MIDI Kalimba with Raspberry Pi Pico

The kalimba instrument is a finger piano with tines that are plucked to produce sounds. Based on the mbira instrument from Zimbabwe, the kalimba first appeared in the late 1950s and was popularized in the subsequent decades. With the advent of inexpensive online shopping, one can now obtain a version of this instrument for well under $20.

After seeing a pair of these appear in my household, the idea was hatched to add capacitive sensing and MIDI interface via a Raspberry Pi Pico board. Thus was birthed (possibly) the world's first capacitive touch MIDI kalimba (as well as the second).

To accomplish this electro-musical hack, I milled out the inside of a solid pocket-sized mini-kalimba, creating just enough room for a Raspberry Pi Pico. To each of the tines, I soldered a 1Mohm resistor which was connected to the ground bus. Each tine was also connected directly to an IO pin via an also soldered-on jumper, and heat shrink was added for isolation, creating the resistive hardware setup needed for Pico capacitive sensing. The Pico then acted as a MIDI interface via code available here.

While a fun diversion, this very small kalimba was somewhat difficult to play simply because the tines are so small. Version two, seen just after the five-minute mark in the video below, instead employs the same sort of capacitive sensing setup on a larger (full-sized?) kalimba, complete with a cat figure on the sound hole for some unknown reason.

In this case, I left the Kalimba largely intact but took out several tines for more spacing. Jumpers were soldered to each tine, but rather than implement resistors directly I designed and implemented the Pico Touch 2 board that includes 1Mohm resistors.

Both devices worked as MIDI controllers and were fun to play. At the same time, you simply touch the tines without plucking, so some might view this as a different instrument altogether, just kalimba-shaped.

However you view it, it was a fun project. On a personal note, I’ll be posting more of this sort of musical hacks on the JCo Audio YouTube channel. I would be honored if you’d like to subscribe!