These Light-Up Dice Have an Inductive Party Trick: No Digital Electronics Inside!

Electronic dice often use microcontrollers or discrete circuits to generate random numbers with LEDs displaying the values. A maker named Gammawave shows how to build inductive LED dice that will become an instant party trick. These inductive dice work without an MCU or other digital electronics. Well, electronics other than an off-the-shelf inductive charger.

The 3D-printed dice measure approximately 20 millimeters cubed. Inside are 21 surface-mount LEDs connected to the die's six sides. Each side has a hand-spun coil of wire connected to them. That is the extent of the dice's electronics: some wire and LEDs! So then, how does the die show a number?

Power for the dice comes from an unmodified inductive charger pad. Gammawave says anything capable of providing five to 15 watts of power with a diameter of 100 millimeters should work.

When the wireless charger pad attempts to access the nearby device, its electromagnetic pulse excites the closest coil parallel to and (effectively) touching the pad. The result is one face of the die's LEDs lights up. Attaching LEDs in a pre-determined pattern means all six sides are numbered one through six.

There are two 3D-printed structures. First, an inner set of panels hold the coils and LEDs. Once you assemble these six sides, place them inside a second structure. The second, or outer, shell helps hide the LEDs' location and gives the overall design a smooth look.

To build one, check out Gammawave's inductive dice tutorial. In addition to the build instructions, there are details on the electromagnetic theory behind the dice!