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Converting a Low Power Inverter to a High Power Inverter

Here we learn about a couple of simple circuit configurations which will convert any low power inverter to a massive high power inverter circuit.

You'll find a plenty of small and medium sized inverters in the market ranging from 100 to 500 watts, the same may be seen posted in this blog. Upgrading or converting such small or medium power inverters into massive high power inverter in the order of kvas may look quite a daunting and complex, but actually it's not.

Analyzing Inverter Topologies

All inverter topologies basically incorporate an oscillator frequency which is then amplified using power devices to high current levels before dumping into the step-up transformer for the final voltage boosting procedures.

The current amplifier stage which employs high current devices is where the upgrade needs to be done in order to achieve any desired power outputs from an inverter.

The modern day inveters heavily rely on mosfets for the above mentioned power conversion stage, nevertheless BJTs can be also used for the same very effectively, in fact much reliably than mosfets...

How to Upgrade Low Power to High Power

The following diagram shows a simple and very effective power output stage which can be integrated with any totem pole IC outputs such as IC 4047, IC TL494, IC SG3525, IC 4017 (clocked with IC555), for acquiring upto 1.5kva conversions.

The key devices in the circuit are the combination of the TIP122 and TIP35 which become a high gain, high current transistor pair, capable of boosting current to the rated massive levels instantly.

Each such device module is rated to produce at least 30 x 24 = 720 watts, so by adding more such modules in parallel any desired kva range can be anticipated from the configuration

Using Power BJTs

Using BJTs could be very reliable and simpler but quiet bulky, if space is your problem and need the upgrade from low to high power inverter in the most compact way, then mosfets becomes the popular choice and may be wired as shown in the following diagram:

The input is derived again from any totem pole IC outputs, the mosfets could be rated as per the desired upgrade from lower to the highest magnitudes.

The diode integration suggests a simple PWM insertion which is optional, but could be used if a modified sine wave output intended to be included in the upgrade.

The above explained simple strategies would be enough to enable you to upgrade, or modify, or convert any small or low power inverter design into a high power inverter circuit with the desired wattage specs.

Need Help? Please leave a comment, I'll get back soon with a reply!


  1. good day sir, i so much appreciate all your work in this blog, may God continue to guide you. please i need a complete circuit diagram for 1.2 KVa pure or modified sine wave inverter with inbuilt charging section.


  2. thanks Muhammed, just integrate a 4047 oscillator circuit with the mosfet power stage as explained above, you would be able to achieve the required specs instantly

  3. Hi if I was to use you circuit as stated above would the original transformer in the 300w inverter work of I was to modify it to plus minus 800w

  4. Hi, how can a 300watt transformer produce 800 watts, sorry that's not possible.

  5. How many volt should i apply to the collector of that bc547 must it be 12volt?

  6. yes it must be 12V, and the trafo center tap must be separately powered with the battery positive if it's higher than 12V

  7. Sir please explain the way you calculated power? 30*24=720 How?

  8. 30 is the voltage that possibly may be used for powering the inverter and the 24 is the max current rating of the transistor.

  9. sir i wish we have a kind and honest person like you in our country to enlighten novice like me in my country too
    All thanks to your quick and fast reply i am able to turn my small ups into a 3000watt pure sine wave inverter within two weeks i pray the lord shall always strengthen you to continue the good work of yours
    sir i nose around for months but your site is the king of site sir i mean the best i wish more people like you will stand up to enlight
    more people like me thanks

  10. You are most welcome abioye, please keep visiting my site, and keep up the good work

  11. I tried to post my question but it seems like it didn't post.
    Dear please provide me a circuit which can be used after my 150v DC smps to control/vary voltage and limit current....volt/current adjustable.

    Thank you..!

  12. You can try the following circuit,

    ignore and eliminate everything that's on left side of C1

  13. sir. i have a 200w inverter which is not design with ics. so pls sir can u explain how i can connect it with the above circuit. cos i see its connected to the ICS here.. am still a fresher in electronics though

  14. Olatunji, if you are already having a fully working inverter then you can simply check the output power devices and replace them with more powerful devices. No need of making the improvements suggested in the above article.

    I am sure your inverter would be using mosfets for the power devices, you just have locate them and replace them with more powerful mosfets, as per your desired specifications.

    And yes, this would work only if your transformer and battery are also accordingly upgraded.

  15. sir please how can i connect a relay in the inverter so that it can automatically switch to the mains when the mains is on,and ratings of the relay. 200w inverter

  16. olatunji, you can follow the following concept


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