PythagotronPythagoras of Samos was a man with many hobbys. I know him primarily for his experiments with strings and their musical properties. Thats why I call this robotic string instrument “Pythagotron”.

It features:

  • 2 octaves of pitch range
  • fast and precise intonation
  • 4 actuators for striking, muting, punshing, damping and shorten the string
  • modular and parametric design (OpenScad)
  • most parts are 3D-printed or easy to gather
  • open source



Lets have a look at some details:

The Pythagotron is tuned by this seesaw mechanism. Turning the orange ring clockwise tightens the string



This actuator controls the pitch of the Instrument by altering the length of the string. The mechanics and electonics of this device are very similar to that of a 3d-printer.






This is a servo-drive
n plectron. It can do alternate picking and it can also mute the string by touching it.



The same kind of actuator I use inside the Techtar. It’s just a 3d-printed linear solenoid actuator with a cap of soft pla-plastic. The velocity is controlled by the width of the driving pulses comming from a mosfet-transistor.



While the plecelec can fully mute the string, the Damper is designed to simulate the continuus muting of a palm. All the white parts are printed with relative soft filament to isolate the the Pickup from the mechanical noise , produced by the actuators.




The pickup consists of a 27mm Piezo and an opamp-driven charge amp.



This is the brain of the Pythagotron, it’s controlled via an Arduino Nano. The stepper motors of the stingshorter an the damper are driven by SilentStepStick motor drivers, which provide very quiet stepper operation. The Kickup is driven by one of the two mosfets. Next to the Arduino sits a StepDown Converter which converts the 20V Input to 5V for the Arduino and the Servo.



Host Software
The Pythagotron is controlled by a software I made with Pure Data, running on a  self made Raspberry Pi based tablet. It features a dedicated Sequencer to control each actuator independently. The Tablet can also take midi information and convert them to pythagotron compatibel serial commands.



Source files are available on Github

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