3KVA Modified Sine Wave Inverter Circuit

The post investigates a 3kva sine wave inverter circuit prototype made by Mr. Marcelin using only BJTs instead of the conventional mosfets. The PWM control circuit was designed by me.

In one of my previous posts we discussed a 555 pure sine wave equivalent inverter circuit, which was collectively designed  by Mr.Marcelin and me.

How the Circuit was Built

Hi Swagatam,

In this design I have used strong cables to sustain the high currents, I used sections of 70 mm2, or more smaller sections in parallel. 3 KVA transformer is actually as solid weighs 35 kg. Dimensions and volume is not a drawback for me. Photos attached to the transformer and installation in progress.

The following assembly nearing completion, based on the 555 (SA 555) and CD 4017

On my first try, with mosfets, earlier this year, I used IRL 1404 which Vdss is 40 volts. In my opinion insufficient voltage. It would be better to use mosfets with a Vdss at least equal to or greater than 250 volts.

In this new installation, I foresee two diodes on the transformer windings.

There will also be a fan for cooling.

TIP 35 will be
mounted by 10 in each branch, like
this:

Complete Prototype Images

 

 

 

 

 

 

Finalized 3 KVA Inverter Circuit

The final circuit design of the 3 kva modified sine wave inverter should look like this:

 

How to Safeguard the Transistors

Note: In order to safeguard the transistors from a thermal runaway, mount the individual channels over common heatsinks, meaning use a long single finned heatsink for the upper transistor array, and another similar single common heatsink for the lower transistor array.

Mica isolation would be fortunately not required since the collectors are joined together, and the body being the collector would get effectively connected through the heatsink itself. This would actually save a lot of hard work.

In order to obtain maximum power efficiency, the following output stage is recommended by me, and must be employed with the above explained PWM and 4017 stages.

Circuit Schematic

Note: Mount all the upper TIP36 over a larger finned common heatsink, DO NOT use mica isolator while implementing this.

The same must be done with the lower TIP36 arrays.

But make sure these two heatsinks never touch each other.

The TIP142 transistors must be mounted on separate individual large finned hearsinks.



223 thoughts on “3KVA Modified Sine Wave Inverter Circuit

  1. Have questions? Please feel free to post them through comments! Comments will be moderated and solved ASAP.
  2. Dear Swagatam

    I have salvaged a 48V transformer. Can you please explain modification required in above circuit diagram so one can use it either for a 24V (two batteries) or 48V (four batteries). I think that such a huge power inverter should be powered through 48V otherwise it doesn't make much sense.

    Regards

    Sam

  3. Dear Swagatam Majumdar
    I'm going to buy a not working tripp lite pv1200 inverter 120v and replace its control board with one of your circuits.
    Could TIP 35 be replaced with IRF3205 in this circuit?
    Could you suggest me the circuit for this 1200 watts transformer?
    Thank you for your time!

  4. Hi sir in this circuit Making a 3KVA Modified Sine Wave Inverter Circuit my question is apart from TIP35 what mosfets can i use to get 3KVA?and also the transformer i can see 38v it a additional winding of the transformer cos i have 12-0-12 transfm 3000watt can i use it for this inverter? thank you im looking forward to hear from you.

  5. sir in this circuit there is two transistors connected to the IC3 4017 it sit a TIP122 OR TIP35 cos i can see 11 TIP35, sir can use this fets BD249 or IRF540N so if possible there is any something that should be change? sir i can see that there is 38v behind the transformer it is a additional separate wounding transformer? thank you sir please answer all this question for me,im looking forward to hear from you son.

  6. sir please what about this BD249 it a bigger the shopkeeper ask me they have bigger and small sir if it can be use in place of TIP35 which of them should i chose? its this a pure sine wave? thank you looking forward to hear from you son.

  7. hi sir i think we have disused a lot about this circuit but i did not build yet due to the component especially the 180k preset,right now i finally got all the component but you said to me i can use 220k preset i search everywhere unfortunately i got 200k preset so im asking you sir can it be use in place of 180k preset? second it this a pure sine wave? i build one of you circuit it work fine but that is not the one im looking for.

  8. sir please you have designed soo many type of inverters circuit so im asking can you please show me which can handle freezer if it build properly?,

    secondly i can see the pics below it is a pictures of this circuit? can this circuit handle what pure sine wave handle i mean all electrical appliances?

    • Bianzz, I cannot provide a guaranteed advise, but according to me the above circuit would be able to handle all types of appliances if its built correctly, within 3kva.

  9. Hi hope you can understand me, I do not know English and translated by google e.
    I wanted to know if the power stage with TIP35, serve me for this inverter I did with a pic16f628. the circuit right out of the network, but it works eventhough only has 60hz 190volt delivery and very low current.
    I do not think that deliver 500w, I thought to use only the power stage with TIP35.
    You think that would work, of course Thank you.

    • Hi, yes you can use the power stage from above to get 500watts by doing the following mods:

      use TIP127 instead of TIP122 as the buffer transistors and feed the TIP35 base from the collector of the TIP127…this will instantly pull up the current to the required levels.

      I hope you got the point.

  10. Hola espero que me pueda entender, yo no se ingles y lo e traducido por g o ogle.
    yo quería saber si esa etapa de potencia con los TIP35, me serviría para este inversor que hice con un pic16f628. el circuito lo saque de la red, pero apesar que funciona ha 60hz solo entrega 190volt y muy baja corriente.
    No creo que entregue 500w, yo pensaba usar solo la etapa de potencia con los tip35.
    Usted piensa que funcionara, desde ya Muchas Gracias.

    • The amp rating will depend upon how much you require from the trafo.
      The trnasistors TIP35 are capable of taking wel over 20 amps each

      the 3.8V tap is an auxiliary winding which may be fed back to the inverter DC circuit for implementing additional features such as overload protection, over voltage protection etc.

  11. which fets can I use to replace tip35 and how would I connect them? I ask because transistors tend to have heating probs so I would use fets tell me how much power and how much fets and which resistors I would use.

  12. I would want to go up to 4k… but saying I am ok with 3k isnt it better to use fets instead of the transistors? if this setup is ok how much batteries would I need, seems like about 3 rated at about 100ah.

    • fets can be at times unpredictable and difficult to diagnose….BJTs are a little bulky but very reliable and easy to configure that's why it's better to go with the BJTs

      By the way you would just need 4 nos TIP35 on each channel instead of the shown 20 for achieving around 4 kv easily.

  13. I was actually referring to the small coil below that in the drawing which just says 3.8v, anyway I wanted to find out how to design a pcb board for this but I am wondering if I o it if the traces can manage the current from the output because I don't no wat size traces I would use nor anything because I have never designed a board.

    • you also asked where was the transformer, right?

      as for the small coil, it's an optional auxiliary winding for deriving a small voltage from the inverter secondary which could be used as a feedback input for monitoring and controlling output voltage of the inverter

  14. In this diagram when showing that 2 lines arent connected you would break it and re-join it after it crossed a line, so if thats the case where the battery positive and negative cross the collecter of the tip35c im assuming none of them should be connected but are they connected to collecters directly since they cross directly over the lines

  15. If i planned to use 24v battery set up would i only need a 24-0-24 transformer and at the 555ics do i need to use thick wires or only at the transistor stage. Do u recommend me running solder on the board or using wire.

  16. Ok because some sections of the circuit clearly showed no connection but there it crossed over i was unsure.

    Where the bbc557 is it seems there is a 1 milliamp diode one the collector is that so.

    • 2.7V zener is OK, 56nF will also do, and 250k will also work just make sure to connect a 1k series resistor with the 250k pot…actually it should be a preset and not a pot.

  17. I have a 3.3v zener not 2.7v im wondering if the 3.3 is ok and should i use 2 250k presets or use 1 for ic1 and use a pot for ic3 to adjust pwm, also the 10k is it a pot or preset… U said to put a 1k resistor in series with the preset should it be for both 250k presets.

    • 3.3V zener will do.
      presets are recommended since the adjustments will need to be fixed only once.

      10k is also a preset….use 1K perset instead since pin5 of the IC does not respond correctly above 1K….unless it's a (7)555 IC.

  18. Is c3 a 1microfarad cap and is it ceramic? I got some 200k presets to buy, should i use those instead of the 250k and 1k resistor… And should i still use the 150k fixed resistor or use the 200k preset in place

  19. Because i wanted to see of i would get output i hooked up a small transformer 12v center tap along with 2 3 amp diodes where i should have the 20 amp diodes, i didnt load the circuit but i didnt get any volt out and ic 2 is giving 148hz from pin 3, i am using a 180k preset for ic1 hz doesnt change when i adjust it and still no out put from the transformer

    • check the stages separately by keeping them disconnected from each other, once all the stage's functioning is confirmed then you can integrate them for the final results…

    • first check IC1, IC2 circuit by connecting a small 12v bulb at pin3/ground….and by adjusting the 10k RMS preset….this should create proportionate dimming and brightening of the bulb…….use 1k preset if 10k preset give improper results.

      the above will confirm the IC1/IC2 stage….do this first then i'll proceed further.

  20. You are correct, and yes its basic we are from different countries we kinda use different terms to refer to things I am not as good as you so I am trying to catch up, i cant get bulbs of that size to buy in my country ill get more leds and resistors plus more 555 because ic4 got hot and i stareted to get only 2 volts from pin 3

    • I did not say it will blink, I said it will become brighter from zero to maximum as the preset is varied proportionately. Use a 1K preset instead of 10 k it will hopefully show the correct indications….if it happens you can be sure your IC1/IC2 stages working OK.

    • 1k preset will give even a better response, anyway it means the IC1, IC2, IC3 PWM stage is working OK.

      now confirm the 4017 stage, by disconnecting the gates of the fets and checking the frequency across these outputs

  21. Ok i took off pin 2 and 7 from the 4017 and ic2 burnt as i applied voltage, so i got a portable scope to borrow and i checked vmax accross ground and pin3 on ic1 and i got 22v. So it seems thats the problem and i am wondering why the voltage is so high i replaced ic2 and i got 353hz from pin 3 and grounds, i was wondering if i should just put a 12v regulator in the positive line feeding the 555 ics

  22. No im using a car battery charger to test thee project… Ita strange to me im not used to using a scope…. Testing the cicuit with my meter across pin 1 and 8 of each ic i would get 13v so after i include a 12v regator ill see of the supply was the prob

  23. I placed a l7812 regulator i connected the in to center top of tansformer where the bat postive is and out to pin 4and 8 of the ics and adj to grounds… Im getting 9v out i expected 12v… I tested the circuit anyway the 4 ics werent getting hot at all i cannot trust the frequency reading i get on the meter so im only working by voltage for now, i got 5 and 6v acrross each lead coming from the out put of the tip135 that seems low… Shouldnt it be about 12v? I connected a 12-0-12 half amp just to see an out put voltage but ic2 blew out.

    • there's absolutely no reason for IC2 blowing of at 12V or 9V…something may be not correct in your circuit.

      did you connect the protection diodes across the trafo primary halves??

  24. yes since i used a half amp transformer to test i connect (2) 3 amp diodes, I cannot get any 20 or 25amp diodes the most i see is 15amp for solar panels, could you tell me what voltage should i be getting out of the 4017 pin 2 and 7, and would i test across each other or between each and grounds.

    just to clear up somethings,
    you said I could use a 250k preset but i didnt I got the 180k preset so i didnt series it with a 1k resistor I hope thats ok I followed the schematic if I should change it let me know.
    I used a 10k preset in which you said I could use a 1k preset, should I keep the 10k pot or use the 1k preset.

    I am going to take out the regulator though because as far as I see the circuit should need one and it heating up because i just placed in temporarily without heat sink.

    • the 4017 outputs will show 50% of the supply voltage.

      The 1k series resistor is necessary to prevent the IC555 from overloading if the preset is accidentally moved on one of the extreme sides.

      1K preset in place of 10k will give a much better response

      with a 12V batt as the supply, 7812 may not be required at all.

  25. I did the replacements and the 4017 is still getting hot i am actually getting 50hz from the outputs at 5v and 7 volts, the output pins arent shorting out and when i check whats comimg to it its only 12.13v., ic4 felt warm but not hot i checked connections and i dont see a problem

  26. I think I am using a wrong type of 4017 because if I use low voltage like 5 I get the 50hz out from ic and half the supply voltage and even 6v from where transformer should be connected but if I increase supply to 12 volts then chip rapidly gets hot and I am sure all connection are correct and then I stop getting output voltage from ic2 and ic4 after that while 4017 is connected.

  27. I knew the ic was the problem the cd4017 ics cannot work in this circuit it seems i bought over 20 of them and all gave the same problem and now I got a tc4017bp and when i tried it the circuit worked perfect the only problem is I got only 20 volts because I was using a car battery charger and its only a 5amp at 12volts.

  28. I connected them between pin 6 and 2 and I got no difference, then I removed 4017 and I got voltage from ic1 pin 3…. So I removed the pin 3 from ic2 and and put back the 4017 and I got output 4.98v from pin and same from pin 7…. I am using 8 tip 135 and the 4 that come from pin 2 on 4017 keeps getting hot and the other 4 is cold, there is no short circuit, I am getting a pulse of 32v ac from both ends of diodes at the output and 0-40v between centre and each end if I connect transformer the side connected gets warm and no output

  29. thank you sir,
    so i am going to start doing work on this project
    actually this inverter which i want is for special purpose,
    where in which i just want to power my system for minimum 2 min ,means only for two min i want 230 v and 3kva power to power up my system.
    so i have choose this project(3 kva inverter),
    there are many que i am having now about transformer and battery ,
    so as i am proceeding, with query i will be in touch with you,and also i must have to make battery charging circuit too,
    there are already most of the que and ans from have already above,and through which most of my idea have clear ,but still with further, i am accepting your kindly assistance,
    Thanks and Regards
    NIkhil Sonar

  30. I see that you updated the circuit, so in this case I can use the tip136 stage instead of the tip135 stage, is that the reason for the update.

    it seems simpler and doesnt use a diode on the output it seems, have you had any timem to test this circuit to verify if it works good.

    • each TIP36 will be able to handle 25amps….so just keep adding as many as you want and multiply the specs for the desired output….in the shown diagram 5nos are shown which constitutes a max output of around 25 x 5 x 12V = 1500 watts, for 24V batt it would be 3kva, with a 48V batt it would be 6kva and so on.

      make sure to add protection diodes across the trafo taps.

  31. oh..k i get the idea,
    thanku sir,
    i need 3 kva inverter ,so i should use 24 v batt(i.e.two 12 volt batteries in series)
    also plz tell me about config of diode that u have suggested to use(i guess those are 20 to 25 amp diode) but i demand in market but they told plz have exaact config.type or id number

    • you can use 5nos 6A4 diodes with a 1 ohm 2 watt resistor in series with each diode for each of the channels

      cathodes will be towards the collector and the anodes towards the ground

  32. sir
    i search for 150 k preset but i could not get exact value not even 200k,whereas i am having 100k value of preset,can u plz tell me that how should i use that to make 150 k preset config

  33. hi sir ,
    first ,let mw have clear idea about my requirement
    actually i want inverter circuit for passanger rescue in elevator,
    because sometimes when main power fails,then lift suddenly will halt at its current position (may be between the floor)so lift should be take its nearest possible level by means of giving standby supply means by invertor
    i will give you details in next post.

  34. as per my calculation of power consumption after power failure by lift (it include motor,lights in lift and drive ) is total about 2.89 kva.
    so i have choose 3kva inverter
    and also plz note that,only 2 -3 min are required after failure to take lift to its possible nearest floor (means we want standby power supply for only 2-3 min)
    as you have said that any appliance within 3kva,this inverter circuit is good solution.
    so i hope this circuit will fulfill my requirement.

    Thanx and Regards
    Nikhil Sonar

    • thanks Nikhil,

      yes the above explained design will definitely work but only if it's built by an expert who is well versed with inverter concepts and has ample experience with all the parameters concerning the relevant field.

    • Nikhil, the IC 4017 is a much straightforward IC and does not require special knowledge to configure, whereas the IC TL494 like SG3525 is not as easy to set up. But if you know how to work with these ICs you can go ahead with the integrations.

  35. and also as this is very high power application ,
    so what I think is to use more numbers of batteries in series to get max input voltage
    and for 48 volt what I am looking by using 4 number of 12 volt battery
    does it make that sense sir,?
    plz suggest

    • so here is my config sir,
      as I am standardizing my project to be for 6kva as per variable need.
      so I am using your updated circuit with 4 numbers of battery i.e 48 volt.
      also sir for to charge my batteries I will be using circuit that u have made which I have took from the same site.(Make this 48V Automatic Battery Charger Circuit)

      so I will prepare total electrical diagram by using autocad software, which will be having detail circuitry i.e. basic inverter circuit ,battery charger circuit ,connection with system .
      and this electrical diagram will share with you,
      will see further ahead.

  36. absolutely ,we have to step down that 48 volt to 12 volt externally, by using voltage divider network or voltage regulator ic
    and also sir,i have made that total circuit diagram in auto cad,i have pdf file for same
    I wanted to share that with you

  37. sir now I have started doing circuitry ,stage by stage .
    unfortunately I am not getting o/p,
    actually there is problem during measurement of frequency at first stage.
    connections for ic1 only I have done where have given supply of 12 v dc,no any other ic connections are there ,
    at pin number three I am not getting constant frequency of 200hz
    and I have measure voltage at same pin where I getting value of same supply voltage,i.e. 11.56v dc
    as per your explanation ,meter is in frequency mode, positive of meter is connected to pin3 of ic1.(as there is no feedback from any other ic to ic 1 so other ic's are not even mounted)
    and negative of meter is connected to ground .and my meter is showing constantly 0000 reading,and there is no effect of variation in preset .but as I unplug positive terminal of meter, frequency meter shows fluctuations in frequency …some what like 50hz.

    I am confused about how to measure frequency .

  38. i got the o/p.. actually it was my mistake,and was so primary,
    i was directly measuring the frequency at pin no 3
    instead of that when i connected small value of capacitor at 3 ,and here i get the o/p of 200hz of frequency for 180 ohm

    • you can measure the frequency directly on the circuit, a capacitor is never required, the meter has inbuilt capacitor so external capacitor is not required…..

      and where is 180 ohm?

    • OK that's great Nikhil.

      but the frequency should be 50Hz at the output pins of the IC4017 (pin2 and pin7)….adjust the R1 preset to get 200Hz at the pin3 of IC1 or pin14 of IC 4017

    • don't think about 3kva initially, first make a 500watt inverter using only one TIP36 on each channel….if it works then you can proceed by adding more number of TIP36 for getting more power.

      The battery for a 3kva implementation will need to be at least 150AH rated.

      but as mentioned above first try with a smaller battery, getting the inverter to work is more important initially.

    • oh..k sir,
      but I don't think that I can offered that huge capacity of battery.(150AH) because, as per my knowledge , cost will be very high for that battery.
      what I was planning is to use 12 volt batteries (no of batteries depends upon confg),and I was hoping for ampere hour rating for those battery will be around 10-15 AH rating,(which will cost I guess 1000-1500 /-)
      sir,
      if possible.
      I am requesting you to plz give us in detail for the selection of battery voltage with AH rating and transformer selection with respect to 3kva ,6 kva.
      I think ,lots confusion is here.
      actually sir,
      with your exact circuit diagram if I use two number 12 volt battery i.e. 24 volt.(it will give 3 kva)
      that time what will be the AH rating for single 12v battery to get 3KVA.
      and transformer I am planning to design as following description ,
      =24v-0v-24v center tap
      =power=3kva
      =o/p=230v
      Thanks and regards
      nikhil

    • I am agree to first go for 500va inverter, initially
      but for that different transformer I have to order.
      and also I have already purchased 10 no of tip 36,
      and transformer will also required for 3kva.
      so I am here ok to go for 3 kva inverter .

    • divide 3000 by battery voltage and multiply with 7 or 8 that will give you the AH approximately

      so 3000/24 = 125 x 8 = 1000AH

      i was wrong when I said 150AH.. you'll a 1000AH battery for getting a 5 to 7 hours back up with 3kva load.

      think and plan your procedures accordingly.

  39. thank you very much sir..
    apologize to ask those elementary concept but sir,it is being very informative and to be clear and on right track,this is just because confusion in my mind.
    as i required backup for 5-7 min so i am choosing two number of 12volt batteries with "15ah" rating.
    { 3000/24 = 125 x7 min = 15 amp-hour }

    Thanks And Regards
    Nikhil
    "Previous post was much fruitful for me"

    • Hi Nikhil,

      the ones which are not mentioned are all 1/4 watt rated. since you are using 24, these 1K resistors will need to be increased to 4k7

      the 22 ohms was taken tentatively, you may have to reduce it further for ensuring optimal power…

      for powering the circuit you can take the positive from one of the 12V batteries whose negative is connected with the inverter negative…in that way you can get rid of an extra 7812 IC

  40. hi sir
    i was referring to T1P122. so i want know if i can use it to drive the mosfets
    Also i want to how if i can use 100ohms instead of 10ohms and for the second circuits i want know if i can use 220 or 200 ohms for the ciruit

  41. hello sir i have an inverter circuit for my school project that is using IC3524 but it doesnot have low battery and over charging cut off so i want u to help me with these circuit for for proper working

    • Hi Timilehin, the points marked as "load" should be connected to the inverter DC input points where normally a battery would be connected.

      Thus the inverter would operate only under two conditions:

      if there is no AC mains input and/or if the battery is optimally charged.

  42. Hi. Just to be cleared on your flyback diodes, are they rated for 25A? I'm busy building a modified sinewave inverter and need high power diodes for my mosfet protection. I'll be using a push pull configuration with centre tap connected to 12V.

    • Hi, yes these should be ideally over 25amps, you can make these by using 5nos of 6amp diodes (6A4 diodes) in parallel with 1 ohm 1/2watt resistors in series with each of these diodes.

  43. hello. please i need your help. i've been given a project topic to design and construct using a microcontroller a 3kva inverter and i dont know where to start from. pls help me out

  44. Hi Sir

    I have build many inverter circuits and all of them has failed, i would like to give your design a go and see how it works, the only problem is some of your parts is not all around availible, can you maybe send me a mail to johan@supplytech.co.za and then we can get into contact.

    • Hi Johan, if you have failed with all the previous designs it means you need to learn the basics of electronics first otherwise you will with my circuits also.

  45. Good day Mr swagatam, please i want to confirm from you if the input voltage of this 3kva inverter circuit is will be 12 or 38 volts because i am seeing 12 volts at the input middle of the transformer side please which one is the prefared voltage for the input voltage of this circuit? will it be 12 volts battery or 3×12 volts battery which will be all together in series 36 volts? also do i want to confirm from you if the transformer is the one with the rated voltage of 230 volts ac to 12 volts ac or 230 volts ac to 38 volts ac. thanks as i will be waiting for your repply as am waiting to start the project. i am Zeal,

  46. Hi Mr swagatam please i want to confirm from your if the voltage input of this inverter circuit is one battery of 12 volts or if i will have to connect in series of 3×12 volts battery which will be total of 36 volts or 4×12 volts battery which will give me 48 volts please don't be offended by my question because am asking because i am seeing on the circuit here 12 volts as the input the, one in red mark, ans also do i want to confirm from u again if the transformer is transformer of 230 volts ac to 12-0-12 volts ac or 230 volts to 30 volts ac as 16.5-0-16.5 volts which equally to 38 volts. thanks so much for your designing work please i will be waiting for your repply as am waiting to start this project… my reguard

    • Hi Zeal, since the proposed wattage of the inverter is huge, therefore a higher voltage operation is strongly recommended, as that would help to keep the cables and the transformer relatively more compact and manageable.

      you can use 36V, 48V, or even 96V as the input, higher voltages will make things more efficient, and will allow incorporating proportionately lower current transformers.

      for a 36V supply the trafo will need to be 36-0-36/220V, for 48V it would be 48-0-48/220V and so on.

    • While you are at it why not just use 220V batteries (18x12V batteries) and you don't even need that monster transformer. Just use higher voltage transistors mounted in H bridge. Enough KW to run the whole house!

  47. Thank u sir i appreciate your help and i think this explanation is exactly what i need to proceed with and also i believe that with this explanation, the project will be so easy to achieve. thanks a lot

  48. Sir can i use a 12-0-12v 3Amp transformer for this circuit above, how about if i use 50-60hz of frequency can you give me an idea. Please give me a partlist for this circuit. It is suitable to use 12v 6ah battery? I am going to use this circuit in my solar panel system project in my college. I think this circuit would help me.

    By the way i am angelous from philippines.

    Thanks in advance.

  49. Sir in the 3kva pure sine wave the stage between the ic 4017 and the Tip 35C TRANSISTORS, THERE ARE TWO TRANSISTORS ONE DRIVING THE TOP ROW AND THE LOWER ONE DRIVING THE OTHER ROW OF THE TIP 35C TRANSISTORS. YOU DID NOT MENTION THE TYPE OF THE TRANSISTORS. CAN YOU PLEASE GIVE ME THE IDENTITY OF THE TRANSISTORS.

    • Bernard, please refer to the last diagram, and use this power transistor stage with the 4017 output.

      don't forget to use freewheeling diodes across the trafo winding for protecting the transistors from the trafo back EMFs.

    • Dear Bernard, do you have any previous knowledge of building inverters??….you cannot directly jump to a 5 kv inverter without practicing on smaller versions first

  50. Dear Swagatam,

    How do you convert a modified sine wave inverter into a pure sine wave in the 3kva inverter. I do understand that you do employ a filter for instance a low pass filter. In which part of the circuit do you employ a filter and in this the 3kva inverter. Is it possible to connect it between 4017 ic and the tip 35 c transistors?

  51. Dear Swagatam,

    I send you several questions, one was on converting modified sine wave inveterter to pure sine wave inverter,using a filter and did ask you for the case of the 3kva inverter which part of the circuit do you place ? and a host of other questions up to now no responds from you sir. Please I need your expertise.

    Bernard Tendengu

  52. hi sir want some help again
    am in the process of making a 7.5kw inverter. so i gave made it with the following ratings
    input voltage: 24v centertap

    inputcurrent: 312.5amp

    output voltage: 240v

    output current: 31.25amp

    mosfet rating Id 50amp/ 200v
    so how can i balance the mosfets for better output and any adverse is welcome sir thanks alot for your help

    • Hi olupot, your calculations are OK.

      since the max amp holding capacity of your mosfet is 50 amp, you would require 312/50 = 6.24 or 7 nos of mosfet in parallel on each channel to run the inverter optimally at full load….and make sure these are mounted on huge heatsinks with fan cooling



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