Instructables user [janw] is a big fan of nixie clocks, but he had never built one before. He decided he would rather start small and build a clock using numitron tubes first, before moving to nixies. He preferred the simpler tubes due to their much lower voltage requirements and the fact that he would not have to use any specialized power supply for his project.
His clock serves double-duty, functioning as a thermometer as well. Timekeeping is regulated with a DS12307, and temperature is monitored using a DS18B20 single wire sensor – both of which are pretty common in these sorts of projects. Both are wired to an Atmega48 MCU which serves as the brain of the clock.
The numitrons were mounted in a handsome 5-layer milled acrylate stand with a pair of buttons mounted on the bottom which allow him to set the time. It really is a spectacular looking timepiece, and a great first effort on [janw's] part.
Be sure to stick around to see a video of the clock in action.