Having acquired some IV-9 Numitron tubes I set out to make a mandatory clock project. I already had a home temperature and humidity logger running so I wanted the clock to double as a simple display for those readings.
The build contains an Arduino Pro Micro which drives the tubes with two TLC5940s. Logger readings are received from the central server using MQTT and an ESP8266-01. On start-up the clock also fetches the current time from the server to initialize its RTC module. The display can be shuffled with a rotary encoder knob. The whole thing is packaged inside an old bakelite field telephone case which suits the retro Numitron look pretty well.