A geeky Christmas decoration made with 56 LED Neopixel and controlled via an Arduino Micro board from Open Electronics:
Let’s take a look, therefore, at the project’s electrical section, that is essentially composed of a set of 56 Neopixel LEDs, that have been arranged so to form two concentric stars; the first 35 RGB LEDs (out of 56) form the bigger, external star, while the other 20 ones form the smaller and internal star. The LED number 56 is placed exactly at the center of the printed circuit board, that has the shape of a five-pointed star.
The Neopixel LEDs are connected in cascade but powered in parallel; such a configuration enables to address each single LED and to individually choose the colour; among the possible hues, the 256 possible combinations for each primary colour (therefore we have 256x256x256 combinations!) determine a total of 16,777,216 colours: that’s what one would call true colours!
More info at Open Electronics’ Open Source projects page.