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The Module


Carbon is a device that translates graphite markings on paper into signals that manipulate sound and visuals. Carbon’s interface is pencil, paper, and an LED screen that reflects the user's marks on paper and translates signals from other modules into light and color. A synthesizer features knobs, sliders and buttons that allow the user to manipulate sound. The opposite ends of a knob or a slider represent two ends of an axis such as slow and fast or low pitch and high pitch, or, in case of buttons, on and off or play and pause. Each of these elements, controlling singular values, combine to form an interface between the musician and sound. On a scale of visible and invisible, the interface of the synthesizer is very visible. It’s difficult to interface with a synth intuitively. The user needs to be knowledgeable about how to make music to experiment or improvise. The interface doesn’t respond to gestures other than turning knobs or dragging sliders. The large number of controls on a synth means these controls need to be arranged in an efficient way. Thus, more important controls which are used more often are more eye catching and easier to reach. While this is important for function, it also creates a bias on ways of interfacing with sound. Some aspect of sound are more important to manipulate while some can be left alone for the most part. Carbon is an experiment on the effect interfaces can have on decision-making and the creative process.

The knowledge of how to use pencil and paper is much more widespread than the knowledge of playing an instrument. Replacing the interface of a synth with a sheet of paper and a pencil opens this device up to people who wouldn’t know how to interact with a musical instrument. The user can make decisions based on the way they want to move their hand or the shape of marks they want to leave on the paper. In a way, Carbon is also a translator between audio and visual. A musician can use the sound output of the synth to guide their drawing in the same way an illustrator can use shapes on paper to control sound. Carbon is born out of a desire to interface with a medium one is unfamiliar with. The lack of technical knowledge in music that started out as an insecurity ended up guiding me through this project in exploring how I can interact with the unfamiliar through the familiar.

Carbon is made based on the synth module Meergranen. Hardware is modified with cables connecting to a piece of paper. Graphite on the piece of paper and the user's body act as potentiometers, replacing the knobs on the Meergranen.

The Process


Initially I wanted to work on a module that has a visual output because I was hesitant to work with sound. I experimented with Processing to combine the synth interface with a visual output instead of audio. I had to abandon this idea after we made a decision that synths need to be functional without a computer. I still didn't want to give up on the visual output concept so I started doing research on LED matrices. Large LED matrices need more pins than the Arduino Nano has, so I decided to work with an Uno. I connected a potentiometer and an 64x64 LED matrix to an Uno and managed to control sizes of shapes on the LED matrix with the potentiometer. My roadmap from here was replacing the potentiometer with graphite and add a sound component.

Experimenting With Graphite:

Graphite is conductive. If we draw a line on a piece of paper using graphite, it can conduct electricity, and the resistance would depend on factors such as length of the line and the amount of graphite on paper. Just as a potentiometer provides variable resistance that arduino can measure as numerical values, it's possible to measure the resistance of a graphite circuit. I taped two jumper wires on paper and connected them to the Arduino the same way I connect pins of a potentiometer. This method didn't work because it wasn't very responsive. I did a little research and found an Arduino library called "Capacitive Sensing Library" and a tutorial on turning graphite drawings into capacitive sensors. With this method the module measures the capacitence of the human body through graphite. This was much more responsive and when combined with the Meergranen module it allowed control of a sound sample's speed, pitch and length.

Final Version

My initial plan was to use the Meergranen at the prototyping stage of graphite interface, and then adapt the results to Arduino Uno and build a module around the uno, which was necessary to include an LED screen in the module. However, with the approaching deadline, it wasn't very possible to rebuild the module and figure out the changes in code. I scrapped the 64*64 screen and went for a much smaller 5*5 led screen. Although the screen worked with arduino mini it did not work together with the Meergranen code, the reason for this is unknown. I decided to experiment with an LED screen at a later time and focused on building the graphite and sound components.

Building the Module

The Components The Capacitive Sensor The Code

The Module in Action

The Manual