here's a schematic to convert dc to ac:
**broken link removed**
but the output needs to be adjusted though, change the values of capacitance and inductance
or you can download the 555 timer datasheet, they contain schematics which will need some parametric adjustments. Either way do it on a breadboard, if you're not into PCBs then do it on a donut perfboard when you want to solder the whole thing together.