There are so few pure sine wave inverter designs available, I just had to put this one together on a breadboard:
This one appears on the pages of Homemade Circuits Just For You, but is designed by an avid reader of that blog, Mr. Theofanakis.
It certainly is a sign wave form, as you can see on the graph on the web page.
This one is put together using the 4017 integrated circuit.
I have not run this one through it's paces yet, and have not tested under heavy load.
However, I have tested on the breadboard with a 4 watt bulb. Unfortunately, the frequency is my concern. I found it hard to hold the frequency at a constant rate, so I have put further testing and completion of this on my waiting to do list.
|300 Watts PWM Controlled, Pure Sine Wave Inverter Homemade Circuits Just For You|
Here, I have the inverter with no load:
|300 Watts PWM Controlled, Pure Sine Wave Inverter with no load|
Here, I have the inverter running a 4 watt light bulb:
|300 Watts PWM Controlled, Pure Sine Wave Inverter with 4W load|
You can click on the images to enlarge, where you might notice that the frequency is getting away from me.
For the moment, the Pure Sine Wave Inverter Using the 4047 (100 Watts, designed by Mr. Swagatam Majumdar) is the one I would like to concentrate on. The initial performance (of the frequency and sine wave) from the 4047 appears to be much better than this one, including after modifications to 250 Watts (or more by using 4 mosfets / 2 in parallel,etc.).