This is the desktop binary clock which [Tim the Floating Wombat ... would have at least one LED on at a time. Hours are easy enough to display, but with just four bits how can minutes be shown?

In fact, there are a number of automatic time-tracking options available on the desktop (in your browser, for example), so you don't need to remember to start and stop the timers. Before long ...

The front panel is a black PCB on which sit the LEDs that form the binary display, and its back holds an ATMega328P microcontroller and DS3231 real-time clock. A smart desktop case is 3D-printed ...