Alternative Power Source:

Aim: To produce 240Vac using natural sources, eg Solar power, Wind.

1/5/2001

Bought a Dick Smith Kit. A 1.5Vdc to 9Vdc inverter.

Bought to test my understanding of inverters.

Also, at the same time, a 1.5V, 500mA Solar Cell was purchased to use as the energy source.

Circuit worked well, but limited use due to low mA rating of the inverter (70mA max).

However, gave me ideas for building my own, more powerful, and hopefully, more efficient version.

The Dick Smith Kit has now been put to good use as a power source for my Digitek DMM. Go here for more info.

6/5/2001

Basic experiment with a 4.5V dc source, and a spare transformer from a Phillips Cassette Deck that I rebuilt.

With an AC Volt meter on 240V side of transformer, quickly touch secondary side with the dc source. Measured 50V.

Next stage is to set up a transistor circuit which will switch the 4.5Vdc source to the transformer on and off.

8/5/2001

Constructed a simple transistor switch. Base of transistor fed with a Function Generator. Circuit works - indicated by a flashing LED.

10/5/2001

Added the transformer to the circuit. Well, it works!

With a supply voltage of 10Vdc, and the transistor switching on and off, I got 86Vac on the transformer's output (a ratio of 8.6 to 1). I found the highest voltage was achieved at a switching frequency of 5.72kHz.

So, the theory works, but I need to do the following:

1.) Improve efficency of the circuit.

2). Get a higher ratio of 24 to 1, and at 50Hz.

Of course, the voltage was measured using a DMM which is only useful on AC when the frequency is below 1kHz, so the measured voltage could be grossly out (hopefully, higher than measured).

Hummm... I need an Oscilloscope... maybe next pay day?

12/5/2001

Set up the circuit as follows:

Function Generator: Max output level (2Vpp), 50Hz Square Wave.

DC Supply, 10V.

ACout was 40Vrms

I also added a diode and capacitor to the DC side of the circuit to see if I could get a stepped up DC voltage. DID I WHAT!! I measured 133V DC out.

So, at 50Hz, I'm getting an AC ratio of 4:1, and a DC ratio of 13:1.

12/5/2001 PM

Looking at making the circuit more efficent.

I connected a Neon Light Bulb to the DC output, and found that it lit up, but drew too much current and the circuit couldn't top up the capacitor fast enough, so the Light went out after a few seconds (when Vout was 80Vdc).

I thought about trying a different coil.

All I had in stock was a home made coil intended for use as an aerial for an AM radio, so I used that.

Discovered the following.

1. Needed a higher switching frequency (which I figured would be the case as the coil was designed for AM radio use). Optimum frequency was 120kHz.

2. More efficent. The Neon Light bulb stayed lit up. The no load voltage was 130Vdc. Loaded with the Neon Bulb, it was steady at 105Vdc.

This is good for the DC side, but obviously, the ac voltage needs to be at 50Hz...