Working with “wireless” LEDs feels a bit like magic. These tiny LED assemblies can emit light without directly connecting to a power supply. The secret to their energy source is a nearby wire coil in which a high-frequency oscillating current generates a fluctuating magnetic field. Each induction-powered LED is attached to its own tiny wire coil, which responds to this changing magnetic field by producing a small (about 2mA) current.
A Little Light Self-Reflection
I often obsess over finding novel ways to use LEDs in projects, such as my weather displaying edge-lit rainbow (build it at here) and Twitter-connected LED matrix handbag. I had impulsively purchased a set of 10 wireless LEDs in mixed colors and a 5V transmitting coil, hoping to generate new project possibilities from this unique LED form factor. Disappointingly, an online search produced numerous articles on how to build your own induction-powered LEDs, but very few examples of ways to use them!
Any project using induction-powered LEDs will be subject to some constraints. Power transfer between the 5V transmitter and the LEDs drops off dramatically over distances larger than a few centimeters, so the coil must remain close to the LEDs. Also, inductive power transmission works best if the receiving and transmitting coils are oriented parallel to each other; this limits the ways in which the LEDs can move while remaining illuminated (see Lee Wilkins’ “Inductive Adornments” in Make: Volume 81, and “Skill Builder: Induction Instruction” and “Inductive Charging Bag,” both in Volume 41].
With these restrictions in mind, I wondered how wireless LEDs would look inside a kaleidoscope. The idea was compelling because a small number of colorful lights could create a large visual impact through repeated reflections in the kaleidoscope’s symmetrically placed mirrors. Induction-powered LEDs are particularly well suited for this use because they’re free to slide around when the kaleidoscope is moved, generating dynamic patterns with their shifting configurations. Encouraged by the possibilities, I designed and built this laser-cut kaleidoscope that uses wireless LEDs to generate colorful illuminated patterns. You can create your own version of the build from the instructions that follow.