Editing Neon lamp

{{For|similar terms|Neon lighting|Neon sign}}
{{Use American English|date = February 2019}}
{{Short description|Light source based on gas discharge}}
[[File:AC powered NE-2 type neon lamp close-up.jpg|thumb|right|NE-2 type neon lamp powered by [[alternating current]] (AC)]]
[[File:Neon lamp schematics.svg|thumb|right|Neon lamp schematic symbol]]
A '''neon lamp''' (also '''neon glow lamp''') is a miniature [[gas-discharge lamp]]. The lamp typically consists of a small glass capsule that contains a mixture of [[neon]] and [[Penning mixture|other gases]] at a low pressure and two [[electrode]]s (an [[anode]] and a [[cold cathode|cathode]]). When sufficient voltage is applied and sufficient current is supplied between the electrodes, the lamp produces an orange [[glow discharge]]. The glowing portion in the lamp is a thin region near the cathode; the larger and much longer [[neon sign]]s are also glow discharges, but they use the [[Glow_discharge#Positive_column|positive column]] which is not present in the ordinary neon lamp. 

Neon glow lamps were widely used as [[Pilot_light#ON_OFF|indicator lamp]]s in the displays of electronic instruments and appliances. They are still sometimes used for their electrical simplicity in high-voltage circuits.

==History==
[[Image:NE-34 LAMP.JPG|thumb|right|A [[General Electric]] NE-34 glow lamp, manufactured circa 1930]]
[[Neon]] was discovered in 1898 by [[William Ramsay]] and [[Morris Travers]]. The characteristic, brilliant red color that is emitted by gaseous neon when excited electrically was noted immediately; Travers later wrote, "the blaze of crimson light from the tube told its own story and was a sight to dwell upon and never forget."<ref>{{cite book|url=https://books.google.com/books?id=SJIk9BPdNWcC&pg=PA287|title=Discovery of the Elements: Third Edition (reprint)|last=Weeks|first=Mary Elvira|publisher=Kessinger Publishing|year=2003|page=287|author-link=Mary Elvira Weeks|archive-url=https://web.archive.org/web/20150322191804/http://books.google.com/books?id=SJIk9BPdNWcC&pg=PA287|archive-date=2015-03-22|url-status=live|isbn=9780766138728}}<!--The probable original source for this quote is Travers' 1928 book: {{cite book |title=The Discovery of the Rare Gases |url=https://archive.org/details/discoveryofrareg0000trav |url-access=registration |last=Travers |first=Morris W. |publisher=Edward Arnold & Co. |location=London |year=1928}}--></ref>

Neon's scarcity precluded its prompt application for electrical lighting along the lines of [[Moore tube]]s, which used electric discharges in [[nitrogen]]. Moore tubes were commercialized by their inventor, [[Daniel McFarlan Moore]], in the early 1900s. After 1902, [[Georges Claude]]'s company, [[Air Liquide]], was producing industrial quantities of neon as a byproduct of his air liquefaction business, and in December 1910 Claude demonstrated modern [[neon light]]ing based on a sealed tube of neon. In 1915 a U.S. patent was issued to Claude covering the design of the electrodes for neon tube lights;<ref>{{cite patent |country=US |number=1125476 |title=Systems of Illuminating by Luminescent Tubes |invent1=Georges Claude |gdate=1915-01-19 |fdate=1911-11-09}}</ref> this patent became the basis for the monopoly held in the U.S. by his company, Claude Neon Lights, through the early 1930s.<ref>{{cite news |title=Claude Neon Lights Wins Injunction Suit: Also Gets Rights to Recover Profits and Damages Resulting From Patent Infringement |work=The New York Times |date=November 28, 1928}} Paid access.</ref>

Around 1917, Daniel Moore developed the neon lamp while working at the [[General Electric Company]]. The lamp has a very different design from the much larger neon tubes used for [[neon lighting]]. The difference in design was sufficient that a U.S. patent was issued for the lamp in 1919.<ref>{{ref patent| country=US |number=1316967 |status=patent |title=Gaseous Conduction Lamp |pubdate= |gdate=1919-09-23 |fdate=1917-11-30 |pridate= |invent1=Daniel McFarlan Moore |invent2= |assign1=General Electric Company |assign2= |class= }}</ref> A Smithsonian Institution website notes, "These small, low power devices use a physical principle called [[coronal discharge]]. Moore mounted two electrodes close together in a bulb and added neon or argon gas. The electrodes would glow brightly in red or blue, depending on the gas, and the lamps lasted for years. Since the electrodes could take almost any shape imaginable, a popular application has been fanciful decorative lamps.<ref name=SI>{{cite web |title=Lamp Inventors 1880-1940: Moore Lamp |publisher=The Smithsonian Institution |url=http://americanhistory.si.edu/lighting/bios/moore.htm |url-status=live |archive-url=https://web.archive.org/web/20050304005429/http://americanhistory.si.edu/lighting/bios/moore.htm |archive-date=2005-03-04 }}</ref><!--There is a long history for these lamps that needs to be developed here. The neon lamp ultimately leads to modern plasma displays.-->

Glow lamps found practical use as indicators in instrument panels and in many home appliances until the widespread commercialization of [[light-emitting diode]]s (LEDs) in the 1970s.<ref name=SI/>

== Description ==
[[File:Glow discharge current-voltage curve English.svg|thumb|right|300px|Voltage-current characteristics of electrical discharge in neon at 1 torr, with two planar electrodes separated by 50&nbsp;cm.<br/>
A: random pulses by [[cosmic radiation]]<br/>
B: saturation current<br/>
C: [[Avalanche breakdown]] Townsend discharge<br/>
D: self-sustained [[Townsend discharge]]<br/>
E: unstable region: [[corona discharge]]<br/>
F: sub-normal glow discharge<br/>
G: normal glow discharge<br/>
H: abnormal glow discharge<br/>
I: unstable region: glow-arc transition<br/>
J: [[electric arc]]<br/>
K: electric arc<br/>
'''A-D region: dark discharge'''; ionisation occurs, current below 10 microamps.<br/>
'''F-H region: glow discharge'''; the plasma emits a faint glow. <br/>
'''I-K region: arc discharge'''; large amounts of electromagnetic radiation produced.]]
A small [[electric current]] (for a 5&nbsp;mm bulb diameter NE-2 lamp, the [[quiescent current]] is about 400 μA), which may be [[alternating current|AC]] or [[direct current|DC]], is allowed through the tube, causing it to glow orange-red. The gas is typically a [[Penning mixture]], 99.5% [[neon]] and 0.5% [[argon]], which has lower [[Breakdown voltage#Gases and vacuum|striking voltage]] than pure neon, at a pressure of {{Convert|1-20|torr||abbr=}}.

The lamp [[glow discharge]] lights at its striking voltage.<ref name="MILLER69">{{cite book |title=Using and Understanding Miniature Neon Lamps |url=https://archive.org/details/UsingAndUnderstandingMiniatureNeonLamps |last=Miller |first=William G. |publisher=Howard W Sams & Co, Inc. |location=Indianapolis |date=1969}}</ref> The striking voltage is reduced by ambient light or radioactivity. To reduce the "dark effect", some lamps were made with a small amount of radioactive material, typically [[Krypton-85]], added to the envelope to provide ionization in darkness.<ref name=MILLER69/> 

The voltage required to sustain the discharge is significantly (up to 30%) lower than the [[Breakdown voltage|striking voltage]]. This is due to the organization of positive ions near the cathode.  Neon lamps operate using a low current [[glow discharge]]. Higher power devices, such as [[mercury-vapor lamp]]s or [[metal halide lamp]]s use a higher current [[arc discharge]]. Low pressure [[sodium-vapor lamp]]s use a neon Penning mixture for warm up and can be operated as giant neon lamps if operated in a low power mode. 

===Limiting current===
Once the neon lamp has reached breakdown, it can support a large current flow. Because of this characteristic, electrical circuitry external to the neon lamp must limit the current through the circuit or else the current will rapidly increase until the lamp is destroyed. 

For indicator-sized lamps, a [[resistor]] typically limits the current. In contrast, larger sized lamps often use a specially constructed high voltage [[transformer]] with high [[leakage inductance]] or other [[electrical ballast]] to limit the available current (see [[neon sign]]).

===Flicker flame===
When the current through the lamp is lower than the current for the highest-current discharge path, the [[glow discharge]] may become unstable and not cover the entire surface of the [[Electrode|electrodes]].<ref name="Glow Lamp Manual">{{cite book |first1=C. R. |last1=Dougherty |first2=T. D. |last2=Foulke |first3=J. D. |last3=Harden |first4=T. L. |last4=Hewitt |first5=F. N. |last5=Peters |first6=R. D. |last6=Smith |first7=J. W. |last7=Tuttle |title=General Electric Glow Lamp Manual |edition=2nd |publisher=General Electric Company |date=1966}}</ref> This may be a sign of aging of the indicator lamp, and is exploited in the decorative "flicker flame" neon lamps. However, while too low a current causes flickering, too high a current increases the wear of the electrodes by stimulating [[sputtering]], which coats the internal surface of the lamp with metal and causes it to darken.

The potential needed to strike the discharge is higher than what is needed to sustain the discharge. When there is not enough current, the glow forms around only part of the electrode surface. Convective currents make the glowing areas flow upwards, not unlike the discharge in a [[Spark gap#Spark gaps as entertainment|Jacob's ladder]]. A [[photoionization]] effect can also be observed here, as the electrode area covered by the glow discharge can be increased by shining light at the lamp.

===Efficiency===
In comparison with [[incandescent lamps]], neon lamps have much higher [[luminous efficacy]]. [[Incandescence]] is heat-driven light emission, so a large portion of the electric energy put into an incandescent lamp is converted into heat. Non-incandescent light sources such as neon lamps, [[fluorescent lamp]]s, and [[light-emitting diodes]] are therefore much more energy efficient than normal incandescent lamps. LEDs are the highest efficiency. 

[[Green]] neon lamps<ref>{{Cite web |title=Neon Lamps, Neon Indicator Lamps {{!}} ILT |url=https://internationallight.com/applications/neon-lamps |access-date=2025-05-16 |website=internationallight.com}}</ref> can produce up to 65 lumens per watt of power input, while white neon lamps have an efficacy of around 50 lumens per watt. In contrast, a standard incandescent lamp only produces around 13.5 lumens per watt.<ref>{{cite web|first=Marcus|last=Thielen|title=LED or Neon|url=http://www.signweb.com/index.php/channel/12/id/138/|date=2006-02-10|access-date=2008-12-30|url-status=dead|archive-url=https://web.archive.org/web/20080409004409/http://www.signweb.com/index.php/channel/12/id/138|archive-date=2008-04-09}}</ref>

===Environmental effects===
The precise values of starting and maintaining voltages of neon lamps is subject to change due to several effects. External light falling on the electrodes provides a source of ionization to start the lamp; in total darkness, lamps may reach a high and erratic starting voltage. One measure to mitigate for this effect is to include a pilot lamp within the enclosure to provide an initial source of light. Lamps are also somewhat sensitive to external electrostatic fields, temperature, and aging. Lamps intended for use as circuit components may be specially processed to eliminate most of the initial aging effects.<ref name=GE/>

== 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.

==Color==
[[Image:Glimmlampe spektrum.jpg|thumb|left|200px|Unlit and lit neon lamps (NE-2 type) and their light [[spectrum]]. |alt=Graphic consisting of four photographs. A row of three photographs at the top all show similar glass capsules with electrodes inside. The left photograph shows the construction of the capsule under normal lighting. The middle photograph shows the capsule with one of the two electrodes glowing. The right photograph shows the capsule with both electrodes glowing. Underneath the row of photographs of the capsule is a photograph of a spectroscope's scale; the scale runs from 700 nm to 400 nm; there are numerous red, orange, and yellow colored lines in the region between 660 and 600 nm, but no lines for readings smaller than 590 nm.]]

Neon indicator lamps are normally orange, and are frequently used with a colored filter over them to improve contrast and change their color to red or a redder orange.

[[Image:NE2COLORED.JPG|thumb|right|Phosphor-colored neon lamps]]
They can also be filled with [[argon]], [[krypton]], or [[xenon]] rather than neon, or mixed with it. While the electrical operating characteristics remain similar, these lamps light with a bluish glow (including some [[ultraviolet]]) rather than neon's characteristic reddish-orange glow. Ultraviolet radiation then can be used to excite a [[phosphor]] coating inside of the bulb and provide a wide range of various colors, including white.<ref>{{cite book |title=Phosphor handbook |last1=Yen |first1=William M. |last2=Yamamoto |first2=Hajime |publisher=CRC Press |year=2007 |page=442 |url=https://books.google.com/books?id=I9O1K20-uo4C&pg=PA442 |isbn=978-0-8493-3564-8 |url-status=live |archive-url=https://web.archive.org/web/20180114235507/https://books.google.com/books?id=I9O1K20-uo4C&pg=PA442 |archive-date=2018-01-14 }}</ref> A mixture of 95% neon, 2.5% [[krypton]], and 2.5% argon can be used for a green glow,<ref>{{cite web|last1=Bogard|first1=Scott|title=Plasma Globe Colors|url=http://www.personal.psu.edu/sdb229/Plasma%20ball%20colors.html|website=Scott Bogard's E-Profile|access-date=22 April 2016|url-status=live|archive-url=https://web.archive.org/web/20160509030653/http://www.personal.psu.edu/sdb229/Plasma%20ball%20colors.html|archive-date=9 May 2016}}</ref> but nevertheless "green neon" lamps are more commonly phosphor-based.

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== See also ==
{{Portal|Electronics}}
*[[Aerolux Light Corporation]]
*[[Gas-filled tube]]
*[[Light art]]
*[[List of light sources]]
*[[Magic eye tube]] 
*[[Neon sign]]
*[[Pearson–Anson effect]]
*[[Timeline of lighting technology]]

==References==
{{Reflist|30em}}

==Further reading==
* ''Using and Understanding Miniature Neon Lamps''; 1st Ed; William G. Miller; Sams Publishing; 127 pages; 1969; LCCN 69-16778. [https://web.archive.org/web/*/http://www.tiffe.de/roehren/neon.pdf ''(archive)'']
* ''Cold Cathode Tubes''; 1st Ed; J.B. Dance; Iliffe Books; 125 pages; 1967. [https://archive.org/details/ColdCathodeTubes ''(archive)'']
* ''Glow Lamp Manual - Theory, Circuits, Ratings''; 2nd Ed; General Electric; 122 pages; 1966. [https://archive.org/details/GE_Glow_Lamp_Manual ''(archive)'']
* ''Applications of Neon Lamps and Gas Discharge Tubes''; 1st Ed; Edward Bauman; Carlton Press; 160 pages; 1966. [http://www.philbrickarchive.org/jlrmsousa/Applications_of_neon_lamps_and_Gas_discharge_tubes-Edward_Bauman.pdf ''(archive)'']
* ''Neon Blinker Saves Batteries''; Radio-Electronics, October 1949, pg 46-47. [https://web.archive.org/web/20230131195733/https://www.worldradiohistory.com/Archive-Radio-Electronics/40s/Radio-Electronics-1949-10.pdf ''(archive)'']

==External links==
{{Commons category|Neon lamps}}
* [https://web.archive.org/web/20130923164732/http://www.cliftonlaboratories.com/relaxation_oscillator.htm Neon Bulb Relaxation Oscillator] - Clifton Laboratories
* [http://vcclite.com/wp-content/uploads/wpallimport/files/files/NeonIndicatorLamps.pdf Neon Indicator Lamp Datasheet] - VCC (Visual Communications Company) parent of Chicago Miniature Lighting (CML)

{{Artificial light sources}}
{{Electronic components}}

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[[Category:Products introduced in 1902]]
[[Category:Types of lamp]]
[[Category:Neon lighting]]
[[Category:Vacuum tube displays]]
[[Category:French inventions]]