What they don't tell you about starting a band is that the hardest part is organizing the people. So, why not skip that step and build a bunch of MIDI controlled robots to play music with?

In this project, you'll mount servo motors over the strings of a lyre. The servos will pluck those strings when they receive MIDI NoteOn messages via a Feather RP2040 running CircuitPython. You can control the lyre with an eternal MIDI controller or by sending MIDI out from your favorite DAW program.

The entire build sits on a plate of acrylic with some 3D printed parts. The servos have 3D printed horn extenders to pleasantly pluck the strings.

The servos are driven by the PCA9685 servo driver breakout. The driver board has an external 5V power input and connects to the Feather RP2040 over I2C.

A Note on Robotic Instruments

All acoustic instruments are slightly different and, as a result, if you build this project, you may need to do some fine tuning to the mechanical aspects of the design for best results. This lyre was used for the build because it seems to be a common shape for budget lyres and is from a known budget music brand (Donner).

The parts that were the most finicky to dial in were the servo horns and the acrylic pegs that lift the acrylic base. It's important to achieve a proper balance between these two measurements for the best timbre from the lyre, with less than a millimeter often making a difference. All of the design files are included and should work as-is, but the source files are also available if you find you need to adjust things.

Parts

Angled shot of black rectangular microcontroller "Feather RP2040"
A new chip means a new Feather, and the Raspberry Pi RP2040 is no exception. When we saw this chip we thought "this chip is going to be awesome when we give it the Feather...
$11.95
In Stock
Adafruit 16-Channel 12-bit PWM/Servo Driver with I2C interface
You want to make a cool robot, maybe a hexapod walker, or maybe just a piece of art with a lot of moving parts. Or maybe you want to drive a lot of LEDs with precise PWM output. Then...
$14.95
In Stock
High Torque Metal Gear Micro Servo  with three pin cable
Add more power to your robot with this metal-geared MG90D servo. The tiny little servo can rotate approximately 90 degrees (45 in each direction) and works just like the standard...
$9.95
In Stock
5V 10A switching power supply brick with IEC power port.
This is a beefy switching supply, for when you need a lot of power! It can supply 5V DC up to 10 Amps, running from 110V or 220V power (the plug it comes with is for US/Canada/Japan...
$29.95
In Stock
Detail of Slotted Aluminum Extrusion end
Oh boy, now you have no excuse for not building that robot! Nothing is easier or faster than building with extrusion and we've added 20mm square aluminum extrusion and components...
$7.50
In Stock
2.1mm DC Barrel Jack cable with Alligator Clip ends
Turn a wall adapter into a mini power supply with this incredibly useful adapter. A high quality molded 2.1mm DC barrel jack is brought out to red (center positive) & black (ring...
$1.95
In Stock
1 x USB C to USB A Cable
2 meters long
1 x Pack of M4 T-Nuts
for 20x20 extrusion
1 x M2 screws
M2 hardware
1 x 16 String Lyre Harp
Donner 16 string lyre harp

This guide was first published on Mar 22, 2023. It was last updated on Jun 20, 2024.

This page (Overview) was last updated on Mar 08, 2024.

Text editor powered by tinymce.