Electronically, the only differences from the previous type 2a clocks are the use of a PIC16F627A processor instead of a 16F84, and the larger Russian Nixies. For this clock, I used a home-made single-sided PCB instead of perfboard construction.

Clock interior photos Here are pictures of the circuit board, with the right tube removed to show the details of the simulated tube sockets. I used large crimp pins (like the kind that go in a hard drive power connector) with the crimp part broken off. They are inserted through the PCB, flared slightly on the back side, and soldered in place.