This tesla coil photo shows beautiful feathery plasma!
The aim of this design was to get the highest voltage (or longest arcs) possible from a singe self contained unit. This coil operates from 12V or 24V SLA batteries. A pair of car ignition coils are used to provide around 20kV for charging the capacitor bank. The ignition coils are driven by a variable frequency square wave from a 555 timing chip and four large transistors (2N3055). – Link