I did a quick test tonight to check/confirm the feasibility of using the ebay solenoid valves I got a while back to control the player piano. I connected one of the valves to a 12V battery pack and a push button, and then held it in front of one hole of the piano’s tracker bar while the rest were taped closed. When I pressed the button, the valve opened, and the piano played the key! With this successful test I can move forward with designing an adapter to connect all 88 valves to the tracker bar.
