Adaptable 12vDC/220vAC Pure Sinewave Inverter

Picture of Adaptable 12vDC/220vAC Pure Sinewave Inverter
Here is a very simple pure sinewave inverter based on the microntoller "PIC 16F628A", "don't freak out !", NO it is not difficult to use microntollers, actually it could not be any easier than this.

For those wondering, Yes I myself designed the circuit concept, schematic and components but had to hire a programmer to write the code since I have no idea how to write software programming, I even paid him money to do this job since no one works for free these days, probably if he see this instructable he would be laughing at me on how I gave everything for free here :-/

The principal used for creating the sinewave:
Most hard work in this circuit is done by the 16F628A chip itself, where it divides the half wave into small segments generating PWM train of pulses to create each half wave as shown in the pic, generated oscillation then go to get amplified by the 4 transistors Q1,Q2,Q3 and Q4 where they feed the power stage to drive the power transistors. Can't be much simpler than that !

There are 2 options to program the 16F628A:
1- Most of the electronic parts selling shops do this service for you for an additional 3$ cost, where you take the program which is a "Inverter.HEX" file in our case, written on a disk to the shop and they will hand you an already programed 16F628A.

2- If you're an electronic hobbiest I suggest you buy your own programing device (I bought mine for 22$) and experiment with it because the microcontroller applications that can be built are endless. I bought the cheapest / smallest USB one which is a DIY K128 it came along with a CD containing the MicroBurn software "older versions known as MicroPro" and a driver for your computer, after setting up the driver and operating the thing, it programed the 16F628A IC in 10 seconds !
Here is a link to see how the programmer looks like.

Note: Both 16F628 and 16F628A will work, the difference is that the 'A' has more memory capacity, but both work the same.

The filter:
The 2.2 uF capacitor which is the filter is a very very important part of this design, without it you'll never get a pure sine wave.
I have included 2 screen shots of the oscilloscope (with-filter and without-filter) so you can see the difference and importance of this capacitor.

Other notes:
- Included is the movie file "IMG_0690.MOV" in case you encounter any problem and need to see the wave form on pins 11 and 12 of the 16F628A how it looks like.

- The PIC16F628A is so sesitive to static, if you're sitting on a plastic chair never touch the IC's pins with your hand.

- You can build bigger versions of this inverter up to 5000w, to see what needs to be done on the power stage please see details on my other instructable here

- Heat sinks are required to cool the power transistors they should be big enough to cool the transistors, they are separate and should NOT touch each other.

- Wiring connections marked in dark black on the power stage section should be thick enough to handle the big amps drain from the batteries.

- A cooling fan will be needed to reduce heat off the heat sinks and transformer.

- Be cautious when building this circuit it involves high voltage which is lethal, any part you touch when the circuit is ON could give you a nasty painful jolt, specially the heat-sinks, never touch them when the circuit is on to see if the transistors are hot.

Do not forget to rate this instructbale with 5 stars "of course if you like it and appreciate the effort done" and also click the "follow me" button to keep updated of future instructables and updates that I do.

We need to get this inverter to perfection by adding some more options to it like:
- Low DC Battery voltage detection to trigger a buzzer and a to auto-stop oscillation at some point.
- Heat detection to trigger a fan ON
- Battery level indicator 3 LEDs (High-Medium-Low) and to trigger charger ON
We'll need some help to code the above..
so any suggestions, help in coding or design on this project to make it better are very welcomed so send your thoughts.
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Hi.can you give me a code hex sine 50hz.thanks all

Yes I was wondering the same thing. Im about to make this circuit. can you either give me the C code of this circuit or HEX file of 50Hz ?

npyasith11 months ago

Hey nick,

I built this circuit but I keep getting high voltages instead of 230V. I used the transistor 3055 instead of 3773. Is this the problem???

I know its a very late reply but it might help somebody else with the same problem.
Try to find voltages without the transformer. Only then you may decide the rated transformer. Like I made an inverter whose schematic showed 12-0-12 Transformer but the output was very low. About 160v without load! So I applied 9-0-9 Transformer and got 230v AC which were excellent! How I figured that out? By finding voltage without transformer.
I hope this helps :)

really? what is the rated input windings of your tranformer? i guess its 6 0 6 or close...

the best relief is to use a 12 0 12 transformer and then replace the transistors with power mosfets like irf2808 or irf z46...... i might be of help.....

shaheers211 days ago

Hi, may i have a source code of that inverter, Please?

Reasion is that i am developing and working on high power inverter, so this may help me a little bit,

if yes, here is my email id:

sanmlight1 year ago
Hi chuksthewoundy,

i don't have a oscilloscope to test the wave form of this circuit.

DMM testing...
12-0-12 12amp transformer , IRFz44N 4pcs
with capacitor 2.2uF:
without load = 218Vac
with load 40W = 199Vac

without capacitor:
withoutload = 238Vac
withload 40W = 214Vac

i'm using 60Hz without on/off hex file.
the on/off functionality is still not working with me even i change the push button switch.

From what i can see its working properly.
1.check if the battery voltage drops when you add a load. measure the Amperage drawn with and without load. and reply!
2.Also test it using an ac fan. The fan should run smoothly at full speed without any noise, this confirms you have a clean sine wave.
electric fan wont run fast and the voltage dropped from 218vac to 157vac
Hi samlight .....i also experienced the same thing the output voltage drops when the inverter is loaded and i discovered that the drive voltage from the oscillator was not enough, so i used an op amp amplifier to boost the voltage. now the output only drops a few volts when loaded.

replace the bipolar transistors with mosfets... irf 2808 would do just fine... contact me for further assistance..

nickk (author)  chuksthewoundy1 year ago
I made many many tests yesterday, here are the results:
-Transformer used 12-0-12  80VA
-1 pair of IRFz44N 
-DC supply : 12.5VDC

Results with NO filter:
-Output voltage: 210VAC not stable (playing rapidly between 180 to 210)
-Waveform: -Witdistorted, has no shape and can't get a reading on the frequency.
-With Load: A 18w compact fluorescent lamp (CFL) was connected, voltage dropped to 190vac, DC still 12.5v

Results with filter:
-Output voltage: 166VAC stable
-Waveform: Sinewave, 61Hz
-With Load: A 18w compact fluorescent lamp (CFL) was connected, voltage dropped to 153vac, DC still 12.5v stable.
-amperes consumption up to 1amp
-Gate driving voltage: 11.5vdc or 3.28vac
-Primary voltage on the transformer: 12.40-0-12.30

In short, this is exactly what happened with my original design and that's why I have in my schematic a 6-0-6 primary transformer.

Hi Nick, as I mentioned in my previous post; I asked transformer manufacturer to provide me a 500watts 12-0-12 transformer -- will it work with this pure sine driver? I'm really interested about finishing this, your help will be greatly appreciated :) Thanks

nickk (author)  sanmlight1 year ago
The waveform is a pretty clean sinewave and the freq. is exactly 61Hz. Please increase the load by an additional 20W or 40W to see if the "with load 40W = 199Vac" will decrease further or it stablised on 199Vac. Be careful not to reach the limit of your transformer. If it decreases further it means that the problem is with the transformer.
every additional load the voltage will dropped 20vac. the dc supply is stable.

for a 60 watts electric fan it wont run fast. the voltage dropped from 218Vac to 157Vac
i will post the schematic for the op amp amplifier that i used.... when i am done testing...
kindly test also the on/off functionality.
RobertC814 days ago

using bipolar transistors such as 2n3055 isnt the best idea... i rather advice u to use a mosfet because they emit less heat and they are extremely very efficient... just two mosfets like irf2808 or irfz46 would do the work of about ten bipolar transistors... give it a try... contact me if for further assistance... CARTER4LIPPTTON@GMAIL.COM

JoremieJ20 days ago

sir why do we have to program the 16F628A ic?

Here is my e-mail
Here is my e-mail

Hello Nick, congratulations on your initiative to publish this his project.

I have a doubt, this project is used transformer 6 - 0 - 6 volts and 12 volts on the center tap?

Thank you,


iceaudio1 month ago
here is my e.mail.
iceaudio1 month ago
here is my e.mail.
iceaudio1 month ago
here is my e.mail.
iceaudio1 month ago
here is my e.mail.
iceaudio1 month ago
gud day sir could you pls post the list of parts needed for this
pure sine wave circuit.. tnks
iceaudio1 month ago
gud day sir could you pls post the list of parts needed for this
pure sine wave circuit.. tnks
iceaudio1 month ago
sir coul you please give me a list of parts needed to make the250w pure sine wave.. thnks
upright1 month ago
Please if u can send the hex file to my email so I can program the pic16f628a pure sine wave. Here is my email >
upright1 month ago
How do I get the program file for sine wave to down load

i'm vietnames

Thanks to nickk for his all wonderful articles specially on power electronics, I want to use the same nickk's circuit for my inverter, but am using pic 16F877A & 20Mhz crystal can any one help me with source codes.

My email is, hope to here from you soon.


nikito522 months ago

Hi, can I use normal 50Hz transformer 12/220Volt or need to use feritte transformer?

EdoNork2 months ago

Hi again,

I have make the PCB of this project and the artwork is available for free here:

Hope this helps someone make this inverter project easily.

nickk (author)  EdoNork2 months ago

Thanks for sharing, did you build the circuit?

EdoNork3 months ago


Nice project. I'm willing to test it. Thank you very much for sharing.

Is there any link to a proper PCB artwork? The one posted in the article is blurrer by JPG artifacts.

Thanks in advance.

Hi Nick

This is Amir Dimitry

I have built the circuit of power 2000VA, using 16 mosfets of type IRFP264 and 2000 VA transformer of 22-0-22 v primary /240v secondary.

I have connected pins 11&12 of the microcontroller pic16F628A directly to the gates of mosfets through a 1K Ohm resistor. When the circuit is working on no load, the output voltage is 230V, 50 HZ, with 2.2 microfarad capacitor on the output . When I apply load of 800 wattes to the transformer, the output voltage goes to 80 volts.

please advise


UmairH3 months ago

Amazing Project bro, i made it using tip35c, just one problem. A transformer is of 50 60 hz normally, you are working on 3 khz, so one i connect the transformer it makes alot of noise which is no doubt because of high switching speed, if my frequency is high then i think the size of the transformer will be smaller. Is there any way i can stop this cuz i cant find a ferrite core transformer. suggestion anyone?

sir??? wat will happen in the circuit if the our battery is 48v? do we have to change the voltage regulator???

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