The twins. A pair of nixie clocks. DSCN0458

The larger clock was made in 1994-1995. It uses the 16 button keyboard
to set it. It has an alarm and it does 12 or 24 hour modes. It uses National
NL-807 tubes for hours and minutes. NL-803 tubes for seconds.
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The smaller clock was made in 2010. It features National NL-6844A tubes.
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Larger clock has upper box made with real glass.
Smaller clock is 1/8 inch clear plexiglas bolted to inside-frame
aluminum angles 1/2 x 1/2 x 1/16. Inches. (no metric around this joint...)

[@hallpet45]

Looks great Mate.Keep it up👍

[@terrygains8327]

Well done you.
Are the thumbwheels and keypad used for setting the time or alarms etc.?
Kind regards,
Terry

[@leroyjones6958]

The thumbwheels are used for setting. The smaller clock is much simpler. It only has 17 ICs total. It uses (6) of the 74HC160 synchronous counters. In an effort to minimize
complexity and parts count, the thumbwheels also serve as the number loaded on the next clockpulse after either 23:59:59 (for 24 hour mode), or 12:59:59 in 12 hour mode.
As seen in the video, it is operating in 24 hour mode, so the thumbwheels must be left at 0000 so that it goes to that at midnight. If it was in 12 hour mode, the thumbwheels
need to be set to 0100 to make it work correctly. When ever this clock gets set, those wheels must be returned to those values otherwise timekeeping won't work.
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The other larger clock uses about 42 ICs and is much more complex. It has a settable alarm. The keyboard is used to set time, set alarm, turn the tubes on and off,
select 12 or 24 hour mode, and keyboard also controls the seconds counter, zeroing it then holding it until time to turn it loose.
When I built that one in 1994, I wanted an easily settable clock. Just punch in the numbers. Easy to set, hard to build.
it is all wirewrapped. The larger older clock uses a pair of 74LS160 counters for seconds. Minutes and hours are 74LS192. Those turned out to need help
resetting to values less than ten, with the aid of 74LS221 pulse maker (monostable multivibrator) to assure a reset pulse of a defined interval instead of attempting
to reset on a spike. I realize now that 74LS192 is not an ideal counter to make a clock out of for this reason, but it's done long ago, works real well and so I leave it that way.
The most recent effort, a clock based upon the rare 74142 counter/driver........it needs help too. had to actually add 3 more counters to "supervise" the 74142s.
But that clock operates ok, and the parts count for it is 16 ics. So I actually beat my old record of fewest ICs by one IC. Those old old TTL counters are hard to
reset properly on the fly to make them be modulo 6 instead of modulo 10, and then the entire modulo 24 business gets even stranger yet. But a 4024 binary counter
came to the rescue there, because bits "16" and "8" are ANDed together, so it spits out a nice pulse when N=24. It needed a 74HC221 to make a solid reset pulse of 100 uS.
74142, by far not the most efficient way, but has it ever even been done before? I wonder.

[@terrygains8327]

@@leroyjones6958 That's Genius.
Thanks so much for sharing and inspiring.