For more documentation go to www.seseyann.com/plinkjet
By Lesley Flanigan and Andy Doro
Plink Jet is a robotic musical instrument made from scavenged ink jet printers. Plink Jet explores instrumentation as a process of structuring noise to create a musical experience, and performance as a relationship between human improvisation and machine order. Plink Jet also explores ideas concerning curiosity, invention, and expression regarding the role of technology in our everyday lives.
Interaction Design, Repurposing of Consumer Technology, DIY, Performing Technology, Robotics, Automation
Plink Jet is a robotic musical instrument made from scavenged ink jet printers. The mechanical parts of four inkjet printers are diverted from their original function, re-contextualizing the relatively high-tech mechanisms of this typically banal appliance into a ludic musical performance. Motorized, sliding ink cartridges and plucking mechanisms play four guitar strings by manipulating both pitch and strumming patterns like human hands fingering, fretting, and strumming a guitar. Plink Jet is designed to play itself, be played, or both. The result is an optionally collaborative performance between both the user and Plink Jet, with the user choosing varying levels of manual control over the different cartridges (fretting) and string plucking speeds (strumming).
Plink Jet is designed to play guitar strings both manually and automatically. The interface consists of four toggle switches, four three-way switches, four dials, a single six-position rotary switch and a single power switch. Each of the four toggle switches and three way switches is associated with a single ink carriage. The rotary switch allows the user to select different pre-programmed patterns while a carriage is under automatic control.
The guitar strings are strung across the printer mechanism where an optical sensor used to be. Cartridges slide up and down the strings and touch the strings just enough to change the pitch, similar to a slide guitar. The farther away the cartridge is from the plucking mechanism, the lower the pitch of the note.
Each carriage is controlled by a toggle switch and a 3 way switch. Toggle switches control whether its associated inkjet carriage is under manual or automatic control. While under manual control, the back and forth motion of each carriage is controlled by a three-way switch. While under automatic control, the carriage is controlled by a micro-controller containing programmed patterns of movement.
The guitar strings are plucked by motors outfitted with a single thin metal strip that strikes the string as it rotates around. Four dials control the speed of the strumming motors. This happens irregardless of whether the associated carriage is under manual or automatic control.
Inside each ink cartridge is a piezoelectric microphone used to pick up the sound of the guitar string being plucked as well as the ambient sounds of the sliding cartridge. Like an electric guitar, Plink Jet has a single half-inch output jack used to connect to an external amplifier.
The printer carriages and motors are from four inkjet printers. The controlling circuits and electronics are custom-designed. The optical encoder of each inkjet printer has been removed and replaced with a tunable guitar string that uses actual guitar tuning mechanisms built into the machine.
While under manual control, Plink Jet’s circuitry is completely analog. The only digital element is the micro-controller used in automatic mode.
3.1.1 DC Motors
A DC motor connected to an H-bridge chip controls the back and forth movement of each carriage. While in manual mode, the three-way switch controls the H-bridge with a 5VDC. While in automatic mode, the H-bridge is under the control of the micro-controller.
3.1.2 Stepper Motors
The strumming mechanism is driven by stepper motors, normally used for the docking procedure of the ink carriages. Each dial is attached to a potentiometer which controls the speed by changing the voltages on an oscillator chip. The oscillator signals are connected to hex divider chip, which acts as a stepper driver. The stepper signals are then relayed through a Darlington array before triggering the stepper motors.
Plink Jet uses an ATMEGA168 chip containing six pre-programming patterns to control the fretting when a carriage is in automatic mode. A six-position rotary switch selects which pattern to use. When a carriage is in automatic mode, the ATMEGA controls the associated motor’s H-bridge.
Plink Jet at ITP Winter Show 2007
4. STRUCTURE AND IMPROVISATION
Plink Jet explores instrumentation as a process of structuring noise to create a musical experience, and performance as a relationship between human improvisation and machine order.
Structuring noise is fundamental to instrumentation and musical composition. As an instrument, Plink Jet amplifies the ticks, clicks, and hums of an ordinary printer. The incorporation of a guitar string highlights structure inherent in a mechanized system by relating pitch and rhythm directly to the mechanics. We made a musical instrument by designing an interface that gives a person playful control over the mechanical operation of these printers and combining the mechanical components with those of a traditional electric guitar.
Numerous options for playing Plink Jet back and forth between manual and automatic control creates a dialog between the player of Plink Jet with the robotics of the mechanisms themselves. Reflecting upon this interplay between a mechanical presence and human player, Eric Singer of LEMUR has said “I believe it is an entirely new experience for the human players. The robots create a physical, responsive presence (unlike synthesizers) which can profoundly affect the humans interacting with them. Because they move as well as sound, they take on a personality of sorts, and inspire the human players in a unique way.”  Intuition, playfulness, and improvisation are key concepts embodied in the operation of Plink Jet. Beyond its direct mechanical relationship to a human player, Plink Jet references a musical collaboration between members of a band and between a single musician with his or her instrument.
5. REPURPOSING OF CONSUMER TECHNOLOGY / DIY
Plink Jet also explores ideas concerning curiosity, invention, and expression regarding the role of technology in our everyday lives. The repurposing of consumer technology is a growing trend for artists and technologists in the DIY genre exploring circuit bending, hardware hacking and retro-engineering . Artists who have used the mechanics of printers for producing sound include Paul Slocum with his dot matrix printer and Eric Singer's scanner-inspired musical instrument, GuitarBot. The innovative American composer Harry Partch also built many of his instruments out of trash and his own carpentry. Plink Jet’s emergence from the process of hardware hacking offers it for consideration as an Infra Instrument, a concept developed by John Bowers and Phil Archer. Infra-instruments come from beneath and are below the standards we would want of well-constructed instruments, but they are a valuable addition to the NIME research agenda with concern for technology, musical practice, and playful aesthetics . Inside an ordinary ink jet printer are the same toy-like, clockwork mechanisms that have delighted people and sparked imaginations for centuries. In the creation of Plink Jet, we have investigated how human improvisation can interact with these mechanical forms. Plink Jet transforms the predicable function of a printer into a unique and irreproducible performance.
We would like to thank Danny Rozin, Todd Holoubek, Tom Igoe, Gian Pablo Villamil.
 Lotti, Giulio. LEMUR: League of Electronic Musical Urban Robots. < http://www.simultaneita.net/lemur2.html>.
 Ramocki, Marcin. DIY: The Militant Embrace of Technology. <http://ramocki.net/ramocki-diy.pdf>.
 Bowers, John, & Archer, Phil. Not Hyper, Not Meta, Not Cyber but Infra-Instruments. <hct.ece.ubc.ca/nime/2005/proc/nime2005_005.pdf >.