page_title: Nixie tube
section_title: Applications and lifetime
hierarchical_section_title: Nixie tube / Applications and lifetime
context_page_description: A Nixie tube, or cold cathode display, is an electronic device used for displaying numerals or other information using glow discharge.
  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.
  Although it resembles a vacuum tube in appearance, its operation does not depend on thermionic emission of electrons from a heated cathode. It is therefore called a cold-cathode tube, and is a variant of the neon lamp. Such tubes rarely exceed 40 °C even under the most severe of operating conditions in a room at ambient temperature. 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, and shaped bare metal cathodes.
context_section_description: 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 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, 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.
  As testament to their longevity, and that of the equipment which incorporated them, as of 2006 several suppliers still provide common Nixie tube types as replacement parts, new in original packaging. Equipment with Nixie-tube displays in excellent working condition is still plentiful, though much of it has been in frequent use for 30–40 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.
caption: Pair of NL-5441 Nixie display tubes
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