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

12V to 220V DC to AC Converter Circuit

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.


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  • pankaj singh

    please send my email any informaion related by electrical education

  • Name *vinit

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

    • joribo

      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)

  • joribo

    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.

  • joribo

    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.

  • joribo

    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.

    • spyros

      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?

  • spyros

    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?

  • joribo

    @ 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.

  • Caleb Wilson

    can i use transformer from my computer ups

  • jpp

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

  • joribo

    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

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