4-LED Octal Clock Demands Colorful Math

We’ve all seen LED clocks where RGB LEDs are used to display time. It seems like the simpler the interface, the more likely you’d need to do math to figure out the time. This Octal Clock by Alex Kurrasch proves the point by using only four LEDs: the top two show hours and minutes, and the bottom two LEDs are multipliers. Using octal numbering, inventor Alex translates the data using a Venn diagram of color mixing. The mapping uses 1 as red, 2 as green, followed by yellow, blue, magenta, and cyan. It ends with 7 as white (all on) and 0 as black (all off).