Long before we relied on smartphones, smartwatches, or even mechanical clocks to keep us on schedule, humans simply looked towards the sky to figure out what time it was. Rich Nelson has rekindled that idea with a custom clock he designed and built, using ever-changing LED lighting and a simulated sun and moon to vaguely express the time of day.
Inside a wooden box are three staggered layers of card stock featuring various silhouettes of the Philadelphia skyline to create depth, with strips of color-changing LEDs in between each one to create lights and shadows that change throughout the day. The whole thing is powered by an Arduino, which ensures the lighting inside the box closely matches the actual daylight conditions in Philadelphia, where Nelson’s brother lives. But that wasn’t the most challenging part of this build.
What took Nelson the longest to engineer and perfect was a mechanical arm, hidden behind a panel at the back of the box, that moved a small LCD display back and forth across a slow arc. The LCD display was upgraded with a brighter backlight so that as it displayed images of the sun and a crescent moon, a ghostly image of each celestial object would appear to rise and set in the background. You can think of it as a very complex way to indicate AM or PM on this shadow box clock, as the position of each one in the simulated sky was also synced to actual sunrise and sunset times.
Unfortunately, Nelson has no plans to build or sell this clock en masse, but the video he shared of the build is quite comprehensive, and he’s posted the underlying code and CAD schematics to Github if you’re tempted to take a shot at building your own.