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Nixie tube

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   Electronic numeric display device
   "Digitron" redirects here. For a calculator company, see Digitron
   (company).
   The ten digits of a GN-4 Nixie tube

   A Nixie tube (English: /|nIk.si:/ NIK-see), or cold cathode
   display,^[1] is an electronic device used for displaying numerals or
   other information using glow discharge.
   Inside a broken Nixie tube

   The glass tube contains a wire-mesh anode and multiple cathodes, shaped
   like 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 often a little mercury or argon, in a
   Penning mixture.^[2]^[3]

   Although it resembles a vacuum tube in appearance, its operation does
   not depend on thermionic emission of electrons from a heated 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 40 DEGC (104 DEGF)
   even under the most severe of operating conditions in a room at ambient
   temperature.^[4] Vacuum fluorescent displays 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.
   [ ]

Contents

     * 1 History
     * 2 Design
     * 3 Applications and lifetime
     * 4 Alternatives and successors
     * 5 Legacy
     * 6 See also
     * 7 References
     * 8 Further reading
     * 9 External links

History[edit]

   Systron-Donner frequency counter from 1973 with Nixie-tube display

   The early Nixie displays were made by a small vacuum tube manufacturer
   called Haydu Brothers Laboratories, and introduced in 1955^[5] by
   Burroughs Corporation, who purchased Haydu. The name Nixie was derived
   by Burroughs from "NIX I", an abbreviation of "Numeric Indicator
   eXperimental No. 1",^[6] although this may have been a backronym
   designed to justify the evocation of 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 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 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.
   This IN-19A (IN-19A) Nixie tube displays symbols, including % and DEGC.

   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.

   Devices that functioned in the same way as Nixie tubes were patented in
   the 1930s, and the first mass-produced display tubes were introduced in
   1954 by National Union Co. under the brand name Inditron. However,
   their construction was cruder, their average lifetime was shorter, and
   they failed to find many applications due to their complex periphery.

Design[edit]

   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 IH-14 (IN-14), used an
   upside-down digit 2 as the digit 5, presumably to save manufacturing
   costs.
   IH-14 (IN-14) Nixie tubes displaying "25". The 5 is implemented with an
   upside-down 2.

   Each cathode can be made to glow in the characteristic neon red-orange
   color by applying about 170 volts DC at a few milliamperes between a
   cathode and the anode. The current limiting is normally implemented as
   an anode resistor of a few tens of thousands of ohms. 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^[4] 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).^[7]^[8]
   Russian IH-12A (IN-12A) and IH-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 IH-12B tubes feature a bottom far left
   decimal point between the numbers 8 and 3.

Applications and lifetime[edit]

   The stacked digit arrangement in a Nixie tube is visible in this
   (stripped) ZM1210.
   Pair of NL-5441 Nixie display tubes

   Nixies were used as numeric displays in early digital voltmeters,
   multimeters, frequency counters 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 calculators, including the first: the Sumlock-Comptometer ANITA
   Mk VII of 1961 and even the first electronic telephone switchboards.
   Later alphanumeric versions in fourteen-segment display format found
   use in airport arrival/departure signs and stock ticker displays. Some
   elevators 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^[2] suggest that incomplete glow coverage of a glyph ("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
     * 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,^[9] 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.^[10]

   As testament to their longevity, and that of the equipment which
   incorporated them, as of 2006^[update] several suppliers still provided
   common Nixie tube types as replacement parts, new in original
   packaging.^[citation needed] 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[edit]

   Other numeric-display technologies concurrently in use included backlit
   columnar transparencies ("thermometer displays"), light pipes,
   rear-projection and edge-lit lightguide displays (all using individual
   incandescent or neon light bulbs for illumination), Numitron
   incandescent filament readouts,^[11] 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 switches 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 diodes
   (LEDs) and vacuum fluorescent displays (VFDs), often in the form of
   seven-segment displays. 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 7441/74141 were
   available to drive Nixies. LEDs are better suited to the low voltages
   that semiconductor integrated circuits 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[edit]

   A Nixie clock with six ZM1210 tubes made by Telefunken
   A Nixie watch on the wrist of Steve Wozniak, co-founder of Apple Inc.

   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.^[12] 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.^[8]^[13]^[7] During their heyday,
   Nixies were generally considered too expensive for use in mass-market
   consumer goods such as clocks.^[7] 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 BCD
   decoder driver have long since been out of production and are rarer
   than NOS tubes. Only "Integral" in Belarus lists the 74141^[14] and its
   Soviet equivalent, the K155ID1,^[15] is still in production. However,
   modern bipolar transistors with high voltage ratings are now available
   cheaply, such as MPSA92 or MPSA42.

See also[edit]

     * icon Electronics portal

     * Genericized trademark
     * Nimo tube
     * Numitron tube
     * Sixteen-segment display
     * Vacuum fluorescent display

References[edit]

    1. ^ "Calculator Displays". www.vintagecalculators.com. Archived from
       the original on August 22, 2013.
    2. ^ ^a ^b (Weston 1968, p. 334)
    3. ^ (Bylander 1979, p. 65)
    4. ^ ^a ^b (Bylander 1979, p. 60)
    5. ^ '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
    6. ^ Sobel, Alan (June 1973). "Electronic Numbers". Scientific
       American. 228 (6): 64-73. Bibcode:1973SciAm.228f..64S.
       doi:10.1038/scientificamerican0673-64. JSTOR 24923073.
    7. ^ ^a ^b ^c "Home of the Nixie tube clock". nixieclock.net. Archived
       from the original on 2012-01-18. Retrieved 2017-09-20.
    8. ^ ^a ^b "KD7LMO - Nixie Tube Clock - Overview". ad7zj.net.
       2014-01-17. Archived from the original on 2017-07-14. Retrieved
       2017-09-20.
    9. ^ "KD7LMO - Nixie Tube Clock - Hardware". ad7zj.net. 2014-01-17.
       Archived from the original on 2017-06-21. Retrieved 2017-09-20.
   10. ^ "Chronotronix V300 Nixie Tube Clock User Manual" (PDF).
       nixieclock.net. p. 6. Archived from the original (PDF) on
       2012-01-05. Retrieved 2017-09-20.
   11. ^ "Numitron Readout". www.decodesystems.com. Archived from the
       original on October 19, 2007.
   12. ^ Zorpette, Glenn (3 June 2002). "New Life For Nixies". IEEE
       Spectrum. Archived from the original on 2009-08-31. Retrieved
       2010-01-31.
   13. ^ "Nixie Tube Clocks". nixieclock.net. Archived from the original
       on 2007-08-08. Retrieved 2017-09-20.
   14. ^ "IN74141N". Integral. Archived from the original on 14 January
       2018. Retrieved 19 October 2017.
   15. ^ K155ID1 [K155ID1] (in Russian). Integral. Archived from the
       original on 16 September 2016. Retrieved 19 October 2017.

Further reading[edit]

     *

   Bylander, E.G. (1979), Electronic Displays, New York: McGraw Hill,
   ISBN 978-0-07-009510-6, LCCN 78031849.

     Dance, J.B. (1967), Electronic Counting Circuits, London: ILIFFE
   Books Ltd, LCCN 67013048.

     Weston, G.F. (1968), Cold Cathode Glow Discharge Tubes, London:
   ILIFFE Books Ltd, LCCN 68135075, Dewey 621.381/51, LCC TK7871.73.W44.

External links[edit]

   Wikimedia Commons has media related to Nixie tubes.

     * Soviet Nixie tube collection with photos and datasheets
     * Brief history of Haydu Brothers
     * Mike's Electric Stuff: Display and Counting Tubes
     * Nixie tube photos and datasheets (in English and German)
     * Giant Nixie Tube Collection (in English and German)
     * The Art of Making a Nixie Tube
     * Nixie Tube Description and Pictures (in English and Czech)
     * The Nixie Tube Story (IEEE Spectrum, 7/18)

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