Plucky Kalimba Plays Itself

[Gurpreet] fell in love with the peaceful, floaty theme from the Avatar series and bought a kalimba so he could hear it resonate through his fingertips. He soon realized that although it’s nice to play the kalimba, it would be a lot cooler if it played itself. Then he could relax and enjoy the music without wearing out his thumbs.

After doing a bit of experimentation with printing tine-plucking extensions for the servo horns, [Gurpreet] decided to start the design process by mounting the servos on a printed base. The servos are slotted into place by their mounting tabs and secured with hot glue. We think this was a good choice — it’s functional and it looks cool, like a heat sink.

[Gurpreet]’s future plans include more servos to pluck the rest of the tines, and figuring out how feed it MIDI and play it real time. For the demo after the break, [Gurpreet] says he lapel mic’d the kalimba from the back and cut out the servo noise with Audacity, but ultimately wants to figure out how to quiet them directly. He’s going to try lubing the gears and making a sound-dampening enclosure with foam, but if you have any other ideas, let him know down below.

We don’t see too many kalimba projects around here, but here’s one connected to a Teensy-based looper.

Via [r/arduino]

23 thoughts on “Plucky Kalimba Plays Itself

  1. I have some ideas:
    * Really long arms to move the servos away from the microphone. Would have to change the mechanism so the arms moved along their long axis from above.

    * Electromagnets to move spring loaded arms, kind of like a solenoid.

    * Pneumatics where the valves are far away from the microphone.

    1. I’d second the electromagnet idea – that’s what I was thinking. Kind of a design change, but a spring-return solenoid to strike the note (check out standard/old doorbell chime guts) – could be a silent note strike with relatively easy electrical control.

      1. I’m in the process of making v2 of this project. I tried out making my own solenoids and it seemed promising, but I kept releasing the magic transistor smoke because it required so many Amps to power.

        My current v2 is 3D printed linear actuator servos that are separated from the kalimba so the noise is better contained.

        Thanks for all the ideas! I’ll look into doorbell chimes. I haven’t heard of that idea. That sounds pretty interesting.

          1. Yeah followed the circuit that i found online properly. When I used the proper resistor nothing would happen, and when i used a really low resistor the solenoid worked for a couple seconds and then a puff of cloud would come from the transistor. Soooo i probably just need a more heavy duty transistor or more windings on my solenoid or both

          2. Yeah i had the proper circuit, but it seemed that I didn’t have enough windings in the solenoid because nothing would really happen when i powered it on. When I lower resistor value to pump in more current the solenoid worked perfectly but the transistor would break in the process.
            Sooo i would need beefier transistors and more windings to get it to work. I will try that in v3 when i probably make my own kalimba.

  2. Could try a bar with a felt pad along the back or maybe underneath? I’m thinking something similar to a piano/vibraphone dampener.
    Linear actuator or something rotary, not quite sure what I’d choose, but somewhere to start.

  3. I’d consider making an adjustable bracket with a screw in it to allow for adjusting the length of the plucking arms. This way you could make them longer/shorter as they wear out and also make the plucking arms just a straight stick. So you could use bamboo skewers or anything of similar shape.

  4. Low hopes for realtime keyboard play-ability thru midi. Lag of servos will haunt you, and they are different due to the different length of the arms. Solenoids are used here universally, they are quick. Look into harpsichord jacks not beach-walker legs.

    I could only hear one note due to the player mechanical voicing issues and the ubiquitous low audio level of so many YouTube videos. Average level is minus 12dB, most notes but that one are at a much lower level. As new sophisticated tech comes online, basics are just forgotten. 3D printing vs. audio recording as an example. A guy demos a roll up rubber keyboard on YT, he plays a regular piano at a good level then he starts talking at -20dB. Next time you use a cellphone try using it from 6 feet (2meters) away! Hello….Hello….click. Talk right into the mic, that’s how it works. If you turn the gain up post edit you will hear room reverb and other noise.

  5. Having just seen the self-playing flute video, I think the same thing could be done here. Put all the servos in a remote box and use strings connected to the servos to activate the plucking mechanism. The pluckers can be 3D printed. They should be springy fingers, normally sprung above the tines, and pulled down by string attached to a servo to pluck the tine, or released to its springiness to pluck the tine on the upstroke.

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