This is my 20-stage Marx generator. The HV power supply is a DC flyback transformer driven by a ZVS circuit. The LV DC supply is two 12-volt lead-acid batteries in series yielding 24 volts. I took this video with the shop lights on. The spark length is 12 inches, probably around 300 KV. Sometimes you can hear the discharge but you can't see it. This is because the discharge time is so fast that it will occasionally fall between the 60 frames per second of the camera.
