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How to Design Your Own Inverter Transformer

Designing an inverter transformer can be a complex affair. However, using the various formulas and by taking the help of one practical example shown here, the operations involved finally become very easy.
The present article explains through a practical example the process of applying the various formulas for making an inverter transformer. The various formulas required for designing a transformer has been already discussed in one my previous articles.

Designing an Inverter Transformer with the Help of a Practical Example

An inverter is your personal power house, able to transform any high current DC source into readily usable AC power, quite similar to the power received from your house outlets. Although inverters are extensively available in the market today, but designing your own customized inverter unit can make you overwhelmingly satisfied and moreover it's great fun.

At Bright Hub I have already published many inverter circuit diagram, ranging from simple to sophisticated sine wave and modified sine wave designs. However folks keep on asking me regarding formulas that can be easily used for designing a inverter transformer. The popular demand inspired me to publish one such article dealing comprehensively with transformer design calculations.

Although the explanation and the content was up to the mark, quite disappointingly many of you just failed to grasp the procedure. This prompted me to write this article which includes one example thoroughly illustrating how to use and apply the various steps and formulas while designing your own transformer. Let’s quickly study the following attached example:

Suppose you want to design an inverter transformer for a 120 VA inverter using a 12 Volt automobile battery as the input and need 230 Volts as the output. Now, simply dividing 120 by 12 gives 10 Amps, this becomes the required secondary current.

Want to learn how to design basic inverter circuits?

The data in hand are:

Primary Voltage = 230 Volts,

Secondary Current (Output Current) = 10 Amps.

Secondary Voltage (Output Voltage) = 12-0-12 volts, that is equal to 24 volts.

Output Frequency = 50 Hz

First we need to find the core area CA = 1.152 ×√ 24 × 10 = 18 sq.cm

We select CRGO as the core material.

Calculating Turns per Volt TPV = 1 / (4.44 × 10^-4 ×18 × 1.3 × 50) = 1.96

Calculating Primary Current = 24 × 10  /  230 × 0.9 (assumed efficiency) = 1.15 Amps,

By matching the above current in Table A we get the approximate Primary copper wire thickness = 21 SWG.

Therefore the Number of Turns for the primary winding is calculated as = 1.96 × 230 = 450

Next, Primary Winding Area becomes = 450 / 137 (from Table A) = 3.27 sq.cm.

Now, the required secondary current is 10 Amps, therefore from Table A we match an equivalent thickness of copper wire = 12 SWG.

Calculating Secondary Number of Turns = 1.04 (1.96 × 24) = 49.

Calculating Secondary Winding Area = 49 / 12.8 (From Table A) = 3.8 Sq.cm.

Therefore, the Total Winding Area Comes to = (3.27 + 3.8) × 1.3 (insulation area added 30%) = 9 sq.cm.

Calculating Gross Area we get = 18 / 0.9 = 20 sq.cm.

Next, the Tongue Width becomes = √20 = 4.47 cm.

Consulting Table B yet again through the above value we finalize the core type to be 6 (E/I) approximately.

Finally the Stack is calculated as = 20 / 4.47 = 4.47 cm

Table A

SWG------- (AMP)------- Turns per Sq.cm.
10----------- 16.6---------- 8.7
11----------- 13.638------- 10.4
12----------- 10.961------- 12.8
13----------- 8.579--------- 16.1
14----------- 6.487--------- 21.5
15----------- 5.254--------- 26.8
16----------- 4.151--------- 35.2
17----------- 3.178--------- 45.4
18----------- 2.335--------- 60.8
19----------- 1.622--------- 87.4
20----------- 1.313--------- 106
21----------- 1.0377-------- 137
22----------- 0.7945-------- 176
23----------- 0.5838--------- 42
24----------- 0.4906--------- 286
25----------- 0.4054--------- 341
26----------- 0.3284--------- 415
27----------- 0.2726--------- 504
28----------- 0.2219--------- 609
29----------- 0.1874--------- 711
30----------- 0.1558--------- 881
31----------- 0.1364--------- 997
32----------- 0.1182--------- 1137
33----------- 0.1013--------- 1308
34----------- 0.0858--------- 1608
35----------- 0.0715--------- 1902
36----------- 0.0586---------- 2286
37----------- 0.0469---------- 2800
38----------- 0.0365---------- 3507
39----------- 0.0274---------- 4838
40----------- 0.0233---------- 5595
41----------- 0.0197---------- 6543
42----------- 0.0162---------- 7755
43----------- 0.0131---------- 9337
44----------- 0.0104--------- 11457
45----------- 0.0079--------- 14392
46----------- 0.0059--------- 20223
47----------- 0.0041--------- 27546
48----------- 0.0026--------- 39706
49----------- 0.0015--------- 62134
50----------- 0.0010--------- 81242

Table B

Type-------------------Tongue----------Winding
No.---------------------Width-------------Area
17(E/I)--------------------1.270------------1.213
12A(E/12I)---------------1.588-----------1.897
74(E/I)--------------------1.748-----------2.284
23(E/I)--------------------1.905-----------2.723
30(E/I)--------------------2.000-----------3.000
21(E/I)--------------------1.588-----------3.329
31(E/I)--------------------2.223-----------3.703
10(E/I)--------------------1.588-----------4.439
15(E/I)---------------------2.540-----------4.839
33(E/I)---------------------2.800----------5.880
1(E/I)-----------------------2.461----------6.555
14(E/I)---------------------2.540----------6.555
11(E/I)---------------------1.905---------7.259
34(U/T)--------------------1/588---------7.259
3(E/I)-----------------------3.175---------7.562
9(U/T)----------------------2.223----------7.865
9A(U/T)--------------------2.223----------7.865
11A(E/I)-------------------1.905-----------9.072
4A(E/I)---------------------3.335-----------10.284
2(E/I)-----------------------1.905-----------10.891
16(E/I)---------------------3.810-----------10.891
5(E/I)----------------------3.810-----------12.704
4AX(U/T) ----------------2.383-----------13.039
13(E/I)--------------------3.175-----------14.117
75(U/T)-------------------2.540-----------15.324
4(E/I)----------------------2.540----------15.865
7(E/I)----------------------5.080-----------18.969
6(E/I)----------------------3.810----------19.356
35A(U/T)-----------------3.810----------39.316
8(E/I)---------------------5.080----------49.803


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  • 213 comments:

    1. Hi Swagatam

      Thank you very much for all your effort and help, a very nice article. Is there any way to evaluate an already available inverter transformer (desi inverter 12v i think) for an estimated or exact wattage or amperage, voltage etc.?

      Thanks and regards

      Sam

      ReplyDelete
      Replies
      1. You are welcome Sam!

        The current of any transformer may be found simply by through a multimeter.
        The output voltage may be found by selecting the voltage range, and the current may be found by selecting the relevant range in the meter.
        However current measurement should be done quickly to avoid heating up of the meter wire.

        Best Regards.

        Delete
    2. Hi swagatam,great job with this piece;its very concise and exlanatory.I have very keen interest in electronics and will like you to mentor me on electronics and electronic design.I am a fast learner and will greatly appreciate any material you may recommend and may give to this end.my personal email is divinelyanointed@gmail.com.we can keep personal correspondence with each other on this matter Through this email.thanks for the support.once again,great work.

      ReplyDelete
      Replies
      1. sir, i parthiban, i very much interested coil winding of transformer. please help my question is howmany turns in KVA? if any DATA SHEET? please send my mail, parthiban_ks@yahoo.co.in (example: KVA------SWG-------(AMP)------- Turns per Sq.cm.)

        [(i.e.,1KVA (1000w)transformer Ex SWG:10 Ex No of turns: 200

        KVA--------SWG------- (AMP)------- Turns per Sq.cm.
        1-----------10----------16.6---------- 8.7
        2-----------11----------13.638------- 10.4
        3-----------12----------10.961------- 12.8
        4-----------13-----------8.579---------16.1 EXAMPLEs ]

        Delete
      2. Possibly I'll try to find the data and inform you regarding it, soon

        Delete
      3. Sir, any data's

        Delete
      4. So far no luck, I tried a lot to find it online but couldn't find any relevant data...

        Delete
      5. Sir ihave 500 watt inverter please sir transformer primary and secondary turns and bubbin size send my email ma2604403@gmail.com

        Delete
    3. TVP=1/(4.44*10^-4*18*1.3*50=1.96?

      ReplyDelete
      Replies
      1. That's right, it's 10^ -4.....

        Delete
      2. hello sir, please i want you to help with the equation that i can use to get the thickness of wire that i will use to wind a transformer for both the primary and the secondary and also equation to get the area of the iron core. the parameters that i have are; 220v supply to the primary, 2v,4v,6v,8v,10v,and 12v to be lead out at the secondary, 50hz, and power rating of 3000VA. my email is khennie12@gmail.com. thank you sir

        Delete
      3. right answer is
        1/(4.44*10^-4*18*1.3*50=1.925 not 1.96

        Delete
    4. Thank you - this is a very useful article.

      However, although some of the numbers in the example are clearly variables (input and output voltage and current) and certain of the other numbers derive from them, it's not completely clear to me which parts of the formulas are constants or how they are arrived at.

      For example, 1.152 is apparently multiplied by the square root of the voltage times the amperage to arrive at the core area. Is the 1.152 a constant, and what is that based on? does it change depending on the core material? In Calculating Primary Current, is the 230 multiplied by 0.9 simply to take into account that the transformer is not 100% efficient, or is it more complicated than that?

      Perhaps I am simply missing these things because I did not find any link to the previous article you said you wrote specifically on Transformer Design, and they are all explained there.

      Thanks again.

      mjf

      ReplyDelete
      Replies
      1. Thank you for showing interest in my article.

        Here's the link of my previous article where I have explained the making of a transformer more elaborately:

        http://www.brighthubengineering.com/diy-electronics-devices/96783-designing-your-own-transformer/

        Regards.

        Delete
    5. Thank you! I will read this this evening!

      ReplyDelete
    6. Hi,
      I am not able to find any of your Inverter designs at Bright hub. Can you send me the link to all those?
      Nowadays I am studying all sort of inverters. I hope your designs might help me alot.

      ReplyDelete
      Replies
      1. Hi,
        I have shifted all my inverter articles from BH to here, kindly find them through the search box....I am sure you would find them interesting.

        Thanks and Regards

        Delete
    7. how is primary voltage 230 when it should be 12-0-12

      ReplyDelete
      Replies
      1. Sir I have 12kva automatic voltage stabilizer 50 to 220v make sir please their turns and bubain size tell me

        Delete
    8. Dear Swagath, thank you for this input, can you give me a design details on a general purpose inverter transformer for a 600 VA Sqwave.

      ReplyDelete
      Replies
      1. Thanks!

        For 600VA, the specs would be:

        Primary current = 600/total winding voltage at DC side.

        Secondary current = 600/total winding voltage at AC side.

        Delete
    9. Hi swagatam
      I need to make a transformer for my school project
      Can I get some help

      ReplyDelete
      Replies
      1. Hi Ekaansh,

        It is difficult, you cannot wind a mains AC transformer with ordinary tools....not feasible for school project, as far as i think.

        Delete
    10. Dear Swagath, Can you help me in designing a 600VA transformer for pure sign wave , not able to get one. I was able to source the board, with transformer design.
      Technical details of transformer given
      up to 800VA800VA 4 No* 3Inch ( is this core detail?-what does it mean)
      Input 230V Primary ( SWG 19-360 turns)
      Out put (1) SWG 13- (3*11 turns)- out put volt 7.5V
      (2) SWG 25-22 turns- out put Volt 14.2V

      I am not able to understand the Core details,
      i have a core of size 6.4cm * 4cm
      can i use this if so then the SWG and turns would vary

      ReplyDelete
      Replies
      1. I do not have any experience with transformer designing so I am sorry I won't be able to help you with it.

        You can ask a professional winder, he would certainly know more about it.

        Delete
      2. Thank you, it is hard to find people who can help like you, i shall try

        Delete
    11. thanks alot for those useful information but could you please help me with simple specific instructions step by step to make a 500 watt (or even more )inverter
      pleaasee

      ReplyDelete
      Replies
      1. Thanks! I have tried to explain as much as possible in the article, it would be difficult for me to provide a step by step narration....

        Delete
      2. ok thanks again my friend but could u please tell me how can i make it a 600 watt

        Delete
      3. Are you referring to a transformer or an inverter....if it's an transformer, then I'm sorry I am not good at it...

        Delete
      4. i'm asking for 600 or 800 watt inverter
        i have a 12V 60A car battary
        many thnx in advance

        :: i'm sorry for disturbing but i really dont know much in electric stuff and i need ur help

        Delete
      5. you can try making this circuit

        http://homemadecircuitsandschematics.blogspot.in/2012/02/how-to-make-simplest-150-watt-mosfet.html

        Delete
    12. i want to design and build 2000 watts inverter help with simple diagram and name the material for me am a mechanical engineer, i want to use for my house
      my

      ReplyDelete
      Replies
      1. you can try the following simple configuration:

        http://homemadecircuitsandschematics.blogspot.in/2012/09/mini-50-watt-mosfet-inverter-circuit.html

        Just attach more mosfets and an appropriately rated transformer for getting 2000 watts

        Delete
    13. hi could pls help me with any simple method in determine the actual wire guage without a micrometer screw guage cos i have some difficulties with that

      ReplyDelete
    14. why 160v winding for charging

      ReplyDelete
    15. hi Swagatam, i am starting a solar powered generator project in which i am building a 1000W inverter. does the solar charging source have any influence on the inverter design compared to an AC charging source? do you have any example 1000W inverter designs?
      Thanks, Derek

      ReplyDelete
      Replies
      1. Hi Derek,

        A solar panel source would be controlled by a charger controller, so the inverter or the battery wouldn't have any concerns with the panel directly, so there's nothing to worry.

        I have one simple 1000 watt inverter design in this blog, you can see it here:

        http://homemadecircuitsandschematics.blogspot.in/2012/05/make-this-1kva-1000-watts-pure-sine.html

        Regards

        Delete
      2. Great thanks,

        I am building a solar generator with 1500 W hours of charge. charge controller, batteries, inverter (1000W) @60Hz. i want to build the inverter and possibly the charge controller. Is this inverter circuit applicable? any other advice would be greatly appreciated. I have been searching and find your info to be the most helpful thanks,

        Derek

        Delete
      3. Thanks!

        According to me this inverter circuit is correct, and would work as specified.

        As can be seen, the circuit is quite straightforward, and wouldn't be so difficult to build.

        Delete
    16. hi swagath ,

      how to calculate the design of 12v 1amp transformer

      ReplyDelete
    17. hi swagatam sir, this mohan i want to learn transformer winding. please help me.give some ideas

      ReplyDelete
      Replies
      1. hi mohan,

        I am sorry i don't have much idea regarding transformer winding.

        Delete
    18. Hello Everybody.

      Can someone tell why the factor 1.152 is used in calculating the core area? where did it come from. and if possible, is there a formula to be used that states the core area depending on the frequency. I'm asking because i want to use high frequency transformers and i need to know what size for wha tpower

      ReplyDelete
      Replies
      1. Hello Gober,

        The above explanation is solely for iron core transformers not for high frequency ferrite transformers...so the calculations won't work for you.

        Delete
    19. My answer is
      Tpv=1/(4.44*10^-4*18*1.3*50)=1.92?
      Thise is right answer?

      ReplyDelete
    20. Hello sir. I appreciate ur link but im confuse. How do I do a calculation for 1kva inverter transformer. My values are not just falling in place with that of the table given. Help me pls

      ReplyDelete
      Replies
      1. yes, I think the above data is limited for upto 20 amp transformer not above that, so im sorry a 1kva could be too large and not within the range of the above data.

        Delete
    21. Sir, pls tell me that meaning of 120VA

      ReplyDelete
    22. Sir, i am ashok.V from hyderabad. i want design a 400watt inverter batteries. .So what is primary current of transformer and battery current.

      ReplyDelete
      Replies
      1. Ashok, please divide 400 by the voltage of the transformer to get the approximate current on the relevant side.

        Delete
    23. hi friend,how are you and your family.my friend,I want to make a transformer for ups to charge 200 amps battery in 30 minute approximately and give good back up and drive about deep freezer (triplet) an water-pump and five fans,five energy savers at once.please
      help me my friend.

      ReplyDelete
      Replies
      1. hi imam,

        you are probably looking at a 10kva inverter design, i have no idea how to design such a huge transformer, please consult a professional trafo designer

        Delete
    24. Sir,

      sir,
      i have just salvaged 2 Nos of ups transformers from an old working UPS "Luminous 750va" double battery, i just want to know that can i use them to build an inverter with a range between 200 to 500 watt power inverter for home. second is that i am confused about the connections of these transformers there are 7 wires coming out from one side and three on the other side. how to identify the wires and check their voltages. i have been posting this every where but i idint receive any response. i shall be grateful if you could help me resolve this thing. the transformer has this marking on it " TX-201-1000-02"

      ReplyDelete
      Replies
      1. Gowhar, While removing you could have at least noted down which taps are terminated as mains outputs for the appliances.
        Anyway, you can connect your home AC mains across the different taps of the trafo randomly with a 100 watt bulb in series....the taps which produce minimum glow over the lamp could be assumed as the 220V winding of the trafo....

        Once you locate this you can keep the mains input with the 100 watt series bulb connected, and take a DMM for checking the AC voltages across the remaining taps...in this way you can go ahead with the required identifications.

        Delete
      2. ....maintain extreme caution while doing the above as the procedure involves lethal mains current.

        Delete
    25. Dear Sir,

      i have a question, suppose i will get an inverter and ups with same rating including batteries, will they give same back up time.
      waiting curiously for your reply
      thanks

      ReplyDelete
      Replies
      1. Dear Gowhar,

        Yes they should have identical backup time

        Delete
    26. thankyou for the prompt reply.
      God bless you.

      ReplyDelete
    27. Good day sir! Nice work keep it up

      ReplyDelete
    28. Hi swagatam, iam ahmad thank you very much for this article.Pls sir can i rewind a transformer rated 1000watts for an inverter that is to produce 850 or 750watts? Or let me say any transformer that its wattage is above my requirement(watts). Can i match the current i got using the above formula with AWG bcos there is not SWG wire in my place and even if there is the current i got is not within the above table. Pls assist.

      ReplyDelete
      Replies
      1. You don't need to rewind the 1000watt trafo, you can use the same trafo for obtaining lower wattages...the optimization will simply depend on the battery current which can be reduced as per the requirements.

        Delete
    29. Hello sir! Iam ahmad. Thank you very much for the reply, god bless, may you continue to reign.Pls sir am i on the right path by building a 750watts inverter using SG3524, L7809 voltage regulator, and four IRF3205 mosfets, 1000watts trafo?.what will be the voltage of 104 caps? Iam using 2k2, 10k, 1k, 200k resistors,will they be a quarter watt?. I want to replace 260k with 200k resistor and 100k variable.I appreciate alot

      ReplyDelete
      Replies
      1. Thanks Ahmad!

        By default the 104 caps can be 50V rated, the resistors 1/4 watt rated. I am not sure about the resistor replacement of 200K...can you show me the exact link?

        Delete
    30. Ahmad-i bought three 104 polyester caps, two of the caps have; 1A 104J,while the third one have 104k 100v writting on it.pls sir will they serve?

      ReplyDelete
      Replies
      1. 104 means 0.1uF, if your circuit requires 0.1uF, then all these capacitors would be OK.

        Delete
    31. Ahmad* Ok sir, but what about the replcement(260k with 200k resistor and 100k variable),and the mosfets? I want to use four IRF3205 (two connected in parallel on each side),and i need 750watts as the final output. Is it okay? Thanks

      ReplyDelete
      Replies
      1. Your link did not open the circuit page, it opened the homepage of the site....provide the exact link of the diagram, only then i would be able to say anything.

        Delete
      2. Ahmad, I have checked the link, yes you can use 200K + 100k variable preset a pin#6.

        first try with single mosfets only...if it works perfectly then you can add one more mosfet in parallel on each channel.

        Delete
    32. Ahmad****Thank you!!! Very much sir, you are one in a million. Once am through with the inverter and it start working i will let you know.thanks again, my boss

      ReplyDelete
    33. Ahmad*** good day sir! I encountered problem while selecting a trafo, my aim was to purchase a 12v-0v-12v ups trafo that would match with my requirement;750watts,12v car battery(though,later i would replace it with a truck battery),but when i went for it i only saw trafos with these specs:6.8v-0v-6.8v(650va), 150v-0v-150v(1200va), 800va(no voltage written). Am confuse right now. Pls sir i would like to know weather ups trafos can perform the task(based on inverter circuit on the website:simplecircuitsandprojects), if they can, what specs should i look for? And if they cant, what type should i go for? Pls explain comprehensively. Pls sir can i use 220k resistor in place of the 200k? 200k is currently unavailable in my place. Thanks

      ReplyDelete
      Replies
      1. you can use the 6.8v-0-6.8v trafo for the referred circuit application, it will surely work.
        220k will be ok in place of 200k.

        Delete
    34. Ahmad*** thank you boss! I feel relieved now

      ReplyDelete
    35. Ahmad***Hello sir! Iam doubting weather 6.8v-0v-6.8v trafo can give me 220volt output with 12v input, can it? The trafo was salvaged from 650va ups,what amount of load can it carry? ---can i use any salvaged ups trafo with primary volt above 12v-0v-12v to give out 220v using 12v bat input? Let say 15v-0v-15v or 16v-0v-16v. Thanks

      ReplyDelete
      Replies
      1. 6.8v trafo will give 400v at the output, you will need to adjust the PWM pot or the load correction pot for adjusting it to 220V.

        You can try 12v or other trafos also, if you wish.

        Delete
    36. Ahmad*** thank you very muc sir! Pls dont mind my too much question, this is my first time in building a circuit. Sir, based on my understanding mosfet(particularly irf3205) has three pins, and pin 11 and 14 of an ic are connected to the gate(mosfet first pin),and trafo wires to the second pins(drain),while the third pins(source) grounded.But yesterday i saw a ups circuit and its trafo wires connected to transistors metal(metallic surface through which screws are bolted) and i was a kind of confuse. Pls explain to me in detail how mosfets are connected. Thank you sir

      ReplyDelete
      Replies
      1. Ahmad, don't bother about such details, concentrate on the basic technique and use only the three leads of the mosfet,

        use the metal tab for attaching heatsinks only and nothing more.

        Delete
    37. Ahmad*** hi boss! Does all the different components share the same copper plane when grounding?

      ReplyDelete
      Replies
      1. what is copper plane? do you mean PCB copper ground track?


        yes, that's correct

        Delete
    38. Ahmad***thank you a million times boss! I have started coupling and nearly done.

      ReplyDelete
    39. hi,
      can we make an inverter for very small voltages like .5 volts using amplifying transistors like 2n2222 or 2n3904, and the output should be around 3-4 volts ac, that can power 2 leds. if yes can you tell me such a circuit. also about transformer, how does it is built for such a low voltage ?
      i need it because i am participating in inspire award.

      ReplyDelete
      Replies
      1. I think we have discussed this earlier, anyway just to remind you we can use a joule thief circuit for this, you may refer to this article for more details:

        http://homemadecircuitsandschematics.blogspot.in/2012/10/1-watt-led-driver-using-joule-thief.html

        Delete
    40. is the self looped motor generator is real?
      if so why yet, it hasnt come to real world?

      ReplyDelete
      Replies
      1. it's fake...
        you can study Adams motor for getting cold electricity, which is a true concept.

        Delete
    41. well I am making an inverter which should be of 100 watt using 12v 7Ah battery. Can you tell me a circuit, also I am a beginner in making inverter.
      Also my teacher insisted me to put an cooler( i dont no why) off coarse a fan, but i told them that it is not necessary but he made it strict to add an fan. so can you tell me how to add a pc fan to an inverter circuit.
      it would be a great help.

      thankx

      ReplyDelete
      Replies
      1. You can try the following circut, it will easily handle 100 wats provided the trafo is correctly rated.

        http://homemadecircuitsandschematics.blogspot.in/2012/09/mini-50-watt-mosfet-inverter-circuit.html

        Fix the fan over a suitable slot on the cabinet facing the mosfet heatsink such that it throws the breeze on the mosfet heasink.

        Delete
    42. I know but where do i connect the power supply for the fan?

      ReplyDelete
      Replies
      1. obviously it will from the inverter battery

        Delete
    43. Please do design a 5Kwatt inverter transformer.

      this will be much more needed since we are all globally going for green energy. And 5kwatt inverter is much sought after, than low power inverter.

      ReplyDelete
      Replies
      1. thanks! I'll surely try to present one in this blog sooner or later.

        Delete
    44. Hai Sir,
      For secondary winding should we double the turns that is 49 centre tap 49 total 98 turns or after 24 turns should we take the centre tap and again wind another 24 turns.

      ReplyDelete
      Replies
      1. Hi Vijeesh,

        please explain your question detail, I could not understand what specification you are trying to make.

        Delete
      2. In the above calculation you got 49 turns for secondary winding.(means in the secondary winding first we will wind 49 turns with 12 swg wire then we take the centre tap then again wind 49 turns,total 98 turns) or we have to take the centre tap from the middle of 49 turns that's after 24.5 turns we take the centre tap and again wind 24.5 turns.

        Delete
      3. It will be from the center of the 49 turns, that is after 24,5 turns or after 24 turns.

        Delete
    45. i have an 200watt inverter with two irfz44n mosfets. how can i increase its power to 400watt.? can i add more mosfets in parallel? plz reply soon.

      ReplyDelete
    46. I really appreciate your tremendous effort in help others out. Please sir, I want you to help me calculate the core size for the primary and the secondary, number of turns, the lamination size for 1kva transformer for inverter. I tried using the method you used above but I halted when it comes to choosing thickness of wire for the secondary in the table because I couldn't find there. Please sir. I want you to give me the wire table that starts from 1 and not 10 and also that of lamination table. I had be very grateful if you do that for me sir. Hope to read from you soon sir.

      ReplyDelete
    47. Pls sir. I want you to help me with the calculation for 1kva transformer inverter. I used the above method but the challenges was that I couldn't find the wire thickness from the table you gave above. Please I will be very grateful if u can upload a table that will start from 1 and not 10 for both thickness and lamination. Or if there is another way of doing the calculation let me know sir. Hope to read from you soon.

      ReplyDelete
      Replies
      1. Thank you khennie, but I am sorry I won't be able to help you with the calculations because I too have no idea regarding the wire SWG calculation which would handle 1000 watts. I got the above data from one of the electronic magazines and I personally do not have any info regarding the specific data that you are asking.

        I would advise you to seek the help of a professional transformer maker, he would charge a bit but finally you would be able to achieve the perfect design as per your requirement.

        Delete
    48. Thanks for your reply,I don't know any professional online but pls if you know one, kindly link me to him

      ReplyDelete
      Replies
      1. getting it online will be difficult, you will have to find it locally in your area, or in your nearest electronic market

        Delete
    49. Hi Swagatam,
      Can you please help me build a 200amp inverter.

      ReplyDelete
      Replies
      1. Hi Shyam,
        please provide all the required specifications, i'll try to help

        Delete
    50. Thank you sir for replying,, actually I am stuck with giving the time delay for the igbt switches in a dual half bridge inverter config. Its for simulation purpose..... because of the dual config. m always getting wrong o/p. please suggest anything.

      ReplyDelete
      Replies
      1. you mean dead time? It's internally fixed in the IC, You can refer to the following diagram for some clue:

        http://easy-electronic-circuits.blogspot.in/2014/05/100-watt-to-1000-watt-pure-sinewave.html

        Delete
    51. Pls I will like to know the type of transformer that can be used for 1kva inverter and also the rating of the transformer. Thanks

      ReplyDelete
      Replies
      1. divide 1kva with the battery voltage to get the transformer secondary current. the primary voltage will be as per the specs of your country.

        Delete
    52. Thanks for ur reply that surelly works

      ReplyDelete
    53. sir,
      the article is really interesting. In order to design a distribution transformer, will the core designing be same as sir has done? Or is there any difference? if so, i would like to request your kindness to elaborate on it.
      Thanks

      ReplyDelete
      Replies
      1. Hi Dozo, yes since all transformers are basically intended for controlling voltage and current parameters, their design calculations will use the same standard formulas and systems.
        However the range provided in the above article is quite limited and it won't probably have the essential data for a distribution transformer.

        Delete
    54. Hi sir,
      In calculating turns per volt, Is the 1.3 a constant no? Does this refers to the magnetic flux density or the saturation of the core?

      ReplyDelete
      Replies
      1. Hi Jerico, it's the flux density and is constant, you may refer to the following post for a detailed info:

        http://easy-electronic-circuits.blogspot.in/2013/07/how-to-design-and-make-transformer-at.html

        Delete
    55. Sir can you plz give me details of inverter transformer with bibbin of E20..and plz tell the details of its windings..

      ReplyDelete
      Replies
      1. hello anonymous, along with the bobbin you will also have to provide other details such as the amp, volts, watts, primary, specs, secondary specs etc,

        Delete
      2. Hai Sir good morning,
        Last week I went to a local transformer/inverter maker for a 800 watt 12-0-12 transformer for an inverter project,he said the primary will be 21 gauge and secondary will be 12 gauge,because of his reputation for supplying good inverters I gave the order for the transformer.as per above calculation 800 watt/12 volt is 66 amp but the chart is saying 12 gauge can carry only 10amp.He is giving a surety that it will carry 800 watt load.What is the trick they are using.

        Delete
      3. Hi Vijeesh,

        you may be right, as per the chart 12SWG should be used for currents not above 10amp but this may be under ideal conditions which will ensure no heating up of the trafo even under full load, however 66 amps is way too high and using 12SWG could be dangerous for this much current.

        although I am not an expert in this field, it looks quite obvious that 66 amps will simply smoke the transformer if a 12SWG is used, or perhaps the person may use many 12 SWG in parallel, that could be a valid possibility, and that would be quite OK....suppose he uses 5 nos of 12SWG strands in parallel then it would just do the job.

        Delete
    56. Can I use Ferrite core for 50 Hz inverter transformer?
      If yes give winding details for a 9-0-9 / 230 volt 500 VA transformer

      ReplyDelete
      Replies
      1. ferrite cores don't work with low frequencies, it will require a minimum 10kHz for proper functioning, so it's not possible

        Delete
      2. Can I connect solar panel to an inverter without a battery?
        I have 6x12 volt 100 watt solar panel and a 12 /230 volt 500 VA inverter.
        Any simple circuit ?

        Delete
      3. yes you can do that, but make sure that during peak sunshine the panel voltage does not become too high than the inverter specifications.

        Delete
      4. My inverter circuit board has LM3525, LM 339, 12F508 ic's and IRFZ 44 Mosfets . It is square wave output. Can I change this circuit with adequate components to get pure sine wave out put. If so please give the circuit. Expecting your valuable reply soon.
        Thank you

        Delete
      5. it could be a modified sine wave or pure sine wave equivalent, can't say with confirmation, although the presence of a microcontroler IC 12F508 and also opamps LM339 indicates a highly sophisticated circuitry which could be a sinewave inverter

        Delete
      6. I am sure, it is not a sine wave because when I connect an inductive load like fan, a humming noise is produced. Your sine wave inverter circuit using TL 494 is very simple. If any kit or assembled board available online using this circuit please inform details or link

        Delete
      7. OK may be it's not a sine wave inverter then.

        Sorry I do not have a kit or assembled board for solving this problem, you may have to inquire it online or in the local market

        Delete
    57. Dear Sir ,what do we mean by the primary and secondary winding area and what is its significance while winding?

      ReplyDelete
      Replies
      1. dear prathamesh,
        the winding area determines the specified number of turns that it can accommodate optimally...that's the only significance it has.

        Delete
    58. how to make 1000 w transformer from above method

      ReplyDelete
    59. Where did you get the (0.9) when calculating the primary current?

      ReplyDelete
      Replies
      1. it's the approximate efficiency count of a transformer, and is a standard fixed value

        Delete
    60. Dear Sir,

      Thanks for such a good document, sir I required 50W transformer for 12V system. So, please help me out.

      ReplyDelete
      Replies
      1. Thanks Saurabh,

        I have provided all the details in the above article, please calculate the parameters accordingly....

        Delete
    61. Hello boss! Hope everything is going smoothly. Am sorry I promised to notify you(7,dec.2013). The circuit(oscillator,power stage) worked,and I have been using it, thanks once again,it was because of your assistance,I sincerely appreciate. Can I connect two identical transformers in parallel (center taped) to my inverter? My aim is to multiply the wattage. Extend my regards to your family.***Ahmed***4rm*****NIGERIA*****

      ReplyDelete
      Replies
      1. You are welcome Boss!
        yes you can connect two transformers in parallel but only for the primary side....the secondary must be used and terminated separately to separate loads.

        Delete
    62. Hello Swagatam, My name is Tobi. Thanks for the tutorials. I'm an Electrical/Electronic Engineering student and I love electronics so much. I've been trying to design an inverter of 100watts or more, just for my personal use. I've seen a lot of inverter circuits on google and youtube but each time I simulate them on my circuit wizard software, they don't work properly. So please can you help me out with a cool circuit that works fine or give me a link or something. I'm very good with theories but I want to be good with practicals as well. Please I really need your help. Thank you.

      ReplyDelete
      Replies
      1. Hello Omoregbee,

        All the circuits that you have tested on the simulator were probably good...because it's your "wizard" that's not efficient enough to check their results, so leave it aside and try one of the selected inverter designs practically, that's the only way you'll learn things correctly.

        Delete
    63. Ok. I will try them out practically, and
      I will get back to you. Thanks.

      ReplyDelete
    64. Hello sir,this is Abdus, plz show me in figure where is core area part?

      ReplyDelete
      Replies
      1. hello abdus, the central pillar cross sectional area of the "E" stack is the core area

        Delete
    65. Hello sir,plz tell me which type of area in sence that primary and secondry winding area are to be maitained,i.e circular,cylindrical or other types?please tell me

      ReplyDelete
      Replies
      1. Hello Abdus,

        it will be as per the structure of the E core. that is rectangular

        Delete
    66. Hello sir,please tell me how to calculate the bobbin size?Also tell me,which windinds should be inner side or outer side?

      ReplyDelete
    67. I am not getting understand that how to understand about winding area,ssuppose I completed total no. of turns, but how to know that this winding area will match to calculated winding area?

      ReplyDelete
    68. Also tell me sir,why did you multiply total winding area to 1.3 ,and what is insulation part,and why you multiplied, why not you added it?

      ReplyDelete
    69. Sir, A mechanic told me that a transformer has a number of different-different size,please tell me about this

      ReplyDelete
    70. Plz reply to all queries immediate, Thank you

      ReplyDelete
      Replies
      1. you can refer to this article for more details:

        http://www.brighthubengineering.com/diy-electronics-devices/96783-designing-your-own-transformer/

        Delete
    71. Helo sir,
      I want make 230v to 120v 1500watts step down transformer,how will calculate,SWG of primary and secondary,and number of turns,primary's and secondary's.please send details to my mail eeemani09@yahoo.com.

      ReplyDelete
      Replies
      1. Hello Manikandan, I have explained the formulas in the above articles please do it according the given info.

        Delete
    72. Hi i am wondering wether it is possible to build an inverter with a toroidal transformer. I have seen a dual input dual output 115/230v to 12v at 300va that is 2 times 12v at 150va each. Would this work via the push pull circuit.? Any advice is much appreciated. I'm assuming if it is possible I would only be able to use it at half its rates output of 150va at 230v

      ReplyDelete
    73. Hi, tried to comment before but don't think it worked. My question is- can I use a toroidal transformer in a push pull configuration? I have seen a 300va 115v/230v to 12v toroidal. It's a dual primary dual secondary wound transformer. If this is possible am I right in assuming I will only be able to use it at 230v at 150va?

      ReplyDelete
      Replies
      1. Hi, yes you can use it by connecting it with a matching inverter circuit.

        all types of transformers can be used for making an inverter, there are no restrictions in this regard.

        Delete
      2. Thank you for replying so quickly. Was I correct in assuming only half the rated output of 150va at 230v. My reasoning is the dual secondary 12v windings in series to give 230v on the primary. However each 12v singly can only deliver 150va

        Delete
      3. 12V in parallel might give you better response at the 220V side....so you can make the two 12V winding in parallel and use a H-bridge inverter circuit to get the best possible results, using single 12V winding will give you 150 watts only

        Delete
    74. This comment has been removed by the author.

      ReplyDelete
    75. Calculating Gross Area we get = 18 / 0.9 = 20 sq.cm
      my doubt is 0.9 is constant value or how did you got this value. thanks in advance

      ReplyDelete
      Replies
      1. it's the approximate assumed efficiency level of the transformer.

        Delete
    76. Is your SWG table is accurate.Because to many on online. can I design transformer with Constant 42 for example 42/18 =2.33 turn per volt

      ReplyDelete
      Replies
      1. yes all the info provided in the above article are accurate as per my knowledge

        Delete
    77. Thanks Sir
      How to check Transformer secondary maximum voltage & current through dummy load
      for example if I have step down transformer with 22-0-22 Vac/3A=132VA how to check this with loaded out please give details.

      ReplyDelete
      Replies
      1. Hi Sandeep you can simply do it by using your digital multimeter at the AC volt and AC current ranges respectively.

        Delete
    78. Thanks sir
      And please tell me how to make 100W dummy load for testing transformer secondary voltage and current.
      and tell me if my transformer is 22-0-22/3A=132VA if i used single 0-22 out its current is 6A or 3A and with 0-44 current should be 3A or what i am bit confused.

      ReplyDelete
      Replies
      1. you can use a high wire wound resistor as the dummy load

        It should be 6 Amp, because 3amp is for the whole 0-44V winding

        Delete
      2. Thanks sir
        But secondary winded copper wire maximum current capacity is 3.5A how can it gives 6A

        Delete
      3. if the wire is not rated for 6 amp then the wire will get hot, if it's rated at 6amp then the half winding will provide you with full 6 amps

        Delete
      4. ....only if the connected load is rated to consume 6 amps

        Delete
      5. Thanks sir
        Can i use this design calculation for tutorial core transformer if yes how to do it properly please help.

        Delete
      6. you can refer to this article:

        http://www.brighthubengineering.com/diy-electronics-devices/96783-designing-your-own-transformer/

        Delete
      7. Sorry for spelling mistake I mean Can i use this design calculation for toroidal (O) core transformer if yes how to do it properly please help.

        Delete
      8. No, it is only for iron core transformers

        Delete
      9. Sir
        Toroidal core is also iron laminated shit roiling in circular you have to wound copper wire direct over to the core not any plastic bobbin is used like EI core. can this calculation work. how to calculate core area of Toroidal core have outer dimater,Inner dimater & height. please help

        Delete
      10. Sandeep, the above data is for EE or EI type cores, so I afraid a torroidal core transformer cannot be calculated using this data.

        Delete
    79. Hello Sir. I am amateur in this field. I want to design a Transformer or a circuit that produce 12v 30am that control my DC motor. Or

      ReplyDelete
      Replies
      1. Hello Aminu, 30 amp is too high, I have no idea regarding it??

        Delete
    80. if we use transformer of less than 10 amp then will there be any problem for the inverter ????

      ReplyDelete
      Replies
      1. you can use any desired rated trafo, it does not matter... the output wattage will be reduced or increased depending on the current of the trafo

        Delete
      2. so I should use center taped trafo of 12V-0V-12V (if I use 12 V battery) of any amp. or watts. Am I right sir ???

        Delete
    81. I can use center taped trafo of 12V-0V-12V (if I use 12 V battery) of any amp. or watts. Am I right sir ???

      ReplyDelete
    82. Hey! I've a ques about 12v battery inverter that can we use 15-0-15 transformer instead of 12-0-12 ?? will it work ??

      ReplyDelete
      Replies
      1. it must be lower than the battery specs, not higher.

        Delete
    83. Hello Sir

      Sorry of asking you again.But I want to know how to make mains transformer with using Toroidal core.I attach Core image and core manufacturer Test certificate. Can you please help me with that information i providw core size is OD-100mm, ID- 60mm and Height-50mm core wet about 1.842 KG (M4 CRGO material)
      https://drive.google.com/file/d/0B5ROBprWe44vYnBURUt0MVNxTkdSRXFqUjhuWHpBUFg5X1Nv/view?usp=sharing
      https://drive.google.com/file/d/0B5ROBprWe44vODRxUGo4cE9TcEE/view?usp=sharing

      ReplyDelete
      Replies
      1. Sorry Sandeep, I have no idea about transformer winding, you should consult a transformer winder or manufacturer for all the details

        Delete
    84. dear brother
      I want to make a 800-1000w transformer for ips. I have bought all component to make it.
      here is the list.
      CABLE:-
      SWG 21 for primary winding,
      SWG 12 for secondary winding,
      CORE:-
      4.5 inch
      FORMER/bubbin:-
      3.05"/7.747c.m.
      1.6"/4.064c.m.
      The transformer is make by 12-0-12V secondry and 0/N-140-220-260V
      Plz help me to find out how many turn will be in primary winding and secondary winding

      ReplyDelete
      Replies
      1. Dear brother, sorry I am good at designing transformers, so can't help with it.

        Delete
      2. I meant to say I am NOT good at designing transformers...

        Delete
      3. can you help me to find out who can tell it?

        Delete
    85. sir what is 42 as constant in transformer design means ? How does that constant forms ? I am giving one example of a transformer design in the link given below in which the transformer design uses that constant..

      Watch "Build an electric transformer (DIY)" on YouTube
      https://youtu.be/s6NyTprQCBI


      i had a 300 W step down transformer with 5 primary terminals and 4 secondary terminals.... i have deassembled the transformer and done the primary winding part... i have the following doubts .. please clarify those...
      (1). According to the video

      the area of the core portion is
      6.3×3.4=21.42

      so no. of turns per volt =
      42 constant/21.42 = approx. 1.96...

      hence no. of primary windings needed = 230 × 1.96 = 450.8 = 451 turns

      and no. of secondary needed = 16 V × 1.96 =31.36


      Are these calculations are correct ? Should i have to select 240 instead of 230 in calculation which will result in increase in no. of primary turns...

      (2). Which configuration of secondary will be better a centre tapped one or with one normal possitive and grnd configuration ?

      (3). how to take 32 V output from the centre tapped config. ?

      ReplyDelete
      Replies
      1. RT, I can't confirm it because I don't often deal with transformers, so although I might have studied the calculations long ago, by now I have forgotten them...

        however the formulas given in the above article are absolutely correct and you can follow those accurately.

        Delete

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