There is something mesmerizing about watching an instrument play itself, which is why player pianos are so enthralling. Player pianos are surprisingly old, and models similar to what we know today date all the way back to the late 19th century. Despite that, they’re a marvel of engineering, and traditionally work entirely by pneumatic or electro-mechanical means. These days modern technology affords a lot more flexibility, which makes instruments like this self-playing harpsichord possible.
Redditor AutoAutoHarp has been working on their AutoAutoHarpHarpsichord for years, and it’s currently on the fourth iteration. A harpsichord, if you’re not familiar, is an instrument that nominally looks like a piano. The major difference between the two is that a harpsichord mechanism plucks the strings, while a piano mechanism strikes the strings. The AutoAutoHarpHarpsichord uses solenoids to tap the strings, which really makes it more similar to a piano or clavichord, but who are we to argue semantics?
Those solenoids are toggled by relays that are controlled by a Raspberry Pi. Originally, it used guitar pickups to amplify the string vibration. But, because of issues with electromagnetic spikes, those were switched to contact microphones. The microphones are attached to the same boards as the strings, so they pick up the notes that resonate through the wood. In total, there are 24 strings that are laid out on four tiers, which yields 24 individual notes. The sequences are programmed with DMX512, which is usually used for stage lighting and effects, but which works for this purpose just fine.