power inverter

[Kelloggrice]

Hey all,
I've built a power inverter, just out of curiosity of mains re-generation. I figure if I can get it going, I can plug in a mobile phone charger and charge my mobile in the car.
I mean, it ain't going to power much more.

Basicaly, I took a sine wave generator from here:-

http://www.national.com/nationaledge/jun04/article.html

At appx50hz, it feeds an old PA amplifier from Maplin Electronics, a TDA 2005 amplifier with a microphone input, and a power transformer in reverse to step up the output from the amp up to 240volts.
I've only been able to get 215 volts so far.
The secondary impedance of the transformer is 00.3 with my meter set to 200ohms range! I take it that, its a 3 ohm load which the amp sees. This must mean maximum transfer of the amps output through the transformer.
Would their be a good enough drive from the oscillator to the amps input, seeing its a microphone input? The volume has to be cranked right up. Without a scope, I can't work out much.
I assume the microphone for this amp, would be a cheapy cassette type of thing, rather than battery type. My supply voltage is 12 volts/car battery and please don't suggest I buy a mains inverter 'cos they're cheap enough. I want to learn, and I'm using what I have to hand. I have made a similar version using the PC to generate a wave, and a 50watt amp and drove a Cassette deck and a CD player with it.
Can you help, remember, I'm only wanting to power a mobile phone charger.
Cheers K

[richie00boy]

I can see your ideas and good on you, but without a scope you really are just flying blind.