Railroad clock
Idea
I like trains, so when someone dropped me a working clock from a train station, I needed to get it to work and put it on the wall. This clock is from the previous era, when things were more analog than digital, so the clocks at a particular station were connected to a single bus. There was one master clock, which reversed the polarity of the bus every minute, and several slave clocks. I naturally got the slave one. Electrically, it is just a DC motor requiring about 15V to run fine. To drive it, I overengineered an ESP32 board described over here.
The clock
