Sunday, February 12, 2012

How to Make a Simplest Inverter Circuit

This super simple design of an inverter circuit does not limit it in any way from providing a high output power and an efficiency of a good 75%. Learn how to build an inverter that will satisfy most of your power requirement at quite an affordable cost.
The article deals with the construction details of a mini inverter. Read to know how to build an inverter which can provide reasonably good power output and yet is very affordable and sleek.
There may be a huge number of inverter circuits available over the internet and electronic magazines. But these circuits are often very complicated and hi-end type of inverters. Thus we are left with no choice but just to wonder how to build an inverter that can be not only easy to build but also low cost and highly efficient in its working. Well your search for such a circuit ends here. The circuit of an inverter described here is perhaps the smallest as far its component count goes yet is powerful enough to fulfill most of your requirements.

Construction Procedure

This mini inverter circuit can be completed through the following simple steps:
Cut two sheets of aluminum of 6/4 inches each.
Bend one end of the sheet as shown in the diagram. Drill appropriate sized holes on to the bends so that it can be clamped firmly to the metal cabinet.
Also drill holes for fitting of the power transistors. The holes are 3mm in diameter, TO-3 type of package size.
Fix the transistors tightly on to the heatsinks with the help of nuts and bolts.
Connect the resistors in a cross-coupled manner directly to the leads of the transistors as per the circuit diagram.
Now join the heatsink, transistor, resistor assembly to the secondary winding of the transformer.





Fix the whole circuit assembly along with the transformer inside a sturdy, well ventilated metal enclosure.
Fit the output and input sockets, fuse holder etc. externally to the cabinet and connect them appropriately to the circuit assembly.

Parts Required for the simple inverter circuit diagram

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

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

R3, R4= 15 OHMS/ 10 WATTS WIRE WOUND

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

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

AUTOMOBILE BATTERY= 12 VOLTS/ 10AH

ALUMINUM HEATSINK= CUT AS PER THE REQUIRED SIZE.

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

How to Test it?

The testing of this mini inverter is done in the following method:
For testing purpose connect a 60 watt incandescent bulb to the output socket of the inverter.
Next, connect a fully charged 12 V automobile battery to its supply terminals.
The 60 watt bulb should immediately light up brightly, indicating that the inverter is functioning properly.
This concludes the construction and the testing of the inverter circuit.
I hope from the above discussions you must have clearly understood how to build an inverter which is not only simple to construct but also very affordable to each of you.
It can be used to power small electrical appliances like soldering iron, CFL lights, small portable fans etc. The output power will lie in the vicinity of 70 watts and is load dependent.
The efficiency of this inverter is around 75%. The unit may be connected to your vehicles battery itself when outdoors so that the trouble of carrying an extra battery is eliminated.

Circuit Description

The functioning of this mini inverter circuit is rather unique and different from the normal inverters which involve discrete oscillator stage for powering the transistors.
However here the two sections or the two arms of the circuit operate in a regenerative manner. Its very simple and may be understood through the following points:
The two halves of the circuit no matter how much they are matched will always consist a slight imbalance in the parameters surrounding them, like the resistors, Hfe, transformer winding turns etc.
Due to this, both the halves are not able to conduct together at one instant.
Assume that the upper half transistors conduct first, obviously they will be getting their biasing voltage through the lower half winding of the transformer via R2.
However the moment they saturate and conduct fully, the entire battery voltage is pulled through their collectors to the ground.
This sucks out dry any voltage through R2 to their base and they immediately stop conducting.
This gives an opportunity for the lower transistors to conduct and the cycle repeats.
The whole circuit thus starts to oscillate.
The base Emitter resistors are used to fix a particular threshold for their conduction to break, they help to fix a base biasing reference level.

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





355 comments:

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

    ReplyDelete
    Replies
    1. Hi Mohan,

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

      Regards

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

    ATTE: Ariel from Argentina

    ReplyDelete
    Replies
    1. Hi Ariel,

      You can try the circuit shown in the following link:

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

      Regards.

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

    ATTE: Ariel from Argentina.

    ReplyDelete
    Replies
    1. Hi Ariel,

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

      Regards.

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

    ReplyDelete
    Replies
    1. Hi Mohan,

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

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

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

      Regards.

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

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

      Regards.

      Delete
    2. yes there is a jump between R3 and R2....

      Delete
  6. sir please see the link i am having this type and please tell me the backup if i use 12v7.5ah battery and 3 amp transformer and is there any jump between R3,R2? http://www.meteorelectrical.com/14-watt-t5-triphosphor-linklight-c-w-lamp.html
    thanks for speedy reply

    ReplyDelete
    Replies
    1. I think it should easily work, but I'm not 100% sure, there's no harm in trying, if it doesn't work, i'll show you a different circuit.

      Delete
  7. OK thank you sir and i'll come back to u after building this circuit.

    ReplyDelete
  8. hi sir i made this circuit and it works fine but it can't drive this type of tube-light!please help

    ReplyDelete
    Replies
    1. Hi Kiran,

      Build the circuit shown in the following link, this will easily take the load of at least two 18 watt CFL lamps. I have tried this circuit it works very well.

      http://www.eleccircuit.com/12v-to-220v-inverter-180w-by-2n3055/

      Regards.

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

    ReplyDelete
    Replies
    1. You may add a 0.22/400V capacitor at the output of the transformer for controlling the excess power, the tube will not burn in this way...

      Delete
  10. sir can u please tell me where are jumps in this circuit given below.please see the link given here.please help me because i am building traffic lights project. http://www.elecircuit.com/digital/TRAFFIC_LIGHTS_Circuit_1835.html#goodfb114

    ReplyDelete
    Replies
    1. The crossing lines which are shown as broken are the jumping wires....

      Delete
    2. Also pin#3 of the right 555 should not touch pin#4 and the 220R resistor.

      And pin#8 of right 555 should not touch the 470R resistor.

      Delete
  11. sir i have some more doubts. Whether 47k resistor should touch 220r resistor and whether pin#8 should touch 220r resistor at the right side.

    ReplyDelete
  12. hi sir when someone passes by i mean when someone breaks the rays the alarm is activated what is this circuit called as?

    ReplyDelete
  13. Hi Kiran,

    It's called motion detector, you may refer the following circuit:

    http://homemadecircuitsandschematics.blogspot.in/2012/04/make-this-simple-motion-detectorsensor.html

    Regards.

    ReplyDelete
  14. can i use 10AMP 12-0-12 volt transformer here.....

    ReplyDelete
  15. Swagatam I wanna learn how this circuit works...each and every component working...Can u plzzz send me working of this circuit on ayesharizwan100@yahoo.com

    ReplyDelete
    Replies
    1. Hello Ayesha,

      I'll try to send the required circuit description to you soon.

      Thanks and Regards.

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

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

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

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

      Got it?

      Delete
    4. I found some information about you, are you a content provider? please do not publish my articles or comments any where else:/

      https://www.odesk.com/exams/Online-Article-and-Blog-Writers_3230731?_redirected

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

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

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

    ReplyDelete
  17. hi sir i have a 4.8v battery charger and i want to charge a 3 volt battery how can i charge it????do u have any circuit for this???

    ReplyDelete
    Replies
    1. Hi Kiran,

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

      Delete
    2. Add two diodes in series for better safety.

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

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

      Delete
  19. Ashish Kumar RathMay 29, 2012 at 8:44 PM

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

    ReplyDelete
    Replies
    1. Hi Ashish,

      Yes you may try it, though the power would be very less from it, the output voltage would not change with lower loads.

      Delete
  20. Ashish Kumar RathMay 31, 2012 at 7:24 PM

    heloo sir
    ashish again


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

    ReplyDelete
    Replies
    1. Hi Ashish,

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

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

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

      Regards.

      Delete
    2. ashish kumar rathJune 1, 2012 at 6:25 PM

      thnk u sir

      Delete
  21. Ashish Kumar RathMay 31, 2012 at 7:38 PM

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

    ReplyDelete
    Replies
    1. It will depend on the rating of the battery also, with sufficient power the 8 amp transformer will hold 40 watts of load and 3amp around 20 watts.

      Delete
  22. hi sir how can i build a rc tx-rx?i wanted to make a rc heli.

    ReplyDelete
    Replies
    1. Hi Kiran,

      I have never built a RC heli, so cannot say anything about them.

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

    ReplyDelete
    Replies
    1. use a 6 amp diode at the input of the panel.

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

    ReplyDelete
    Replies
    1. Hi Avisek,

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

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

      Regards.

      Delete
  25. Then which circuit will deliver max efficiency

    ReplyDelete
    Replies
    1. You can try the following circuit:

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

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

    ReplyDelete
    Replies
    1. Hi Foysal,

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

      Regards.

      Delete
  27. Is it okay if I will use 12-0-12, 1A?

    ReplyDelete
    Replies
    1. With 1amp, it will provide only 10 watts of power, that too if the battery is 12v7ah.

      Delete
  28. sir
    can i connect 2CFL Bulp of 14watt parrellally to 40watt inverter

    ReplyDelete
    Replies
    1. Yes, only if the transformer used is 12-0-12V, 5 amp and the battery is 12v 7.5 ah minimum.

      Delete
  29. hai,
    i am a engg mech student .i want to make inverter for home uses devices .how i can make ?

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

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

    ReplyDelete
    Replies
    1. It's not very critical, you may cut two pieces of 6 by 4 inches aluminum plates 2mm thick and use it as heatsinks.

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

      Delete
    3. Presently it's not there with me, I'll try to search for an appropriate circuit as required by you, if I get one, will surely update it here for you.

      Delete
  31. Can I use E13007 Transistor with that circuit?

    ReplyDelete
    Replies
    1. No, you cannot use this transistor....

      Delete
  32. Hi,how do u calculate to get 50HZ yet no capacitors!!your circuit is very simple!!

    ReplyDelete
    Replies
    1. According to Motorola's original circuit, the design generates around 50HZ frequency, no formula was provided.

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

    ReplyDelete
    Replies
    1. Hi Kiran,

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

      Delete
  34. any videos are there related to this experiment

    ReplyDelete
    Replies
    1. Sorry, presently there's no video for the above circuit.

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

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

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

      Delete
  36. where is the positive terminal of the battery been connected to??

    ReplyDelete
    Replies
    1. battery center tap is the positive....

      Delete
    2. sir i didnt get you!!!

      Delete
    3. The left side transformer winding has three wires, the center wire will go to the battery positive............

      Delete
  37. Hello sir swagatam im junver sir and im from the philippines. Sir can you give me a circuit diagram of 500 watts power inverter with parts list that available in our country?thanks sir. Email me at junver_sobrecarey87@yahoo.com thanks a lot. I will wait for your reply.

    ReplyDelete
    Replies
    1. Hello Junver,

      You can try the following circuit:

      http://homemadecircuitsandschematics.blogspot.in/2012/09/make-400-watt-mosfet-sine-wave-inverter.html

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

    ReplyDelete
    Replies
    1. sir if i connect a rellay in that connection directly
      will it work??

      Delete
    2. where? in place of DPDT? yes it will work.

      Delete
    3. na i will connect the rellay as a connection between the motor and dbdt?

      Delete
    4. I am unable to understand your wiring so can't suggest much...

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

    ReplyDelete
    Replies
    1. Hi Rhum,

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

      Regards.

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

    thank u

    ReplyDelete
    Replies
    1. Hi Ben,

      I am sorry you cannot use the above circuit for operating sophisticated appliances, you will need a pure sine wave inverter for that.

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

    ReplyDelete
    Replies
    1. Hi Junver,

      You may use an ordinary step down transformer.

      Yes you can light a 15W CFL, if the battery is at least 10 AH rated.

      Delete
  42. sir my question is about the above circuit sir...its me junver again... pls reply asap...

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

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

    "haryofootball93@yahoo.com"

    thanks in advance

    ReplyDelete
    Replies
    1. Hi Haryo,

      Nice to meet you too!

      You can make the following circuit which will work better:

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

      A 24AH battery should back up for more than 8 hours for a 40 watt load.

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

    ReplyDelete
    Replies
    1. Hi Rhum,

      If you have enough knowledge about theoretical and practical electronics then you may try the following circuit:

      http://homemadecircuitsandschematics.blogspot.in/2012/09/make-400-watt-mosfet-sine-wave-inverter.html

      Delete
  45. sir its me junver again sir... sir kindly try to see this link sir http://www.eleccircuit.com/12-volt-to-220-volt-inverter-500w/ .do you think it works will sir? and what hz it will produce sir? 50-60hz sir?i will build this circuit sir once if you approved sir..and what type of transformer should i use in this circuit sir? and what wattage value of the resistor sir?thanks in speedy reply sir?

    ReplyDelete
    Replies
    1. From the figure it looks it will work, but unless you make it practically, complete results cannot be confirmed...

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

    ReplyDelete
    Replies
    1. Hi Vinod,

      With 6V 4.5 AH you won't get more than 6 watts of power output, will it be OK??

      Delete
  47. hello sir Swagatam. I have a question, I built this inverter circuit, and it works great
    the question is .. I can add a PWM with LM555? for better waveform? as here: http://homemadecircuitsandschematics.blogspot.com.ar/2012/02/how-to-make-500-va-pwm-controlled.html and I also I want to know which frequency ranges
    thank you very much
    jose

    ReplyDelete
    Replies
    1. Hello Jose,
      Thanks!

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

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

    ReplyDelete
    Replies
    1. Hello Tribhuvan,

      I'll try to design the circuit, if I succeed I will post it here with your details.

      Delete
    2. Hi Tribhuvan,

      your info is not sufficient, please provide full application details.....

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

    ReplyDelete
    Replies
    1. What should the processor analyze between the three sensors, what should it differentiate between them.

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

      Delete
    3. OK it means the temperature on S1, S2 and S3 should be between 60 and 70 degrees, if it's above or below this level for any sensor, the motor should stop. right?

      Delete
  50. no temp. range of all thermometer should be from 15 to 35.

    ReplyDelete
  51. sir i dont know how to start the circuit diagram is not clear 2 me so kindly tell me how to begin with this

    ReplyDelete
    Replies
    1. Buy all the parts first then I'll suggest how to join them....

      Delete
  52. sir can i test it by making connection through a breadboard

    ReplyDelete
    Replies
    1. You may do it, but the transistors will need to be mounted on heatsinks.

      Delete
  53. sir, how can i(manoj kumar) make a room heater safely.
    plz help.

    ReplyDelete
    Replies
    1. Use this circuit with the heater coil for safety:


      http://homemadecircuitsandschematics.blogspot.in/2012/03/how-to-make-25-amp-1500-watts-heater.html

      Delete
  54. sir
    inverter initially we test 12 v source via 12v 2amp adapter

    ReplyDelete
  55. Sorry, 2 amp will not give results, use 5 amp adapter

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

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

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

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

      Delete
  57. SHALL WE USE ORDINARY 100/10W RESISTORS IN ABOVE CIRCUIT.IF NOT WHAT WILL HAPPEND IF WE USE

    ReplyDelete
    Replies
    1. 100 ohms/ 10 watt wirewound types, others will burn...

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


    ReplyDelete
    Replies
    1. Yo! Thanka!

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

      Delete
  59. Really nice idea. What is the formula to calculate the frequency of oscillation? How it oscillates without Inductor/Capacitor?

    ReplyDelete
    Replies
    1. Thanks!

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

      Delete
  60. Hi Swagatam Majumbar,
    This is fareed, i am planning to build home Inverter, which can resist one bulb and one fan for consistently 4 Hours, so please help me regarding this.
    It will your favor, if you can reply to my Mail fareedabdul15@yahoo.com,
    Thanks for reading...

    ReplyDelete
    Replies
    1. Hi Fareed,

      Please refer to the following article, it will be just fine:

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

      Delete
    2. swagat,

      Thanks for responding,
      i saw the link, which you send, please go through this link below and advise me, enough output power required to run 3-4 hours constantly for this process, i have less knowledge about electronic and circuits, so that, i can follow early without any problem sir, this plan is for coming summer.

      http://www.youtube.com/watch?v=zR9CA8lJGvs

      Delete
    3. The link shows a fan cooler system....the inverter in my link will be able to support such fan and the pump quite easily, provided the battery is rated at 32AH min.

      Delete
  61. Hi Swagatam.....

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

    ReplyDelete
    Replies
    1. Hi Priyam,

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

      Regards.

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

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

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

    ReplyDelete
    Replies
    1. Hi Vivek,

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

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

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

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

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

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

      Regards.

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

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

      Thanks.

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

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

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

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

      Thanks anyway, appreciate it very much!

      Delete
    5. Okay... If You get any detail on that Pls keep me posted.
      Thanks.

      Delete
    6. As you had said the trick is in the transformer, I googled it and I got a link with details. http://tacashi.tripod.com/elctrncs/inverter/inverter.htm

      Delete
    7. Thanks!

      Yes, It's a much simpler circuit with all the details, great for powering small CFLs with battery power.

      Delete
    8. One thing I cannot understand is that what is the role of the transistor in it?

      Delete
    9. It's there for switching the high frequency current into the transformer primary.

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

    ReplyDelete
    Replies
    1. Hello Prashant,

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

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

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

    ReplyDelete
    Replies
    1. Hi,

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

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

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

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

      Delete
    2. Hi swagatam,
      can you guide me in designing an efficient sine wave inverter??

      Delete
    3. Hi Sneha,

      You may post your queries, I'll try my best to help you out.

      Delete
  65. dear sir , i did this circuit. working well.

    ReplyDelete
  66. Dear Swagatam,

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

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

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

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

    Regards.

    ReplyDelete
    Replies
    1. Dear Samarth,

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

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

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

      The transistors should be mounted on separate heatsinks.

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

      Regards.

      Delete
    2. Dear Swagatam,

      Thank you so much for your much awaited response.

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

      Regards,
      Samarth

      Delete
    3. Dear Samarth,

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

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

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

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

      Regards.

      Delete
    4. Silly Me!

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

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

      Regards

      Delete
    5. Dear Mr. Swagatam,

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

      Thanks a lot for your help.

      Regards,

      Samarth

      Delete
    6. Dear Samarth,

      That's great! Congrats!

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

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

      Regard.

      Delete
    7. Dear Mr. Swagatam,

      Thank you so much for your efforts.

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

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

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

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

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

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

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

      Hope to hear from you soon.

      Regards,

      Samarth

      Delete
    8. Dear Samarth,

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

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

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

      Regards.

      Delete
  67. I am a beginner. Pls how do i lean to build inverter.

    ReplyDelete
    Replies
    1. you may read the following article and gain some basic knowledge about inverters, then probably you can proceed with the practical stuffs.

      http://homemadecircuitsandschematics.blogspot.in/2012/02/how-inverter-functions-how-to-repair.html

      Delete
  68. hello sir, can you guide me in desgning sine wave inverter?

    ReplyDelete
  69. hiii sir
    can u tell me that ,what is the function of r3 and r4 here....the circuit is working without r3 nd r4

    ReplyDelete
    Replies
    1. Hi Kartik,

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

      Or even pics will do.

      thanks.

      Delete
  70. can you tell me the common cost of all the parts needed to make the circuit
    i need it urgently

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

    waiting for your replay

    ReplyDelete
  72. ok sir i will give u feedback

    ReplyDelete
  73. i used ceramic resistor 5 watts. not suitable for that place ?

    ReplyDelete
    Replies
    1. as mentioned in the article it should be 10 watts, wire-wound type.

      Delete
  74. thanks so much on this program but i don't really get anything but am very good in electrical work
    nursing from Nigeria

    ReplyDelete
  75. how can i connect a transformer with no center tap?...i mean on 12-0 VAC.....

    ReplyDelete
  76. so...can u suggest any dc to ac converter at 12v.....for checking transformer windings....

    ReplyDelete
    Replies
    1. sorry, i did not understand your question..

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

    ReplyDelete
    Replies
    1. Dear Shei,

      yes it can be done using boos converter circuits, an example circuit can be seen below:

      http://homemadecircuitsandschematics.blogspot.in/2012/09/led-emergency-light-circuit-using-boost.html

      Delete
  78. Sir, thank you very much, i ve been greatly educated by. Plz how do i merg two 100 watts circuit to get 200 watts? thanks

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

      Delete
  79. Hi,

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

    Thanks a lot!
    Simon.

    ReplyDelete
    Replies
    1. Hi Simon,

      what's your transformer specs?

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

      The output would follow the transformer specs exactly...

      Regards.

      Delete
  80. hello sir , i got a project of doing an inverter of 60 watt .what are the requirements for doing this project if i came to know from you??

    ReplyDelete
    Replies
    1. Hello,

      You can try the following circuit:

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

      Delete
  81. Hi
    sir is there a particular way to charge the battery when it is low?

    Femi

    ReplyDelete
    Replies
    1. Hi,

      I have discussed many battery charger circuits in this blog, you may find them through the given search box....and use them.

      Delete
  82. hi swagatam sir.....
    what is actual output wave form of thi inverter and is it generate both the positive nd negative cycles of a.c.

    ReplyDelete
    Replies
    1. Hi Kartik,
      Output waveform is distorted square wave....yes its with both positive and negative half cycles...

      Delete
  83. what is capacitor 205/400,ppc ?.... plz tell me in microfarads.

    ReplyDelete

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Readers are advised to proceed with the construction of the presented circuits only after understanding the concepts from the core. Not adhering to this can lead to failures and frustrations.