Split-Flap Analog Clock Display

Split-flap displays – which literally flip flaps to show what is on them without using further energy – were once common in areas like airports and train stations that need to display intermittently changing information. They can also be used for digital clocks, sequencing through flaps that have different numbers printed on them. The Klapklok clock, as featured on Yanko Design, implements this retro-tech a little differently, using split-flap pixels to “spin” analog-style clock hands.

The Klapklok is built from 69 separate split-flap pixel elements, arranged in a rounded square pattern, or what one might call a low-resolution circle. Flaps flip from black to white as pixels with a resolution of one-half dot per inch, causing the displayed hour and minute hands to rotate around the face. The device is 13mm thick, or roughly one-half inch on one’s wall, though you’d need to leave some space for the actual flap movements.

Flaps change every 2.5 minutes for hand advancement, and per its split-flap nature, it doesn’t emit its own light, sort of like an e-paper display. It also shows the hour as numbers once per hour, and can show low-res pictures via a simple drawing app. As something of a bonus, changing the flaps emits a subtle sound that marks the advancement of time.

While details on the build are rather scant, miniot describes what’s going on beneath the surface as “an advanced array of spools, magnets and electronics.” The description does mention Bluetooth, so perhaps there’s an ESP32 or nRF chip involved. These clocks are available for purchase, but one could also view them as an excellent source of inspiration for your own project!