Editing Neon lamp (section)

== Applications ==

=== Visual indicator ===
[[Image:Socket 5.jpg|thumb|Switch on a [[power strip]], illuminated by a neon lamp]]
Even after the widespread availability of cheap [[LED]]s, small neon lamps are still widely used as visual indicators in electronic equipment and appliances, due to their low power consumption, long life, and ability to operate on mains power.

=== Voltage surge suppression ===
Neon lamps are commonly used as low-voltage [[surge protector]]s, but they are generally inferior to [[Surge protector#Gas discharge tube (GDT) spark gap|gas discharge tube (GDT)]] surge protectors (which can be designed for higher voltage applications). Neon lamps have been used as an inexpensive method to protect RF receivers from voltage spikes (lamp connected to RF input and chassis ground), but they are not suitable for higher-power RF transmitters.<ref>{{cite news|title=Let's Use Neon Bulbs|url=http://www.rfcafe.com/references/qst/neon-bulbs-qst-july-1953.htm|publisher=QST Magazine|access-date=October 2, 2017|date=July 1953|url-status=live|archive-url=https://web.archive.org/web/20171002165635/http://www.rfcafe.com/references/qst/neon-bulbs-qst-july-1953.htm|archive-date=October 2, 2017|last1=Cafe|first1=Kirt Blattenberger RF}}</ref>

=== Voltage tester ===
[[Image:Neonlamp3.JPG|right|thumb|+DC (left), -DC (center), AC (right) supplied to NE-2 type neon lamps|alt=Photograph of 3 small glass capsules. Each capsule has 2 parallel wires that pass through the glass. Inside the left capsule, the right electrode is glowing orange. In the middle capsule, the left electrode is glowing. In the right capsule, both electrodes are glowing.]]

Most small neon (indicator-sized) lamps, such as the common '''NE-2''', have a [[Breakdown voltage#Gases and vacuum|break-down voltage]] of around 90&nbsp;[[volt]]s. When driven from a DC source, only the negatively charged electrode ([[cathode]]) will glow. When driven from an AC source, both electrodes will glow (each during alternate half cycles). These attributes make neon lamps (with series resistors) a convenient low-cost [[Test light|voltage tester]]. By examining which electrode is glowing they can reveal whether a given voltage source is AC or DC, and if DC, the polarity of the points being tested.

=== Voltage regulation ===
The breakdown characteristic of glow-discharge lamps allows them to be used as [[voltage regulator]]s or [[overvoltage]] protection devices.<ref name="Miller2">Miller, W.G. (1969) ''[http://www.tiffe.de/roehren/neon.pdf Using and Understanding Miniature Neon Lamps] {{webarchive|url=https://web.archive.org/web/20170517085459/http://www.tiffe.de/roehren/neon.pdf |date=2017-05-17 }}'', p.25-35</ref> Starting around the 1930s, [[General Electric]] (GE), Signalite, and other firms made voltage regulator tubes.
=== Switching element/oscillator ===

Like other [[gas discharge lamp]]s,<ref name="Raju">{{cite book | last1 = Raju | first1 = Gorur Govinda | title = Gaseous Electronics: Theory and Practice | publisher = Taylor and Francis | date = 2006 | pages = 453 | url = https://books.google.com/books?id=I7Qi5vb2nB4C&q=negative+resistance&pg=PA453 | isbn = 978-0849337635 | url-status = live | archive-url = https://web.archive.org/web/20140708020551/http://books.google.com/books?id=I7Qi5vb2nB4C&pg=PA453&dq=#v=onepage&q=negative%20resistance&f=true | archive-date = 2014-07-08 }}</ref> the neon lamp has [[negative resistance]]; its voltage falls with increasing current after the lamp reaches its breakdown voltage.<ref name="GE">{{cite book | last1 = Daugherty | first1 = C. L. | last2 = Tuttle | first2 = J.W. | title = G.E. Glow Lamp Manual, 2nd Ed. | publisher = General Electric | year = 1965 | location = Cleveland, Ohio | pages = 2 | url = https://books.google.com/books?id=JhgoAQAAMAAJ | display-authors = etal | url-status = live | archive-url = https://web.archive.org/web/20180114235506/https://books.google.com/books?id=JhgoAQAAMAAJ | archive-date = 2018-01-14 }}</ref><ref name="Bauman">{{cite book | last = Bauman | first = Edward | title = Applications of Neon Lamps and Discharge Tubes | publisher = Carleton Press | year = 1966 | location = USA | pages = 18 | url = https://www.scribd.com/doc/7086241/Applications-of-Neon-Lamps-and-Discharge-Tubes-Incomplete | url-status = live | archive-url = https://web.archive.org/web/20140416182155/http://www.scribd.com/doc/7086241/Applications-of-Neon-Lamps-and-Discharge-Tubes-Incomplete | archive-date = 2014-04-16 }}</ref><ref name="Dance">{{cite book | last = Dance | first = J. B. | title = Cold Cathode Tubes | publisher = Iliffe | date = 1968 | location = London | pages = 7 | url = https://books.google.com/books?id=8gAjAAAAMAAJ&q=%22negative+resistance | url-status = live | archive-url = https://web.archive.org/web/20140708015603/http://books.google.com/books?id=8gAjAAAAMAAJ&q=%22negative+resistance | archive-date = 2014-07-08 }}</ref> Therefore, the lamp has [[hysteresis]]; its turn-off (extinction) voltage is lower than its turn-on (breakdown) voltage.<ref name="Gottlieb">{{cite book | last = Gottlieb | first = Irving M. | title = Practical Oscillator Handbook | publisher = Elsevier | date = 1997 | pages = 69–70 | url = https://books.google.com/books?id=e_oZ69GAuxAC&q=%22negative+resistance&pg=PA69 | isbn = 978-0080539386 | url-status = live | archive-url = https://web.archive.org/web/20140708015607/http://books.google.com/books?id=e_oZ69GAuxAC&pg=PA69&dq=%22negative+resistance | archive-date = 2014-07-08 }}</ref> This allows it to be used as an active switching element. Neon lamps were used to make [[relaxation oscillator]] circuits, using this mechanism, sometimes referred to as the [[Pearson–Anson effect]]<ref name="Bauman" /><ref name="Gottlieb" /><ref name="GE2">{{Cite book |last=Department |first=General Electric Company Miniature Lamp |url=https://books.google.com/books?id=JhgoAQAAMAAJ |title=General Electric Glow Lamp Manual |date=1966 |publisher=The Company |language=en}}</ref> for low frequency applications such as flashing warning lights, [[stroboscope]]s<ref name="Burton">{{cite journal | last = Burton | first = Walter E. | title = Magic with neon glow lamps | journal = Popular Science | volume = 152 | issue = 2 | pages = 194–196 | publisher = Popular Science Publishing Co. | location = New York | date = February 1948 | url = https://books.google.com/books?id=RigDAAAAMBAJ&q=neon+blinker+stroboscope&pg=PA194 | issn = 0161-7370 | access-date = April 14, 2014 | url-status = live | archive-url = https://web.archive.org/web/20140704190814/http://books.google.com/books?id=RigDAAAAMBAJ&pg=PA194&dq=neon+blinker+stroboscope | archive-date = July 4, 2014 }}</ref> tone generators in electronic organs,<ref name="Bauman" /> and as time bases and deflection oscillators in early [[cathode ray oscilloscope]]s.<ref name="Wahl">{{Cite web |last=Wahl |first=Horst D. |url=http://www.hep.fsu.edu/~wahl/phy4822/expinfo/crt/neva_crt.pdf |title=Tutorial Oscilloscope |work=Phys4822L Advanced Lab-Experiment 11: Studies of electrons with a CRT |publisher=Prof. Horst D. Wahl, Physics Dept., [[Florida State University]] |year=2005 |access-date=14 April 2014 |url-status=live |archive-url=https://web.archive.org/web/20150924025714/http://www.hep.fsu.edu/~wahl/phy4822/expinfo/crt/neva_crt.pdf |archive-date=24 September 2015}}</ref> Neon lamps can also be [[Bistability|bistable]], and were even used to build [[digital logic]] circuits such as [[logic gate]]s, [[flip-flop (electronics)|flip-flop]], [[Binary numeral system|binary]] [[memory|memories]], and [[digital counter]]s.<ref name="GE3">{{Cite book |last=Department |first=General Electric Company Miniature Lamp |url=https://books.google.com/books?id=JhgoAQAAMAAJ |title=General Electric Glow Lamp Manual |date=1966 |publisher=The Company |language=en}}</ref><ref>{{Cite web |last=Koscielny |first=Laurent |date=2020-05-10 |title=Rowabi Lighting |url=https://www.rowabi.com/ |access-date=2025-05-16 |website=ROWABI |language=en}}</ref><ref name="Hendrix">{{cite journal |last=Hendrix |first=C. |date=September 1956 |title=A Study of the Neon Bulb as a Nonlinear Circuit Element |journal=IRE Transactions on Component Parts |volume=3 |issue=2 |pages=44–54 |publisher=Inst. of Electrical and Electronic Engineers |doi=10.1109/TCP.1956.1135748 |issn=0096-2422}}</ref><ref name="Miller1">{{cite book |last=Miller |first=William G. |date=1969 |title=Using and Understanding Miniature Neon Lamps |url=http://www.tiffe.de/roehren/neon.pdf |publisher=Howard W. Sams |pages=49–59 |isbn=978-0572006693 |url-status=live |archive-url=https://web.archive.org/web/20170517085459/http://www.tiffe.de/roehren/neon.pdf |archive-date=17 May 2017}}</ref> These applications were sufficiently common that manufacturers made neon lamps specifically for this use, sometimes called "circuit-component" lamps. At least some of these lamps have a glow concentrated into a small spot on the cathode, which made them unsuited to use as indicators. To provide more repeatable lamp characteristics and reduce "dark effect" ( a rise in starting voltage observed in lamps kept in total darkness), some types of lamp such as NE83 (5AH) include a small amount of a radioisotope to provide initial ionization. <ref name="GE" /> A variant of the NE-2 type lamp for circuit applications, the NE-77, have three wire electrodes in the lamp (in a plane) instead of the usual two, the third for use as a control electrode.

=== Detector ===
Neon lamps have been historically used as microwave and millimeter-wave detectors ("plasma diodes" or glow discharge detectors (GDDs)) up to about 100&nbsp;GHz or so and in such service were said to exhibit comparable sensitivity (of the order of a few 10s to perhaps 100 microvolts) to the familiar 1N23-type catwhisker-contacted silicon diodes{{citation needed|date=October 2017}} once ubiquitous in microwave equipment. More recently it has been found that these lamps work well as detectors even at sub-millimeter ("terahertz") frequencies and they have been successfully used as pixels in several experimental imaging arrays at these wavelengths.

In these applications the lamps are operated either in "starvation" mode (to reduce lamp-current noise) or in normal glow discharge mode; some literature references their use as detectors of radiation up into the optical regime when operated in abnormal glow mode. Coupling of microwaves into the plasma may be in free space, in waveguide, by means of a parabolic concentrator (e.g., [[Winston cone]]), or via capacitive means via a loop or dipole antenna mounted directly to the lamp.

Although most of these applications use ordinary off-the-shelf dual-electrode lamps, in one case it was found that special three (or more) electrode lamps, with the extra electrode acting as the coupling antenna, provided even better results (lower noise and higher sensitivity). This discovery received a US patent.<ref>{{cite web |last1=Farhat|first1=N|last2=Kopeika|first2=N|title=Glow discharge millimeter wave detector and method of biasing same|publisher=US patent 3790895 A|date=19 Oct 1972|url=http://www.google.co.uk/patents/US3790895|url-status=live|archive-url=https://web.archive.org/web/20180114235506/http://www.google.co.uk/patents/US3790895|archive-date=2018-01-14}}</ref>

=== Alphanumerical display ===
{{Main|Nixie tube}}
[[Image:Nixie2.gif|thumb |right |The digits of a [[Nixie tube]]. |alt=Sequence of ten photograph of a glass tube. Each photograph is shown for 1 second, and shows a red, glowing numeral. The photographs are presented in the series 0, 1, 2, ..., 9, and then sequence starts again at 0.]]

Neon lamps with several shaped electrodes were used as alphanumerical displays known as [[Nixie tube]]s. These have since been replaced by other display devices such as [[light emitting diode]]s, [[vacuum fluorescent display]]s, and [[liquid crystal display]]s.

Since at least the 1940s, argon, neon, and [[phosphor]]ed ''glow [[thyratron]]'' [[Flip-flop (electronics)|latching]] indicators (which would light up upon an impulse on their starter electrode and extinguish only after their anode voltage was cut) were available for example as self-displaying [[shift registers]] in large-format, crawling-text [[dot-matrix display]]s,<ref>{{cite web |url=http://tubedata.milbert.com/sheets/013/z/ZC1050.pdf |title=Philips, 1968: ''ZC1050'' data sheet |access-date=10 May 2013 |url-status=live |archive-url=https://web.archive.org/web/20131012022948/http://tubedata.milbert.com/sheets/013/z/ZC1050.pdf |archive-date=12 October 2013 }}</ref> or, combined in a 4×4, four-color phosphored-thyratron matrix, as a stackable 625-color RGBA pixel for large video graphics arrays.<ref>{{cite web |url=http://www.decadecounter.com/vta/pdf2/ITM2Mdatasheet.PDF |title=Melz, 1944: ''ИНДИКАТОР ИТМ2-М'' data sheet |access-date=9 May 2013 |url-status=usurped |archive-url=https://web.archive.org/web/20131012031227/http://www.decadecounter.com/vta/pdf2/ITM2Mdatasheet.PDF |archive-date=12 October 2013 }}</ref> Multiple-cathode and/or anode ''glow thyratrons'' called [[Dekatron]]s could count forwards and backwards while their count state was visible as a glow on one of the numbered cathodes.<ref>{{cite web |url=http://tubedata.milbert.com/sheets/022/g/GCA10G.pdf |title=ETL: ''GCA10G/GSA10G'' data sheet |access-date=10 May 2013 |url-status=live |archive-url=https://web.archive.org/web/20160303221541/http://tubedata.milbert.com/sheets/022/g/GCA10G.pdf |archive-date=3 March 2016 }}</ref> These were used as self-displaying [[Frequency divider#Digital dividers|divide-by-n counter/timer/prescalers]] in counting instruments, or as [[Adder (electronics)|adder/subtracters]] in [[Calculator#Development of electronic calculators|calculators]].

=== Other ===
In 1930s radio sets, neon lamps were used as tuning indicators, called "tuneons" and would give a brighter glow as the station was tuned in correctly.<ref>{{cite web|title=Tuneon|url=http://www.radiomuseum.org/tubes/tube_tuneon.html|website=Radiomuseum|access-date=12 October 2015|url-status=live|archive-url=https://web.archive.org/web/20151016220126/http://www.radiomuseum.org/tubes/tube_tuneon.html|archive-date=16 October 2015}}</ref><ref>[http://www.mif.pg.gda.pl/homepages/frank/sheets/060/t/TUNEON.pdf TuneOn] {{webarchive|url=https://web.archive.org/web/20180114235507/http://www.mif.pg.gda.pl/homepages/frank/sheets/060/t/TUNEON.pdf |date=2018-01-14 }} and [http://www.mif.pg.gda.pl/homepages/frank/sheets/060/t/TUNEON-BUTTON.pdf Tuneon-Button] {{webarchive|url=https://web.archive.org/web/20180114235507/http://www.mif.pg.gda.pl/homepages/frank/sheets/060/t/TUNEON-BUTTON.pdf |date=2018-01-14 }} data sheets</ref>

Because of their comparatively short response time, in the early development of [[television]] neon lamps were used as the light source in many [[Mechanical television|mechanical-scan TV]] displays. [[Aerolux Light Corporation|Novelty glow lamps]] with shaped electrodes (such as flowers and leaves), often coated with phosphors, have been made for artistic purposes. In some of these, the glow that surrounds an electrode is part of the design.