The 12VDC to 120VAC inverter project on this website is too simple and doesn't work. Its output is only about 25W at maybe 100V. It is a transistor multivibrator oscillator (look in Google) driving a stepup transformer. Its capacitor polarities have recently been corrected but the transistors have avalanche breakdown of their reverse-biased emitter-base junctions that wastes a lot of power and causes the capacitors to blow up. Also the transistors do not have enough base current to make a powerful inverter.