Tag Archives: pcb

Pneuma World

Design and programming of hard/firm/software for networked control, sensing, and sequencing of pneumatic sculptures by Chico MacMurtrie at the Muffathalle in Munich.  Each piece has its own Raspberry Pi which handles network communication and runs local control algorithms via an Arduino MEGA with specially designed PCB shields operating the valves and reading the sensors.  Puredata is used to translate UDP network data to/from standard MIDI for master sequencing in Ableton Live through each piece’s custom Max For Live device.

Audio Control Unit

Developed and built for the Tsai Art and Science Foundation, this ACU is an updated version of Tsai’s original design which takes audio input from a microphone and translates it into a control voltage that precisely modulates the frequency of a strobe light synchronized to the RPM of the motor driving a kinetic sculptures.


An original analog ACU Left, Arduino/analog hybrid Right

After analyzing the original analog CMOS circuits, I developed a hybrid design that employs the same analog input and output stages, but uses an arduino to handle the analysis and timing stages of the circuit for improved range and stability.



Inside the hybrid ACU

Like Tsai’s originals, this version has it’s power supply built in, 1/4″ jacks for the microphone input (which bypasses the built-in microphone) and strobe output, two trimpots for fine adjustment and a large knob for microphone sensitivity.


Hybrid ACU


Drawing Machine

Developed in collaboration with Olafur Elaisson and his studio in Berlin and exhibited at Tanya Bonakdar Gallery, this machine ‘listens’ to two electro-magnetic transducers on either side of a divided string and uses these pitches to drive two phase-locked sine wave oscillators (transposed 12 octaves lower) which regulate the AC voltage across the voice coil actuators pushing and pulling the intersecting arms holding the pen on an X and Y axis while a disc holding the paper slowly rotates and travels from one side of the table to the other.  The ratios generated by the divided string allow the user to extrude Lissajous curves in a continuous spiral.  In addition to the paper drawing, all drawings are recorded to hard disk and can be played back later, for multiple editions of a single drawing.
This video is of the machine in the installation (well, ‘video mode’ on my handheld point-and-shoot camera).

Electromagnetic Oscillator


After trying and trying to come up with a bow wheel that could maintain effective friction on a surface while isolating the noise of the motor and mechanics from the acoustic resonating chamber, I decided to investigate making an electromagnetic bowing device, like the E-bow. Pictured above is the prototype for such a device. A physical oscillator. There are two coils around AlNiCo (Aluminum Nickel Cobalt alloy) magnetic poles, one a pickup and the other a driver. These are wired to the input and output of an audio amplifier IC and fed back into one another through the spring steel tongue (pictured here with a piezo element under it’s bridge terminating at the 1/4” jack). A digital potentiometer regulates the amount of voltage driving the circuit for dynamic control. Staccato articulation can be achieved by instantly reversing the electrical polarity of the driver to stop the vibration. The gain of the audio amplifier goes quite high, all the way to the 12V rail supplying it and reads as a square wave on a scope even at low gain settings. Because the steel tongue, like a speaker cone in a back-feeding guitar amplifier, is physically unable to jump to the +/- DC poles and has to ‘slide’ to them, a near-perfect sine wave results.

Digitally Controlled Acoustic Percussion

Miniature, modular instruments designed to affix to virtually any structure thereby allow the composer musical control of anything from a battery of specially designed instruments to structural surfaces within pre-existing architectural space.

With an emphasis on simplicity, each of these mechanisms’ design usually consists of only one electromechanical actuator (a rotary motor, or linear solenoid) which responds to varying degrees of supply voltage remotely regulated by a microcontroller. This single-actuator design philosophy demands that all mechanical movement within the instrument be subordinated on the physical capabilities of the lone motor or solenoid employed and, while this may sound like a limitation, such use of mechanical design (as opposed to more ‘intelligent’ electronic design) manifests a reliability, mechanical consistency and modularity that would otherwise not be possible.

Each device can be fitted with a variety of harnesses for mounting and is connected to the brain (box containing the PIC microcontroller and DC power supply) via a single run of cable. Thus, the microcontroller administers the appropriate voltage to hit, shake, scrape, bow, spin, whip, or pluck sound from any sonorous object with the exact precision one would expect from digital control.

Installations and Performances in New York City (Harvestworks, Chelsea Art Museum, Gigantic Art Space, Eyebeam Gallery, Angel Orensanz Foundation, P.S.1 Clocktower Gallery, and The Frying Pan), and worldwide at 2004 NIME conference in Hamamatsu, Japan, 2004; iMAL festival in Brussels, Belgium; 2004 Audio Arts Festival in Krakow, Poland; When The Time Traveller Kills His Grandmother (a survey of current sound art curated by Fritz Welch) 2005 London, England.

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