Many of the clocks we feature here on Hackaday are entirely built from scratch, or perhaps reuse an unusual display type. But sometimes, an old clock is just perfect as it is, and only needs a bit of an upgrade to help it fit into the modern world. One such example is the lovely 1960s Copal flip clock (in German, Google Translate link) that [Wolfgang Jung] has been working with — he managed to bring it squarely into the 21st century without changing its appearance one bit.

Like most flip clocks from the 60s and 70s, the Copal clock uses a small synchronous AC motor to advance the digits. Because this motor runs in step with the mains frequency, it also acts as the clock’s timing reference. However the original motor had died, and a direct replacement was impossible to find. So [Wolfgang] decided to replace it with a modern stepper motor. He designed a small PCB that fit the original housing, on which he placed a Trinamic TMC2225 stepper motor driver, a Wemos D1 Mini and a small 5 V power supply.

Thanks to its WiFi connection, the D1 can find out the correct time by contacting a Network Time Protocol (NTP) server. Displaying that time would be tricky with the original hardware though, because there is no indication of which numbers are displayed at any time. [Wolfgang] cleverly solved this problem by placing an IR proximity sensor near the lowest digit, allowing the D1 to count the number of digits that have flipped over and thereby deduce the current state of the display.

There’s plenty of fun to be had with classic flip clocks like this, and with a bit of hacking any old split-flap display should be usable for your own clock project. If none are available at your local thrift store or yard sales, you can always roll your own.