His plasma speaker does do the job well though, and in particular he’s put a lot of thought into the design of its drive circuit. At its heart is the ubiquitous TL494 PWM controller that you may ...

To get these currents into a workpiece, [bwang] used a TL494 PWM controller as an oscillator. The output of the TL494 is filtered and amplified a few times to generate a huge amount of AC current.