Miniaturization has long been the primary factor that has pushed technology forward. Modern processors can have billions of transistors — each a tiny switch — on a chip that easily fits in the palm of your hand. A 7nm transistor is just 14 silicon atoms long, and is small enough to start experiencing quantum tunneling. Even the smallest LEDs are many, many orders of magnitude larger than modern transistors, which is why its so impressive that Imgurian Fredtemp was able to cram 384 RGB LEDs onto single 16mm cube — and do it by hand.
16mm is the same size as common dice, and if we do the math, that means that each side of Fredtemp’s cube has 64 individual RGB LEDs on it. Those are arranged in a matrix of 8×8 LEDs, which works out to a pitch of just 2mm. Each of those LEDs measures just 1x1mm, and has four points that need to be soldered. The LEDs have either a common anode, or a common cathode. Three pins are needed for red, blue, and green, which is why four total pins are required. As you’d expect, these are all SMD (Surface Mount Device) components, as there isn’t nearly enough space for through-hole versions — if those were even manufactured at this scale.
The back side of each 8×8 RGB LED matrix has a IS31FL3733 LED driver chip that can be controlled over I2C. A seven board hidden inside of the cube contains an STM32FG04 microcontroller that connects to the LED driver chips. The final part of the recipe is a Qi wireless charger, which powers the cube through a pair of thick enamel wires that act as a pillar between the power receiver and the cube. With a simple glass jar acting as a cover, this LED cube is a miniature and colorful work of art. The soldering required to connects the LEDs is very impressive, as was the design work that way into designing the matrices.
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Author: Cameron Coward