Elide Sulsenti © 2021
DIY MOTORISED INSTRUMENTS
Designing and building a new circuit to play Lisa Streich's Pietà
How it started…
This project I share here documents the reconstruction of the motorized system for Pietà, a piece by Swedish composer Lisa Streich for motorised cello and motorised instruments installation. This work originated from a very concrete situation: the original system, created at IRCAM when the piece was first conceived, was characterized by a particular delicacy, meaning the unpredictable behaviour of the system, but also his sensibility to every movement or sound of the performer.
My re-design was not just technical, but relational. I worked in dialogue with the composer, carefully studied existing versions, and designed a new Arduino-based circuit capable of automating the motor movements through a synchronized timeline. The result is a system that is more stable, reproducible, and with a more legible script, allowing the performer to interact with the setup more naturally guided by a click track and able to focus more deeply on interpretative expression.
This reconstruction stands, for me, as a clear example of how taking care of technical objects is an essential part of the performative act. Caring for a fragile system, making it transmissible, turning it into something truly usable and understandable, is a gesture that speaks as much to the technical dimension as it does to the ethics of making music today.
How to build a circuit for performing PIETÀ by Lisa Streich
Materials List
To build the motorized circuit, you will need:
Electronic Components
Power and Connectivity
Control Interface
Step 1 – Preparing the Enclosure
To start building the circuit, the first step is preparing the enclosure.
I used a standard cable management box, like the ones typically used in offices to hide wiring.
I drilled 11 holes in the front panel to fit the 11 male XLR connectors that will serve as the outputs of the motor control system.
Each hole should match the diameter and positioning of the selected XLR connectors to ensure a stable fit.
After this, I also drilled an additional hole on the side or back of the box to house the DC power input — in my case, a 2.1 x 3.5 mm jack suitable for the 9V 5A power supply used for the system.
Step 2 – Building the Control Circuit Boards
Once the box and XLR holes are ready, the next step is to assemble the individual circuits for each motor.
Each of the 11 motors is controlled by a dedicated small copper board, where the following components are soldered:
(The very important flyback diode it’s soldered directly on the XLR attach)
You will find a photo showing the wiring diagram and assembly example in the following section.
Here there is a video of the circuit assembly:
…and here of how to solder the circuit (you can judge my soldering skills :) )
Step 3 – Wiring the XLR Inputs and Adding Diode Protection
Each XLR connector on the front panel of the box requires a protection diode soldered between Pin 1 (signal) and Pin 2 (ground).
This diode setup helps protect the control circuit from reverse polarity or unexpected voltage spikes at the input.
A wiring diagram illustrating this setup will follow this section.
Once the diodes are installed, solder the connections, fasten the XLRs in place, and proceed with internal wiring toward the motor controller boards.
Each XLR connector is then connected to its corresponding MOSFET output:
The negative lead (pin 2 of the XLR, where the cathode of the diode is also connected) must be wired to the drain of the assigned MOSFET. This ensures that the negative signal passes through the MOSFET to complete the switching circuit.
Step 4: Preparing the Screw Terminal Blocks (skip this step if you have ready-made bus bars)
To turn each Screw Terminal Block into a continuous rail (i.e., making all its terminals electrically connected), you need to bridge the terminals manually. Start by cutting a piece of insulated wire into several short segments, each about 2 centimeters long. Strip approximately 5 millimeters of insulation from both ends of each segment. Then, insert each wire segment across two adjacent terminals: connect terminal 1 to terminal 2, terminal 2 to terminal 3, and so on, until all terminals in the block are interconnected. Tighten the screws to secure each wire segment in place. When done, each terminal in the block will be electrically linked to the next, forming a shared positive or ground rail, depending on its intended function in the circuit.
Step 5: Connecting Screw terminal blocks / bus bars to the power supply
Now, take the power jack connector, compatible with your power supply. Connect the positive-bus bar with the positive of the connector (usually the pin in the center), the negative-bus bar with the negative.
Step 6: Final Circuit Integration
At this stage, all components of the circuit are connected. The positive and negative bus bars are directly powered through the jack input mounted on the enclosure. From here:
This configuration ensures that power is distributed correctly across all components, with a unified ground reference and safe current routing via the MOSFET-controlled motor lines.
Step 7: Assembling the Motors and Cabling System
For each of the 11 DC motors, I prepared a dedicated cable of approximately 1.5 meters in length, consisting of a positive and a negative wire. Each wire was soldered directly to one of the two motor terminals: the positive wire to one terminal, and the negative wire to the other. I then connected the wires to an XLR female connector, where the positive wire was soldered to Pin 1, and the negative wire to Pin 2, following the standard configuration used in the control box.
Once each motor was connected to its XLR cable, I moved on to building custom holders for instrument mounting. These supports were tailored to each use case:
Additional Instrument Motor Mounts
Following the setup of the motors for the solo motorized cello, I proceeded with the installation of the motors on the remaining instruments involved in the installation. Each setup was adapted to the physical characteristics of the instrument and the acoustic behaviour of the motor activation.
Step 8: Downloading and installing the scripts/projects
Download THIS FOLDER
It contains a MaxMSP project (adapted from a previous project by Alessandro Perini, to perform his piece “Epicentro” for piano, 10 vibration motors and two contact microphones), including Port D and Port E patches; a Reaper Project, with the timeline and each motor line; the 2 Arduino scripts for Port D and Port E.
To install the scripts into arduino, first install on your Computer ArduinoIDE. Then write both scripts, port D in one Arduino, Port E in the other.
Step 9: Connecting motors-circuits with Arduinos
Last step to make the circuit work it’s to connect each circuit to Arduino.
Take 11 male-female circuit connections for Arduino, the male side goes to the pin header on the circuit of the single motor, the female on one PWM pin of Arduino.
I connected as following. The second number corresponds to the corresponding MIDI channel in the Reaper Project
I suggest to write the numbers on each board and under each XLR attach, and the name of the corresponding Port on each arduino.
Step 10: Play with the circuit
Once you have everything done:
- Connect each motor to the XLR attach
- Connect to the computer first Arduino Port D, then Arduino Port E (in this order)
- Connect the power jack to the power supply
- Open the Max sitoPatches, press D on the patch of PortD, E on the patch of PortE
- Open Reaper Project, make sure that communicates via MIDI with MaxMSP
- Plug your headphones for Click track
- Now play with it …if it doesn’t work, you can contact me Here :)