I first saw this on a You Tube video called Homemade Modified Sine Wave Power Inverter(350/500w) by electronicsNmore.
O.K., first I have to admit that I was not able to get it working the first time through. I had let it sit on the back burner while I worked on some other things. But, today, I gave it another shot, and am happy to see it working from a breadboard.
The circuit was designed by John Parfrey, as is indicated in the schematic.
|Homemade Modified Sine Wave Power Inverter(350/500w) by John Parfrey|
Second time through, I wanted to test that it was functioning by leaving out the 7808 voltage regulator, just to make sure that it worked. After confirming that it did work, then I add the 7808 voltage regulator, upside down on the breadboard, simply because the schematic shows the input to pin #1 was to the right, and I wanted to visualize that. The remaining parts are laid out pretty much as the schematic has it.
There are at least two things that do not match to specifications (on my breadboard), the transformer and the 0.1uF electrolytic capacitor (to the left of the schematic). The design calls for a 10-0-10 center tapped transformer, and I am using a 12-0-12, 4 Amp transformer. Also, I do not have the 0.1uF electrolytic capacitor, and am currently using a 1uF electrolytic capacitor (until I can order the correct capacitor).
Otherwise, I am using the STP55NF06L mosfets, for the 500 watt version (as is shown in the schematic).
I did observe that the waveform is indeed a modified sine wave (using a 4 watt light bulb):
|Modified Sine Wave from John Parfrey's Power Inverter design|
You might also notice that the frequency is nowhere near the 60 Hz that I want it to be, indicating that the change to a 12-0-12 transformer may require less resistance than indicated in the schematic. You might note that ElectronicNMore YouTube video indicates that he is using an old microwave oven transformer, so the design can be modified successfully. Other factors that can affect frequency would be that I am using the 'cheap' version of the 4017, which does not operate as effectively as more expensive versions, and my battery amperage on this breadboard is minimal. (You can see from the breadboard photos that my power source is AA batteries. I also test with a 7 Amp Hour battery, and a 22 Amp Hour battery). A more powerful battery under a larger load would be more likely to deliver a different frequency.
Being relatively new at this, I think one of my initial problems was that I had not seen the breadboard on this one. So, I will add breadboard pics for others who may want to try it out.
Homemade Modified Sine Wave Power Inverter(350/500w) on a Breadboard
Here is a close up view with the positive rail at the top:
|Homemade Modified Sine Wave Power Inverter(350/500w) on a Breadboard02|
Here is a view from the other side, which shows that after the 7808 was added (upside down), I used the inner rail for the positive side downstream of the 7808:
|Homemade Modified Sine Wave Power Inverter(350/500w) on a Breadboar03|
Finally, I am including a link to the You Tube video that shows the inverter in action.
You will want to read the text following the video, as ElectronicsNMore also added circuit inrush protection, a fan, and a low battery indicator. You can search the ElectronicNMore video channel for the design (and video) regarding circuit inrush protection.
Also in the video, he demonstrates his finalized project, using a both a hand held sander and high power garage light. You may notice in the video, he is using the 350 watt version of the schematic (by using IRF3205 mosfets). Nice to see a video of the inverter in action.
You Tube Video "Homemade Modified Sine Wave Power Inverter":
Modified Sine Wave Mosfet Inverter Schematic by John Parfrey
Videos from electronicNmore:
Homemade Modified Sine Wave Power Inverter(350/500w)
Simple/Effective Solution To Inrush Current Problems
12V Lead Acid Battery Low Voltage Alarm Circuit
His temperature activated cooling fan (above) uses the bimetal sensor normally used with NiMH battery packs, available on Amazon and Ebay. Here's a link to an Amazon listing:
Amazon (Normally Closed??) "High Quality KSD9700 250V Bimetal 45 Celsius NC Temperature Control Switch Pack Of 10."
Amazon (Normally Open??) "10 Pcs Bimetal Temperature Control Switch Thermostat 40C N.O TLRS9700"
YouTube video link:
Electronic Projects Circuits Blog Article: