The ZM1040 is a large Nixie tube produced by various European manufacturers, with this particular unit made by Valvo. Tesla, a Czechoslovakian manufacturer, produced a version of the ZM1040 that featured a square anode grid, setting it apart from the one shown here. To enhance contrast and filter out blue light emitted by the included mercury vapor, the tube is covered with a red filter. A variant without this filter was also available under the designation ZM1042.
The DGM01 is a modern Nixie tube produced by Sadudu and his company iNixie LAB in China, comparable in size to the Soviet IN-18. Like the R|Z568M by Dalibor Farný, the DGM01 is assembled by hand in small quantities. Each digit in the tube has a distinctive design, with the numbers one and five standing out in particular. Notably, the DGM01 features a right decimal point which is unusual for tubes of this size and was specifically incorporated for use in replicas of the Divergence Meter from the popular anime series Steins;Gate. Unlike the R|Z568M and tubes made by Millclock, which have a large metal bases, the DGM01 utilizes proper pin-to-glass seals, enhancing its authentic appearance. The glow discharge exhibits the characteristic blue tint seen in tubes containing mercury vapor, which is indicative of long-life Nixie tubes.
The CD66A, produced by NEC in Japan, is a medium-sized Nixie tube capable of displaying all ten digits along with a right decimal point. It features a distinctive anode design made up of multiple horizontal wires, differing from the typical hexagonal or square grids stamped from sheet metal in most Nixie tubes. A variant of the CD66 with a left decimal point was also available. Additionally, the CD66A is pin-compatible with the European ZM1242, which has a more conventional design.
The B-7971 is a very large alphanumeric display tube developed by Burroughs, originally designed for use in stock tickers. Unlike regular Nixie tubes with numerals arranged on a stack, the B-7971 contains 14 individual segments that can be combined to display every letter of the English alphabet as well as the digits 0 through 9. An additional segment in the bottom can be used to display an underscore.
Known for its exceptional longevity, with later models—distinguished by an “antenna” on the anode cage—supposedly lasting even longer, the B-7971’s has become a popular choice among collectors for creating large Nixie clocks. Since the tube’s total current draw varies with the number of segments lit, a single anode resistor cannot effectively limit the current. Instead, each cathode must be connected to its own resistor. The datasheet suggests using different resistor values for different segments to ensure uniform brightness. The most frequent failure mode of a B-7971 appears to be two or more cathodes shorting together. This may occur due to physical impact or the tube being overdriven for prolonged periodes of time. New old stock of B-7971 tubes is virtually nonexistent, as nearly all units available today have been salvaged from the aforementioned stock tickers.
The XN1 is an early Nixie tube produced by Hivac in Great Britain and Lorenz in Germany. The earliest documentation referencing this tube I could find is dated September 9, 1961, shortly after the invention of Nixie tubes. This particular unit features an evaporative getter at the top, giving it a distinctive appearance typically associated with vacuum tubes (often seen in VFDs). However, versions with a getter located behind the anode cage were also manufactured. The tube’s anode cage is notably restrictive, limiting visibility to mostly straight-on angles. Unlike many other tubes of similar size, the XN1 does not include any decimal points.
The E1T is a decadic counting tube developed by Philips, predating the invention of gas-filled Dekatrons. Each pulse advances the tube’s internal count by one and generates a voltage spike, which can be used to trigger specific actions. Internally, the E1T operates as a small cathode ray tube with a ribbon-shaped electron beam that occupies one of ten stable positions. The current position of the beam is indicated as a glowing strip, with each position marked with its corresponding value on a piece of film affixed to the tube’s glass envelope. The tube’s envelope is coated with a transparent protective layer, which is prone to cracking over time, particularly in damp environments. Consequently, E1Ts in pristine condition have become increasingly rare.
The DR2010 is a Numitron developed by RCA, with units sold under the Apollo brand by IEE bearing the same model numbers but substituting “DR” with “DA”. The DR2010 is identical with the DR2000 except for the latter lacking a decimal point. As shown below, some units feature a flat top, while others have a convex top. This seems to be a manufacturing variation and does not necessarily correspond to different model numbers.
With its 40mm digits, the IN-18 (“NH-18”) is the largest Nixie tube mass-manufactured in the Soviet Union. It shares the same envelope diameter with smaller Nixie tubes, such as the ZM1040 and Z566M, which gives the IN-18’s digits a slightly elongated appearance. Today, the IN-18 is among the most popular Nixie tubes, often used in large Nixie clocks. Although vast quantities were manufactured and remain readily available on online marketplaces like eBay, IN-18 tubes have become quite expensive. Unlike many Soviet Nixie tubes, the IN-18 features a proper cathode for the number five rather than an inverted two. Its gas mixture includes trace amounts of mercury vapor, which significantly extends the tube’s lifespan and imparts a faint bluish tint to its glow.
The IV-17 (“NB-17”) is a medium-sized sixteen-plus-two segment VFD tube manufactured in the Soviet Union by Reflector, known today as Sovtek. Unlike the IV-12 seven-segment tube, the IV-17 can display all letters of the English alphabet in addition to the numbers zero through nine. Sixteen segments are dedicated to displaying characters, while the remaining two are used for the left and right decimal points. The character set used in the photos below is based on the one suggested by the datasheet of the Burroughs B-7971 sixteen-segment Nixie tube.
The IV-12 (“NB-12”) is a large seven segment VFD tube produced in Soviet Union by Reflector (known today as Sovtek). It closely resembles the IV-11 but lacks a decimal point and has solid pins instead of flying leads. This allows the tube to be installed in a common 10-pin socket still being produced in China. Like most VFD tubes, the IV-12 includes a grid that can be negatively charged to interrupt electron flow without disabling the filament. This capability allows for multiplexed operation (see schematic shown below) and effectively turns the tube into a triode.
The GR-211 is a large Nixie tube produced by Rodan-Okaya in Japan. It ranks as the third-largest Nixie tube made by Rodan and succeeded the short-lived GR-11. Later models were rebranded as CD94. Notably, the GR-211 includes a left decimal point, which is uncommon for tubes of its size. In devices using larger Nixie tubes, a separate neon bulb typically represented the comma instead. Interestingly, the datasheet marks the decimal point’s pin as “not connected.”
The R|Z568M is a massive modern Nixie tube produced by Dalibor Farný and his company. Each tube is manufactured by hand in the Czech Republic. As the name suggests, its design is meant to be reminiscent of the Z568M, the largest Nixie tube produced in the GDR. A picture below shows a comparison between the R|Z568M, an original Z568M, and a Z566M. Despite being the smallest of the three, the Z566M, with its 30mm digit height, is still considered a large tube. This makes the impressive scale of the R|Z568M, featuring 50mm digits, even more striking. The manufacturing process of an R|Z568M tube is documented in this video.
The Z566M is a large Nixie tube manufactured by RFT. It is pin compatible with the ZM1040 but differs in design, featuring a flatter top and a top-evacuation design, though some earlier units were evacuated from the bottom. In some instances, Z566Ms have even been rebranded and sold as ZM1040s (see picture at the end of this page). A variant without the pre-applied red filter was marketed as the Z5660M.
The Z566M was primarily utilized in laboratory equipment such as voltmeters and frequency counters. Its large size also made it well-suited for devices designed for use in educational settings, such as schools. A Nixie tube featuring various symbols, designed to complement the Z566M/Z5660M, was marketed under the names Z567M and Z5670M.
The MG-19B is a tiny, segmented neon-filled display tube produced by Rodan and marketed under the Elfin brand, designed for use in small electronic instruments. It features two additional diagonal segments, enabling it to display the digits ‘1’ and ‘7’ more naturally, as well as certain other alphanumeric characters. The tube also includes a right decimal point. Unlike Nixie tubes, each cathode in the MG-19B requires an individual resistor, as the current needed varies with the number of illuminated segments. With a 180V breakdown voltage and a recommended 230V anode voltage, the tube operates at significantly higher voltages than most Nixie tubes. This made driving the MG-19B more complex, as affordable high-voltage transistors were not readily available when the tube was introduced.