Simple frequency-tunable spark generator?

Question

This may sound weird, but...

I am attempting to design a steampunk / gothic horror-styled electric harpsichord, with sparkgaps as the sound source in the vein of musical Tesla coils.

Unlike musical Tesla coils, any particular spark generator need not be dynamically tunable for different frequencies--there will be 88 of them, one per keyboard key, manually tuned to a single note at a time. I would prefer if the frequency could be tuned by screwing a threaded steel rod into or out of a solenoid to alter inductance, but a potentiometer or variable capacitor any other sort of mechanically-adjustable tuning component is acceptable. Also unlike musical Tesla coils, the sparks need not terminate in open air--and I imagine it's probably best if they don't, since there will be 88 of these things packed fairly close together.

To fit the aesthetic, it would be ideal if such a circuit could be constructed entirely out of resistors, capacitors, and inductors--i.e., discrete components that I can make by hand by winding wire into coils, rolling up laminated sheets of metal foil and paper, etc., but if a transistor or or diode or something is required per spark generator, so be it.

The intended behavior is that, on activating a switch (keyboard key), a spark should be generated which produces a specific audible tone, and either continues indefinitely while the switch is activated, or decays after a fixed but significant amount of time (analogous to a plucked string ringing down).

What is the simplest / most robust circuit I could build to do that?

Answer 1

I am attempting to design a steampunk / gothic horror-styled electric harpsichord, with sparkgaps as the sound source in the vein of musical Tesla coils.

The device you are describing is, functionally, very similar to a spark-gap radio transmitter. The use of these devices has been banned by international law (!) since the 1930s, as they produce wide-band radio interference.

Unless you have a specific, detailed plan in mind for preventing this device from producing radio interference and confirming that its emissions are negligible, I would recommend that you consider alternative effects, or a simulation of a spark gap. The potential for a device like this to cause havoc by (e.g.) interfering with public safety radio systems is too great.