The build relies on that old stalwart, the Arduino Uno, to run the show. It’s hooked up to a DS3231 real-time clock module so it can keep accurate time for long periods, as is befitting a clock.

The PS/2 synchronous serial clock is easy to interface with an Arduino ... The 16u2 is normally used as the Arduino Uno’s USB interface. The only external hardware needed is a single 120 ...