An interesting plasma speaker using a Tesla coil

[Bob Bruhns]

http://www.youtube.com/watch?v=x0J53x9KJ7s&mode=related&search

I did something similar at a radio station back in 1967. I jammed a wad of steel woll into the arc gap at the base of the main
tower. The steel wool caught fire, and I could hear the station audio in the arc. But one of the engineers drove up, because the
station had suddenly started splattering the whole broadcast band! I was SUPPOSED to be digging up ground radials for
maintenance, so I got back to that.

  Bob, WA3WDR