Nixie Tube life expectancy.

[Biggles]

Hi all, I was just wondering about your experiences with nixie tube life in general. I have had a clock running for quite a few years now which uses nixie tubes for the display. There doesn't appear to be any obvious degradation, and considering the tubes were ex-equipment they seem to be doing well. I am running them at a pretty conservative current, but they are of what I would call normal brightness. As with any device which uses neon gas, I would expect there to be a service life, although I understand this will depend on anode current, and maybe cycling of digits, which does happen in a clock application.
Alan.

[MrBungle]

Depends which tubes and which failure mode you deem acceptable. It's not uncommon for 10-20 years continuous use though. I've had some ZM1000 tubes given to me from a clock which were apparently on for 15 years non stop and they looked the same as the other ones I had.

Not sure there is an answer to this really. Personally I'd buy a few spares while you can

[Marconi_MPT4]

Hi,
Not surprisingly, life expectancy depends on the discharge current and if continuously showing a single figure, cycling through or operating at low temperatures.

Mullard life expectancy figures are quoted at 5000 hours for a static display and 30,000 hours when sequentially changing less than every 100 hours.

Low temperatures below zero degrees Celsius result in a higher proportion of sputter deposited on the other electrodes. This may lead to premature darkening or patchy display.

When used in a clock at room temperature at correct anode current, I would expect Nixie tubes to last a long time.

Rich

[Al (astral highway)]

Originally Posted by Biggles

Hi all, I was just wondering about your experiences with nixie tube life in general.

Hi Alan,

I had some of the larger and more beautiful types in a clock I built a while back.

I found, unsurprisingly, that the tubes displaying seconds lasted the shortest time. I think it was three years of continuous service.

[Peter88gate]

I built a mechanically driven nixie tube clock from a design in Practical Electronics in 1965. It was set running in Jan 1966 and is still running today, and the nixie tubes show no degradation despite continuous use (apart from a break while I moved in 1976) ever since!

See my post from 2011 https://www.vintage-radio.net/forum/...7&postcount=20 .

As Marconi_MPT4 says the rated life of the nixies was 30,000 hours which it has somewhat exceeded!!

Peter

[barrymagrec]

Some early nixie drive circuits didn`t completely remove the voltage from the unused segments, they just dropped it to bias level below the "on" voltage in order to reduce the need for high voltage switching transistors. This technique causes extra contamination of the "off" digits and shortens the operating life.

I built my Nixie clock in 1999 using secondhand tubes (from eye testing equipment, left on all day at 00) still going strong. After a few years one zero started to get a bit uneven (the hours one) I swapped it to the seconds position and after a short while it was fine.

The datasheets do give life for a permanently illuminated digit and also say they last longer if switched (but not how much longer though). 19 years of life so far, over 160k hours.

[Biggles]

Thanks for the input. It just crossed my mind when I realised how long my clock has been running, and also the fact that the previous hours runtime was unknown in my case. The tubes came from a timer counter, used in a workshop long before I worked there, so I would assume they spent most of their time idle on zeros.
Alan.

[Tractorfan]

Hi,
I bought a Nixie tube from a surplus shop many years ago (Just the one, so not much use, really).
It's an end display tube with a 12 pin CRT type Bakelite base which has a thirteenth pin on the central spigot. I have mounted it in a box together with an eleven way single pole switch, a ballast resistor and diode for demonstration purposes.
The display is nice and bright, but the lead wires from the base to the digits glow almost as much as the digits themselves. I can't see any debris lying in the tube, so no insulation has crumbled off the wires. Maybe it's just apart of the aging process?
Cheers, Pete.

[Nicko]

Early nixie tubes had no Hg anti-sputtering - later tubes do - you can tell which have Hg and which don't by looking at the glow round the digits - typically, those that do have Hg doping have a slight purple haze (no Jimi Hendrix comments please).

Non-Hg nixies have low life expectancies, typically around 5,000 to 30,000 hours only.

Doped nixies, e.g. the later Burroughs ones, quote at 200,000+ hours...

This all then begs the question of what is "end of life" for a nixie? According to Weston, it's when 50% of a digit is obscured - for most of us, we'd "call time" sooner than that!