Incandescent Displays

The pantheon of incandescent displays includes a wide range of display types whose illumination is provided by an array of incandescent filaments. Projection displays, light pipe displays and other similar devices use traditional incandescent lamps to illuminate the display elements, while Numitron and Minitron displays are discrete multi-filament lamps, with filaments arranged to display a segmented digit or other character. Incandescent displays have a significant advantage over Nixie tubes, Panaplex displays and VFDs, as they are typically driven at +5VDC or other similarly convenient voltages. Minitrons were once particularly popular in aerospace applications due to their ruggedness, wide viewing angle and long operational lifespan, and a brightness significantly higher than competing LED displays. Additionally, the wide spectral output of incandescent illumination allows for extreme versatility in color filtering.

Burroughs SD-11-B-1000-635
 Burroughs SD-11-B-1000-635

Although it resembles a typical projection display, the Burroughs SD-11-B-1000-635 Message Display Unit is actually a sphericular optic display. At the rear of the display is an array of 11 lamps, one for each digit plus a decimal point. At the front of the display is a screen assembly constructed from three layers. The rear layer is a transparent plastic sphericular lens plate covered in a grid of plano-convex lenses. Each lens measures 0.025" square, with a focal length of 0.078". In front of the sphericular lens plate is a message screen, positioned at the focal plane of the lens plate. The message screen is constructed from a plastic film with an array of printed dots which selectively block the lamps' illumination to generate each digit's respective dot pattern. The final layer of the screen assembly is a diffusing layer which increases the display's viewing angle.

Burroughs manufactured at least two variants of the SD-11. The SD-11-B-1000-635 pictured here has black digits on an illuminated background, while the SD-11-W-1000-635 has illuminated digits on a black background.

Special thanks to Victor Rizzardi for donating these rare displays.

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Dialight Incandescent Display
 Dialight Incandescent Display

Dialight manufactured a number of different seven-segment (plus decimal point) displays built from eight discrete incandescent lamps. The device pictured here is designed to accommodate a 16-pin decoder IC, and uses standard midget flange lamps held in place with spring terminals mounted to a PCB back.

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Fuji Minitron 3015F
 Fuji Minitron 3015F

The Fuji 3015F is the archetypal example of Minitron-style filament display technology. Unlike Numitrons which are packaged in a tubular glass envelope, Minitrons have a planar envelope, consructed from a glass window hermetically sealed to a sheet metal bathtub enclosure. This improvement mirrors a similar transition in gas discharge displays, from the tubular envelope Nixie tube, to the planar Panaplex display. Several internal variations of this device are known to exist, including a variation which omits the internal digit mask. The 3015F has a 14-pin DIP outline, and is rated for 50,000 hours of continuous operation.

Fuji 3015F & 3015G Datasheet (PDF)

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IEE 10000-1819-B
 IEE 10000-1819-B

The IEE 10000-1819-B In-Line Readout is a typical example of a projection display - a technology which competed with Nixie tubes and various mechanical display technologies through the 1950s and 1960s. Projection displays operate by casting light from rear-mounted incandescent lamps through an array of masked lenses which then pass through a second set of focusing lenses, projecting an illuminated digit onto a front-facing translucent screen. Each lamp represents a separate digit or other character.

Projection displays of this type were bulky, complex and expensive compared to the dominant Nixie tube. IEE later produced miniaturized types which addressed the extreme bulk of displays like the 10000-1819-B, but did nothing to compensate for the relatively poor viewability of projecton technology under normal lighting conditions.

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IEE Apollo DA-2000 Series
 IEE Apollo DA-2000 Series

Devices included in this entry:

RCA DR2000 numeric filament display (9-pin envelope)
IEE DA-2010 numeric filament display (9-pin envelope; pictured in thumbnail)
IEE DA-2020 overflow indicator filament display (9-pin envelope)
RCA DR2020 overflow indicator filament display (9-pin envelope)


The IEE Apollo DA-2000 is a definitive example of Numitron-style filament display technology. The DA-2000 features a single seven-segment digit, and the improved DA-2010 adds a decimal point constructed from two crossed filaments. The DA-2020 is an accompanying overflow indicator, capable of displaying +1 or -1. DA-2000 series devices were manufactured by a number of other companies, the RCA DR2000 series being the most common. Both IEE and RCA devices were manufactured in round- and flat-top variations.

IEE DA Series Datasheet (PDF)

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IEE Apollo DA-2110
 IEE Apollo DA-2110

The Apollo DA-2110 is the flagship of IEE's DA-2100 series of miniature Numitrons. Like its full-size counterpart, the DA-2010, the DA-2110 is a seven-segment numerical display with a cross-shaped decimal point. The DA-2110 is packaged in a miniature envelope with a nine-pin base, occupying less than half the volume of a DA-2000 series device.

IEE DA Series Datasheet (PDF)

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IEE Aurora FFD21
 IEE Aurora FFD21

The IEE Aurora FFD21 is a large Minitron-style seven-segment numerical display wtih a decimal point. With a 17mm digit height and a 100,000-hour operational rating, the FFD21 doubles both the size and longevity of the Fuji 3015F. IEE also manufactured the FFD51, a high brightness variant of the FFD21 rated at 40,000 hours of operation.

IEE Aurora & Apollo Datasheet (PDF)

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Pinlites DIP651R
 Pinlites DIP651R

The Pinlites DIP651R is a Minitron-style filament display with a 14-pin DIP outline. Unlike most Minitron types, the decimal point element of the DIP651R is separate from its seven-segment digit array. Pinlites also manufactured the DIP651L, identical to the DIP651R but with a left-side decimal point.

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RCA DTF104B
 RCA DTF104B

The RCA DTF104B is an unusually large end-view Numitron filament display with a Compactron-sized envelope and a 9-pin Novar B9E base. Although the DTF104B does not have a decimal point, the construction of the internal ceramic support suggests that decimal point variants of this device may have been produced.

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Wamco KW-104S-AU8P & KW-105
 Wamco KW-104S-AU8P & KW-105

Devices included in this entry:

Wamco KW-104S-AU8P numeric filament display (custon 8-pin base)
Wamco KW-105 numeric filament display (8-pin DIP; pictured in thumbnail)


The Wamco KW-104S-AU8P and KW-105 are highly miniaturized numerical Minitron displays, widely used in avionics systems. The primary difference between the KW-104 and KW-105 are their operating voltages: the KW-104 operates at +4VDC, and the KW-105 operates at +5VDC. The KW-104-AU8P variant has gold-plated pins in a non-DIP configuration. Unlike larger Minitrons, the KW-104 and KW-105 make no provision for a decimal point. Readouts requiring a decimal point must include KW-104S-DP or KW-105S-DP decimal point indicators in the display stack.

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Wamco KW-105AL
 Wamco KW-105AL

Unlike typical filament displays which have a seven-segment numerical readout, the Wamco KW-105AL is a 16-segment device, capable of displaying a full alphanumeric character set. The KW-105AL is height-matched to the standard KW-105, with an 8mm digit height, but is slightly wider to accommodate the additional diagonal segments. The KW105AL has an unusual base with 17 tubular pins along three sides of the device, which mates with an equally unusual male socket.

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