I'm converting an old player piano to play midi files running on a Pi using IoT windows 10 programmed in C#.
It's connected to 6 MCP23017 IO expanders with 88 Mosfet Transistors and solenoids.
Tempo is not quite right, but I'm working on it.
https://youtu.be/tQ9mmbXtOOA
https://youtu.be/pkPDW-SyZ7k
https://youtu.be/38MMZEJtzP0