORMER= 9- 0- 9 VOLTS / 8 AMPS.

AUTOMOBILE BATTERY= 12 VOLTS/ 10AH

ALUMINUM HEATSINK= CUT AS PER THE REQUIRED SIZE.

VENTILATED METAL CABINET= AS PER THE SIZE OF THE WHOLE ASSEMBLY

How to Test it?

The testing of this mini inverter is done in the following method:

For testing purpose connect a 60 watt incandescent bulb to the output socket of the inverter.

Next, connect a fully charged 12 V automobile battery to its supply terminals.

The 60 watt bulb should immediately light up brightly, indicating that the inverter is functioning properly.

This concludes the construction and the testing of the inverter circuit.

I hope from the above discussions you must have clearly understood how to build an inverter which is not only simple to construct but also very affordable to each of you.

It can be used to power small electrical appliances like soldering iron, CFL lights, small portable fans etc. The output power will lie in the vicinity of 70 watts and is load dependent.

The efficiency of this inverter is around 75%. The unit may be connected to your vehicles battery itself when outdoors so that the trouble of carrying an extra battery is eliminated.

Circuit Description

The functioning of this mini inverter circuit is rather unique and different from the normal inverters which involve discrete oscillator stage for powering the transistors.

However here the two sections or the two arms of the circuit operate in a regenerative manner. Its very simple and may be understood through the following points:

The two halves of the circuit no matter how much they are matched will always consist a slight imbalance in the parameters surrounding them, like the resistors, Hfe, transformer winding turns etc.

Due to this, both the halves are not able to conduct together at one instant.

Assume that the upper half transistors conduct first, obviously they will be getting their biasing voltage through the lower half winding of the transformer via R2.

However the moment they saturate and conduct fully, the entire battery voltage is pulled through their collectors to the ground.

This sucks-out dry any voltage through R2 to their base and they immediately stop conducting.

This gives an opportunity for the lower transistors to conduct and the cycle repeats.

The whole circuit thus starts to oscillate.

The base Emitter resistors are used to fix a particular threshold for their conduction to break, they help to fix a base biasing reference level.

The above circuit was inspired from the following design by Motorola:

473 Replies to “Making a Simple Inverter Circuit”

  1. Hi Swagatam,
    This is Mohan.
    This circuit is very nice, even a beginner can do it.
    Can you tell me the rating of the Transformer? Is it 5A(Mentioned in Circuit Diagram) or 8A(Mentioned in Parts Details).
    One more doubt, Can I increase the voltage from 12v to 24v so that I can obtain higher wattage.

    1. Hi Mohan,

      Thanks!
      You may use 24 volts for operating the circuit, but the transformer will also need to be changed to 24-0-24V.
      A 5 amp transformer will be good to begin with, later on you may try a 8 or 10 amp transformer for increasing the wattage of the unit.
      Use large heatsinks for the transistors.

      Regards

  2. hello sir Swagatam I have a question, you have a circuit to test lamps CCFL LCD TV because I have a 42 inch LCD TV does not have the inverter and I want to make a circuit to light the lamps… please thank you very much.

    ATTE: Ariel from Argentina

  3. hello sir Swagatam thanks for replying but that circuit only gives 220Vac at a frequency of 60 or 50 Hz. I need 1500 to 3000 VAC and 35 to 40 kHz…thank you very much

    ATTE: Ariel from Argentina.

    1. Hi Ariel,

      Just type "fence charger circuit" in the above given search box, make the second circuit shown in that article.
      However remember that the circuit can produce upto 20000volts, so you may need to reduce the input voltage by selecting a lower voltage (3Votls) transformer.

      Regards.

  4. Hi This is Mohan again,
    can I add a pair of transistor in parallel with the existing transistor. if yes means how much watts will be obtained with the 12v 5A transformer.

    1. Hi Mohan,

      Only by increasing the number of transistors will not help, you will have to use a bigger transformer and battery also for generating more power.

      12v/5 amp will provide upto 12 * 5 = 60 watts or even less power.

      However the above design won't support more than two transistors.

      Regards.

  5. dear sir is there a jump between R3 and R2?and if i use 2amp transformer can i run a 20 watt fluorescent lamp?and what will be the backup sir?
    thank-u
    from Kiran

    1. Hi Kiran,
      Fluorescent tubes require high initial currents, that means it will consum 40 watts of power during initial striking, so a 2 amp transf may not be enough.
      You might need at least a 3 amp transformer and a 12v7ah battery.

      Regards.

  6. sir i tried to light up this type of tube light with a 40 watt inverter it lit up but if i exceed the wattage the tub light burns up so i think its not suitable for this circuit of inverter.

    1. Swagatam two days ago i asked u to me send the complete description of the circuit… but still no reply….. Plzz send me as soon as possible its urgent…..

    2. Ayesha, I can explain it here, as mentioned in the article, when power is applied one of transistors conduct first through its base resistor 100 Ohms, let's say T2 conducts first through R1, in the course it activates one half of the winding of the transformer which in turn generates a negative voltage at the base of T2, switching it OFF.
      Once T2 switches OF, T1 gets the chance to conduct and the above process repeats with T1 also, giving rise to continuous oscillations.

      This to and fro pumping of the transformer winding generates the AC across its other winding.

      The 15 Ohms resistor are placed for setting up the correct biasing voltage at the base of the transistors so that the above oscillations can initiate.

      Got it?

    3. No i m not a content provider.Don't worry about anything.I am a engineering student and i am going to build an inverter that is why i m asking 4 u…

    4. And Plzz tell me about any site where i can find electronic projects(micro-controller etc.) with full description… I will be very grateful to u..

  7. dear sir,
    i have a 4.8 v battery charger. i want to charge 3v ni-mh battery. how can i charge it as the battery charger voltage is higher than battery. ????? do u have any circuit to charge my 3v battery?

    1. Hi Kiran,

      Just add a 1n4007 diode in series with the positive of the charger. The anode of the diode will get connected to the charger positive and the cathode of the diode to the battery positive, the negative of the charger will directly get connected to the battery negative.

  8. Swagatam i implemented this circuit on proteus (ISIS) its not working Can u check that this circuit is working right…If it is right then plz send me the simulations of this circuit on my ID. plzz

    1. Ayesha, simulators don't always interpret correctly especially the circuits which depend on random or regenerative kind of functioning, as in the above case.
      I have tested this circuit practically and it works.
      But this circuit is not very efficient due to its low part count.

  9. heloo sir
    cn i use a 12-0-12 volt /3 amp transformer in this circuit and will this cause any change in the output voltage

  10. heloo sir
    ashish again

    cn u gv me sm info abt the cost of the electronic goods that i will be using in this project.
    actually its my 1st big electronic project
    so every chance of getting mis lead by the others
    it will be vry kind of u to give me info abt the cost of different items been used here

    1. Hi Ashish,

      It is difficult to estimates the proces because they depend on number of factors, the quality, company, particular dealer etc.

      Just roughly I can say that the 2N3055 would cost you around Rs50/- each,

      Resistors around Rs8/- each
      The transformer around Rs500/-
      and battery 12V 7ah at around Rs.1000/-

      Regards.

  11. sir one mre thing
    wat all appliances wld i be able to run through it if i use a 12-0-12 volt transformer with 8 amp range .
    and wat all i use in a 12-0-12 volt transformer with 3 amp range

  12. sir i am manu,
    i use solar panel to charge 12v 4.5amp battery
    what componnet i should add in b/w to avoid reverse flow from battery to panel?

  13. Dear sir please suggest some modification to increase the efficiency of the inverter circuit,I made it and running super smoothly,but efficiency is less,
    And is there any need to change the resistor value for various amps of transformers,Please give me the formula,so that i can use 3,4,5,6,7 or 8 amp with efficient configuration,
    I am using only cfls so squre wave is not a problem,only i want to increase the efficiency
    And can i incorporate this circuit with this ,then how http://homemadecircuitsandschematics.blogspot.in/2012/05/load-independentoutput-corrected.html
    Thanks

    1. Hi Avisek,

      The above circuit is the simplest, so please do not expect more from it, it's not possible to increase it's efficient by any means.

      Don't use the PWM circuit for this inverter, it will not work.

      Regards.

  14. Hi sir,
    Iโ€™m an engineering student. I have three questions to you.
    1) My father has a motor cycle and there have a 12V battery, I want to use that battery for making an inverter circuit when the motorcycle stay in my house at night. Is it harmful for the motor cycle or for the battery?
    2) Can I use a 6V battery on this inverter circuit, if not then what components should be used for a 6V batteryโ€™s inverter circuit and what will be the circuit of that inverter?
    3) How can the battery of your inverter circuit be charged? Are there need another rectifier circuit? If yes then what will be its circuit?
    Please help me by replying.
    FOYSAL

    1. Hi Foysal,

      1) If you use the battery for inverter purpose, it will get discharged and your motorcycle will not start with it.
      2) The circuit presented in this article will work better with only a 12v battery, it cannot be modified for 6v applications.
      3)I have published numerous battery charger circuits in this blog, please search it through the given search box given at the top right side of this page.

      Regards.

    1. Hi,
      Hopefully very soon i'll be publishing one article covering inverter basics, it will be especially dedicated for the new users so that they can learn and make these at home for their personal benefit…

  15. Hello sir ! May you please tell of complete specifications of the aluminium heatsink to be used in this mini inverter ?

    1. Hello sir !
      I want to make a digital wrist watch configuring 4 digit 16 segment led (2 digits for hours and 2 digits for minutes) and 2 digit 7 segment led for seconds.
      So please tell me sir which micro-controller and other equipments shall i use. And may you please provide me with a schematic diagram of same.
      Thank you sir.

  16. sir i how can i make my own transformer?or can i get an used one from an old ups but it has more wires and i am confused?or how can i get a cheap one? i am using 1 amp but it is giving only about 10 watts please help

    1. Hi Kiran,

      You can buy an ordinary 12-0-12V/5 amplifier power supply transformer from the market…..it would cost you around Rs.400/-
      Don't buy if it's cheaper than this, that would mean it's not 5 amp rated.

  17. 1. sir can i use a 9 volt and a 3 volt battery as the source battery instead of that 12 volt automobile battery??
    2.. sir i have read above that resistors 2 and 3 are havng a jump in between??
    dose that mean that they both are simply connected?

    3. where will i connect the grond point in the input circuit ?
    shall i give it a wire and connect it to the ground terminal of the output socket??

    1. 1) You will have to use a battery having minimum 10 AH capacity at 12V.
      2)R3 is connected to R2, but not to R1 and R4.
      3)Here ground means the negative of the battery, there's no need of connecting it to the earth pin of the socket.

  18. sir i want to ask something not related to this topic.
    my question is can i gv a direct 9 volt supply to a dc motor of 150 rpma nd 9 volt specification.
    and connect it to a dbdt switch

  19. sir swagatam, i know basic electronics, i think i can build an inverter with the posted diagram, but the problem is how can i charge the battery using the ac output of the inverter considering that i am living in an island and we have no source of electricity to charge the battery. can you help me sir…. pls…pls email me on ramil.gamao@gmail.com. thank you in advance.

    1. Hi Rhum,

      You cannot use the AC power from the inverter itself for charging the battery, you will have to employ may be a solar panel for charging the battery since you don't have an utility electricity source.

      Regards.

  20. sir swagatam, i dont know much about electronics but still want to ask u if i can use this circuit for making a ups for running small electronics and that too for personal use… such as television or mixer…and for that do i need to use the same kind of battery??? if there is any other can u prescribe one for me…preferably small compatible in a ups box container…

    thank u

  21. hello sir swagatam im junver sir my question is what type of transformer i will use in this given circuit sir? step up or step down transformer sir? 12-0-12 step up sir 5 to 10 amperes?am i right? will this circuit can light up 3 15 watts cfl light??? sorry for my english sir i not good on it…pls reply asap…

  22. Hallo,Mr Nice to meet you
    I haryo from Indonesia

    I have 2 bulbs of 20 watts each
    How efficient power inverter for both light
    I do not understand the circuit and could send me the circuit
    I have a 12 volt 24 Ah accumulators
    how long the battery can last with both the light
    send to my email

    "haryofootball93@yahoo.com"

    thanks in advance

  23. sir,
    what inverter can you suggest to me since i am in an island, that could be used for my laptop, small fan for my kids and lights during night. please sir help me build n inverter and a charging mechanism that could be suitable. i thank you in advance sir for sharing your expertise to us… can you send it to my email sir @ ramil.gamao@gmail.com. please…and thank you very much…

  24. Hi Swagat,
    I have a 6v 4.5Ah battery and 6-0-6 3A transformer in my hand. All i need a circuit to make an inverter. When i googled for a 6v to 220v inverter, i reached here but i can't find any 6v circuit here. Please help me

    1. Hello Jose,
      Thanks!

      This circuit is a crude form of inverter and does not have a buffer stage, therefore it won't be feasible to connect the 555 PWM stage in this design.

  25. HELLO SIR,
    this is tribhuwan & i want to make an electronic circuit for a electrical motor(1 hp,220v,50Hz) for automatic switch OFF/ON which is done with 3 thermal sensors.And final circuit should ON the motor when all three thermal sensors(say S1 S2 S3) have same temp. reading and should OFF the motor when thermal sensors S1 and S2 have same and S3 has different temp. reading.

  26. hello sir,
    this is tribhuwan , there may be a problem with design due to thermal sensors but for ur kind knowledge i want to say that there should be one processor in the circuit which analyze the readings of all three thermometer(not only sensor) then give command for ON/OFF.
    and application is simple turn ON/OFF the 1 hp water pump(in which capacitors are used) of 220v/50Hz thats all.
    Thanx …..:)

    1. ok sir,
      let us take a example of 2 condition-
      cond1-S1=S2=S3=60(any) degree c then motor should ON
      cond2-S1=S2=70(any) but S3=50(any) degree c then motor should OFF.
      so there should be three thermometer which read temp. and send it to processor for further operation of comparing them whith each other and
      check whether cond1 or cond2 is satisfied and do finaly ON/OFF.

  27. sir i have an old UPS…for which battery was dead…by seeing many videos about converting an UPS into a inverter by replacing it's battery with car battery on internet..finally i also made the same by replacing my UPS battery with tractor battery(which has rating of 85ah)…but the problem is my ups is get triped after working fine for only few minutes…but if we again turn it on means again it is working for few minutes and again it gets tripped of……..My ups name is "numeric digital 600 ex-c"…which has rating of(600va/360w)….and its actual battery rating is (12v/7ah)…finally what i want to know is…weather is it reallly possible to convert an ups into an inverter by replacing its battery…if it is possible means please tell me the specification of battery which is suitable for my UPS

    1. May be the devices are getting hot quickly, therefore the overload circuit is tripping it.

      Try it without connecting any load at the output, that will prove the a above doubt.

      alternatively you may try keeping the devices cool through an external fan so that the circuit doesn't trip of.

  28. Yo swagger how do i educate myself on basic electrical theory i can run wires just fine and know how relays and solenoids work and the workings of an alternator. I've wired ac and dc with no issues. I desire to learn the way tesla,Edison bell and that one dude sending radio waves across oceans How did they invision electricity and magnatsim

    1. Yo! Thanka!

      Yes indeed, these men were gifted with unique brains, they have done such amazing inventions…..not sure how such men taught themselves with so much of knowledge…..may be it was some divine intervention that helped them…

    1. Thanks!

      The formula is not known to me presently, it oscillates due to the slight natural imbalance between the transformer windings, you may refer the bottom document which explains the basic functioning of this inverter.

  29. Hi Swagatam…..

    I'm Priyam, Hey can you give details how to simulate this circuit in MATLAB, I mean its not possible to connect the battery's positive terminal to transformer's primary as the diagram shows.

    1. Hi Priyam,

      Sometimes simulation softwares are unable to initiate or respond to a particular circuit design because they strictly work on logical calculations……a software will find the above circuit difficult to initiate because the above circuit initiates depending upon a slight imbalance in the transformer winding halves….the simulator won't "agree" to this principle, peobably.

      Regards.

  30. Hi Swagat….
    I got the hardware for an inverter, it is made of diodes and a Transistor.the circuit diagram is here http://www.flickr.com/photos/91629848@N08/8320543927/

    I connected it to a 12 volt battery and it did work to light a 24 watt CFL.
    The problem is that I do not understand the working of this hardware. It would be very helpful if you please explain how the circuit works.

    From the diagram, the input is on the right side that is of the 12 volt battery (used in computer ups), the diodes are IN4007, the transistor present is 2N3005. Below the variable resistance, the label is 407K. Rest of the resistances are of 330 ohm. The transformer on the left is a 12V , 40 watt D.T (Drive Transformer). I don't know what is this drive transformer, I googled it but with no benifit. Rest I believe is clear in the circuit diagram.

    1. Hi Vivek,

      There are a few things I couldn't understand, why there are two diodes marked 12V on the right side?

      Are the "earth" and the "0V" connected?

      Why there's a "X" mark over the link which connects the 0V and C(100uF/25V)?

      What are the tap voltage ratings of the transformer primary (input side)?

      By the way I am interested to see the photos of the prototype made by you….if you can make the video of it that would be even better.

      The circuit is very interesting and I would like to post it as a new article in my blog with full explanations, but I would be able to do it only after you provide me with the above answers.

      Regards.

    2. Hi,
      Thanks for your reply and especially your keen interest. Actually I didn't made it, I got it from a shop. This type of prototype is available in some local market. I wanted to know how it works so I asked for the circuit diagram and that is what I got. I'll give you the video of the prototype in a day or two and I'll try to find out the other things you've asked. I am not able to do it right now as I'm out of station.

      I'll get back to you as soon as possible.

      Thanks.

    3. Hi,
      Sorry I'm late.
      The snaps of the prototype is here http://www.flickr.com/photos/91629848@N08/8360118433
      (in the photo stream two snaps one of the front and one from the back )

      The diodes are marked 12V because the input of 12 V DC will be given using any of the two terminals and the one that is connected to the capacitor(+ve to the diode terminal and -ve to the capacitor's). I can see from the prototype that only one of the two diodes is connected to the input terminal. The other one is not connected to anything so can be assumed useless.

      Form the prototype's snaps, the two blue ones are capacitor of rating 100 micro-farad, 25V. The slightly elevated one is a variable resistance. The transformer doesn't have ant tap changing rating on it, so sorry… but I believe that the input to output voltage ought to be 12-220.

    4. Thanks Vivek….. the transformer is the main component here which needs to be investigated thoroughly, if the transformer details are correctly noted down, then the rest of the circuit is just a piece of cake.

      Thanks anyway, appreciate it very much!

  31. Helo swagatm sir,
    i want to ask a question, the transistor 2n3055 mentioned is from motorola,can we use the same from STmicroelectronics.what is the polarity of the transistor,is it NPN?is its collector emitter voltage is 60v,collector current 15a.Can we use 8amp transformer in the same design without any change in transistor.

    1. Hello Prashant,

      All 2N3055s are exactly similar, irrespective of the manufacturer.

      Yes you may use a 8 amp transformer without changing anything in the circuit.

  32. Hi,
    What is the output frequency of this circuit and how will you vary the frequency in the above circuit?
    As I know the part of the circuit which switches the continuously is called the drive of the circuit, so which part of this circuit is used as drive?
    Hope you'll explain in detail.

    1. Hi,

      The above circuit is probably the most basic in its form so there are no specific stages here.

      The oscillation starts due to the small natural imbalance between the two half winding of the transformer and the oscillations are sustained once it gets triggered.

      Since no capacitors are involved calculating frequency is not known to me neither do I have any formula.

      For more info, You may read the document presented at the bottom of the article.

  33. Dear Swagatam,

    Samarth this side – we've been discussing your inverter design to be implemented in my project for "electronic ignition system". Earlier, I had selected the circuit given at http://homemadecircuitsandschematics.blogspot.in/2012/09/making-200-watt-compact-pwm-inverter.html but you suggested this design.

    I've made this circuit but this isn't working. I cannot determine the cause; Let me put up the whole thing in detail:

    o I made the circuit with parts as listed by you.
    o The circuit is not giving output.
    o When I measure the values of Resistors, I don't get 15 ohms & 100 ohms respectively
    o Both the 100 ohms' resistors and one of the 15 Ohms' resistor heat up a little bit when I attach the battery (12V, 75AH).
    o 15 Ohms' resistors show around 30 Ohms on my multimeter
    o 100 Ohms' resistors show between 100 & 300 Ohms changing value every time I check them.
    o The resistors are 15 Ohms / 10 Watts & 100 Ohms / 10 Watts, wire wound.
    o I've changed the resistors even, still the same thing.

    Please let me know about the cause of this. Rest of my circuit is working fine.

    Regards.

    1. Dear Samarth,

      as you can see the circuit is too simple for any issues, should start operating immediately, I have tested this circuit and it worked instantly.

      If the print over the resistors are as per the given ratings then I think the resistors should be OK.

      Check the transistor pin connections, they might be wrongly connected.

      The transistors should be mounted on separate heatsinks.

      There's isn't much to troubleshoot actually… so cannot suggest anything further..

      Regards.

    2. Dear Swagatam,

      Thank you so much for your much awaited response.

      The Transistors are mounted on separate heat sinks. I'll once again check the transistor pin connections.
      I tried simulating this circuit in Circuit Wizard. It works as long as the battery is 9 V. As soon as I select 12 V battery, the output goes 0! I don't know what's happening. You say that this worked when you tried it. I know I must be doing something wrong but being a non electronics guy, I don't know how to debug it. Please tell me one thing – How do I know E, B & C of a transistor.

      Regards,
      Samarth

    3. Dear Samarth,

      OMG!! how did you connect the transistors without knowing their pin outs???

      And Never trust simulators, I don't understand how can a simulator know about the all the parameters at any instant, because all component parameters are never accurate, the battery can be at 13.5V instead of 12V, the transformer may be slightly different from the actual specs, the transistors may be slightly different with its characteristics and so will the resistors….

      Please check the following diagram for knowing the pin outs of the transistor!

      http://datasheetoo.com/power-discrette-device/transistor/on-semiconductor-2n3055-power-discrete-devices-datasheet.html/attachment/2n3055-and-its-feet-diagram-thumbjpg

      Regards.

    4. Silly Me!

      I did locate the pins correctly but while printing the circuit layout, did not mirror the Component Side to Solder Side hence everything went haywire!

      Thanks for your Response Dear Swagatam. Now, I'm gonna redo the circuit.

      Regards

    5. Dear Mr. Swagatam,

      I re-did the circuit, this time on a small PCB (1" x 6"), made the heat sink myself with base plate 5 mm thick and cooling fines 1 mm thick, height of heat sink is about 1.5", the circuit is working but resistors are heating up when I light up a CFL (27 Watts). I'll using a small CPU Cooler to cool everything. though with CFL, the transformer blew up – it was 9-0-9, 1 Amp.
      The circuit is still working, I'll be replacing the transformer today – a 9 – 0 – 9, 5 Amp.
      I want to discuss the complete project with you but can't do it here on this public forum. I've taken a few photo which I'll be sending to you through email.

      Thanks a lot for your help.

      Regards,

      Samarth

    6. Dear Samarth,

      That's great! Congrats!

      If you can wait for a couple of days, I would be publishing the entire circuit of an electronic enhanced ignition system in this blog.

      It'll provide you with a complete idea regarding everything that needs to be done.

      Regard.

    7. Dear Mr. Swagatam,

      Thank you so much for your efforts.

      Somewhere in this page, among the comments, somebody has mentioned that R3 & R4 can be removed, can you verify this? Being at a remote place and with meager resources, I'm a little bit hesitant with experiments. I'm eagerly waiting for your Electronic Enhanced Ignition System. In the meanwhile, I've a query as follows:

      o In my system I'm connecting the output of this circuit to a 35 Watt heating load (element) and a rectifier circuit (in series) that coverts 220 / 240 V AC to 220 / 240 V DC.

      o 16 Diodes are connected in series to this 220 V DC output.

      o The other side of the circuit takes input from the Ignition Coil (22 KV) and again passes it through 16 Diodes in series.

      o I then combine the outputs of these to series of Diodes and pass this combined output to the Spark Plug.

      My question is what is the ampere draw on this inverter circuit. My simulation in Circuit Wizard shows between 200 & 300 ma and I know that something is not right here.

      When I use a UPS everything works fine and spark is great. I've to decide on the transformer rating and inverter circuit because reliability is the key factor to be considered here.

      Hope to hear from you soon.

      Regards,

      Samarth

    8. Dear Samarth,

      It's better to stick with the original design, because it's been recommended by Motorola.

      The ampere of the inverter will depend on the battery AH and the transformer input winding rating…..as you increase these, the power output and the consumption also increase proportionately.

      I'll try to publish the proposed design soon….:)

      Regards.

    1. Hi Kartik,

      That means you have further simplified this circuit, can you upload a video in you tube and provide the link for the viewers here?

      Or even pics will do.

      thanks.

  34. dear sir ,
    i am bala. i did the above said circuit.i used 12.0.12 /5 amps transformer and loaded 15 watt cfl (230 volts A.C) .the problem R1 is getting over heated. the transformer output is 210 volts A.C and the cfl is glowing well.

    waiting for your replay

  35. Dear swagatam, i have question, can i convert 8 volts to 12 or 220 volts.Is there any solution for this problem..I am waiting for your reply.Best regards…

    1. Thanks! you can't merge two inverter outputs, that's not safe. you may build two of the above circuits and terminate their outputs separately for operating two separate loads.

  36. Hi,

    My name is Simon; I recently built this circuit as an integral part of a solar power project that I'm building in college. Firstly, I just want to thank you for posting the circuit, due to its simplicity I was very sceptical that it would function correctly, however I've had it on an oscilloscope and though the waveform is pretty rippled it seems to register quite nicely as AC. The only issue that I've run into is that the output which I'm getting seems to be at 120V. This was measured across an open circuit. The circuit which I built is built exactly to you specifications above. Any idea on why this is happening? Or what I can do to fix it? I've contemplated buying another transformer however I though that maybe you would like to throw me a hit.

    Thanks a lot!
    Simon.

    1. Hi Simon,

      what's your transformer specs?

      It should be 9-0-9V at the input and 220 (or 120) at the output as per requirements.

      The output would follow the transformer specs exactly…

      Regards.

  37. hi sir…..
    i'm sherwin from mumbai.
    I wish to clear off the following facts before i could build an inverter.

    1.Could connecting multiple transistors in parallel along with the original 2n3055 NPN transistor help in sharing heat amongst them???

    2.I'm also familiar with Mica sheets and plastic washers. I'm sure about to use them in a SERIES arrangement if i'm placing many transistors on a single good sized HEATSINK.

    3.In which arrangement(series or parallel) would the transistor switching function be fast and powerful which could result in driving the transformer well?????

    4.I also want to know about the switching frequency from the transistors. Could using many transistors in parallel increase the switching frequency or reduce?????

    5.Could connecting 100 ohms resistors in parallel(eg 2 or 3)result in a totally different resistance????just want to confirm?????

    Thanks!

  38. Hi sir.
    I'm Sherwin from Mumbai.

    I wish to clear off the following facts:

    1.Placing many 2n3055 transistors in parallel does increase the switching current and frequency?????

    2.My resistors are rated [SUN 15E 12W 15%]. What does 15% mean????

    3.What volt/amp of transformer to use in suitablly enough to start a LCD monitor?????

    I'm waiting for your reply.
    My email address is sherwinbaptista94@gmail.com

    Thanks well in advance

    1. Hi Sherwin,

      1)the above circuit cannot be and shouldn't be modified in any way.

      2) 15% indicates +/- tolerance/accuracy level of the resistor.

      3) the above circuit cannot be used for operating LCD monitors.

  39. hello swagatam sir,
    this is Prashant here.Sir if i use 12-0-12,8amp transformer it will produce 96watt. sir can i use it to glow five 15watt cfl lights. If no,then what are the improvements should be done in this circuit to meet the above requirements.

  40. hi sir.
    I'm sherwin from mumbai.

    I wish to clear off the following things:

    1. what rating of transformer should i use in the rectifier circuit to charge a 12v 7ah battery???
    one more thing, should the transformer need to be center tapped on the output????

    2. To drive an 19" LCD monitor what must be the transformer amperage on a 12- 0 12v center tapped model.

    thanks!
    I'm waiting for your reply.
    my email id is sherwinbaptista94@gmail.com.

    Thanks once again!!!

  41. Hi Sir, Have one car inverter of 150W and one capacitor of 16V 100uf keep broken (blast in use of few hours) if there any replacement of other value so long last

  42. hello sir…this is rey.

    does this inverter support all kinds of appliances? like electric fan for example? as long as it is 230v. right?

  43. Hello swagatam sir,
    this is prashant here again,i have made the circuit and it is operating my sub-woofer system and monitor very properly.But its unable to glow up 15w cfl bulb made by crompton greaves ltd.I think its need more current can i add a current mirror circuit or add a capacitor at the o/p.the specification of cfl is as follows 15w, 220-240v,6500k,765 lm,pf=0.85,suggest me what modification i should make to meet the same.Thanks

    1. Hello Prashant,

      Actually it's not recommended to use this inverter circuit for operating audio video equipment.

      however if you are already using it, try increasing the transformer rating, and also the battery rating for operating all of them together.

  44. Hello Ashok,

    yes that's correct, for 48v battery, you would require a 48-0-48 transformer…..also the 100 ohm resistors would require some adjustments…..

  45. hello Sir,
    I have a motor I have made โ€‹โ€‹it a generator,it generates electric between 12v dc to 14v dc, so Can I use this power to inverter 500 watt which is input is 12v DC 220v AC? if yes how

  46. Hi Swagatam Majumdar
    i am student Engineering

    1-how make Convert DC to DC without Transform (Down 48 v to 12 and 5 V )??

    2- i 'm search about this i find more thing
    *Voltage Divider
    * Chaper Circuit
    but have voltage un stable how mae it stable

    and Thanks

  47. hello sir i have implement this circuit but circuit is not working . i am using my car battery as a 12 volt battery source my transfermer became slightly hot but transister remain cool . any idea where am i mistaking .
    volt meter show zero voltage at the secondary side and bulb remain off. bulb is of 25 watt . need your help

    1. Hello Waleed,

      You might have connected the transistors wrongly.

      The circuit would start working immediately if everything's connected correctly.

      Transistors will start becoming hot as soon it's powered so it must be mounted on heatsinks.

    1. you can bend it in any shape preferably in "L" shape, the two leads must not touch the aluminum so the holes must be drilled sufficiently big in diameter.

      use separate heatsinks for the two transistors.

  48. sir, i am beginner. i am regular viewer of your blog. i dont know much about electronics. and i didnt get propper education. but i am highly interested in electronics. please forget this if i am asking stupid questions. is it possible to use four 3v 1000mAh batteries? the transformer that i have has onlyv two input wires. how to use that transformer? its 12v

    1. you would get 12v by connecting them in series, but the current is too low, so it won't drive this inverter, you would require at least 10 ah battery for this inveter circuit.

  49. Hello Sir,
    First,I would like to thank you for your ideas and circuit diagram which you have posted.
    Sir,I want to build this circuit but with output power rating of 200watts..As,I want to drive 2 fans with it.What changes should be done in this circuit???
    If it is not possible to increase this circuit power rating then can u suggest me another circuit with 220VAC and 200watt output power…The circuit should be tested/verified…As,I have tried one from some other site and it didnt work..:(

    THANKS..

    1. Hello Kanwal,

      Thanks,

      first of all I would like to say that if you lack good basic knowledge of practical as well as theoretical electronics, you wouldn't be able to make any circuit successfully, most of my circuits are good and would work, others may require some tweaking but the concepts are all perfect.

      for your requirement you may try the following circuit, but again as said above, success would depend on your capability:

      http://homemadecircuitsandschematics.blogspot.in/2012/07/simplest-and-best-100-watt-inverter.html

    2. Helo kanwal,

      It is not recommended, but it's also not very critical for appliances like fans. It can be operated at a slightly lower voltage having a square waveform.

      The above circuit cannot be used for getting 200 watts because the transistors cannot be paralleled.

  50. Hello Sir,
    Good Day.

    I just need to know that can I run a fan on it ? My fan is of 220v, 100w.
    I just googled and found a bit similar circuit with a note " please don't run inductive load on it".

    Thank you.

    Rashid

    1. Hello Rashid,

      By mistake I replied to another reader instead of you.

      It is not recommended, but it's also not very critical for appliances like fans. It can be operated at a slightly lower voltage having a square waveform.

    1. hi kartik,

      this inverter won't produce more than 60 watts, that's the max power it can handle even with a 12-0-12 10 amp transformer and a 12V 10ah battery.

  51. hi sir
    recently my bpl fluorescent emergency lamp burnt(pcb)i want to repair it by replacing the board but that same board is not available so i am planing to build my own.i searched every where but all of them work on 12v but i need 6v one.can i use this circuit by replacing the transistors to d882 and 6-0-6 tranformer?if not possible then any other circuits?and i even want to build the charger circuit for this.i have a 12v adaptor and want to charge 6v battery.please suggest a circuit for this also.additional info-6v battery,11watt fluorescent bulb.

  52. hello Swagatam sir
    I am charu sharma. i want to make an inverter. i want to know can i use this inverter to lit 1 tubelight and 1 fan.

  53. sir,
    if i use 10 Ah Transformer and want to run about 80 Watt load so What battery should i use.
    Can i use 12v17Ah Battery.

  54. Hello sir, am Lawrence from Kenya. This has to be the simplest circuit on this that I have found. Thanks for coming up with it. Now, I have created its simulation on Multisim but it can only power up to 10 Watts lamps. Where could the problem be? I have used ordinary TS PQ4 20 transformer.

    1. Thanks Lawrence, I have tested this circuit practically and I could illuminate a 60 watt brightly. The transformer should be 9-0-9V 5amp rated and battery 12V/10ah

  55. Dear Sir,

    I just completed the above circuit but it didn't work. I checked twice the connections, everything is in according to the schematic. The transformer is of rating is 220V, and 18-0-18, 5A. When I connected the battery only resistors are getting warm (not hot). But nothing on its output. What do you suggest ??

    Thanks.
    Rashid

    1. Dear Rashid,

      Check everything once again, with correct connections the circuit will start working immediately, absolutely no doubt about it.

      I made this circuit without any issues during my school days, I could light up a 60 watt bulb using a 9-0-9/5amp trafo and a 12V 6AH Kinetic Honda battery.

  56. helo ..can u tell me , why dont we feed d.c supply directly to transformer rather than passing it through the resistances and transistors ,i actually mean what is the use of these components?

  57. Hello Sir,

    I make this circuit and it is working fine. But it is only operating 1 energy saver bulb of 220v, 25W.

    Sir, how can I modify it to operate 220v, 150W fan.

    Thank you in advance for your precious time.

    Rashid

  58. hi this is shadab,
    i saw your many inverter circuits, an thy were awesome.
    this year I have made microbial fuel cell.
    I am getting readings through multimeter around 200 mili volts thats of 0.2 volts. so do you have any kind of blocking oscillator or any inverter which converts or make a led glow from that much voltage or please design it.

    please please…………

    thankx

    1. o.2v is too low, no converter circuit will work on that voltage, moreover for boosting a voltage its current must be significantly high, in your case this might be also lacking.

  59. hi, this time I have made microbial fuel cell, and I am readings around 200 milivolts that of 0.2 volts can you please have any type of blocking oscillator or inverter which can light a led using this cell.

    please please please

    thanks

  60. hi friend,
    As I told you that I have made microbial fuel cell, and i asked you to give a circuit or oscillator which can light a led from 300 millivolt (0.3 volts).because it was very little in voltage you cannot.
    one day while i was searching in internet i got a youtube user called lid motor he made led glow out of 0.5 volts.(500 milivolts),you just have a glimpse on it –
    http://letsreplicate.com/wp-content/uploads/2011/12/Penny.png
    by looking to this can we make or extend the minimum voltage to 0.3 volts?
    or i have seen another site, of google science fair, it of making a hollow flash light which runs through hand temperature.I dont want and thermal electric power, but in that, i read that using very few milivolts the led lit up.
    please please read that project carefully especially summary and research, and tell me some clues and ideas and try to make a circuit,or tell me can we construct like so,
    https://www.googlesciencefair.com/en/projects/ahJzfnNjaWVuY2VmYWlyLTIwMTJyRAsSC1Byb2plY3RTaXRlIjNhaEp6Zm5OamFXVnVZMlZtWVdseUxUSXdNVEp5RUFzU0IxQnliMnBsWTNRWXA2ZVVBZ3cM

    from my best regards
    shadab

    thanks

  61. Hi sir, am Robert 20yrs and i study electronics in collage,i just want to ask you something if you don't mind,
    (1) can this inverter power a laptop which use input of 100v-240v~ 50-60Hz 1.5A,and other home use componet,if no can you suggest for me a simple circuit which can do.
    (2) how can i know if a tranformar is 12-0-12 5amp or above(i mean how to test it using digital multmeter)
    (3) I have an adapta which have an output of 31v dc 26A,I want to reduce it to 20v or 19v dc 4A.what can i do,which circuit can i make,help me please.
    Sorry for asking many question but i need your help.

  62. Hi sir. This is Sherwin. i have the foll queries:

    1.what is the output frequency of your circuit.

    2.Is it possible to convert a distorted square wave output into perfect square wave output.

    3. what capacitor to use at the output section of the inverter to keep the o/p in control.
    pls reply to me at shermaster6@gmail.com

  63. hi swagata
    This circiut is working properly……….am using 12v 26 ah battery for this circuit…..when ac supply is ON the battery get charged over above 13v i need cut off 12v for the battery charger plsssss

  64. hi sir……

    am electronics and communication engineering student am going to do a major project of this simplest inverter but there is one disadvantage in this circuit.if u provide cut off for charging battery it will 100% efficient and also helpful to me

  65. Hello swagatam sir,I am nivedan and I am making an inverter. I waned to aks a question-if I use 12v/7ah battery,then how much ohms resistor should I use and how much amps transformer should I use? Even I am not getting 10 watts wire wound resistors. Can you suggest any alternatives? Can I use 2n3055 transistor with these materials or I have to use some other transistor? Please help!!

    1. Hello Nivedan, I had used a 300 watt 9-0-9v transformer when I first made this circuit using a 12v 7ah battery, so you can also use the circuit as is given.

      if 10 watts are not available then you can look for higher wattage alternatives but not lower ones as they could get hot quickly.

      you can use 2N3055 or tip35 ransistor

  66. hello swagatam sir. i am nivedan and i am making an inverter. if i use 12v/7ah battery then what other materials may i need as i want to only power a CFL.it may give a output of 36 watts if i use a 3amps transformer .can you list the other parts? help!

  67. Hi there,
    I love the simplicity of the circuit but need to convert 12v DC to 12v AC to power an air pump for a fish tank where the pump is designed for mains power, stepped down to 12v but 50Hz.
    Is this possible with this circuit and what would the modifications be?
    All the best,
    Tom Hodgkins

    1. pure sine will be free from disturbances and its average V will be equal to the appliance requirement.
      square wave will be full of disturbances, and will have average voltage a lot higher.
      modified sine will be with lesser disturbances and with correct average voltage like sine wave.

  68. i have followed this circuit., and used tranformer 240v/ 12-0-12v . but the 2n3055 transisters are heating too much, like hot smoke gases releasing.,, i used 7ah battery., NO output., any solutions??

    1. transistors will become hot but not to this extent, you should mount them on heatsinks anyway.
      with the mentioned results it seems you might have done something terribly wrong with the connections….check them all

    2. i checked all connections and they are correct., i just changed transformer to 1amp 12-0-12 . instead of using 10amp transformer.,

      but when ever i connect battery., its giving just a blink of output to light., not continuous., any solutions.??

  69. Hi Sir,
    (100 OHMS./ 10 WATTS WIRE WOUND,15 OHMS/ 10 WATTS WIRE WOUND) these two resistors are very had to find here, can I replace it with some other resistor,or have any other solution.

    1. Hi Vijeesh, these values are very standard and should be commonly available with all spare part dealer shop, you can approach a TV repairing shop for the same, you could get them from there.
      other values are not recommended and could give undesirable results.

    1. Hi, the output voltage will depend on the rating of the output winding, if it's wound to produce 24V then it would generate 24V, in the above article its wound for 220V therefore we are able to obtain the same from it,

  70. Hello sir!
    I made this circuit using R1, R2= 100 OHMS./ 2 WATTS

    R3, R4= 15 OHMS/ 5 WATTS

    T1, T2 = 2N3055 POWER TRANSISTORS.

    TRANSFORMER= 12- 0-12 VOLTS / 5 AMPS.

    AUTOMOBILE BATTERY= 12 VOLTS/ 7AH
    The output is 230V AC. I tested it using a 15 watts night lamp and it glows but a 10 watts CFL does not glows. It blinks once when turned on. What may be the possible reason for this? Please reply.
    Thank you.

    1. Hello Sudipta,

      Use 9-0-9/5amp transformer, and make sure your the weight of the transformer is around 5kgs otherwise it's not 5amp.

      2 watt resistor is not recommended, make all the resistors 10 watt for an improved response.

      Do the above and you'll find even a 18watt CFL glowing brightly.

    1. john, 2 amp will give you just 20 watts of output power, and moreover the trafo voltage rating should be always less than the battery voltage rating, if your battery is 12V a 15v trafo will produce voltages much lower than the specified levels….so in short your suggested trafo is unfit for the project.

  71. hi swagatam,
    i have 5 hp solor pump set running ,now i want to use for home when not in use for pumping water ,the panels connected in serious for vfd dc 700 volt ,now i want to convert dc 700 volt to ac so that i can stepdown to 36 volt by transformer and feed it to battery for that i need same above circuit model for dc 700 volt for that which transister or mosfet can we use please answer me.

  72. Hi sir,
    We are having a project that converts mechanical energy to electrical energy using a dynamo. we will be using a motorcycle rechargeable battery 12V. Our problem now sir is that, what inverter are we going to use to power up a UV light 220V, 6 W?

    Thank you again sir for the answer. Godbless.

  73. i am interested in building a pv inverter. 1000 watts, 12volts dc, 220 volts ac. my problem is i cannot not read a schematic diagram. can you give some references or materials where i can start. also, i need to know where i can buy the parts for my project. please help. thanks. gm

  74. Sir, it is very helpful post. can i use 12V battery for this inverter? i see many posts about Homemade inverter but i can't successful to make anyone ๐Ÿ™ I use every method. now i find your post. i hope i will get success. kindly help me i really need it. waiting for your response.. Thank

    1. Kashif, if you are unable to make an inverter even after many attempts, it means you may be doing something wrong or your knowledge regarding the subject may not be sufficient…you can try circuits from this site also, I wish you all the luck.

    1. use a transformer having a lower voltage rating than the battery, for example if you are using a 12v batt then use a transformer with a primary rating of 9-0-9V

    1. Dear Kwaku, you can use the same circuit and connect it with your solar panel, however your solar will need to be rated at least at 5 amps for producing a meaningful wattage from the inverter.

      the list of components is given in the article itself.

    1. Hi Suriya, with a 5AH battery you can use a 3amp or a 5amp transformer, however the output power from your set up will not be able to exceed above 30 watts

  75. hello sir, i want to make a 500 watt inverter with 12v input.
    if it is possible please send me the circuit diagram .
    i also dont know how to place all the component in one ic.give me some idea about it

  76. HI' I'm newbie engineering student' My name is Steve
    I understand the diagram in my own understanding but I want to know, How many Volts Ampere of battery and how amount of ohms resistor and also amount of transistor That I'm going to use & how high Power/watts need to run a 2 or 3 15watts Light bulbs'
    Is it correct using a formula P=VI or Power=Volts*Current for inventer? and what formula I need to use that include a ohms and micro/farad to know the Power or Watts will be the output that I'm going to make"

  77. Hi' I'm Steve
    What if Im going to do to make more Power/watts output of inverter?
    because the above components can produce 70watts only as indicate'
    How about 500 watts? or more? what I'm going to do? and going to use components?
    I hope you will response ๐Ÿ™‚

    1. Hi Steve,

      the circuit won't be able to produce more than 60 to 90 watts maximum, neither can it be upgraded in any manner.

      you can opt for a IC 4047 inverter for your requirement.

  78. HI' I think 70 watts inverter is enough for me'
    but It is ok to use a transformer is 12-0-12 volts?
    and what type of transistor going to use to that diagram? BJT, JFET, or MOSFET?
    The above requirement is Transistor 2N3055 I'm not familiar what it looks like?

    Thanks for your response' ๐Ÿ™‚

  79. HI' I've already bought the materials but I have my own transformer it is only 12-0-12 V 4 amphere' it is ok to use?
    I read others article if the battery is 12 volts is need to use 12-0-12V transformer, I'm confused.
    Please Help"

    1. if you use 12-0-12V with 12v battery you'll end up with only a 200V output….in order to get full 230V you'll need to use a slightly lower rated trafo, for example a 9-0-9v trafo

    1. thanks, just multiply the voltage with the amp rating to get the wattage delivering capacity of the trfao…this would enable you to decide how much wattage you might want to extract from the design

      for example 9 x 1 = 9 watts or in reality 5 watts only.

  80. I came accross this wonderful page via Google while searching the simplest and easiest way to make an inveter as I am having SERIOUS difficulty using the readymade inverters I have bougth so far to power my Capacitor and diode Voltage Multiplier connected to my High Voltagge Low Amp Air-Core Electromagnet..

    The said ready-made inverters always trigger oveload whenever I connect the said load. Only the 200W modified sine wave inverter I bougth recently works with the load.

    But then, I need an higher output inverter of minimum of 500W to provide the needed AC to the Voltage Multtiplier Circuit which will then generates the needed High Voltage from 1000vdc and above.
    But I find it extremly hard to understand complex DIY inverter circuits. But the one you provided here is non-complex to bรฉ honest. However, my understanding of it is still very much limited as I am not trained at all in Electronics.

    However, I can with the help of a friend decode further (Simplified Drawings) the circuit.

    But my main question now is, HOW can I upgrade the circuit to generate 500W output? What Mosfet or say transistors will I need to change to? What transformer, resistors and batteries capacities will I need to change or upgrade to? If I have 24V battery, what and what will bรฉ needed to upgrade in the circuit to generate 500W at least?

    What are the exact equivalence of the Transistors in the Circuit?

    Please may I have your replies one after the other to my barrage of questions Sir Swagatam?

    1. Thanks stone world,

      making an inverter is actually extremely easy since today we have ICs which are specifically designed for handling this application….however the above circuit which you have liked might not be suitable for a 500 watt output.

      I would recommend the following design which is quite straightforward yet is capable of handling massive loads:

      http://www.homemade-circuits.com/2014/11/48-v-inverter-circuit.html

      here 48V is recommended in order to keep the dimensions of everything smaller…however you can use lower voltage batteries too but that might call for larger transformer and larger battery and larger heatsinks on the transistors.

  81. Please Swagatam, may I know if I can use this circuit to Power a Voltage Multiplier made with Capacitors and Diodes?

    Also, how do I connect the positive and negative arm of the battery? I mean at what point in the circuit?

    1. Janet,

      yes 3.5uF or 2.2uF it can be used but it might drop the voltage to some degree, so a lower value around 0.5uF could be tried

      please do not comment on this page as it's loaded with comments.

    1. Angelous, just multiply 12V with 2amp…it will give you the approximate wattage from the output.

      use the components as suggested in the parts list for proper response

  82. Hi sir:

    Good day!

    I have just found your website on Google, I am looking a circuit for inverter. I found this circuit, I am interested in your circuit posted above.however, I just have a few question regarding this circuit, could I use 12-0-12v, 220v transformer and 12v 6ah baterry? And how to calculate its output wattage?

    Advance thanks you sir.

  83. Hi sir its me again, can u give me a circuit of a pure sine wave inverter at least 500watts that is easy to build and also the components is more available. I am going to propose it as my project in college.

    Thanks.

  84. hello sir currently I have 12-0-12v to 230v ,1amp transformer and a 12v,7ah battery. is it possible to make any simple inverter using the above mentioned components along with some required electronic components which can deliver 20 to 30 watts?? if yes will it be efficient?
    what is the minimum amps of transformer of any simple inverter required to deliver 20 to 35 watts with 12v, 7ah battery, if 7ah is not possible please suggest me different ah battery
    please help me sir

    1. Hello Akshay, if you multiply 12 with 1, you get 12, that's 12 watts in the most ideal situations. so you cannot expect more than 12 watts from your transformer, now if you divide 35 watts with 12, it gives around 3, meaning you'll need a 12V 3 amp trafo minimum to achieve anything near 30 watt output

      7ah is the backup capacity of the batt, for 3 amp load this battery will last for not more than 1 and 1/2 hours.

  85. hi sir,
    I here doing APC inverter sales & service. In 850va iam facing problem please help me in this 1) Case one, three light are blinking so this guide me

  86. Hi Swagatam,

    I finally opted to make this simpler inverter. I didn't get 100 ohm so used 120ohm 10W resistors. And I used 12-0-12 4amp transformer along with 7Ah battery. The first issue was output voltage, which consistanly stayed more than 350V. I added a 4.7ohm 3W resistor between the battery +ve terminal and transformer's center tap to drop the input voltage, which brought the output down to 220v.
    The next issue was output power. I could only lit up a ~zero power 220v night lamp. My 15W 220v CFL didn't work. For 4amp transformer, I should have very well got atleast 20watt. Isn't it? Any idea what went wrong?

    I measured the current between battery +ve terminal and transformer's central tap. It was no more than 600mA. Is that lower than expected? Atleast if you could guide me to identify the testing points, I will be grateful.

    Thanks in advance, Prithwiraj.

    1. Hi Prithwiraj,

      please remove the series resistor and connect the bulb with the available 350V…the voltage will automatically settle down to the bulb voltage specs, please do this and check the response…

      and please do not comment on this page, because it's already loaded with comments..and I have to press "load more" many number of times to see the comments here.

      1. Syed, maine do bar jawab diya hai, please pehle wale comment dekhe.

        Phir se batata hoon: This transformer will not work as an inverter transformer…it's only a choke or a suppressor coil

  87. Hi sir i have 4 questions

    1. Can i use 2N3055 STMicroelectonics model? 2N3055 motorola model are not available on my area.

    2. Wat is the frequency of this simple inverter? I need to power a 220-240v small electricfan that requires 60hz or nearly 60hz 5%+,- (57-63hz) will do.

    3. What is the frequency of this simple inverter.

    4. Where can i post my future questions or comments so that it wont be hassle for you to click "load more"..

    Thank you in advance.

    1. Hi Kelichii,

      1) yes you can use it.

      2) it's around 60Hz, and can be used with a fan.

      3) you can post your questions under any other inverter circuit article which has less than 200 comments

    2. Sorry wrong question in number 3…

      What is the wave form of this inverter? Modified? Square? trapezoid?

      Thank you for answering my previous question. And thank you in advance sir..

    3. Now i understand.. thank you sir…. we have power crisis here in philippines.. mindanao area..and i am wondering for alternatives. this will be usefull projects in small load. Specially on small electrifan. (20-40watts consumption) cuz we are in warm climates…

      i am an associate industrial electicity graduate. im lucky i can read basic electronics connection. ๐Ÿ™‚

      Thank you

  88. Hi Abhishek,
    the shopkeeper is correct, an inverter transformer is same as our usual step down transformers, they just need to be connected in the opposite manner for an inverter….12-0-12V 8 amp will do….but for better results you must use a 9-0-9V / 8amp or 10amp transformer

  89. Dear sir!
    I am working in a cauntry side where often there is a break down of AC light.I want to use this inverter.Can you please suggest some modification of it with the following spisification?
    :-As long as there is AC ,the source of the light for the bulb will be AC source.But when ever there is a break aut of AC,it has to jump to the source of the inverter or DC automatically and if the AC come back again,also it has to jump to the AC source again.

    Thanks a lot!

    1. I have already explained the concept comprehensively under "UPS" and "relay changeover" sections….please search these two topics in my site and you will be able to find many good options to choose from.

  90. Good day,Sir!

    This is beni writeing.

    Before some days,I wrote a question to you.I am not sure if you got it.My question goes like this.I am working in a cauntryside where breakaut of the existing AC light is usual.so,if it is posible i beg you to modify this circuit.
    My idia goes like this:There must be some type of a signal contact between this circuit and the AC light and both of them are useing a common bulb.So,as long as there is AC current,this inverter circuit makes it self off.and when again breakaut of AC light happens,the inverter circuit comes to `ON` position.
    greetings from Beni
    counting on your usual support.

  91. Hi sir, I want to ask question about something else, if I give AC supply to astable multivibrator circuit from the side where we apply DC, then what is the outcome and output from AC output side of that circuit.
    Regards :Aabhishek Sharma

    1. High Abhishek, if it's an AC then the AMV will get damaged immediately, if the AC is in the form of pulsating DC, then the output will be in the form of bursts of frequency, whose value will depend on both the pulsating DC and the AMV frequency

  92. OK sir let's make it clear, I want to give the output of one astable multivibrator as input to other and want to know the quality of output from that one which is supplied with the output of first astable multivibrator. And would the output be good in quality?

    1. You mean this wouldn't give better output power. Sir, can you please give me a circuit for 100 watts output inverters using only transistors and MOSFETs, no ICs. Because the 40watts inverters which I have made is not able to drive my LED TV and setop box together. And also I want a circuit to convert 240v square wave output to sine wave. Please help

  93. hi sir
    i made this Simple Inverter 4 years ago just to learn how to make one
    it may be called Simple. but after Hurricane Matthew we where with out power here in NC for days. but i had made 4 of them. and we had lights when everyone eles was in the dark.so i thank you once again ๐Ÿ™‚

  94. Good day sir, pls how can i replace a variable resistor having 3 pins,( pin 1 connected to power supply, pin 2 to ground and pin 3 to feedback diode) with a fixed resistor having 2 pins. because atimes i need to adjust the variable resistor.

    1. measure the pot resistances across its center and outer pins, and connect an two fixed resistors equivalent of these two values between +/- rails, and connect the feed back diode at the junction of these two resistors.

  95. Hi Engineer, pls how can i replace a variable resistor-220k ohms( 3 pins- connected to power supply, feedback diode and ground) with a fixed resistor( 2 pins) because the var resistor needs adjustment a few times.which value fixed resistor will i use, thanks

    1. measure the pot resistances across its center and outer pins, and connect an two fixed resistors equivalent of these two values between +/- rails, and connect the feed back diode at the junction of these two resistors.

  96. Hello Swagatam Sir, this is Samar from Howrah,WB…I am the die hard fan of ur projects….every circuit u posts in timeline I watch it carefully and try to understand the circuitry…already I hve made the popular 'autocut stabilizer' using BC547 within a old,unused PSU module of pc…wow it works…!!!and kept the ac voltage from 200v to 258v…Sir u r awesome.. I want to work with u professionally…

    1. Thanks a lot Samar, it's a pleasure that you are enjoying my site, please keep up the good work. If you would be residing in Mumbai then possibly we could have worked together….unfortunately we are across two extreme ends of the nation.

  97. Sir plz help me.
    I am Jitu sarmah. I'm student of B.sc electronics from Gauhati univ.(Assam). I have an old frontech computer UPS and there has a transformer this transformer have one side 4 terminals and other side have 2 terminals my question
    1)plz sir tell me, is the transformer is step up or step down.??
    2) I'am not identified which the side is out and input please tell me sir, output and input side (terminals)??
    3) I have 2N3055 transistor I'am not identified base, collector and emitter.

    1. Jitu, a mains transformer can be a step-down or step-up, it depends how you have connected it….so a step down transformer can be used as step up trafo and vice versa, both are one and the same.

      in your transformer, first identify which wires were associated with 220V, then connect these wires with the mains and verify the voltages across the other wires

      you can identify the wires by checking their resistance values…the wires having the highest resistance could be the mains 220V wires, still to be entirely safe connect a fuse in series while confirming the wires which you may decide to test with mains 220V

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