This 7-Segment Clock Is a Mechanical Marvel

Seven-segment displays form the heart of many electronics projects. The vast majority of them are, of course powered by LEDs, or perhaps some other light source. Michael Klements' clock, however, doesn’t use lighting at all, but instead implements 28 micro servos to manipulate its 3D-printed segments. When a segment is to be shown, it’s rotated parallel to a backing plane, fully displaying its green surface area. When “off” each is flipped at 90 degrees, only revealing a slim side portion that’s painted black to blend in.

If this sounds familiar, we featured his prototype two-digit trial here, but now he’s expanded things to four digits to indicate hours and minutes, two dots for separation, and a black backing plate that holds things together. Servos are driven by a pair of PCA9685 PWM modules, which are in turn controlled by an Arduino Uno via I2C. The system utilizes a DS1302 RTC module to keep the clock running on time.

It’s a neat take on timekeeping, reminiscent of flip-dot displays that were at one time common sights in transportation hubs and the like. As with those, this clock features a unique mechanical sound when changing digits, and since up to 62 of these drivers can be chained together, one could theoretically control well over a hundred digits!