Reliving elementary school with a robotic recorder
The recorder is a type of flute that is very popular in elementary schools because the instrument is so simple and inexpensive. If you were born in the last four decades and grew up in a western country, then there is a very good chance that you were required to learn how to play some basic melodies on a recorder. But like all instruments, the recorder is difficult to play well. So Luis Marx built a robotic recorder that could do the tricky parts.
Marx still has to blow into the mouthpiece to play this robotic recorder, but it takes care of the rest. A standard recorder has eight holes: seven finger holes on top and one thumb hole on bottom. The player’s spare thumb and finger help them stabilize the instrument. This contraption uses eight solenoids to close or open the holes according a pre-programmed sequence. It doesn’t appear that Marx integrated MIDI capability, but that would make it much easier to play new songs.
The current implementation has the sequence of notes programmed into an Arduino sketch. That sketch runs on an Arduino Nano board, which controls the solenoids through eight MOSFETs. Power comes from a 650mAh LiPo battery and everything attaches to the recorder via a 3D-printed frame. As you can hear in the video, this works quite well. Foam earplugs on the solenoid rams ensure an airtight seal on the finger holes, resulting in clean sound as long as Marx’s blowing technique is good.