My single tube nixie clock. This clock shows HH:MM, one digit at a time, pauses, then repeats. Like the other clock, it also takes its timebase from the 50Hz mains. The time is counted out by 4 binary counters. The output of these is sent to 4, four-channel multiplexers which feed a 4 to 10 line decoder to drive the cathode transistors. Two timers are used, one supplies four pulses at a time that drives the select lines of the multiplexers as well as the tube anode transistors. The second timer is slower, and is used to initiate the "time displaying sequence". The tube is a Russian IN-1. I think. Here's my other clock.