Soviet-Era 7-Segment Display, Built Like a Tank

In a way, all 7-segment displays are alike; at least from the outside looking in. On the inside it can be quite another story, and that’s certainly the case with the construction of this Soviet-era 7-segment numerical display. From the outside it may look a bit sturdier than usual, but it’s still instantly recognizable for what it is. On the inside is an unusual mixture of incandescent bulbs and plastic light guides.

The black-coated blocks of plastic on the left (shown from the rear) act as light guides. The holes are for nesting the incandescent bulbs. Note the puzzle-like arrangement of the uniquely shaped pieces.

The rear of the display is a PCB with a vaguely hexagonal pattern of low-voltage incandescent bulbs, and each bulb mates to one segment of the display. The display segments themselves are solid blocks of plastic, one for each bulb, and each a separate piece. These are painted black, with the only paint-free areas being a thin segment at the top for the display, and a hole in the back for the mating bulb.

The result is that each plastic piece acts as a light guide, ensuring that a lit bulb on the PCB results in one of the seven thin segments on the face being lit as well. An interesting thing is that the black paint is the only thing preventing unwanted light from showing out the front, or leaking from one segment to another; usually some kind of baffle is used for this purpose in displays from this era.

More curiously, each plastic segment is a unique shape apparently unrelated to its function. We think this was probably done to ensure foolproof assembly; it forms a puzzle that can only fit together one way. The result is a compact and remarkably sturdy unit that shows how older and rugged tech isn’t necessarily bulky. Another example of small display tech from the Soviet era is this tiny 7-segment display of a completely different manufacture, which was usually used with an integrated bubble lens to magnify the minuscule display.

32 thoughts on “Soviet-Era 7-Segment Display, Built Like a Tank

    1. …Displays segment you? I dunno, I feel like there’s something in there but I can’t quite grasp it. The displays of our social media devices segmenting the American populace, maybe?

      Meh. Fuggit. I got nothing either.

  1. I have a couple of recent 7 segment displays that look like big chunky LCD’s but they’re actually made with LEDs lighting up behind translucent red plastic “segments”. Much cheaper to make and just as effective

    1. LEDs that look like LCDs? Are you sure? 7-segment LCDs are usually a clear screen, silvery reflective background, and black segments making the digits. The segments darken to form the numbers. 7-segment LEDs I’m sure you know are the ones that light up the segments, usually red but can be any colour. You can even get RGB ones, actually, full RGB control over each segment. Would love a few of those to play with just for the novelty value.

      I suppose some of those smart-LEDs and a bit of 3D printing I could make one. Brother in law’s got a 3D printer, I’d just need some translucent medium. Maybe use hot-melt glue poured into shells for the segments.

      Anyway… also 7-segment LCDs are usually a lot cheaper than LEDs, LCDs are cheaper in general. Unless you mean the full-colour hi-res LCD screens that show actual pictures.

  2. I grew up in Soviet Russia. In Siberia. And it was the best years of my life.
    Socialism. Everyone work. Since nobody can get rich, the life is not busy. Lot of time to tinker parts “found around”.

    1. Some animals are more equal than others, though. Nobody can get rich, but the guys in charge never seemed to starve.

      Same is true here, and probably all over the world. Communism, like democracy, is great in theory, but when real people are thrown into the theory, they tend to think of their own wants and needs before doing what they should be doing.

      1. Like Winston Churchill put it:
        “Capitalism distributes wealth unequally.”
        “Socialism distributes poverty equally.”

        I also like the Margaret Thatcher quote:
        “Socialism seems like a good idea until you run out of other people’s money.”

        It’s all about tyrinnacal elites who are more equal than the others, the kind of folks the Americans thumbed their noses at back on July 4th 1776. Below Divinity, the individual citizen is the highest level of government. All larger, more lowly groupings are only legitimate when they honor the authority of their members. In that context hacking and discovering the nature of any product is a God given right that no government may take away. Individually they may be able to stop us, but they are unable to make it the right thing to do no matter what they say or do. :-) …the shot heard round the world…the start of the revolution (Thinking of Schoolhouse Rock :-) )

          1. So much hatred. So little content. Her statement is still true whether you like it our not. Don’t like it from her. Fine. Then I am saying it. I doubt it was an original expression when she said it anyway.

            Socialism seems like a good idea until you run out of other people’s money.

    1. They do. But it costs you an arm and a leg.
      Look at medical stuff or electromechanical things rated for mitary use or for nuclear power plants. Lots of 1/2inch thick aluninum front panels there…

  3. I love these vintage types of displays. I’ve been trying to find a set of those incandescent IEEE projection displays I saw on Franlab for awhile for a price that wont break my wallet, seems an impossible task. I wonder if I could cast the lens’ in epoxy, print a mask with the numbers on overhead transparency, and 3D print the shell with LEDs to make a diy replacement module?

        1. Youtubers like Fran should relocate to places where rent is super-cheap, there is general reign of law and order, the power stays on, internet works, and parcel delivery companies are willing to visit. (This describes most of Nebraska, my home…great place to live unless you have allergies. Our state flower, goldenrod, is a wicked alergen generator…but the people are nice, especially if you like the color red :-) )

          1. That’s the spirit! :-) When life gives you lemons….(er goldenrod)… make lemonaide (great tea).
            I’ve never heard of the goldenrod tea thing but I’ll look into it. I’m more of a freebasing-Folgers-black kind of guy but I’m up to the occasional new thing. :-)

      1. It looks like the design has a provision for a decimal point but this particular display did not need one and so they didn’t install the extra bulb. You can see the empty bulb-sized hole in the pc board in the first picture. (half of which seems to be reversed)

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