Singing Arcs or Musical Tesla Coils

A few words about safety:

1. Burning steel produces some really nasty fumes. When mixed with Ozone and NO2 they will surely do you harm. Therefore ensure adequate ventillation and don't breath the fumes.
2. The plasma is hot ! If it starts steel burning in seconds, it will damage skin in milliseconds. Do not take an arc to the skin or any held object.
3. Hot metal particles are showered everywhere, and the screwdriver remains hot for some time after the power is cut. There is a real risk of setting fire to nearby objects or burning your skin. Give things plenty of time to cool before touching.

The hardware store where I got my screwdriver wouldn't honour the "lifetime guarantee" either ;-)

There are many ways of modulating a SSTC (solid state tesla coil), the 2 most popular being AM (amplitude modulation) and what i will call "PRF Modulation". PRF stands for pulse repitition frequency. The reason these 2 modulations exist, is because there are 2 (actually more) distinct types of SSTC. Those that can produce a continuous spark output (that is, a flame like plasma that exists at 100% duty cycle) and those that make what appear to be a continuous spark, but are rather producing sparks at several hundred times per second with a rest between each spark event. The first (continuous) type of SSTC lends itself to audio modulation. Normally the output spark is a silent plasma flame. By modulating the amount of power put into the plasma flame, we can modulate the physical volume of the plasma. Modulating the size of the plasma will cause the expansion/relaxation of air surrounding the plasma, thus producing sound waves.

Now go for it here!
Or go for Ward and Larson's twin Tesla coils!