Wendell Kapustiak has built a self-playing wooden pipe organ. The organ has 42 wooden pipes (representing 3.5 chromatic octaves). Each wooden pipe is different and had to be custom-cut to play the right note. A “blower” used to cool data centres was modified to keep it quiet and enclosed; air pressure from the blower feeds the organ’s wind chest which provides the air for the pipes. The valves for the pipes (which cause them to ‘play’) are opened and closed using solenoids. The main processor is a Raspberry Pi which provides a user interface for selecting songs and sends MIDI instructions to an Arduino Due which has a pin assigned for each pipe. A transistor board boosts the activation signal so that the solenoids fire. It certainly makes a beautiful sound in full flow. You can see it in action in the video above, which features an interview with Wendell, and you can read more about the build over on his blog.