ColorChanging LED Makes Techno Music
As much as we love addressable LEDs for their flexibility, why do we still need control? At least the members of the MusicMaker HackLab, part of the Artifact Festival this February, learned that sometimes we just need to sit down with our electronics and listen.
As the Artifact festival drew to a close, they still had the color-changing LEDs left over from a neat toy reverb mic. When powered by a 9V battery, the LED lights up with a small indicator light that blinks on and off and mixes the best of the three primary colors. Acoustically, however, he spent most of his time mute.
As you know, this type of LED has a small integrated circuit. This integrated circuit modulates the current through the light-emitting junction according to the programmed pulse width, producing a colored light effect.
To make the LED sound, participants added a 1 kΩ series resistor to the LED's "anode," which effectively converts changes in current through the LED into measurable voltage changes. This signal can then be fed to a small speaker or mixer. Ice expressed his gratitude for the life-changing changes by singing his own disco song.
This particular ICT operates at a switching frequency of around 1.1 kHz, and the resulting square wave noticeably dominates the mix. However, what we hear there cannot be explained by PWM alone. There is this "percussive" rhythmic sound, pitch and amplitude, and much more that needs to be analyzed and studied. We don't want to spoil your fun by figuring out the horns and squeals (you can spoil as much as you want in the comments), we just say enjoy the video and thanks to the guys at STUK Belgium for sharing their knowledge.