Some guys made a Tesla coil “sing”—change pitch. Of course the perfect tune to do on it is from Mario Bros., which just about always has been the perfect tune to play on anything, going back to when my friend John learned it (or at least the level 1b underground part) on bass in 5th grade.
I’m not quite sure how they did it. Tesla coils require two coil whose resonant frequencies are tuned to each other. Perhaps they were able to change the resonant frequency of both at the same time? There’s possibly a much simpler solution I’m overlooking. (By the way, I’m an engineer; I geek out sometimes.)