The 2 tube nixie display is a small compact module that will display a 2 digit number on its 2 NOS (New Old Stock) Soviet IN-17 nixie tubes. It has a 6 pin header for power and serial communications. Its operating voltage is 3.3 volts and it uses serial communications handled by a 74HC595 serial input, parallel output shift register. I/O voltage is also based on 3.3 volt logic levels.

I made it because I wanted a simple, stackable way to make nixie displays for the various projects I like to construct, without having to worry about generating extra voltages or deciding on how to interface them, etc. I ended up liking them so much, that I thought others could benefit from the design as well.

What makes it special is how easy it is to use. it only has 4 serial interface pins and a single 3.3 volt supply and I/O, it's compact in size, its excellent power efficiency, and ease of stack-ability when you want more than 2 digits.

For the user manual and a picture and video of 3 of them running as a clock on a raspberry pi, see the documentation link. The actual python code they are using is there as well.