Editing Nixie tube

{{Short description|Electronic numeric display device}}
{{Redirect|Digitron|a calculator company|Digitron (company)}}
[[File:Nixie2.gif|thumb|The ten digits of a GN-4 Nixie tube]]

A '''Nixie tube''' ({{IPAc-en|lang|ˈ|n|ɪ|k|.|s|iː|}} {{respell|NIK|see}}), or '''cold cathode display''',<ref name=Vintagecalculators>{{Cite web|url=http://www.vintagecalculators.com/html/calculator_displays.html#ColdCathode|archive-url=https://web.archive.org/web/20130822171631/http://www.vintagecalculators.com/html/calculator_displays.html|url-status=dead|title=Calculator Displays|archive-date=August 22, 2013|website=www.vintagecalculators.com}}</ref> is an [[electronics|electronic]] device used for [[display device|displaying numerals or other information]] using [[glow discharge]].

The glass tube contains a wire-mesh [[anode]] and multiple [[cathode]]s, shaped like [[Hindu–Arabic numeral system|numerals]] or other symbols. Applying power to one cathode surrounds it with an orange [[glow discharge]]. The tube is filled with a gas at low pressure, usually mostly [[neon]] and a small amount of [[argon]], in a [[Penning mixture]].<ref name="Weston 1968 334">{{Harv|Weston|1968|p=334}}</ref><ref>{{Harv|Bylander|1979|p=65}}</ref> In later nixies, in order to extend the usable life of the device, a tiny amount of [[mercury (element)|mercury]] was added to reduce [[cathode poisoning]] and [[sputtering]].

Although it resembles a [[vacuum tube]] in appearance, its operation does not depend on [[thermionic emission]] of [[electron]]s from a [[hot cathode]]. It is hence a [[cold cathode]] tube (a form of [[gas-filled tube]]), and is a variant of the [[neon lamp]]. Such tubes rarely exceed {{cvt|40|C}} even under the most severe of operating conditions in a room at ambient temperature.<ref name="Bylander 1979 60">{{Harv|Bylander|1979|p=60}}</ref> [[Vacuum fluorescent display]]s from the same era use completely different technology—they have a heated cathode together with a control grid and shaped phosphor anodes; Nixies have no heater or control grid, typically a single anode (in the form of a wire mesh, not to be confused with a control grid), and shaped bare metal cathodes.

==History==
[[File:NixieFrequencyCounter.jpg|thumb|Systron-Donner [[frequency counter]] from 1973 with Nixie-tube display]]

Nixie tubes were invented by David Hagelbarger.<ref>{{cite web
 |title        = The Computer Museum Report
 |url          = https://tcm.computerhistory.org/reports/TCMReportWinter1987-88.pdf
 |year         = 1987
 |access-date  = 2023-07-24
 |url-status   = live
 |archive-url  = https://web.archive.org/web/20140810153557/https://tcm.computerhistory.org/reports/TCMReportWinter1987-88.pdf
 |archive-date = 2014-08-10
 |publisher    = The Computer Museum
 |volume       = 21
 |page	       = 3
 |quote	       = The prototype Nixie Tube and the patent material were presented to the Museum by its Inventor, David Hagelbarger.
}}
</ref><ref>{{cite web
 |last         = Pike
 |first        = Robe
 |title        = Microblog post, 24 July 2023
 |url          = https://hachyderm.io/@robpike/110768696007449946
 |date         = 24 July 2023
 |access-date  = 2023-07-24
 |url-status   = live
 |website      = Hachyderm
 |archive-url  = https://web.archive.org/web/20230724113837/https://hachyderm.io/@robpike/110768696007449946
 |archive-date = 2023-07-24
}}</ref> The early Nixie displays were made by a small vacuum tube manufacturer called Haydu Brothers Laboratories, and introduced in 1955<ref>'Solid State Devices--Instruments' article by S. Runyon in ''Electronic Design'' magazine vol. 24, 23 November 1972, p. 102, via Electronic Inventions and Discoveries: Electronics from its Earliest Beginnings to the Present Day, 4th Ed., Geoffrey William Arnold Dummer, 1997, {{ISBN|0-7503-0376-X}}, p. 170</ref> by [[Burroughs Corporation]], who purchased Haydu. The name ''Nixie'' was derived by Burroughs from "NIX I", an abbreviation of "Numeric Indicator eXperimental No. 1",<ref name="sciam">{{cite journal |last1=Sobel |first1=Alan |title=Electronic Numbers |journal=Scientific American |date=June 1973 |volume=228 |issue=6 |pages=64–73 |doi=10.1038/scientificamerican0673-64 |jstor=24923073|bibcode=1973SciAm.228f..64S }}</ref> although this may have been a [[backronym]] designed to justify the evocation of [[Nixie (folklore)|the mythical creature with this name]]. Hundreds of variations of this design were manufactured by many firms, from the 1950s until the 1990s. The Burroughs Corporation introduced "Nixie" and owned the name ''Nixie'' as a [[trademark]]. Nixie-like displays made by other firms had trademarked names including ''Digitron'', ''Inditron'' and ''Numicator''. A proper generic term is ''cold cathode neon readout tube'', though the phrase ''Nixie tube'' quickly entered the vernacular as a generic name.

Burroughs even had another Haydu tube that could operate as a [[Counter (digital)|digital counter]] and directly drive a Nixie tube for display. This was called a "Trochotron", in later form known as the "Beam-X Switch" counter tube; another name was "magnetron beam-switching tube", referring to their derivation from a [[magnetron|split-anode magnetron]]. Trochotrons were used in the [[UNIVAC 1101]] computer, as well as in clocks and frequency counters.

The first trochotrons were surrounded by a hollow cylindrical magnet, with poles at the ends. The field inside the magnet had essentially-parallel lines of force, parallel to the axis of the tube. It was a thermionic vacuum tube; inside were a central cathode, ten anodes, and ten "spade" electrodes. The magnetic field and voltages applied to the electrodes made the electrons form a thick sheet (as in a cavity magnetron) that went to only one anode. Applying a pulse with specified width and voltages to the spades made the sheet advance to the next anode, where it stayed until the next advance pulse. Count direction was determined by the direction of the magnetic field, and as such was not reversible. A later form of trochotron called a Beam-X Switch replaced the large, heavy external cylindrical magnet with ten small internal metal-alloy rod magnets which also served as electrodes.

Glow-transfer counting tubes, similar in essential function to the trochotrons, had a glow discharge on one of a number of main cathodes, visible through the top of the glass envelope. Most used a neon-based gas mixture and counted in base-10, but faster types were based on argon, hydrogen, or other gases, and for timekeeping and similar applications a few base-12 types were available. Sets of "guide" cathodes (usually two sets, but some types had one or three) between the indicating cathodes moved the glow in steps to the next main cathode. Types with two or three sets of guide cathodes could count in either direction. A well-known trade name for glow-transfer counter tubes in the [[United Kingdom]] was [[Dekatron]]. Types with connections to each individual indicating cathode, which enabled presetting the tube's state to any value (in contrast to simpler types which could only be directly reset to zero or a small subset of their total number of states), were trade named ''Selectron'' tubes.

At least one device that functioned in the same way as Nixie tubes was patented in the 1930s<ref>{{cite web
 |title        = Boswau, Hans P., Signaling system and glow lamps therefor, United States Patent 2142106A, filed 1934-05-09, Issued and published 1939-01-03
 |url          = https://patents.google.com/patent/US2142106A
 |year         = 1934
 |access-date  = 2023-07-31
 |url-status   = live
 |archive-url  = https://web.archive.org/web/20230731130004/http://www.jb-electronics.de/downloads/elektronik/nixies/patente/US2142106.pdf
 |archive-date = 2023-07-31
 |publisher    = United States Patent Office
 |volume       = 21
 |page	       = 3
 |quote	       = 70 appear in approximately the same place. In this manner, any one of the ten numerals may be displayed by causing the corresponding cathode to glow.
}}</ref>
. There were a number of relevant patents filed by Northrop and others around the early 1950s, and the first mass-produced display tubes were introduced in 1954 by National Union Co. under the brand name Inditron. However, the construction of the first Inditrons was cruder than that of the later Nixies, lacking the common anode grid, so that the unlit numerals were held at anode voltage to function as the effective anode. Their average lifetime was shorter, and they failed to find many applications due to their complex drive needs.

== Design ==
[[File:ZM1210-operating edit2.jpg|thumb|upright|The stacked digit arrangement in a Nixie tube is visible in this (stripped) ZM1210.]]

The most common form of Nixie tube has ten cathodes in the shapes of the numerals 0 to 9 (and occasionally a decimal point or two), but there are also types that show various letters, signs and symbols. Because the numbers and other characters are arranged one behind another, each character appears at a different depth, giving Nixie based displays a distinct appearance. A related device is the '''pixie tube''', which uses a [[stencil]] mask with numeral-shaped holes instead of shaped cathodes. Some Russian Nixies, e.g. the ИH-14 (IN-14), used an upside-down digit 2 as the digit 5, presumably to save manufacturing costs.

Each cathode can be made to glow in the characteristic neon red-orange color by applying about 170 [[volt]]s [[direct current|DC]] at a few [[ampere|milliamperes]] between a cathode and the anode. The current limiting is normally implemented as an anode [[resistor]] of a few tens of thousands of [[ohm]]s. Nixies exhibit [[negative resistance]] and will maintain their glow at typically 20 V to 30 V below the strike voltage. Some color variation can be observed between types, caused by differences in the gas mixtures used. Longer-life tubes that were manufactured later in the Nixie timeline have mercury added to reduce [[sputtering]]<ref name="Bylander 1979 60" /> resulting in a blue or purple tinge to the emitted light. In some cases, these colors are filtered out by a red or orange filter coating on the glass.

One advantage of the Nixie tube is that its cathodes are typographically designed, shaped for legibility. In most types, they are not placed in numerical sequence from back to front, but arranged so that cathodes in front obscure the lit cathode minimally. One such arrangement is 6 7 5 8 4 3 9 2 0 1 from front (6) to back (1).<ref name="nixieclock home" /><ref name="KD7LMO Overview">{{cite web |url=http://ad7zj.net/kd7lmo/ground_nixie_clock.html |title=KD7LMO - Nixie Tube Clock - Overview |website=ad7zj.net |date=2014-01-17 |access-date=2017-09-20 |url-status=live |archive-url=https://web.archive.org/web/20170714192451/http://ad7zj.net/kd7lmo/ground_nixie_clock.html |archive-date=2017-07-14 }}</ref>  Russian ИH-12A (IN-12A) and ИH-12B (IN-12B) tubes use the number arrangement 3 8 9 4 0 5 7 2 6 1 from front (3) to back (1), with the 5 being an upside down 2.  The ИH-12B tubes feature a bottom far left decimal point between the numbers 8 and 3.

==Applications and lifetime==
Nixies were used as numeric displays in early digital [[voltmeter]]s, [[multimeter]]s, [[frequency counter]]s and many other types of technical equipment. They also appeared in costly digital time displays used in research and military establishments, and in many early electronic desktop [[calculator]]s, including the first: the Sumlock-Comptometer ''[[Sumlock ANITA calculator|ANITA Mk VII]]'' of 1961 and even the first [[TSPS|electronic telephone switchboards]]. Later [[alphanumeric]] versions in [[fourteen-segment display]] format found use in airport arrival/departure signs. Some [[elevator]]s used Nixies to display floor numbers.

Average longevity of Nixie tubes varied from about 5,000 hours for the earliest types, to as high as 200,000 hours or more for some of the last types to be introduced. There is no formal definition as to what constitutes "end of life" for Nixies, mechanical failure excepted. Some sources<ref name="Weston 1968 334" /> suggest that incomplete glow coverage of a glyph ("[[Hot cathode#Failure modes|cathode poisoning]]") or appearance of glow elsewhere in the tube would not be acceptable.

Nixie tubes are susceptible to multiple failure modes, including:
* Simple breakage
* Cracks and [[hermetic seal]] leaks allowing the atmosphere to enter
* [[Hot cathode#Failure modes|Cathode poisoning]] preventing part or all of one or more characters from illuminating
* Increased striking voltage causing flicker or failure to light
* [[Sputtering]] of electrode metal onto the glass envelope blocking the cathodes from view
* Internal open or short circuits which may be due to physical abuse or sputtering

Driving Nixies outside of their specified electrical parameters will accelerate their demise, especially excess current, which increases sputtering of the electrodes. A few extreme examples of sputtering have even resulted in complete disintegration of Nixie-tube cathodes.

Cathode poisoning can be abated by limiting current through the tubes to significantly below their maximum rating,<ref name="KD7LMO Hardware">{{cite web |url=http://ad7zj.net/kd7lmo/ground_nixie_clock_hardware.html |title=KD7LMO - Nixie Tube Clock - Hardware |website=ad7zj.net |date=2014-01-17 |access-date=2017-09-20 |url-status=live |archive-url=https://web.archive.org/web/20170621191026/http://ad7zj.net/kd7lmo/ground_nixie_clock_hardware.html |archive-date=2017-06-21 }}</ref> through the use of Nixie tubes constructed from materials that avoid the effect (e.g. by being free of silicates and aluminum), or by programming devices to periodically cycle through all digits so that seldom-displayed ones get activated.<ref name="nixieclock manual">{{cite web |title=Chronotronix V300 Nixie Tube Clock User Manual |page=6 |website=nixieclock.net |url=http://www.nixieclock.net/manuals/Manual_V400_English.pdf |url-status=dead |archive-url=https://web.archive.org/web/20120105191449/http://www.nixieclock.net/manuals/Manual_V400_English.pdf |archive-date=2012-01-05 |access-date=2017-09-20}}</ref>

As testament to their longevity, and that of the equipment which incorporated them, {{as of|2006|lc=y}} several suppliers still provided common Nixie tube types as replacement parts, new in original packaging.{{Citation needed|date=August 2008}} Devices with Nixie-tube displays in excellent working condition are still plentiful, though many have been in use for 30 to 40 years or more. Such items can easily be found as surplus and obtained at very little expense. In the former Soviet Union, Nixies were still being manufactured in volume in the 1980s, so Russian and Eastern European Nixies are still available.

== Alternatives and successors ==
[[File:Beckman SP-352.jpg|thumb|A 2-digit seven-segment ″Panaplex″-display made by Beckman (1974)]]

Other numeric-display technologies include light pipes, rear-projection and edge-lit [[lightguide display]]s (all using individual [[incandescent light bulb|incandescent]] or [[neon lamp|neon]] light bulbs for illumination), [[Numitron]] incandescent filament readouts,<ref>{{Cite web|url=http://www.decodesystems.com/numitron.html|archive-url=https://web.archive.org/web/20071019102215/http://www.decodesystems.com/numitron.html|url-status=dead|title=Numitron Readout|archive-date=October 19, 2007|website=www.decodesystems.com}}</ref> Panaplex seven-segment displays, and [[vacuum fluorescent display]] tubes. Before Nixie tubes became prominent, most numeric displays were electromechanical, using stepping mechanisms to display digits either directly by use of cylinders bearing printed numerals attached to their rotors, or indirectly by wiring the outputs of [[stepping switch]]es to indicator bulbs. Later, a few vintage clocks even used a form of stepping switch to drive Nixie tubes.

Nixie tubes were superseded in the 1970s by [[light-emitting diode]]s (LEDs) and [[vacuum fluorescent display]]s (VFDs), often in the form of [[seven-segment display]]s. The VFD uses a hot filament to emit electrons, a control grid and phosphor-coated anodes (similar to a [[cathode-ray tube]]) shaped to represent segments of a digit, pixels of a graphical display, or complete letters, symbols, or words. Whereas Nixies typically require 180 volts to illuminate, VFDs only require relatively low voltages to operate, making them easier and cheaper to use. VFDs have a simple internal structure, resulting in a bright, sharp, and unobstructed image.  Unlike Nixies, the glass envelope of a VFD is evacuated rather than being filled with a specific mixture of gases at low pressure.

Specialized high-voltage driver chips such as the [[7400 series|7441/74141]] were available to drive Nixies. LEDs are better suited to the low voltages that semiconductor [[integrated circuit]]s typically use, which was an advantage for devices such as pocket calculators, digital watches, and handheld digital measurement instruments. Also, LEDs are much smaller and sturdier, without a fragile glass envelope. LEDs use less power than VFDs or Nixie tubes with the same function.

==Legacy ==
[[File:Nixie clock.jpg|thumb|A Nixie clock with six ZM1210 tubes made by [[Telefunken]]]]

Citing dissatisfaction with the aesthetics of modern digital displays and a nostalgic fondness for the styling of obsolete technology, significant numbers of electronics enthusiasts have shown interest in reviving Nixies.<ref>{{cite web
 |last        = Zorpette
 |first       = Glenn
 |title       = New Life For Nixies
 |url         = https://spectrum.ieee.org/new-life-for-nixies
 |work        = [[IEEE Spectrum]]
 |date = 3 June 2002
 |access-date  = 2010-01-31
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20090831074550/http://www.spectrum.ieee.org/consumer-electronics/gadgets/new-life-for-nixies
 |archive-date = 2009-08-31
}}</ref> Unsold tubes that have been sitting in warehouses for decades are being brought out and used, the most common application being in homemade digital clocks.<ref name="KD7LMO Overview" /><ref name="nixieclock shop">{{cite web |title=Nixie Tube Clocks |website=nixieclock.net |url=http://www.nixieclock.net/pi1065517655.htm?categoryId=0 |url-status=dead |archive-url=https://web.archive.org/web/20070808232541/http://www.nixieclock.net/pi1065517655.htm?categoryId=0 |archive-date=2007-08-08 |access-date=2017-09-20}}</ref><ref name="nixieclock home">{{cite web |title=Home of the Nixie tube clock |website=nixieclock.net |url=http://www.nixieclock.net/ |url-status=dead |archive-url=https://web.archive.org/web/20120118082635/http://www.nixieclock.net/ |archive-date=2012-01-18 |access-date=2017-09-20}}</ref> During their heyday, Nixies were generally considered too expensive for use in mass-market consumer goods such as clocks.<ref name="nixieclock home" /> This recent surge in demand has caused prices to rise significantly, particularly for large tubes, making small-scale production of new devices again viable.

In addition to the tube itself, another important consideration is the relatively high-voltage circuitry necessary to drive the tube. The original [[7400 series]] drivers integrated circuits such as the 74141 [[binary-coded decimal|BCD]] decoder driver have long since been out of production and are rarer than [[New old stock|NOS]] tubes. The 74141 is still available as NOS from various web suppliers and the Soviet equivalent, the K155ID1, is still in production. However, modern [[bipolar transistor]]s with high voltage ratings are now available cheaply, such as MPSA92 or MPSA42.

==Contemporary Manufacturers (2011...)==
[[File:Dalibor Farny RZ568M Nixie Tube.jpg|thumb|An R\Z568M Nixie tube manufactured by Dalibor Farny]]
Since 2011, in Czech Republic, Dalibor Farny manufactures new Nixie Tubes. Started as a hobby, it has become a small business. They sell around 2.000 clocks per year (as of 2024) but they also sell standalone tubes. <ref>https://www.daliborfarny.com/</ref>

==See also==
{{Portal|Electronics}}
* [[Genericized trademark]]
* [[Nimo tube]]
* [[Numitron tube]]
* [[Sixteen-segment display]]
* [[Vacuum fluorescent display]]

==References==
{{Reflist}}

==Further reading==
* {{Citation | surname=Bylander | given=E.G. | title=Electronic Displays | publisher=[[McGraw Hill]] | place=[[New York City|New York]] | year=1979 | isbn=978-0-07-009510-6 |lccn=78031849}}.
* {{Citation | surname=Dance | given=J.B. | title=Electronic Counting Circuits | publisher=[[Elsevier|ILIFFE Books Ltd]] | place=[[London]] | year=1967 |lccn=67013048}}.
* {{Citation | surname=Weston | given=G.F. | title=Cold Cathode Glow Discharge Tubes | publisher=[[Elsevier|ILIFFE Books Ltd]] | place=[[London]] | year=1968|lccn=68135075}}, [[Dewey Decimal Classification|Dewey]] 621.381/51, [[Library of Congress Classification|LCC]] TK7871.73.W44.

==External links==
{{commons category|Nixie tubes}}
* [http://www.warrennj.org/wths/haydu.htm Brief history of Haydu Brothers] {{Webarchive|url=https://web.archive.org/web/20120414191819/http://www.warrennj.org/wths/haydu.htm |date=2012-04-14 }}
* [http://www.electricstuff.co.uk/count.html Mike's Electric Stuff: Display and Counting Tubes]
* [http://www.tube-tester.com/sites/nixie/nixie-tubes.htm Nixie tube photos and datasheets] {{in lang|en|de}}
* [http://www.jb-electronics.de/html/elektronik/nixies/n_sammlung.htm?lang=en Giant Nixie Tube Collection] {{in lang|en|de}}
* [https://www.youtube.com/watch?v=wxL4ElboiuA The Art of Making a Nixie Tube]
* [http://danyk.cz/digitrony_en.html Nixie Tube Description and Pictures] {{in lang|en|cs}}
* [https://spectrum.ieee.org/nixie-tube The Nixie Tube Story (IEEE Spectrum, 7/18)]
* [https://www.ase-museoedelpro.org/a/The%20trochotron.pdf The Trochotron Beam-Switch Counter]
* [https://www.ase-museoedelpro.org/Museo_Edelpro/Catalogo/Overview/The%20Trochotron.pdf Trochotron Beam-Switch Counters and Numeric indicators]

{{Display technology}}
{{Electronic components}}

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[[Category:Obsolete technologies]]
[[Category:Vacuum tube displays]]