I have been working on and off designing this nixie clock. I was inspired to build an alarm clock with old display tubes after having assembled the Ice tube clock from Adafruit. As a mater of fact I took quite a few design cues from the Ice tube clock. The microcontroller used is a ATmega 328p that has a watch crystal attached to keep time, a pwm output is also used to generate the high voltage necessary for the nixie tubes.
The tubes are old soviet IN-12b nixie tubes an INS-1 neon bulbs. They are the cheapest nixie tubes one can get a hold of on eBay. The guts of the clock consists of 3 PCBs, one for the “brains” of the clock, one just for the nixie tubes and a interconnect board to connect both PCBs together.
The Optibboot bootloader is used on the microcontroller so that it can be easily reprogrammed with the help of a serial breakout board that can be plugged into the header pins on the back side of the clock.
At first the PCBs where designed with Eagle but since then I have used Kicad more extensively. For that reason I converted the project over with the help of a handy collections of scripts available here on github. I had to fix quite a few issues with the converted files but even then it saved me lots of time.
The source code and Kicad files for this project are available here: