The Vintage Technology Association

Filament Displays

Filament displays were a niche alternative to the neon Nixie tubes that were the numeric display of choice during the 1960s. Sometimes sold under the brand name of Numitron, a filament display uses thin low voltage wires sealed in a vacuum to generate a lighted digit, similar to the way a lightbulb works. Unlike Nixie tubes, filament displays use a very low voltage, normally five volts or less, which makes them ideal for interfacing with modern TTL chips.

The tube-shaped Numitron later evolved into smaller DIP-style Minitron and Pinlite displays, still used in aircraft instrument panels due to their high visibility and extremely low failure rate.

IEE Apollo DA20xx Series

Devices included in this entry:

RCA DR2000 seven segment display (9 pin envelope)
IEE DA2010 seven segment display with decimal (9 pin envelope; pictured in thumbnail)
IEE DA2020 overflow indicator display (9 pin envelope)

Tubes like the DA2010 shown to the left are the definitive examples of filament tube construction. The tube uses a seven segment digit with a set of crossed filaments to represent a decimal point and possesses a standard nine pin miniature tube base. Note the flat envelope top, a feature distinctive to many IEE filament display tubes. This tube was manufactured in a myriad different types by many companies, some with different style envelopes or different characters and decimal point configurations.

IEE Numitrons Datasheet (PDF, covers numerous devices, including the DA2010 and DA2020)

[View Detail]

IEE Apollo 2110

A subminiature version of the 2010. Tube has a seven segment display with decimal point and a nine pin flying lead base. As with the 2010, the 2110 has holes in its plate for a plus symbol that are unused in this model of tube.

IEE Numitrons Datasheet (PDF, covers numerous devices, including the DA2010 and DA2020)

RCA DTF104B

The RCA DTF104B is one of only a handful of end-view numitrons available, and is also one of the largest. This tube uses a large 'novar' style nine pin base, a fairly common socket when compared to some exotic display tubes. The tube does not have a decimal point, though vacant holes in the ceramic indicate that a decimal point may be present on some models.

[View Detail]

'Minitron' 3015F

A minitron is an advancement of filament display technology that follows the same evolutionary step as a panaplex neon display. Instead of being sealed into a tube, minitrons are constructed into rectangular DIP-style envelopes that can be easily integrated into modern circuit layouts. The 3015-F is a fairly standard example of such a device: it has a glass front bonded to a sheet metal case, which is covered with a removable plastic cover. This model of minitron was manufactured in at least two different styles, one of which has a black matte around the display area. Digit height on the 3015F is 10mm and the package is 23mm long from end to end. When operated at 5VDC, the 3015F is rated for 50,000 hours of continuous operation.

3015F / 3015G Datasheet (PDF, 173kb)

[View Detail]

IEE Aurora FFD21

The FFD21, a 'minitron'-style display made by IEE, comes in a 15 pin package, which contains a single seven segment display and a separate filament to represent the decimal point. This display has a much larger display area than the 3015F: with a digit height is 17mm and a package length of 28mm, it is one of the largest 'minitron'-style filament displays ever made commercially available. The small pin in the bottom center of the display is a hollow metal tube that would have been used during construction to pump the air out of the enclosure. The FFD21 is rated for 100,000 hours of service at 5VDC and normal drive currents, twice as long as the more common 3015F minitron display.

IEE Aurora Family Devices Datasheet (PDF, 95kb)

[View Detail]

Wamco KW-105

A nearly modern implementation of minitron display technology, and almost surely the smallest minitron model ever made. This display is truly minuscule, the digit height being only 8mm. Wamco still manufactures these displays for use by the highly conservative avionics industry.

[View Detail]

Wamco KW-105AL

Wamco made minitron-type displays in a wide variety of styles. These tiny KW-105AL filament displays are 16 segment devices, and can display a full alphanumeric character set. Though they are wider than the KW-105s pictured above, digit height is the same at only 8mm.

[View Detail]

Lamps, Inc. 'Numeralamp'

The Lamps, Inc. 'Numeralamp' is a fairly typical seven segment display with a standard nine pin base. The unusual feature which sets this device apart from other similar tubes is that it has a small stand-alone incandescent lamp as its decimal point indicator, technically making it a multi-envelope device. The Numeralamp also appears to have a second attachment point for another incandescent lamp at the top of the tube.

Special thanks to reader Guido Mennen for identifying this previously anonymous device.

IEE Apollo 2110
	A subminiature version of the 2010. Tube has a seven segment display with decimal point and a nine pin flying lead base. As with the 2010, the 2110 has holes in its plate for a plus symbol that are unused in this model of tube. IEE Numitrons Datasheet (PDF, covers numerous devices, including the DA2010 and DA2020)

RCA DTF104B
	The RCA DTF104B is one of only a handful of end-view numitrons available, and is also one of the largest. This tube uses a large 'novar' style nine pin base, a fairly common socket when compared to some exotic display tubes. The tube does not have a decimal point, though vacant holes in the ceramic indicate that a decimal point may be present on some models. [View Detail]

Wamco KW-105
	A nearly modern implementation of minitron display technology, and almost surely the smallest minitron model ever made. This display is truly minuscule, the digit height being only 8mm. Wamco still manufactures these displays for use by the highly conservative avionics industry. [View Detail]

Wamco KW-105AL
	Wamco made minitron-type displays in a wide variety of styles. These tiny KW-105AL filament displays are 16 segment devices, and can display a full alphanumeric character set. Though they are wider than the KW-105s pictured above, digit height is the same at only 8mm. [View Detail]