I finished my Nixie tube clock. (My first try at this was around 1971.)
http://www.swtpc.com/mholley/PopularElectronics/Dec1970/PE_Dec1970.htm
I could not figure out how to wire the tens of hours module to the hours
module. The magazine article was very vague and even misleading about that.
So one night I sent an email to Gary Kay, the designer, and the next morning
I had a response. How is that for tech support 35 years after the fact?
Gary Kay later designed many of the SWTPC 6800 computer systems.
http://www.swtpc.com/mholley/History/Gary_Kay.htm
http://www.swtpc.com/mholley/BYTE/BYTE.HTM
Michael Holley