by windgat on Fri Jun 08, 2007 1:28 am
Its basically an inverter, which yes, does lose some energy. And yes they generally use transformers to inclrease the voltage.
Some inverters (more expensive) can monitor the mains current, and invert the DC supply into a since wave which matches the phase of the mains.
Cheap inverters just invert to a square wave, or to a combination of square waves.