Choosing components -- colors

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7 years 1 month ago #5604 by sudorandon
The tubes I have are made by National, which I think might be US made? I was hoping it was the opposite actually, maybe that these Nationals were newer tech "ultra long life" with extra murcury and that Soviets might just be basic neon.... No such luck it sounds like!

Question 12 talks a bit about the subject: www.nixieclocks.de/english/faqs.html

Can you guys provide any additional information or references about the impact of multiplexing on tube life? I haven't found much info on this on the web.

I've seen some sites (including same FAQ linked above) that claim increased tube life I think primarily due to the reduced average power/brightness that can be (often unintentionally) achieved. I haven't really found any technical or specification sources that discuss this.

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7 years 1 month ago - 7 years 1 month ago #5605 by Ty_Eeberfest

sudorandon wrote: The tubes I have are made by National, which I think might be US made? I was hoping it was the opposite actually, maybe that these Nationals were newer tech "ultra long life" with extra murcury and that Soviets might just be basic neon.... No such luck it sounds like!

Question 12 talks a bit about the subject: www.nixieclocks.de/english/faqs.html

Can you guys provide any additional information or references about the impact of multiplexing on tube life? I haven't found much info on this on the web.

I've seen some sites (including same FAQ linked above) that claim increased tube life I think primarily due to the reduced average power/brightness that can be (often unintentionally) achieved. I haven't really found any technical or specification sources that discuss this.


Okay... I'll speak my piece on multiplexing and then I'll STFU and see what others have to say. I have never seen any conclusive research published anywhere that answers the question once and for all. Plenty of conjecture, assumption and opinion, but nothing like real proof.

My opinion is obviously "don't multiplex".

1) I have never (yet) seen a data sheet that says "do not multiplex these tubes", BUT...

2) I have seen plenty of data sheets that say, in essence, "this tube is new and special because you CAN multiplex it". So by inference we weren't supposed to multiplex the "non-special" ones.

3) My educated GUESS is that pulses of high current (above device absolute max rating, as seen in most multiplex designs) are worse for the tube than continuous (or PWMed for dimming) current that is within the tube's normal ratings.

If anybody has any real facts to prove me wrong I will be happy to listen. I am not unwilling to change my mind if there is solid info.

EDIT to add: One other minor point against multiplexing: multiplexed displays almost always look terrible (flicker) when you make a video of them. There's no easy fix for this that I'm aware of.

Look into it later when the dust is clearing off the crater.
Last edit: 7 years 1 month ago by Ty_Eeberfest.

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7 years 1 month ago #5606 by TiredOfThis
Replied by TiredOfThis on topic Re: Choosing components -- colors
In Manufacturers datasheets/literature or in books citing manufacturer datasheets/literature you can see that it is possible to drive a Nixie (not all but some) with anything from pure smoothed DC, sinusoidal AC, half wave rectified AC, pulses like thyristor controlled half wave rectified AC and also DC-pulses. This can be found from manufacturers like Valvo, Mullard, RFT and more - there is also the ZM1200 series (Pandicons) of multiple digit Nixie tubes which can only be driven in multiplexed mode since they only have one set of cathodes for all digits and one anode for each digit.

The important thing is that you will have to get hold of the manufacturer information on which Nixies that has been developed, or tested, for multiplexed drive as you will need to know what limits the anode current can work within and also what pulse times to use to drive the Nixie properly. In a few German books from Valvo and RFT and also other German literature you can read about these limits. A book which mentions these limits and driving properties is "Amateurreihe Electronica, Winfried Müller, #171, Elektronische Anzeige-bauelemente" where some of the ZM-series of Nixies are described in pulsed driving situations with the extended data for this.

Books like "Mullard Electronic Counting - circuits techniques devices" and "Electronic Counting Circuits by J.B. Dance" mention Nixie life and driving properties in some small detail.

It all comes down to what current and switching times that you use and if the Nixie is designed for this kind of driving. All nixies can be driven by pulsing them even if they are not designed for it (don't forget that swithcing them on and off changing digits is also a kind of pulsing although with longer intervals than multiplexed driving). How much life you get out of them and at what apparent brightness they shine at depends on their driving conditions, where multiplexing is one part.

Don't forget the current flowing in the "off" cathodes as that also affects the haze around these which might impair the look of the glow.

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7 years 1 month ago #5607 by Jeff
Equipment manufacturers used multiplexing schemes as a hardware simplification and cost-cutting measure.

It's that simple.

Multiplexing nixies has suffered badly in the last decade.
One of the top questions from a prospective buyer to builders/sellers is whether their clock is multiplexed, if it's not disclosed in the sales literature. I've witnessed some rather poor clock designs using multiplexed nixies. The common problems are poor visibility in normal room lighting, visible flicker in peripheral vision, and audible noise (buzzing).
The noise problem is universal with larger tubes, aside from the segmented displays like the B7971.

Regards, Jeff

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7 years 1 month ago - 7 years 1 month ago #5608 by Andrew_R
First of all: I´m german and english is not my first language. So i beg your pardon if some words don´t match.

Nixies were mainly used from 1960 to 1980. In this time internet was not born, so the knowledge of mankind was documented in books. Today, if you try to find information of vintage products, you mainly will find them on private sites of people who care for this vintage stuff because its their hobby. So it is not easy to find scientific papers for Nixies at www. After 1980 Nixies were replaced by the new VFD-tubes and later by LEDs. If you try to find information for LED nowadays, you will find millions of sites.
For example: I tried to find out whats the lifetime of Nixies. You´ll find information from 5000 to 100000 hours. With my IN-12 and IN-14 Nixies I got the original manufacturer document to this tubes, that tells abaut 5000 hours lifetime. That would mean that at 24/7 use they die after 208 days... They do not! To my Z566 Nixies I fond information of 100000 hours. So what to believe?
The reasons for Nixies to die:
1. Mecanical damaga (vibrations, shocks)
2. Air gets in trough leakage of the pins
3. Cathode poisoning
4. Cathode sputtering

And cathode sputtering is heavily dependent on current.
What i found on www is that this sputtering is not in a linearly dependent to current but rather in a logarithmic. That means that even if your current at multiplexing is within the recommended range, the sputtering is higher than driving them with low current on a dc-voltage.

Anyway, price for a IN-12 Nixie is about 3$, for a IN-14 about 10$ and for a Z566 about 50$.
The price for 60 transistors, 60 resistors and 8 shiftingregisters is in total about 8$.
So why should I let these rare and expensive Nixies die early? To save some $ for transistors. I let them run with half of the recommended current. With this they glow beautifull and hope they have a long and happy life.

Regarding the purple haze:
If you visite my site:

www.a-reinert.de/NIXIE_Uhren/nixie_uhren.html

and scroll down to my nixie #6 you will find some good quality pictures, that show you how marginal this purple haze is. The reflections in the surface of the hi-gloss-enclosure are tighter to reality than the dirct view to the tubes. And what I found out: Once the tubes run 20-30 hours, the purple haze gets less. Don´t ask me why.
And if you take tubes with orange coating the purple haze is history and you have a perfect orange glow. First I got this tubes i did not like them, but now I love them, and when you look at them in a dark room, you will not even recognize that they are coatet!

And I could not see a big diference between russian and german tubes. The german tubes seem to have a little more purple haze.
Last edit: 7 years 1 month ago by Andrew_R.

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7 years 1 month ago #5611 by Andrew_R
Hello,

today I made 4 pictures of my first Nixie clock with backlight switched off. The 4 pictures were made with different exposure times. I put this pictores together to one picture. It is the last picture on my nixie site.

www.a-reinert.de/NIXIE_Uhren/nixie_uhren.html

I made it to show that these IN-12 Nixies have no purple haze at all. The picture has full scale. So if you copy it to your PC, you can enlarge it for more details.
That´s what I told, when I made the first run of this clock, the tubes had a purple haze and after some days it was gone.

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