A very simple way of converting Direct Current to Alternating, by means of relay switching.

First the power supply is ran to the relay switching coil, then from the coil directly to the relay's Normally Closed switch contact. From the switch contact to a transformer and back to the power supply.

This DC-DC works as you can probably allready visualise, by powering the relay, the relay then close's not instantly because of the resistance of the switching coil. Which give's you a alternating current "the model I made pulse's at 10Khz" to power a transformer, cascade or any other device you need a AC source for.