I understand more or less to concept of how these work, i.e. you send width modulated pulses, proportional to the frequency of the incoming sound signal, into the primary circuit.
Easy to implement with 555s and mosfets etc when you are driving a flyback transformer driver at 36V/12V or what ever.
But how would you implement such a scheme with a tesla coil primary. They are normally driven with NSTs at 8,000V or so and you clearly can't have a mosfet in the parimary circuit as a switch as you can with the flyback transformer driver.
I have not been able to get any clear description of how it is implemented in the tesla primary and what sort of power source they are using with audio signal injection.
There are examples of people using optic coupling from the audio processing circuit to the tesla primary so as to avoid any direct electrical connection. But the question remains what is at the other end of the fibre optic cable. What device is the optical signal driving?