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Old 29th Jul 2022, 10:51 am   #1
agardiner
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Default Nixie Clock

So, further to a request from another member, I received for repair an interesting Nixie clock. I guess from the construction that it is probably early to mid 70's. I didn't realise that any clocks using Nixie tubes had been commercially made; thought it was a recent thing made by hobbiests who wish to keep Nixie technology alive.

Plugging in the unit, it was immediately obvious what the issue was; all the nixie tubes just glowed on all segments; just a mush. On disassembling, I was surprised to find that it was all discrete logic chips, plus a nixie driver chip for each tube. I don't know what I was expecting to be honest. Does anyone know when the first all in one clock IC appeared? Anyway, a lot of IC's crammed into a small package. A visual inspection showed a rather cooked looking component, which looked like a resistor marked at 120K. Removing it and testing proved that it was in fact a diode and was OK. It was the rectifier for the HV supply for the tubes. As it was charred, I replaced anyway with a 1N4007. Turning my attention to why the clock didn't work, I quickly established that there was no LV supply for the IC's. The supply was a conventional transformer, bridge, capacitor and then a TIP29C transistor as a regulator for 5V. The LV AC component was also fed via a 1N4148 to the counter circuit.

The fault was then traced to an open circuit PCB track from the transformer to the bridge. Everything else tested OK, so I remade the track and presto, the clock was running again. An interesting piece, and a nice looking unit. Photos below.
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Old 29th Jul 2022, 11:21 am   #2
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Default Re: Nixie Clock

Well done and thanks for the report. Fixed in one post!
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Old 29th Jul 2022, 11:33 am   #3
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Default Re: Nixie Clock

Nicely done to get it up and running, any chance of close-up photos of the two boards - if the original owner allows? I've seen a few of these over the years on the Internet but none that has the history like this one.

This short article with interesting links seems to describe the first Nixie clock: https://www.eeweb.com/worlds-first-nixie-tube-clock/
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Old 29th Jul 2022, 1:30 pm   #4
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Default Re: Nixie Clock

Sorry Martin, unit has already been shipped back.
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Old 29th Jul 2022, 5:56 pm   #5
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Default Re: Nixie Clock

Quote:
Originally Posted by Dekatron View Post
Nicely done to get it up and running, any chance of close-up photos of the two boards - if the original owner allows? I've seen a few of these over the years on the Internet but none that has the history like this one.

This short article with interesting links seems to describe the first Nixie clock: https://www.eeweb.com/worlds-first-nixie-tube-clock/
The electromechanical clock will predate the one described in that website, Dymec had one in 1960 for example, it was made for turning a digital recorder into a datalogger with several print rates, this was used with voltmeters & counters from HP.

https://worldradiohistory.com/hd2/ID...-07-IDX-67.pdf

David
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Old 29th Jul 2022, 8:14 pm   #6
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Default Re: Nixie Clock

Hi Folks, details of the design of a nixie clock were included in one of the Texas instruments 1970's seminar books as well as their "Designing with TTL Integrated Circuits" book published at a similar time. Note that these have some errors in their schematics.

Many differing types of tubes available, I have used end view types in the one I recently built for my son. There are still plentiful, cheap supplies of the standard SN74 chips available without the need to try to source a dedicated clock chip

Ed
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Old 31st Jul 2022, 4:10 pm   #7
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Default Re: Nixie Clock

I've used this ready made circuit with in-14 tubes in the past. All you need to do is solder the leads to the tubes.12v DC supply and IR remote for settings. In use every day for 4 years without issue. With slot machine effect to stop cathode poisoning.

https://www.instagram.com/p/CG0ZhEsJ...d=YmMyMTA2M2Y=

Of course building a circuit from scratch is half the fun.

Ps: prices of nixie tubes have gone up a bit these last fewyears
Gabriel
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Old 31st Jul 2022, 4:37 pm   #8
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Default Re: Nixie Clock

I remember borrowing a frequency counter ( RacaI
I think ) from work , in 1974. It used Nixie tubes and it was interesting watching all the tubes barrel round and then stop for a couple of seconds with the reading, before going off again.

Aub
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Old 31st Jul 2022, 4:51 pm   #9
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Default Re: Nixie Clock

I think I still have one in the loft, I was lucky enough to be offered a couple at a fiver each years ago, one I used as donor tubes for a clock project, the other is for spare tubes, but they will probably last for years!
I ought to dig it out and see if it still works.
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Old 31st Jul 2022, 7:30 pm   #10
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Default Re: Nixie Clock

Probably best to use USSR surplus tubes, it's getting much harder to find certain tubes for repairing old test gear.

David
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Old 1st Aug 2022, 12:43 pm   #11
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Default Re: Nixie Clock

How many Nixie clocks use a PCB and have TTL on-board? It strikes me as very curious, as if you had access to those technologies, you probably had access to far more modern ways of showing the digits! Steampunk before steampunk!
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Old 1st Aug 2022, 12:43 pm   #12
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Quote:
Originally Posted by Aub View Post
I remember borrowing a frequency counter ( RacaI
I think ) from work , in 1974. It used Nixie tubes and it was interesting watching all the tubes barrel round and then stop for a couple of seconds with the reading, before going off again.

Aub
I had a beige coloured Racal FC with Nixies. I gave it away and have regretted the decision ever since!
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Old 1st Aug 2022, 12:48 pm   #13
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Default Re: Nixie Clock

Quote:
Originally Posted by knobtwiddler View Post
How many Nixie clocks use a PCB and have TTL on-board? It strikes me as very curious, as if you had access to those technologies, you probably had access to far more modern ways of showing the digits! Steampunk before steampunk!
The chips are dated '71 / '72, so I should imagine nixies were still cheap as chips, and LEDs were expensive newcomers.
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Old 1st Aug 2022, 4:47 pm   #14
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Default Re: Nixie Clock

Yes I would agree with that. Nixie's were becoming outdated in the very early 70's, but massive stocks remained, so much cheaper than the new LED's. As of course were the driver ICs.
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Old 1st Aug 2022, 6:19 pm   #15
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Default Re: Nixie Clock

Hi Folks, I designed a 4 digit millisecond timer as a young engineer at Reyrolle. This was used for testing the power system protective relays that were part of the company's product range. It used end view GN 4 tubes and 74141decoder drivers with 7490 counters
Quite a few were made and it became the government job of choice for a good few of the other engineers to build the clock version. We even got nice teak sleeves made up in the joiners shop!!

I recently built one based on this design for my son in Melbourne

Ed
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Old 1st Aug 2022, 7:27 pm   #16
agardiner
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Default Re: Nixie Clock

Lovely. Have you any pictures Ed?
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Old 3rd Aug 2022, 1:03 pm   #17
Ed_Dinning
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Some pictures as requested. This is the modern version in a small Ali case. Built on veroboard as there were non of the specific PCB's left after all these years and using a small custom wound transformer

Ed
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Old 3rd Aug 2022, 3:03 pm   #18
agardiner
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Oh, very nice!
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