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Vacuum Fluorescent Displays

Vacuum fluorescent display tubes share more in common with a cathode ray tube than they do with the Nixie tubes they tend to mimic. A VFD tube has a low voltage filament which is energized in a vacuum, causing electrons to 'boil' off. Metal plates covered with a phosphor coating are charged to between 25 and 50 volts, causing electrons leaving the filament to strike the plates and illuminate the phosphor. Later models of VFD also have a control grid, a metal screen that is placed between the digit and the filament. The control grid acts as a valve, allowing the digit to be turned on or off without the need to power down and re-heat the filament.

General Electric Y1938

Devices included in this entry: General Electric Y1938 (nine pin base) General Electric blue-dipped Y1938 (nine pin base; pictured in thumbnail) General Electric prototype Y1938 (nine pin base) An early VFD tube, the General Electric Y1938 is an attractive display in a classic nine pin envelope. This device is a bit higher quality piece of construction than the Tung-Sol Digivac VFDs shown elsewhere on this page--Y1938 tubes have more evenly lit digits and higher build quality overall. Some 1938s have holes where a decimal point would have appeared, while others do not. Some units also have a thick blue coating over the glass, to improve the color of the digits. It is unknown whether this blue coating was applied by GE or by a secondary manufacturer. Prototypes of this tube had a radically different internal construction, incorporating a printed VFD material on a ceramic substrate instead of the separate tiles used in production VFD's. It is unknown why this apparently superior manufacturing process was abandoned in production devices. Of important note to the modern day hobbyist is that this tube lacks a control grid, a refinement not added to VFDs until after this tube was manufactured. With no control grid, this display can not be multiplexed General Electric Y1938 Datasheet (PDF, 136kb) [View Detail]

General Electric Y4075

The rather hard to find Y-4075 display tube is the smaller cousin to the General Electric Y-1938 display shown above. Like the Y-1938, this tube is constructed using a series of phosphor coated tiles that are arranged in a seven segment pattern with decimal point. This is a very early VFD part number, and like other early tubes it lacks a control grid, making it nearly impossible to multiplex. The example shown here was actually repackaged in an Archer blister pack for sale at a Radio Shack retail store. The mind boggles at the thought of a time when Radio Shack sold things other than batteries and bottomless piles of tawdry consumer goods. [View Detail]

Futaba 9CT06
	The Futaba 9CT06 is a tiny 9 digit VFD, designed for use in handheld calculators. This display has a long tubular envelope with a central evacuation nipple and conventional 7-segment digits with decimal points. The 9CT06, like most VFD's, has a control grid installed above each digit to allow for multiplexed displays. [View Detail]

Iseden Itron DG10A

This flying lead display tube has color coded plastic sleeves on its leads, which makes it easier to wire than most VFD tubes. The tube is smaller than most, the envelope height is only 26mm and digit height is 9mm. An interesting sidenote about this tube is that they are very well packaged compared to most other tubes. Instead of being rudely stuffed into a cardboard box, the samples we have were carefully wrapped in tissue paper and then individually sealed in rigid plastic containers.

Iseden DG12C
	The DG12C is an eight segment display, capable of generating both numbers and signs. The display has a right decimal point and a left colon indicator. Digit height is 11mm and the envelope is 42mm high. This tube has a somewhat more rounded top than most newer vacuum fluorescent tubes, which some find more visually pleasing.

Iseden DG19E
	The DG19E is a large, attractive VFD with a curved top and shaped flying leads. Digit height is 15mm and the envelope is 41mm long. The display has a control grid and an eighth segment, allowing the tube to display a plus sign in addition to normal seven segment numbers. [View Detail]

Tung-Sol DT-1704C 'Digivac'

An early VFD tube in a narrow 9 pin envelope, seven segments with no decimal point. Like other early VFD tubes, this device predates the inclusion of a control grid and therefore can not be multiplexed. This model of tube seems to be very failure prone; bent heater filaments and uneven or partially unlit segments are common. The pinouts of this tube are identical to the General Electric Y-1938 display shown above. [View Detail]

Tung-Sol DT-1741C 'Digivac'

A "symbol" variant of the Digivac tube listed above, with two elements, one labeled 'TAX' and the other labeled 'CRD'. The tube has the same narrow nine-pin envelope as the DT-1704C, though only five of the pins are connected. This tube was originally salvage from the old NCR factory, and was intended for use in a NCR cash register. Though practically useless to the modern enthusiast, VFDs such as this which display something other than a segmented display are exceedingly rare.

NEC LD8012
	The LD8012 is a VFD tube designed for upside down mounting. The tube has twelve flying leads which exit the upper surface of the tube, the nipple and getter are on the underside. Digit height is 20mm and the envelope is 37mm high. The picture to the left was taken with a digit voltage of 25 volts and a filament voltage of 1 volt. [View Detail]

NEC LD8113

The LD8113 is a large, attractive VFD tube with a flat top and flying leads. The tube's unusual segment arrangement allows a single tube to generate both numbers and signs, as well as some alphabetical characters. Though the tube appears to have 10 segments, the four horizontal and vertical segments in the center of the display are ganged together to form an 8-segment tube. Digit height is 14mm and envelope height is 43mm excluding the tube's nipple. [View Detail]

Sovtek IV-4

The IV-4, a Soviet tube, is one of only a handful of single digit alphanumeric VFD tubes available. This large VFD display tube has a 17 segment display with left and right commas, for a total of 19 controllable display elements. This tube has a proper control grid for multiplexing, unlike some earlier single digit VFD's such as the Y-1938, shown above. The tube has a 22 pin flying lead base and can be directly soldered into a PCB without need for a special socket. [View Detail]

Sovtek IV-18
	The IV-18 is a Russian multi-digit tube, which contains eight separate seven segment displays in a single envelope. Each digit has a decimal point, as well as its own separate control grid for multiplexing. The tube also has a separate overflow indicator digit that is half the width of the numerical digits. [View Detail]

Sovtek IV-21
	Sovtek's IV-21 display is a size-reduced sibling to the IV-18, designed for use in pocket calculators. The IV-21 is an eight digit, seven segment display with sign and overflow indicators. [View Detail]

Sovtek IV-22

The IV-22 is a Soviet single digit end-view VFD display tube, one of only a handful of end-view VFD devices manufactured. The tube's oval envelope is suitable for horizontal and vertical stacking and is very similar to the common 8422 nixie tube in dimensions, in fact an IV-22 can be shoehorned into an 8422 socket in times of desperation. The tube's large 18mm display includes a control grid for multiplexing applications. The IV-22 is a fairly common tube and a good choice for a project, both the tubes and sockets are readily available from eBay and myriad smaller online resellers. [View Detail]

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