But if you use a car battery then the voltage output will change with battery voltage.
Normally not very important but depends what you will use it for.
You can use oscillator, square or sine wave, drive two power transistors, to supply current to the secondary of a 50 watt transformer, you get the ac at the primary.
I have a circuit in 300 circuits book from elektor electronics, unfortunatelly, my home PC is out for maintainance, I will scan the circuit for you, but give me time to do so.