Building a clock the hard way

[Adam Vaughn]

Very cool! I have yet to build a nixie clock of my own (though I have a Numitron clock project in the works), but I am the 'lucky' owner of a vintage nixie clock, circa 1972. It was sold in kit form by a company called "B&F Enterprises", which was an early source of nixie tubes and other digital components. It uses Amperex ZM1000R nixie tubes with a red-orange coating, and a series of 74xx-series logic chips (7490 and 7492 counters, plus a 7410 for the hours tens).

As acquired, it had bad filter caps, which I found out the hard way. After replacing those, plus the rectifier diodes they took out, it kept time, though not without numerous random glitches. After several operations, both by myself and friends, it now keeps time rather well. Anyway, here are some pictures:




Getting back on-topic for this site, I also have a HP 59309A HP-IB Digital Clock. Meant as a real-time clock reference for HP's early microcomputers/calculators and digital test instruments using the HP-IB interface, it offers both time and date readout, using the same sort of bubble digits as HP's early LED calculators (same 5-digit clusters as the HP-35, I think). I'm not sure exactly what it uses for the logic (likely TTL), as the circuitry is densely packed inside the small cabinet, but it's quite capable for its time, with provisions for external frequency standards as well as leap year correction.