Digi-Vista Nixie Clock From 1970

[Mitch]

I just finished doing a little restoration on this clock. I replaced the electrolytics and missing feet, cleaned the contacts, and dusted it off. One of the ZM1000s was bad, but only because I dropped it on the floor. I bought the clock several years ago, It came with both issues of the magazine, a complete set of extra tubes, ICs, circuit boards, and various components including documentation from Southwest Technical Products. Obviously the builder had in mind to keep it running through the ages. 

This version also reads tenths and hundredths of seconds. The original projects in consecutive issues of Popular Electronics from December, 1970, and January 1971, were for four and six digit clocks, so the builder customized the design himself. I don't plan on keeping it running continuously, just special occasions. 

[Mitch]

I don't remember how I got it. This is the same clock.

http://shadowtron.com/2017/03/11/a-hand-built-nixie-tube-clock-based-on-the-digivista-design/

[Keith Moore]

This is absolutely glorious!  I love it. 

It would be swell to create a modernized BoM and see if a modern simulated kit could be assembled for broader use by us nixonians here. 

[Terry S]

Interesting. Based on the 60 HZ AC line, so the last two digits show 60th's of a second, not 100th's. I can't decide if I like that. I know I don't like the frantic counting in general. I really am not even fond of seconds on some clocks.

Mitch, does your clock actually show 100th's? If so, how is derived?

Terry

[GastonP]

I could think of using a higher frequency PLL and synching based on 10Hz. This would allow the circuit work on 50Hz mains countries too, and as this kind of clocks are appreciated mostly based on long-term accuracy, it would not be very difficult to implement too. Kind of overkill, yes, and I don't know if they would implement such kind of solutions for a clock back in the 70's.

[Mitch]

Terry, I never even thought that the last tube was running at 60Hz! The tenth seconds digit does appear to cycle through all ten digits within one second, though. 

All five circuit board that hold the tubes, appear to be identical.

[Terry S]

Mitch, in the video you linked to, the last 2 digits are clearly counting 00 -> 59. 

[Terry S]

I take that back!!! I slowed down the video to 1/4 speed -- and the last two digits are counting 00->39,50->59,40->49 ..... That next-to-last tube is mis-wired somehow or the counter is seriously messed up.

I can't slow it down enough to tell if the last tube is counting 0->9 correctly.

Funny! Great opportunity to troubleshoot the clock. 

Terry

[Mitch]

Terry, I think I'll leave it the way it is, and I may build another one with six digits, as in the magazine. The only major part missing from the spare parts box that came with the clock, is the transformer.

[Terry S]

Argghhhh! It would drive me nuts and I'd HAVE to fix it. It's probably just a couple swapped wires at the tube socket.

Good luck on the build.

Terry