A re-visit of 2018’s ornament but with a more refined design. 2018 has auto-colour-changing LEDs directly across 2 AAA cells with the current draw being rather high. This iteration replaced them with standard RGB LEDs, driven by a IS31FL3733 LED matrix controller and a STM32G030 generating the patterns. A single AA cell is used with a 3V boost to give steady brightness over discharge and a dramatically longer battery life than before.
The construction is a controller and LED PCB at the back, with a diffuser PCB on the front and a light baffle in between to minimise light-bleed. A 3D printed-in-place surround captures the diffuser PCB and press-fits onto the controller.
Fred Temperton 