|A traditional Nintendo Entertainment System creates 8-bit game sounds using an Audio Processing Unit known as the RP2A03/RP2A07 chips. The sound composition of tunes that are played by the NES and systems of that era primarily consists of square and triangle waves meant to be output on an analog speaker. Instead of using an analog speaker as our sound output medium, we would like to use the electrical discharge of a Tesla Coil.
Our overall project goal is to create a Tesla Coil that uses solid state devices and is able to modulate its discharge frequency in accordance with the register contents of the NES APU, so that the sound emitted by the electrical discharge matches the sound being output by the APU.
The way that we would get the contents of the NES APU in real time is through an open-source emulator. One such emulator that could work is FakeNES. We would run a modified version of FakeNES on a Raspberry Pi and change the Software sound module, so that it can send sound register contents to the GPIO module. Then we will design another circuit to read the contents of the GPIO module and change that digital signal into the sound corresponding wave that should be emitted by the discharge sounds of the Tesla Coil. The discharge sounds can be controlled by properly interrupting the switching circuit that drives the coil's primary side.
As far as safety is concerned, we will be building the coil at such a scale where the discharge is not large enough to pose a problem.
One major problem I can see us having to overcome in this project is combining the multiple sound channels, so that they can be output on a single coil. The way we will overcome this issue is by playing all of the channels out of the coil in a round-robin format. That way each channel can contribute to the air vibration that we interpret as sound simultaneously. We would make the round-robin switching of channels occur at such a high frequency that the attenuation of sound between the switching is not significant enough to affect the sound.
While musical Tesla coils do exist, none exist such that they seek to model the APU output of the NES directly. In addition, there exists no Tesla Coil drivers that seek to modulate the Triangle wave of the NES's APU, most musical Tesla Coils are only designed to output sounds that are square waves. We will achieve the Triangle Wave output by feeding our switching circuit that produces square waves into an integrator and feeding the output of the integrator into the coils primary.