Tag Archives: Mozzi audio library

Field Lines: An Arduino-powered interactive instrument

Designed by Charles Peck, Field Lines draws on a number of disciplines including physical design, carpentry, circuit design and coding. The instrument itself includes three sections of magnetic material: magnetic sand, a compass array and zinc-plated iron.

“Audiences are able to manipulate these materials with a magnet in the space below each case while infrared sensors pick up their movement,” Peck wrote in a recent blog post referenced on the official Arduino site. “The sensors send that information to an [Atmel-powered] Arduino board, which then creates unique music for each section.”

Field Lines premiered at the Bakken Museum in Minneapolis to a mostly adult crowd this past March.

“I ran into a few kinks, which I was subsequently able to solve, but for the most part I was able to enjoy meeting with the curious audience and seeing how they interacted with the musical and physical materials,” Peck explained. “Since then, the piece has found a home at the Works Museum, which caters to elementary age students. There it has been integrated into their ‘Sensor Zone’ exhibit.”

According to Peck, Field Lines is powered by an Arduino Mega 2560 (ATmega2560), which was selected due to its 16 analog inputs and the Mozzi audio library.

“This is a terrific ‘almost 9-bit’ open-source library for the Arduino platform. Having said that, the library comes with its limitations (or at least it did, it is being improved by leaps and bounds every day). The main issue being a high and continuous ringing pitch, which seems to be derived from the sample rate (16kHz),” he continued. “After a bit of digging, however, I discovered that this issue can be solved with a small electronic circuit. The circuit combines a low pass filter and a twin-t notch filter in series and you can find the schematic floating around on the Mozzi website.”

Interested in learning more about the Arduino-powered Field Lines? You can check out the official project page here.