A Nixie tube is an electronic component for the representation of signs according to the principle of the glow lamp. Due to their special appearance, Nixie tubes have now become popular again, so they are used by hobbyists, for example, to build digital clocks. Nixies have therefore been restored for some time now.
A glow lamp is a gas discharge tube that uses the glow discharge to generate a weak glow light. The glass bulb of a glow lamp is filled with a low-pressure gas. Usually, the noble gas neon is used, which glows with an orange-red colour. Sometimes mercury and/or argon vapour (Penning mixture) is used. Two electrodes are embedded in the glass bulb. The glow light is generated at the cathode, and when operated with alternating voltage, both electrodes light up alternately. Since glow lamps are usually filled with the noble gas neon, they are considered neon lamps in this design. There are also glow lamps with other gases, which allows for different colours.
The characters to be displayed, usually the digits from 0 to 9 with a decimal point or decimal point, but also other characters depending on the application, are punched out of fine sheet metal or bent from wire, one behind the other and electrically isolated from each other arranged as cathodes in a tube filled with an inert gas (often neon – for orange-red fluorescent paint). All around in front of this set of digits is an anode in the tube, usually designed as a fine metal grid, and a black background at the very back. When a voltage is applied between the anode and one of the cathodes, the gas glows in a thin layer around the corresponding character.
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Different inert gas mixtures can be used to achieve different colours. The height of the digits ranges from 8 to over 120 millimetres. Due to the need to place all cathodes spatially separated from each other in the tube, the number of possible characters per tube is limited to about twelve. To improve contrast in external lighting, the tubes are coated with a transparent red varnish layer or they work behind a color filter.
The principle of the Nixie tube has been known since the 1910s and 1920s. However until the advent of digital signal processing in the 1950s, the tube had little use. “Nixie” was registered as a trademark and the abbreviation for “Numeric Indicator eXperimental No. 1”. In the 1960s and 1970s, Nixie tubes were mainly used as a numerical display in measuring instruments and electronic calculating machines. Later, with the advent of vacuum fluorescence, light-emitting diode (seven-segment) displays, and liquid crystal displays, they quickly lost their importance.
Source of image: https://hackaday.io/project/19310-multipurpose-nixie-display
Examples of Nixie tubes: ZM1000, ZM1020, ZM1040, ZM1080, ZM1082, ZM1210, ZM1212, ZM1080, ZM1032, CD66A, Z566M, IN 8-2, IN-12, IN-14, IN-16, NL-5441.
“Burroughs Corporation, National Electronics, Raytheon in the USA, Mullard in England, Gazotron in Ukraine, Philips in the Netherlands, RFT, Telefunken and Siemens in Germany, Rodan in Japan, Tesla in the Czech Republic all stopped the production lines and scrapped the delicate tools and machines used to produce nixie tubes. Tools and machines to which hundreds of engineers and maintainers have dedicated their lives.” (www.daliborfarny.com).
