Nixie Clock 2

After completing Nixie Clock 1 over a year ago, I still had an extra set of IN-12B tubes that were not being put to good use. Time to build another one. Actually, I ordered yet more tubes and driver ICs so I could build 3 more.

The basic design is almost the same as Clock 1: Russian IN-12B with a K155D1 driver for each tube, shift registers to run the drivers, and this 180V power supply design. A DS3232M is provided for the RTC. There are a few changes; remembering some lessons learned when I built clock #1, I made the following list of improvements:

• Simpler (or no) sockets. Most of the time towards building the first clock was wiring the 72 pins on the tube sockets. If I could somehow avoid doing that, it would save me lots of time. I ended up using pins from cheap DB25 connectors, which when taken apart (easily) get you 25 pins which are the perfect size to accept the IN-12 pins. They might work for other tubes also.
• PCB for components. After designing some PCBs for some of my other projects, I realized that it really isn't that hard. Having a PCB should make everything smaller and neater, and cut down on assembly time. I made 2 PCBs: one has the power supply, microcontroller, RTC and drivers, and the other serves as the "socket" for the tubes, which plugs into the driver board. This makes for a very compact design for the IN-12 end view tubes, and I could change out the carrier board if I ever want to experiment with other tubes.
• Some kind of case (3D printed) which is easily replicated and doesn't require many hours of hand filing like Clock 1.
• ESP8266 powered. This would give Internet access, and I could also use UDP for some remote control features instead of an IR remote, which would allow greater flexibility when interfacing with other projects, as I have always intended for these displays.