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    This DIY 12V to 220V DC to AC converter is built with CMOS 4047 that is the main component of this small voltage converter that transforms a 12VDC into 220VAC. 4047 is used as an astable mutivibrator, at pins 10 and 11 will have a symmetrical rectangular signal (square wave) which is amplified by 2 Darlington transistors and finally reach the secondary coil of mains transformer (2x10V/60W).

    Video Presentation 1 – without load

    Video Presentation 2 – with load (light bulb)

    With the help of P1 the output frequency can be adjusted between 50Hz to 400Hz. Although this is not part of any professional dc ac converter it can be used quite effective on some home appliances. Be aware that the output signal is square and not sine wave. So you cannot use it for powering TV, Laptops, monitors. Use it only for lighting, power tools and other non-expensive equipment.

    60 Watt DC to AC Converter Circuit Schematic

    DIY 12V to 220V DC to AC converter built with CMOS 4047

    I used BD651 transistors instead of BD699.

    For more DC to AC voltage converters check the related posts.

    Check out the tags for more 12 Volts to 220 Volts converters.

    ask a question

    252 Responses to "12V to 220V DC to AC Converter Circuit"

    1. Very informative site.Please keep it up.

    2. Hi! it is possible to use this with a synchronous ac motor?

    3. How about the program code for the 4047?

    4. Gabriel Aizcorbe says: on February 9, 2009 at 11:13 pm

      Jens, don’t get me wrong, but I’m pretty sure that CMOS 4047 it is not a micro-controller either a plc, is just a monostable/astable vibrator, there is no program for this IC, the only thing is to do some soldering and done.

      May be you are confused with other IC?


    5. wonderfully!the precise.

    6. is it okay with frequency that can change .

    7. any one try to make inverter DC 12v To AC 220?

      • wesley says: on June 5, 2009 at 5:59 pm

        base on your advert, i think i am in need of ypur help

      • yes I have, I did the tony roan/ Harry Lynthal “version, very simple using the 2-2n3055’s a couple of resistors and a re-wound Microwave transformer. only where I live it is 110Vac so I wound my center tap accordingly. Worked very well till I took her to her limits and burnt up my 3055’s But now I know and will build another with a second step on the 3055’s to handel more current draw,,or find more powerful transistors.

      • puiubalas says: on February 1, 2012 at 9:55 am

        how did you rewind the trans?

      • Can you post the.. I did the tony roan/ Harry Lynthal “version schematic with resistor values. or the link to this schematic version.


    8. sserunkuma muusa says: on May 23, 2009 at 7:18 am

      my oppinion is to know how to come up with aconvater and have more knoledge about it

      remain your
      sserunkuma musa

    9. based on your advert i believe i need your asistance

    10. common that’s what i need

    11. What is Z=1,5A/T?
      Is there any replacement for CMOS 4047?

    12. what is Z helpppp

    13. houssein jamal di says: on August 27, 2009 at 9:21 am

      that is a very importly site . thank you very much

    14. Hi,i really admire your good work there but is it a square wave or a sine wave stuff and if its a square wave how can it be converted into a sine wave?

    15. I want asking all friend here
      how do a inverter square wave to sine wave. Give me scematic diagram.thk

    16. Type IC 4047 is same with Type ic other example like type ic is…

    17. How nuch the IC, because i’m interested of the circuit & the IC is available in the market. I’m in the philippines .

      • D.MOHANKUMAR says: on November 11, 2009 at 2:54 am

        IC CA3130 is a 15MHz BiMOS operational(8pin) amplifier with MOSFET inputs and CMOS output.Gate protected MOSFETs are used in the inputs so that the IC has very high input impedance. It is very sensitive and requirs very low input current.It is a general purpose Op-Amp which is commonly available

      • Chinmoy Mitra says: on August 8, 2010 at 5:22 pm

        You have mentioned IC CA3130 in this post, but I cant see it in the circuit schematic of the inverter.

      • yah. you mentioned CA3130. but i didn’t see it in the schematic?

      • cdhrew says: on May 29, 2010 at 9:55 pm

        je to výborny.amíci

    18. What means the Tr= 2*10v/3amp

      Transformer of 3 amp I understood but what about 2*10v cant understand
      It is inverter transforer or any other.
      Plz guide us

    19. Good site.pls mention the transformer& transistor specifications for high wattage output like 600w,1000w.

      • i have an generator of 220 volt but the invertor module is demaged i want to make a connection with the 12 volt ac means direct from coil output to 220 volt
        but i need 1000 watt output is thee some genius can help me with a diagram or etc

    20. What is P1 here??????? and can i use a 12V transformer in place of current 10V????

    21. Can this inveter charge the battery?

    22. Nice diagram, It is very simple. more info about the transformer, please?

    23. VERY GOOD SIR!! Is that a buck transformer there I saw? I have many many different “used transformers and most are bucks so I was wondering because I would like to try this, and then,,,move up two a M.O.T with the secondary rwound to a center tap what do you think?? I have a few M.O.T.s too.
      Basically I have a bunch of stuff I scanvanged from old throw aways,,, even a flat screen I found in the dumpster!

    24. Johnny Beloved says: on June 13, 2010 at 11:18 pm

      I need a clue on the general methods of how to convert a square wave to a sine wave. thanks.

      • You can find this circuit by “Googling” “12Vdc to 120Vac sinewave inverter circuit schematic. I too was wanting to build one, but found the circuit a bit to complex for my limited knowledge and experimental funds. So for now,,just little steps. The sinewave you are looking for is graduated squarewave steps, still square but the peaks/pulse intensifies up a few steps to the desired peak then down in equal steps then up again and so on. Done with microprocessor to manage the pulse train

    25. one can build a better,robust and PWM featured Inverter using SG3524 and IRF540 or IRFZ44 mosfets.

    26. sir can u plz tell me wat type of component is “z=1.5A/T” waiting for ur reply

    27. pleas I want a circuit diagram that can convert 12vdc to 220vdc without the use of any transformer.thank you

    28. Pls sir P. marian I also want a circuit that can convert 12vdc from a 12v/200ah battery to 220vdc without the common EI lamination transformer just like converting 12vdc to 24vdc using an op-amp ic and a torodial inductor. Pls this will lead to a perfect standalone transformerless pure sine wave pwm inverter.

    29. sir
      ineed help.c5591 any replace

    30. hi my quastion
      what mean z=1.5A/t are u mean resistance

    31. how can i repair a circuit wich is patend with some hard black soked material is just like a blackbox of a car

    32. its a inverter module eurom IG 1000

    33. can i use it efficiently? and please tell me what r the t1 and t2 transistors are? r they normal or special ones?

    34. how many watt output.

    35. i have inverter no output

    36. hellow sir ,what is the replacement of BD699?

    37. Can this circuit be modified to use the omni available 555, 40xx to hard to locate here without high dollar shipping

    38. for thee price of shipping the 4047 plus about $40.00, I can have a 800watt/1600watt peak modified sine from almost any auto supply store w/ a 1 year warranty, how about we try to post circuits with readialy available parts from local electronics store’s. Radio Shack has 555’s and 741’s ect but not these odd ball ic’c

    39. can i replace transister to IRF540 N-Channel MOSFET?

    40. Hey,can i replace transister(BD699 Common Collector) with IRF540N N-Chanel MOSFET?

    41. Hola voldria saber si 12 v. de poténcia es sinonim d’ alguna altre mesura de poténcia com per ejemple en watios.

    42. can I use 12V to 220V Voltage Converter Circuit as an inverter circuit.if not do help me with an inverter ciruit that would power 2 air condition. Thanks

    43. that is a very important site, thank you very much

    44. i need to know is it possible to transform 12v dc current to 220v ac and getting an output of 3000 watts using some kind of transformer of diodes

      • To run this 3000watt inverter from 12 volt you will need a 12 volt supply giving 255 amperes! THAT IS A STARTER MOTOR TURNING A DIESEL 6 CYLINDER ENGINE!! Be realistic you must allow for losses ……

    45. i want this project with circuit idea

    46. hello cai i use transitor D1047 instead of bd699 thx in advance w8ing 4 u reply

    47. simple circuit to build,,very great schematic…. keep it up

    48. sir i am doing a miniproject in our college on this inverter please help me.
      what is meant by tr=2*10/3A tell me the transformer code.what is meant by p1.and again what is z=1.5A/T can i get this outside specially or we have to make it

    49. Dear Mr D., This CD4047, can I with changed componets replace the 4047 with a 555 timerusing pin 3 output open and close gated mosfets? or is it to slow of a Ic?

    50. Cont- Mr. D. I quess what I am asking is the 555 chip capable of producing 50-60Hz signaling to the control mosfets?

    51. What means the Tr= 2*10v/3amp
      Transformer of 3 amp I understood but what about 2*10v cant understand
      It is inverter transforer or any other.
      Plz guide us

    52. 1.how many watt output ???
      2.is it possible to transform 12v dc current to 220v ac and getting an output of 3000 watts using some kind of transformer of diodes???

      Best Regards:)

    53. can we convert 2.5dc into 110ac or 220ac ?plz help me bcz i cant understand that??????

    54. Assalam Alekum!
      nice work sir can you please tell me the name of the transformer mean how i can bye this from my local shop with pakistani name>>>..?thanks

    55. sir can i use 12 0 12 /220 5amp transformer please tell….

    56. hi, its a simply circuit yet looks efficient, one thing i want to tkow is the transformer’s specs. iwant to wind my onw transformer with an output of thousand of volts with 2 to 5amps. can you guys help me? thank you very much.

    57. Please help me i dont find ic4047 can i use another ic help please…….

    58. hi sir i want 12v automatic battery charger circuit please help me

    59. I need to know which is the inductor I will use and how many truns and how much henry I need this as impossible as you can to reply me thank you.

    60. sir, plz tell me equialent mosfet/ transistor of BD699 . I can not get it.Can i used IRFZ44, or IRF540, transistor 2N3055: Plz, Tell me Thanks, you sir

    61. any replacement for cmos ic 4070

    62. sir i know transformer will nor for dc
      because dc does not varying flux.can u explain how it works please sir from
      enginneeing student reply immediately
      i eagerly waiting for u r reply.

    63. sorry i made spelling mistake,transformer will not work for dc
      how it works

    64. what is the wattage of this inverter? and secondly how to increase wattage?

    65. what is the current rating of this transformer?

    66. very nice I will try

    67. What is the replacement for BD699?

    68. nice method

    69. I can’t see anywhere a clear statement of the max continuous output. Surely this is a strange oversight.
      I note also the absence of a pilot light & fuse, easily added I know, but why post a circuit without?
      You offer to build for $18 but say the component cost might be $50; I guess that’s a clear statement of your intent.

    70. sir plese this circket circuit diagram or brieg ditels send me this e mail address


    71. Adeleke Zakariyau says: on February 11, 2012 at 9:18 pm

      I came across this site lately, what i want to know is, how many watt of the inverter output. I in need of 2000watt.

    72. What is difference between Zener & MOV

    73. What is advantage of this will comparing with chopers

    74. Hi,
      Can you plz tell me how to get a simulation result of this inverter circuit using CD4047?Is there any simulator in which CD4047 can be simulated?

    75. Jayakarthigeyan P says: on February 19, 2012 at 5:06 pm

      Where can I get the internal circuit of IC 4047… Please give me a link or post it here… I got the pin configuration but I want to know the internal circuit…

      • m.kasthuri rangan says: on November 28, 2012 at 1:48 pm

        zener used for breakdown voltage if you want to clampdown particular voltage u can do that where as mov is used once high voltage occurs at particular say mov for 220v more than that occurs it shorts and there will be know power beyond

    76. Dear sir,

      I need Transformer details and circuit diagrams, please do the needful
      Best regards


    77. vivek soni,harsh patel,sunil rajput, rohit sharma says: on February 29, 2012 at 10:36 am

      there are no BD 699 transistor in my state and u r using outdated parts…

      so be helpful enough to anyone….

      • Rutam Sable says: on March 20, 2012 at 10:59 am

        You can use equivalent transistors. Even i made the circuit with one BD699 and the other with the equivalent one and it worked as expected.

      • RK Murthy Challa says: on June 12, 2012 at 9:53 am

        Dear friends,

        I have seen your comment today. But I don’t know you are succeeded in procurement of transistor.
        If so plz drop a comment again. shall tell you
        Than Q

    78. I have made the circuit and it works beautifully. One thing everybody are mistaking, the z=1.5A/T is not a fuse, it is an impedance coil.

      • RK Murthy Challa says: on August 11, 2012 at 4:56 pm

        It is a fuse for safty. If any means if the Transistors draws excess of current, it may blow up to avoid damage.

    79. To get the transistor BD699 replacement, go to Google search, type “BD699 equivalent, or BD699 replacement”, avoid datasheet, Doc files and PDF files if you are using Java Phone

    80. please, I need the component listing for a 12VDC to 220VAC converter

    81. BD699 transistor equivalent are ‘MJ3055, 2N3055

    82. i think a 12 v transforner also can be used insted of 10v by adding 3 nos 6amp diodes in series with d fuse

      • mr. biju, first thing you are mistaking is that the 1.5A/T is not a fuse, but an impedance coil. and yes you can use 12V transformer and it will surely run as you have used a battery of the same voltage.
        and let me tell you, that i have also used a 12V transformer and yes my circuit has worked very well. i had also mistook the impedance coil with fuse before. but later i understood…

      • electron_revolution says: on October 8, 2012 at 3:54 pm

        555 timer IC is much cheaper :-)

      • thank u

    83. Nice and simple…..

    84. Anandhan Varatharajan says: on April 9, 2012 at 8:59 pm

      how much amps we get in out put

    85. Anandhan Varatharajan says: on April 9, 2012 at 9:00 pm

      i need input 6v into 230 v output with 3Amps

    86. Sir how can we increase its output watt means power.

      • RK Murthy Challa says: on June 12, 2012 at 9:47 am

        Dear Salman Bacha,

        The Power Can be increased by;
        1. Using 2 more output transistor of same specification
        2. Use of transformer with increased Current rating

    87. What means the Tr= 2*10v/3amp
      Transformer of 3 amp I understood but what about 2*10v cant understand
      It is inverter transforer or any other.
      Plz guide us

    88. 2 * 10V means the input of the transformer has two tapings like that of an auto-transformer with one neutral in between them. so there are two 10V inputs to the transformer.

    89. K.G.unnikrishnan says: on April 23, 2012 at 3:07 pm

      thank you sir,please help me to make 100-120 va inverter with automatic cut off&charging,sir whether it possible that converting&charging doing by single transformer?or use capcitor for charging?please give complete details

    90. Sir,
      I am thinking to use solar panel instead of batter, Does it works ?

      Please can you share trasnformer detasil as well.



      • RK Murthy Challa says: on June 8, 2012 at 7:59 pm

        Dear friend,

        Your idea use of a solar panel for the 12V to 220V is good and naturally. When you have such idea, you must have a concept on the Solar panel, i.e., How it works, When it works. means it delivers its maximum Current when the sun is in full illumination. 2. It is not source of Static energy like a battery. 3. A converter/ Inverter of above type always requires a study DC current, to give a study VA output, i.e., your load applied to the converter. So now you can easily imagine the use of solar panel.

        Coming to the Transformer details, a transformer with 12-0-12/5A=6Amp rating is needed for the above circuit and the transistor BD699

        Than Q

    91. The domonation corp. Of domoland® says: on June 2, 2012 at 5:38 am


      Puedo sustituir los darlington por transistores de potencia en paralelo? Supongamos (usar varios 2N3055 en paralelo)


    92. sir weather it work please tell me

      • RK Murthy Challa says: on June 12, 2012 at 8:49 am

        Dear Vishnu,

        It works definitely. As I have done the same and using for the Laptop of my Son during power failures for more back periods
        Try it very simple.

    93. what is 470 before t1 and t2 weather it is resistor

    94. i dont get bd699 transistor instead of that what i have to use

    95. send me ur mail address i face a small problem its output is only 7v……..

      i have seen in video u have used diodes and capacitors but i has used connection as per the circuit diagram …it s output is 7v.only…..please help me………..

    96. i don’t get the transformer 2*10v, i have a Transformer of 2*12v /3amp,I can use it…

      n what transistor can i use in the place of BD699.

    97. can it possible without transforme ,, if so ,,so tell me boss



    99. Adelusi Tosin says: on July 14, 2012 at 1:29 pm

      i don’t really understand what you mean by, “z =1.5 A/T” moreso, can 100nf can be subtitude? if so, what are the equivalet subtitution. With kind regards.

    100. The problem am having with this circuit is the IC, i replace the transistor with LEDs, instead the LEDs just on instead of blinking. The conclusion is that, the output voltage is 40v, i need your help

    101. NILESH KAPURIYA says: on August 10, 2012 at 10:00 am

      Dear sir,
      please tell me about total cost of this project. i want to make it as my final year diploma project

    102. RK Murthy Challa says: on August 10, 2012 at 2:38 pm

      OK. Well Mr. Nilesh. The cost of components varies from one to another location. I do not know which state/district you belongs.

      Any how, the Transformer ( 220V-12V/6Amps) may cost much more i.e., INR/100-200/- and the remaining will be up to Rs.100/- and a total of less or more Rs.300/- will be incurred against this project.

    103. the transformer u have used is center tapped. can a normal transformer can be used instead???

    104. RK Murthy Challa says: on August 11, 2012 at 5:01 pm

      Yes. Otherwise the out put will be half. Instead of 60VA, you will get 30VA and the load to be connected should be in the range of 30VA to work properly.

    105. .,Sir ,,,’hi will advise the post of dis circuits to replace cd4047 to sg3524 becoz cd4047 is not suitable for standard inverter is a low astable multivator …..d best Ics for inverter project is Sg3524….and some descrete component… Dis chip hav 16pin while pin16 have constant 5volt ..while pin10 is shutdown,and pin6 and pin7 is frquency calculation, hi will post 1000watt inverter circuits using sg3524 which u can ever found dis circuits in any website hi a can asure of dis….absolutely ………speaking..aslo post inverter low battery shutdown circuits dat can can b connect to pin10 of dis chip also changeover circuits,,more details add me at facebook john jay,and eskimi john1904 …u can meet at electroshematics.com ..capacitor

    106. ,Sir ,,,’hi will advise the post of dis circuits to replace cd4047 to sg3524 becoz cd4047 is not suitable for standard inverter is a low astable multivator …..d best Ics for inverter project is Sg3524….and some descrete component… Dis chip hav 16pin while pin16 have constant 5volt ..while pin10 is shutdown,and pin6 and pin7 is frquency calculation, hi will post 1000watt inverter circuits using sg3524 which u can ever found dis circuits in any website hi a can asure of dis….absolutely ………speaking..aslo post inverter low battery shutdown circuits dat can can b connect to pin10 of dis chip also changeover circuits,,more details add me at gta3vcsr@gmail.com

    107. sir/madam, iam from 2nd ece department .noew iam doing my mini project based on the circuit from the internet.my mini projects is solar based multipurpose charger,through this charger iam going to charge 3 batteries (i.e.leadacid battery,nicd battery, and mobile battery)the total voltage iam getting from the panel is 22v to charge this batteries,instead of that can i store that charge in some other other batteries ?and also if i want to convert that into 230v is that is possible?plsss tell me the result as soon as possible.

    108. nice for giving the holy information….i expect that u give wholesole information about ele…thanx..
      bt give me more knowledge about the dc to ac convertor

    109. The converter can’t charge battery due to lack of rectification, and battery sensing level. It’s advisible to build a battery monitor and battery charge

    110. it was good!
      i need a circuit for convert 12v AC to 220v AC
      thank u

    111. Mehdi if you have 12 volts A.C. then just use a transformer in reverse

    112. can you send me the schematic diagram of a 1100 watts, 12VDC-220VAC inverter power supply? plz.. it’s for our group project… tnx a lot GOD BLESS! :)

    113. thank for these info. Please i have a question,how do i use a car battery 12V to power my refrigerator compressor(220V-240V,50Hz,65WATT,0.75A)watt kind of inverter can i use.thank you in anticipation.

    114. a refrigerator compressor has nearly always an under-oil induction motor, which is started by an auxiliary winding. This is quite normal and usually you would use a capacitor to generate the phase shift between main and auxiliary winding. But in order to save it, the refrigerators have a resistive auxiliary winding. The capacitor is replaced by a resistor, and also this is saved by making the winding partly bifilar. There is a starter relais, which switches the aux winding shortly on and very quickly off again when the motor is running. This starter relais reacts on the main winding current. During startup it is high and the simple relais activates the auxiliary phase. When the current drops, this auxiliary phase is switched off.
      That means a high current peak during startup. I have measured up to 10A on a 120W compressor. When connecting the refrigerator to the inverter (similar as above) the inverter voltage broke down, and the motor did not start. It tried again, did not succeed etc. This instability damaged the contacts of the starter relais without ever starting.
      I solved the problem by using a 600W inverter for the 120W compressor and putting a large capacitor in series with the auxiliary phase to reduce the current at equal phase shift. I think it was around 20uF MP type.
      In your case I would guess you need an inverter of about 300W and the mentioned capacitor to handle the start problem.

    115. @joribo thanks for giving a straight forward answer.you explain eloquently like a lecturer or even better than most…..if i understand you correctly all i need to get is a 20uF capacitor MP-type and a 300watt inverter…… i would give it a try

    116. …well, I wrote so much to give background info. So that you have a better start when solving the problems which will certainly come.
      Yes, i recommend to use an oversized inverter at first, then try the capacitor. It needs to be put into the auxiliary phase. Also, I recommend compensating the motor to reduce the current, and take care that there are strong freewheeling diodes in the inverter, else it cannot handle the inductive load of the compressor motor.

    117. …made a hand sketch how to connect these thingies, but how can I add a JPG to the comment?

      • @joribo, upload the sketch to imgur.com then paste the link in a comment.

      • Afreh Agyei says: on October 14, 2014 at 4:28 am

        please can I get different diagram which is transistors only and no ic in because that ic 4047 is not esey for me to get

      • you can take a very classical multivibrator
        the schematic in figure 1.
        The transistors 2N2222 or similar, probably BC547 will also work.
        Resistors R1 and R4 about 1kOhm.
        Resistors R2 and R3 estimated at 10 kOhm, capacitors to generate 50Hz output (there is a formula in the wiki further down).
        Then from the collectors of the transistors to the switching transistors BD699. These are more exotic than the 4047 but you can combine a darlington by two individual transistors. Typical combination for example 2N1613 plus 2N3055. Sorry for just writing text, right now cannot make a sketch (on work outside home).

    118. thanks, http://imgur.com/uuPLwuD
      valid for “normal ” refrigerator compressors using a resistive auxiliary phase. It is a troublesome load for an inverter.

    119. This diagram worked out for a 220v 50Hz. 20 watt motor without any load.
      Alas for my projects it didn’t work out properly, the voltage collapsed when I pulled up the frequency.
      I need a stable 220v ~ at a higher and adjustable frequency (50 to ± 200 Hz.)
      In the Capstan motor ( Papst 220v.50Hz 2.5w ) the magnetic field collapses when the voltage drops.

      So I’m working on this one now ,with thanks to http://www.circuitstoday.com and Nickk.
      Got all the parts here,want to buy the PCB from NICKK.


      I use The PWM output (0-10v DC) of the PLC to generate a resistor parallel over potmeter R1 (100K)
      with a LED shining INTO the LDR using the LDR as variable resistor depending on the light output of the LED. http://led.linear1.org/1led.wiz

      The LED/LDR are in an enclosed housing.
      this works , is tested with THIS Oscilloscope http://www.sillanumsoft.org/prod01.htm (THX Alfredo)
      REMARK :Be VERY careful with your audiocard/voltage !!

      So work goes on and on 😉 T L.

    120. the voltage needs to rise about linearily with frequency when driving a motor with variable speed.

      In the schematic according to the link above, are 3 transistors as darlington, this costs a lot of voltage drop, roughly 1.5V are lost in fully conducting state, so the transformer should have a reduced voltage winding.

      The LED-LDR will work. In 1981 ELV had an inverter where they used a small lamp and an LDR together in a closed casing and called it “effective value coupler”.
      Because the lamp lights as bright as the effective value of the voltage is, no matter if rectangular or sinusoidal.

      I have just made a 160W inverter. If someone likes to have the schematics pls mail me, will send them. The IMGUR picture platform is down.

      • I would like to see the schematic!

      • Hey Joribo,

        That’s why there is potmeter R9 on the feedback from the ‘created’ 220v ~.
        I might have to do there something similar as what I do with R9 in conjunction with potmeter R1 , we’ll see.
        That’s the beauty on this inverter, adjustment of voltage .AND. frequency.
        Nickk made an addition to it, up to 5000 wattt !!


        See also the pictures a bit lower in that page.

        I first have to build and try it out.
        If this inverter doesn’t do the job I got a circuit with pure sinus laying around as well.
        Alas , ‘Time’ :/
        Primary working on the PLC now , the software Simulation over the Ethernet and REAL-time switching are .NOT. exactly the same.

        THX for your input,
        RGDS, T L.

    121. You should remember when cascading power transistors in an invertor like this the output Q(impediance) becomes lower to the point where an almost dead short can be applied to the the output of your invertor also note that the current now controlling your invertor can make your power supply go up in smoke if the parammeters is being exceeded. Also note the Q on the primary winding should be updated as well where some guys rewind a microwave transformer where 2mm wire is being used the thickness of the wire should rise proportionally to the amount of cascaded transistors being used….

      • Hey Philip ,
        You’re fully right about the wiring sizes.
        On Instructables , the site where the circuit diagram came from , Nickk has also noted this under
        tab 7>
        You can also see it on the pictures of the transformers.

        For me that is less important ,
        I need only 2.5 watts output from the inverter
        at a steady 220 volt with a variable frequency.
        Even starting the motor will be from the standard 220v. mains and then completely taken over, when needed, with interlocked relays. (both ~ .AND. N )

    122. Hi, wonderful circuit. Will it work for 100W fan ?
      Please help.

    123. ..if the fan has an induction motor, it will run at both rectangular and rectangular-with-gaps voltage, but at reduced power. The motor should be compensated to relief the inverter from unnecessary reactive current. For example, I have operated a laundry spin-dryer.
      If the motor is a “universal motor”, which is a series-wound DC motor with commutator, the motor will run well. But if there is a phase-cut control unit for speed control, this will not work.
      If the motor has an auxiliary winding with capacitor, the capacitor size needs to be changed by test and trial. And the power is reduced.
      As a special problem, it might happen that an induction motor runs up to a partial speed and stays there and becomes hot. In this case it helps to use an LC filter (L in series and C in parallel to the motor) to round off the sharp edges of the rectangles. This will reduce the harmonics content.
      Refrigerator motors are something special and very difficult to operate on inverters.

    124. Thank you joribo for your answer. Actually I just want to know that ceiling fan 220V (A.C) 100W will work on it or not ??

    125. yes, as above, you need to tell us what motor is inside. If it is like in India, it is an induction motor with rather bad power factor, needs compensation. I can try to give support by mail, have experimented a lot with such things.
      br George (georg.bohmeke@futurepower.fi)

    126. Yes it is just like in India, it has a capacitor in it which has value of 4.3uF, 250V.

    127. ok then it is an auxiliary phase induction motor, will run on the inverter but with reduced power, higher losses and needs two small modifications.
      One is to compensate the motor by adding a compensation capacitor in parallel to the whole motor (basically to the secondary side of the transformer), and the second is to optimize the capacitor which is now 4.3uF. It might need to be enlarged a bit. I would start with the compensation capacitor and try to get best possible operation with least current. Rough estimate for starting: 10uF.
      The 4.3 uF is the phase shifting capacitor, that may be better with 5 to 7, but I can just guess as I have not seen the motor. Aim of this capacitor is a 90 degree phase shift in the winding currents between main and auxiliary winding. You can optimize this quickly if you have a 2-channel oscilloscope. Else just need some trial and error.

    128. Thank you Joribo, secondary side of the transformer is which one! 12v or 220v ??, because in this circuit stepdown transformer is used in revers.

      And also what would be the value of this compensation capacitor ?

    129. It belongs to the 230V side (in some countries 220V). The reason for this compensation capacitor is to neutralize the reactive current of the motor. If this is done correctly, the inverter will supply only the needed power to the motor and not additionally a lot of reactive power, circulating around. This circulating around of reactive current happens through the transformer and the freewheeling diodes on the 12V side into the battery and back again. Although the reactive power is no real power which is consumed, it makes real losses when circulating, so we try to avoid it. I would roughly guess as a starter value for experiments that 10uF might be ok. (pls try some 5 to 20uF)

    130. Thanks a lot joribo! really appreciate your help.

      Thank you again.

      Best Regards.

    131. This is an old technology for amateur!!!

    132. Amature,professional regardless the situation it still is a nice little circuit to experiment on most of the ppl on this site is not professionals nor do they have doctorates in electronics thus leave the kids let they play with their electronics.

      “Men grow old so is technology”

    133. Yes, true (old technics)
      But this is why I like this forum.
      There are many other electronics websites, and often on high level. But we need something to help the beginners to climb up the ladder. And we need explanations, because the electronic device has few value. The value is KNOWING HOW IT WORKS and there it is good to start with simple things.
      Next step would be a sine-inverter. I have tried some circuits at home but I am not yet fully safisfied. When it runs well, will put it here (sorry, some delay due to my work).

    134. hello….
      plzz tell me how to convert 150v(8.3amp)dc to 230vac…plzz rp fast.

    135. No simple solutions on this one –there are two means:

      1. A 1:2 115 to 230VAC 60HZ step-up transformer driven by a bridge inverter consisting of (4) high voltage MOSFETS.

      2. A 1:2 boost converter to generate 325VDC, and a 230V bridge inverter using high voltage MOSFETs.

      High voltage bridge inverters work –I have done this for AC motor controls, but they are very unforgiving if not EVERYTHING is done properly –not recommended for the casual experimenter.

      • Good info from joribo

        I forgot to mention IGBT power devices –they are preferred over MOSFETs as high voltage switches. Big issue is how to drive the gates –International Rectifier has nice half-bridge drivers. And a microcontroller is required to generate the “6 step” or PWM waveform and handle voltage feedback & current overload issues.

        Also, this is considerable power involved –1.25kW!

      • pepesoup says: on July 3, 2015 at 5:20 pm

        I will like to know the quantity of MOSFETs that will be needed to drive a particular tranformer of 12-0-12 volt DC to 230 volt AC. iS There any special calculation for this?
        Thanks and looking forward to hearing from you.

      • joribo says: on July 3, 2015 at 8:50 pm

        Author: pepesoup
        I will like to know the quantity of MOSFETs that will be needed to drive a particular tranformer of 12-0-12 volt DC to 230 volt AC. iS There any special calculation for this?

        Joribo: There is a hard limit and a soft compromise. The hard limit is simply that the MOSFETS need to carry the current without overheating. The current of the inverter is known by its basic data. The data sheet of the MOSFET tells us the rated current. But this is given for good cooling conditions, MOSFET on a thick& fat aluminum cooling fin.

        The second soft limit is the voltage drop. In case of an inverter it is important to have high efficiency, as the energy is often from solar and is earned with high cost. So we dont want to waste it. On-resistance multiplied with the current is the voltage drop, and this should be below 0.3V with a 12V inverter. So the conductive losses are around 2.5%. But this needs more MOSFETS and costs more money. This is why its a compromise between cost and efficiency. The BUZ11 is old-fashioned, cheap and easy to get, has 30-40mOhm. But other ones have lower ON-resistance, for example the IRLB-3034-PBF has just 1.7 mOhms. It is 6 times more expensive but has 17 times lower resistance. Would be reasonable if you can get it. I usually calculate cost per resistance as a kind of decision number.

    136. …two reasonable ways:

      1. Like the above mentioned 12V to 230V inverter, but using high-voltage MOSFET’s as switching elements. The transformer should be an autotransformer (if you dont really need the galvanic separation), so there are two windings with 150V and on top of this winding the rest to make 230V. The transformer operates at 50 Hz and has a metal sheet core. Preferred is ring core or U-core.

      2. Like most of the far-east inverters. The 150V is switched with ca 25 to 40 kHz to a transformer with ferrite core. The output voltage is rectified with fast diodes. A DC smoothing capacitor makes smooth DC. Detail: dont use electrolytic but foil capacitors. Now you have DC which shall have a voltage level of the output peak voltage. Now comes an H-bridge (four MOSFETS) which alternatively switch over cross with a zero time in between. At the output you get a rectangle with gaps, same as with proposal -1.

      1 is simple and needs more space, is heavier.
      2 is more compact, lighter, tricky, needs some filters against EMC, and is sensitive to capacitive loads.

      Both 1 and 2 give “modified sine” which is just a rectangular wave with gaps, providing both correct effective and peak voltage values. If you need pure sinusoidal output, its more complicated. Recommended reading (german):
      Franz-Peter Zantis: SCHALTNETZTEILE, published by ELEKTOR (= ELEKTUUR), page 173 ff.
      FUNKSCHAU Nr. 9 -1991 they published a four page article with schematics and PCB for a small sine inverter, from which the power part could of course be modified or enlarged.

    137. how can we use power supplies for water purification ?

    138. what can be done with dirty water water:
      1. normal filtering (no energy besides pumps)

      2. active carbon filter (no energy besides pumps)

      3. desinfection, alternatively or in combination
      3.1 generating Ozone with a high-voltage power supply and mixing this into the water
      3.2 passing the water slowly through a quartz glass tube inside of a transfer mirror which has elliptic cross-section, in one focal point is a strong UV-lamp and in the other focal point is the water tube.
      3.3 mixing up desinfecting substances into the water, usually based on chlorine.

      Suitable power supplies can do this job, but the above mentioned 12V / 230V inverters are not especially designed for just this purpose.

    139. What voltage is condensatoru.

    140. Which one?
      the smoothing capacitors which are in parallel to the supply (usually battery) should have a certain safety in voltage because in case of inductive load the freewheeling diodes push some current back into them with 2 x operating frequency. This gives additional stress. An electrolytic capacitor does not like strong charge/discharge. So, for 12 V supply you can select 16V or 25V rated capacitors (standard values) , and in my private opinion I would use 25V just for safety.

      A capacitor on the secondary 230V side to supress voltage spikes should be rated at least 400V better 630. This is a foil capacitor for example type MKP.

      The capacitors for running a motor on the inverter will usually be MP (Metal-Paper)types and should be rated around 400V. For getting the right uF values please browse for STEINMETZ-circuit or HILGENBERG-circuit.

    141. Can this circuit be used to control the speed of a synchronous motor? What will be the transformer specs for a 110volt synch motor?.

      Thank you

    142. yes, you can basically drive a motor with this inverter. If the motor is 3-phase it has to be switched into a single-phase connection according to STEINMETZ, for startup possibly according to HILGENBERG. Or using the STEINMETZ connection with two capacitors, one for continuous operation and one in addition, parallel, for start.
      And you should add one more capacitor in parallel to the output transformer winding with the connected motor, in order to keep the reactive current as low as possible. The inverter transfers both active and reactive power to the motor, so the motor shall be compensated as well as possible.

      The transformer:
      If using full square wave and 12 V supply it would have 2x 12 / 1 x 110V. There should be a bit of additional winding to compensate for losses and transformer voltage drop due to leakage flux. For example 110V plus 10V plus 10V so you can connect the best one.
      Using the method of a half-time pulse (5msec pulse plus 5 msec pause plus 5 msec negative pulse plus 5 msec pause) the transformer is reasonable with 2 x 12 / 1 x 168V plus some additional windings for compensating losses.
      This will very probably work, I have operated a laundry spin dryer this way but on an induction motor. If you have a synchronous motor, it needs possibly a starting aid. This can be an additional short-circuited winding around the poles (damper winding). With good luck, it starts as it is.
      For example, a bicycle dynamo runs on AC as a small motor although it is synchronous.

    143. Please can you e-mail me the schematic design for the DC to AC Converter 12v to 220V. Thank you in advance.

    144. http://www.electroschematics.com/9176/12v-dc-to-220v-ac-inverter/

      there is the one which has gaps between the pulses,
      some others (pls look under POWER SUPPLY) are directly square wave.
      It depends on your consumer, which one is preferable.

      Best is pure sine wave, I have a schematic from the journal FUNKSCHAU in paper mode, author is Franz-Peter Zantis, from the 1980ties. I have built it but was not yet satisfied and need to redesign it. Is under work, hopefully ready in a few months.
      If you like this schematic i can give it privately to you (I have no legal right to put it into the internet)

    145. I need a solar panel of an AC output with about 1500w to 3000w and of 220v. What is the price range. Thank u

    146. http://www.wholesalesolar.com/gridtie.html#SolarSkyAstronergy

      the above link as an example, you would need about 5200 US-Dollar for 3000W. This would be without battery, and with a German-made grid-tied inverter. In case of a stand-alone system you need more money, as the battery comes in addition. If you can get Chinese components directly, the price level would be lower, maybe roughly only 75%.

    147. Please help. We got circuit made but when we wire there is no power coming out. Powertransistors getting hot fuse blow but no power out.not even power a globe. I’m using the transformer 220v 10-0-10 60w centre tap.

    148. which one, the simple rectangular wave with the CD4047 or similar?
      1. to check the transformer without inverter at grid voltage, are the 2 x 10V comming out in correct phase? So, two times 10V and between the outer lines 20V?
      2. To check without the basis connection to the transistors, there must be no current, else the transistors are defect. In case of MOSFETS you need to connect Gate to Source, they might pick up any kind of static voltage.
      3. Look at the output signal which feeds the basis (or gate) with an oscilloscope. You can make a simple improvisation by feeding this voltage into a LED and put it on a short stick and swing with your fingers. You see a chain of small light dots. If no dots but a continuous light, then there is a bug in the impulse generating circuit.
      Checking this, you may use a trick. The frequency generating parts can be replaced just for test by a larger capacitor or larger resistor to make about 5 to 10 Hz instead of 50Hz. This frequency you can see with a LED. If the oscillator makes the LED flicker correctly, you need to replace the original values back before connecting the transformer, but at least the oscillator seems to work.

    149. sir, I want dc to ac converter so Pl. help me

    150. ..you would need to tell us more about the driven device, your voltage source, the type and power of inverter etc. Then we could give you some hints what is best. You find several schematics here in the forum, generating square wave or square with gaps (this is called modified sine by some manufacturers, although this is not really correct).

    151. Bom in detail sir. What are the values. Tried many times what now

    152. ..all values are given in the schematic. The schematic is correct, my inverter works fine. Please follow the above given hints from 1 August.
      Somewhere is a wiring problem or defect component. Have you especially checked that the transformer windings are in correct phase? If you operate it on grid voltage with disconnected transistors you should measure 18V between the connection of the collectors / drains and 9 V between these points to the “plus” wire. If this voltage is not 18V (2 x 9V) but somwhere around zero, one of the two transformer windings has to be inverted.

    153. @nico

      Well, I can understand that it is very frustrating if something does not work. Especially when you dont have an oscilloscope at hand.
      But please believe me, that the schematic is correct, as my inverter works well.
      There is any kind of wrong wiring, or a component is defect. You should check the project from the transformer backwards. So, first to ensure that the windings are connected to make 18V as a whole, with the center tap being connected to the PLUS of the battery. Then, check the driving transistors individually. For example, just on the workbench, using a bulb as a load. Then, check the pulse generating circuit by enlarging the frequency-determining capacitor by a factor of 20. You should see the pulse-generating outputs blink, when you connect LED’s for test (dont yet connect the driving transistors). If they blink correctly, revert the capacitor back to the correct value. You will find some defect parts or wrong wiring.
      A simple oscilloscope is an old plastic ruler with a LED attached to the end. You press it on the desk and let it vibrate. Or swing it through the air. A pulse frequency appears as a chain of small light dots. DC makes just a strip of light.

    154. Hi sir.

      If I use a 12.0.12 tranformer what do I need to change

    155. ..if you use 12V battery voltage and the transformer has 12-0-12 to 230V then you need to use a full rectangular wave shape as mentioned above with the 4047. The output has then an effective voltage of nearly 230V.
      The peak voltage is less.

      If you use the schematic with the rectangles and gaps in between (the one which came from me, or similar ones from other sources), then you get far less voltage. I guess it is around 170V. You can compensate this by adding windings to the 230V side to get an effective 230V again.

      • Joribo Hi! I made a similar inverter for a friend of mine some years ago I only used loose transistors and the transformer. I tried various configurations and the only transformer that gave a reasonable output was 7 0 7 volt with a 60 watt lamp the voltage dropped to 220 volts and shot up to 265 volts no load. I used a 100 watt transformer. With 12 volts and a 12 0 12 winding the output was 230 volts no load but dropped as soon as any load was connected I only had a 10 watt lamp and it dropped a lot so use a big transformer and the heaviest Darlingtons that you can get or afford.

      • yes, I believe these data. The darlingtons are imho not optimum for high power, as they eat up between 1 and 2 V depending on the current. So they make not only high losses but also make the voltage soft, large variations between idling and full load. One solution is using a lot of power-FET’s in parallel (BUZ11 or IRFZ44 or so). So I did with my posting of an inverter (the one which has the gaps).
        An other old-fashioned solution is using a driving transformer for conventional 2N3055. These little transformers were wound 12 to 3 V and the 3V winding was put directly on Base-Emitter. It pulled up the BE-voltage to over 1 V in the conducting phase, and the negative voltage later assisted in fast switching off. The CE-voltage under full current was just 0,3V.
        On page 3 of the data sheet, the lots of diagrams, left row middle diagram. If fully saturated and loaded with 4A/transistor, we can get really low conductive losses. Usually you have to pay this with high base current losses, but the transformer reduced them by a factor of 3/12. This also worked well, I made this in 1986. Today I would recommend power Mosfets, if available, they are imho best.

    156. Hi sir. Could you please send a image of the pcb. My am will not open it.

    157. Hi sir. Please give me the top and bottom of the board. Image please.

    158. sorry, I did not post this one, my post was the inverter with the gaps between the pulses, and there was no PCBoard provided. Pls contact the admin, maybe he can help you(?)

    159. I would like to drive a 6 Watt/230VAC Resistive load, My queries are:-
      1. Which transistors to use
      2. Transformer rating

      If the same load to be run continuously for 10 hrs what will be the 12v battery mAH be? ( I want to use a small 12V battery pack)
      If you have chosen the mAH of the battery Can you publish the suitable recharging circuit?

      Thank you

    160. 1. Transistors. The BD699 would do, but they are rare. A rather popular 2N4923 would do, but it needs a base current of some 40mA to deliver the current. This would be a resistor of 270 or 330 Ohm instead of the 470 Ohm from the IC to the transistors. The IC might be overloaded. In this case you can add a BC547 to each 2N4923 to generate your own built-up darlington and the resistor may be 1 kOhm.

      2. Transformer is best 2 x 11V to 230V in anticipation of 1V of losses at the transistors. This is not standard, you get only 2 x 12 V. If you add windings on the secondary side to come to 2 x 12 / 1 x 251V then everything is ok again. Rated size about 10W is recommended. You need to buy a transformer which you can open and add turns.

      3. If the efficiency is around 70% you take 6W/0,7= 8,6W on the 12V-side. After 10 h the energy consumption is 86Wh and in case of a 12V battery it is 7,2Ah. This is typically a motorcycle battery. You need to apply a safety factor on this value because few batteries deliver full capacity, and the voltage might go down to an unusably low value when the battery is exhausted. So somewhere 10-12Ah might be a good choice. These small batteries are usually “dry” ones.

      4. Charger, please look at the schematics which are already here in the forum, you might find a lead-gel charger (dry battery). The difference to a liquid-acid charger is the reduced charge stop voltage and reduced buffer voltage. Else you can charge normally with constant current of C/10 over 14 hours or to 14,5V, then buffer to 13,6V. C/10 means, for example, if the battery has 7 Ah then you charge it with 0,7A.
      NiCd and NiMH have to be charged differently.
      Li-Ion and Li-Poly and Li-Fe-Phosphit also need special chargers (but probably you don’t use such expensive ones).

    161. Sir Joribo

      Thank you very much for the answer.

      Warm Regards

    162. Hi Sir.

      What resistance would be required to achieve 50 Hz. I am using transistor bcx 53b and have 230v ac, 12.0.12 transformer.

      This is working but can’t get to the frequency.

      Thanking you.

    163. hello, cannot test it because I am just working far away from my home, but the above mentioned potentiometer should make it possible to generate 50 Hz. If you have no oscilloscope there are two tricks to adjust to 50 Hz.
      Trick 1: Put a normal transformer on the desk and your inverter transformer beneath. Both hum and the desk vibrates slightly. Then trim to zero beat frequency (the interference, difference). You can hear it when you listen carefully and there is few noise from outside.
      Trick 2: You need a separate transformer 24V. Connect a small bulb, possibly with resistor, made for about 48V to one collector and the external transformer, and the other connection of the external transformer to the other collector. Then trim for very slow flickering of the bulb.


    165. that is a very important site . thank you very much
      any other IC inspite 4047 and BD699 transistor, plz inform….

    166. hi electroschematics.this is my circuit for you.but itisnt doing well.i need for help.
      for converter 12dc to 12ac.do i need for indocture????????????

      • this is a very classical boost converter. The inductivity has to be designed for the power and for the frequency.The frequency is a compromise between switching losses of the FET and iron losses of the core of the inductivity.
        Suggestion to do it like this: At first determine the transferred power. Only the added power (added voltage level) is relevant for the choke, as the voltage from this choke is put on top of the power supply voltage. Then look in a diagram roughly what ferrite volume you need. Select a suitable core. Look what number of windings and copper wire fit inside. Take so much windings that the choke (inductor, inductivity) is not saturated during the longest expected pulse. Then check again if the copper wire cross section is enough to bear the current. If not, next larger size of ferrite core.
        They are usually good for 20-40kHz and B= 0,1 to 0,3 T of induction.
        Your converter makes 12V DC to some higher voltage DC, for example you can reach 15-20V DC with this circuit. It does not make AC. If you want to convert 12VDC to 12VAC it needs a different schematic. If you want to convert 12VDC to more than 24V DC then you should not use a boost converter but a transformer-based forward converter (besides if you need only some milliwatts and the effort is not justified)

    167. Ramsanjeevan verma says: on February 6, 2015 at 11:17 am

      Hi! How to make a circuit without ic and which should not more complicated to draw for making

    168. for a boost-converter or buck-converter (converting DC to higher or lower DC) you can use a classical multivibrator for generating the pulses. As the pulse width needs to be adjusted, it needs a potentiometer across the basis resistors. The appended schematic ( I hope it works, else I can put it into IMGUR) shows a buck converter, but the pulse generating part can be used also for a boost converter. The potentiometer decides the pulse/pause-ratio and the C and R at the transistor basis determine the frequency. If any kind of closed loop control is added, you need to influence the circuit in the same way as if you would turn the knob on the potentiometer manually.

    169. How will an inverter gives output when we give input? And how it’s increases the frequency?
      Pls send to my mail pls
      Thank you

    170. In case of the very first schematic in this thread, with the 4047, the capacitor 100nF and the variable resistor 220 kOhm determine the frequency, which would be usually 50 or 60 Hz. The transistors switch the 12 V from the battery alternatively to the 10V windings and at the transformer output you get a rectangular voltage of ca 230V. The loss of ca 2V on the transistors is compensated by using a 10V winding, fed by a 12V battery.
      You can increase the frequency up to ca 400 Hz with this circuit, which brings only benefits if you want to make a very small induction motor run fast, or want to rectify the output voltage. Airplanes have internally 400Hz-grids. Unless you rewind the transformer, the power does not increase when increasing the frequency.

      When you look at the schematic of bahman from 24 january, this is the power part of a boost converter. The FET is activated and current flows through the inductivity. Then the FET is switched off and the stored energy is set free as voltage pulse, adding up to the supply voltage. The voltage spike is pushed through D1 into C2. How high the voltage rises is depending on the load. Without load it runs away and might damage your capacitor C2 or the diode. Usually the inductivity would be wound on a ferrite core and the FET gets impulses between 20 and 40 kHz, this is optimized according to the ferrite core and the FET.
      When you look at my hand-sketched schematic, there is a classical multivibrator made with 2 transistors. The potentiometer is to adjust the pulse-pause-ratio. The frequency is fixed. The pulses are given to the FET. When it is conducting, the motor gets current and the inductivity is charged. When it is switched off, the stored energy flows over the freewheeling diode and the motor in the same direction. By giving short impulses the motor runs slowly and with long pulses fast. The motor is a DC motor from an old dentist drill. But I use it for driving a jigsaw. The principle of this schematic is called a buck-converter.
      The frequency has been selected to fit to the existing inductivities, especially the core material. Ferrite cores are typically operated on 20-40kHz, with rising tendency over the years. Sheet iron cores are used up to ca. 400Hz.
      Only the very first schematic (that with the CD4047) gives you AC, the other two ones output DC. The boost converter adds up voltage, the buck converter reduces the voltage. In both DC converting circuits the switching frequency is smoothed out by capacitors and you don’t see much of it on the output. You may browse the net for “converter, buck, boost, buck-boost, AC/AC-converter” etc, good explanations are usually also in Wikipedia or in the free material of high schools.

    171. can we step up 230 ac volt to high dc volt and how much can we step up voltage ??

    172. 230V-AC to high DC, three ways. Which one is optimum depends on your application.

      Method-1: Rectify the AC-230 to ca 320V DC, then chop this voltage and give it on the primary winding of a ferrite core transformer. Frequency typically 20-40 kHz. If you need high voltage and current, the forward-converter is best. if you need a very soft high voltage (for example for testing) the flyback converter is best. The high voltage is rectified with special fast diodes. Output with special transformer shapes up to ca 30 kV.

      Method-2: First step up using a transformer, then rectify. There are transformers for the ignition of oil /gas heaters, they output around 3 kV. Also some Neon tubes (the long ones in shape of letters on top of a
      building) use high-voltage transformers. The rectifying diodes can be slow type, as we have just 50 Hz. Output is around 3-5kV at high current (dangerous).

      Method-3 Cockroft-Walton rectifier cascade, in Europe called Greinacher-cascade. lots of diodes and capacitors, goes from 230V -AC without transformer to about 10 kV -DC but has high internal resistance. Often used for ionisators to generate Ozone. High efficiency.

    173. Hi how i can test battery ups thx

    174. is it 230V input, battery, inverter 230V output? Some UPS have a battery for the full DC circuit voltage. These have all problems with symmetry and charge instability. Need balancers over each battery unit. You would need to tell more details to give some assistance

    175. this 12v to 220v converter can charge the battery in reverse way

    176. can i use transformer from my computer ups

    177. @ Wilson, depends on the UPS. If the UPS uses a transformer on 50 Hz, then probably yes by rewinding. You can recognize it by being made of a metal sheet stack, size about like a fist or larger. Humming with 100 Hz (some countries 60 Hz / 120 Hz).
      If your UPS has a ferrite transformer, then it is difficult, needs a different schematic, needs rather high frequency pulses (about 20 to 50 kHz). This transformer can be recognized by being small, about the size of two matchboxes, and it is silent in operation, and the core is ferrite, a homogenous material, no sheets. Also, it has usually odd shapes. The probability is maybe 10% against 90% of having a low-frequency transformer in the UPS. Since ca 1985 the are nearly all based on ferrite transformers. They make a high voltage, which is rectified for example plus-minus 400V against ground, and this voltage is then chopped to a sine wave 230V AC 50 Hz. The same principle is used with all these cheap compact camping inverters 12V DC / 230V-AC, all made in China. “Modified sine wave” means just a rectangle with gaps.

    178. My ac transformer are 12V to 220V 150VA but it wont have the third middle (center) wire which goes to the Z = 1.5 AT. It only has 2 wires from both primary and secondary coil connectors. Where to connect this schematic’s third wire in my old transformer?

    179. two possibilities:

      1. Open the transformer, wind down the secondary and generate the middle tap connection, wind complete again, insulate and assemble. Not possible if the transformer core is welded or if the windings are vacuum impregnated with epoxi.

      2. Make a full bridge with 4 switching elements, for example two n-channel Mosfets and two p-channel Mosfets and the transformer is in the middle across the two pairs of Mosfets. Also possible with normal transistors, then PNP and NPN in combination.

      • I also have a second transformer with the same ratings if that helps.

        I believe that the 2nd option is more suited to my case, but I can’t have experience with electronics other then to change capacitors or to construct a simple circuit. Can you provide me this type of circuit you mention in your previous post with the mosfets or with transistors? I know how to make a rectifier bridge with 4 diodes but I don’t know how to make a “full bridge” with the mosfets or transistors and the wikipedia had only a general schematic. I think you mean something like the design 6 at http://www.talkingelectronics.com/projects/H-Bridge/H-Bridge-1.html but that schematic has 2 poles (positive and negative) on a motor in the center where I should have the transformer.

        I also have a third 12V to 220V 500VA transformer without the center tap and I don’t know where to make a connection in the coil which is huge in both 150VA and 500VA and it need some special machinery to unturned.

        Also is that type of square pulse current presented in this topic sufficient and well suited to power a small desktop PC or a laptop?

    180. you could make a bridge like in the link. A and B for example IRF9530 P-channel power Mosfets. C and D for example BUY11 or IRFZ44 or similar. Then comes a small problem. If you just connect the gates together, the circuit is not fully “clean”. For a very short moment both upper and lower MOSFET could be conducting, thus shortening the supply voltage. I have tried this with a low frequency and it worked anyhow. A clean solution is to control A and C with a slight delay. For example using a control voltage with a slight slope and using triggers on different voltage levels. If you allow ca 1-2 usec of safety time this should be ok.
      Alternatively you might connect two identical transformers on the primary side in series to have 2 x 12 V and on the secondary side in parallel. This generates something like a single transformer with 2 x 12 V.
      I forgot to mention that it is not enough to just MAKE a center tap but it needs rewinding WITH center tap. If you rewind. Just making a center tap gives you 2 x 6V instead of 1 x 12 V.
      For powering a desktop or laptop the rectangular wave is not good. The internal power supplies will rectify the voltage. Rectifying 220V AC gives you about 310V DC minus ca 5% voltage drop, so nearly peak voltage. But rectifying 220V rectangular wave gives you 220V DC. Too low. If you would make 320V rectangles, then the peak is correct but the effective voltage is far too high. The aim is to have both peak and effective voltage close to grid voltage. That is done using pulses with gaps in between. Often it is 50/50% impulse/pause. You find another schematic in the ELECTROSCHEMATICS where is such an inverter of 160W with adjustable pulses of ca 320V and gaps with zero voltage in between to match the effective voltage also. The cheap chinese inverters call this “modified sinus”. But that is just advertisement.
      Winding transformers is not so easy and needs special equipment, is something for electromachinery-freaks who also make motor armature winding.

    181. the instructables inverter makes a rectangular wave from the 555 and this is then possibly given as a rounded-off square wave or a near-sinusoidal voltage to the driver transistors 2N3055. So the inverter is like an amplifier in B or C mode (I cannot see this directly from the schematic, would need to simulate or test). The trick how to make sinusoidal voltage is the combination of C5 and the stray inductivity of the transformer, which need to be in resonance on 50 Hz. C5 should be a foil capacitor, it is highly stressed. I have build such an inverter around 1980 and found it to be very sensitive. If you connect an inductive load, the resonance is shifted and the voltage is no longer sinusoidal. So if you have always the same load, you can tune it and make the voltage sinusoidal. You need to vary C5 to achieve this. Or you need to compensate the load to be fully resistive by adding C’s on the 220V side. The efficiency is low, because the transistors are not in C-mode with just on/off (as far as i understand it from just looking on the schematic).

      Using your two transformers is in my opinion best. Connecting the 12V windings in series and 220V in parallel couples the transformers well enough. Problem is, that with a simple square wave you get 220V square. Rectified that stays 220V.
      Rectifying 220V-effective sinusoidal voltage makes about 300V DC. So about 80V are missing.
      A computer power supply usually rectifies the grid voltage and then chops it again with ca 30-50 kHz. But sometimes they are surprisingly insensitive to the input voltage because they have an internal control loop.
      So you could try, maybe it works. It depends on how large range of internal control is inside the computer power supply.
      Using the inverter schematic with pulses and gaps needs a transformer wound for 2 x 12V / 310V, probably you dont have such one and dont want to rewind.

    182. Comment can i prepare same circuit using any different IC if yes then plz may know thnks

      • most easy is a normal astable multivibrator using two transistors. This would not even need any IC. Important is the symmetry, both pulses to the right and left side of the transformer have to be exactly equal in length, else the transformer is magnetized with DC and the efficiency goes down. The very classic astable Multivibrator is in Wikipedia and in many more sites, certainly also somewhere here. (Sorry cannot make a hand sketch or dimensioning right now, travelling somewhere in China)

    183. please send my email any informaion related by electrical education

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