Tiny TV Celebrates The Forgotten Tech Of CRTs

For those of us who grew up before the Internet, the center of pretty much every house was the TV. It was the shrine before which we all worshipped, gathering together at the appointed times to receive the shared wisdom of mass entertainment. In retrospect, it really wasn’t that much. But it’s what we had.

Content aside, one thing all these glowing boxes had in common was that which did the glowing — the cathode ray tube (CRT). Celebrating the marvel of engineering that the CRT represents is the idea behind [Matt Evan]’s tiny desktop TV. The design centers around a 1.5″ CRT that once served as a viewfinder on a 1980s-vintage Sony camcorder. [Matt] salvaged the tube and the two PCB assemblies that drive it, mounting everything in a custom-built acrylic case, the better to show off the bulky but beautiful tube.

The viewfinder originally used a mirror to make the optical path more compact; this forced [Matt] to adapt the circuit to un-reverse the image for direct viewing. Rather than receiving analog signals off the air as we did in the old days — and we liked it that way! — the mini monitor gets its video from a Raspberry Pi, which is set to play clips of TV shows from [Matt]’s youth. Rendered in glorious black and white and nearly needing a magnifying glass to see, it almost recaptures the very earliest days of television broadcasting, when TVs all had screens that looked more like oscilloscope CRTs.

This project is a nice homage to a dying technology, and [Matt] says it has spurred more than one conversation from people you grew up knowing only LCD displays. That’s not to say CRTs are totally dead — if you want to build your own old-school TV, there’s a kit for that.

35 thoughts on “Tiny TV Celebrates The Forgotten Tech Of CRTs

      1. You create a universe in a bubble where you wrote what you wanted and then swap it with this universe. The you in the new universe then destroys this universe and the edit is complete.

    1. Wow. That will get you enormous fan points in these parts. It must be worth a fortune now! I hope it is well protected and preserved.

      Are the linked pictures your actual unit? That’s the first time I have seen pictures of the modular card edge connectors. From memory they were the first (and probably only from that era) press fit/connect edge connectors. It would be great to have a picture of the underside of the main board.

      It would also be great to have pics (top and bottom) of all the boards so it can be reproduced in future just we like to do with old stuff today. There would be many people from organizations that would be willing to help you document the full unit including making schematics.

      Also the linked page refers to the wire memory as “magnetostrictive”. From memory which appears to be confirmed by these pictures it was torsion wave delay memory.

      I love that from 70’s (and earlier) tech. Um I need some memory – oh I’ll just use a bit of wire.

      1. You’d be surprised how little some of this older stuff is worth monetarily because no one knows about it. I don’t know about this this thing in particularly but I would be fairly confident in saying that barely anyone knows what it is, so the demand for it is probably not much bigger than supply. At least old video stuff seems to be able to sit on eBay for cheap and time out. I don’t really know anything about stuff earlier than ’80s. Delay line memory sounds quite interesting but I thought it was only bucket brigade devices. I didn’t know you could just use a wire. I’ll have to read up on that. Its amazing how something like that calculator can generate vector characters like that.

    1. More of a problem is the lack of ventilation. The thermal cycling will cause the electrolytic capacitors to expel their electrolyte (dry out). I digital clock that bounces around the screen would be better to prevent phosphor burn.

  1. “In retrospect, it really wasn’t that much. But it’s what we had.”

    It was much for three reasons beyond the technology:

    1. It was the first access to visual broadcast entertainment and (limited) access to other cultures, and in the US it was intentionally free once you bought the television. It wasn’t the internet, but that’s not a bad thing.

    2. The devices were largely repairable, often by the end-user.

    3. More importantly, in most areas there were limited broadcast sources, like US commercial broadcasters ABC, CBS, and NBC, plus pubic service networks like PBS. That narrow scope provided us the gift of common culture – we all saw and heard the same things: the same news, the same documentaries, the same entertainment. In emergencies, all channels were interrupted, emitting an attention-getting tone followed by a stentorian voice describing the urgent issue at hand. All of these became common knowledge, reliable touch-points that formed easy social connections across a large spectrum of the population. Broadcast radio was much the same: limited ranges meant local areas offered limited options, and everybody knew all of them. It wasn’t the internet, but that was a good thing.

    1. “2. The devices were largely repairable, often by the end-user.”

      I’m going to show my age, here: there used to be vacuum tube testers in pretty much all drugstores, and even in some supermarkets. They were usually somewhere near where the camera film, flashbulbs, and batteries were. These sat at the top of a self-contained cabinet that held a stock of the most common tubes used in radios and TVs. They had somewhere around 50 sockets on their top surface to cover the different common tube pinouts, and a booklet or chart telling which socket to plug each tube into, and a big analog meter with red, yellow, and green arcs to indcate the status of the tube. For any that came up red, you would get a store employee to unlock the cabinet and sell you a replacement. These ranged from $3 to $10 for most tubes. There isn’t really an equivalent today, because nothing today is considered “user serviceable”. Of course there’s the plumbing sections of hardware and department stores, so you can get replacement parts for leaky faucets and toilet valves, but that’s different because hardware stores are kind of DIY stores, while drugstores aren’t.

      1. Yes! I was the tinkering kid who inherited all of the neighbors’ old TVs and stereos (and lawn mowers and go-carts and kitchen appliances), and learned to fix them – not least thanks to the drugstore tube-tester and local Radio Shack folks who really knew their stuff and were willing to share.

      2. Ah, but the problem was that you needed that level of support/supply because the damned things were prone to burn out. I remember our family getting a fairly early hybrid TV (part valve, part transistor), and the only things that went wrong were the power amp valve (from memory a PCL86), which we went through several of, and the CRT tube, which towards the end of its life had a habit of going bright green for a while (normally curable by a thump).
        Modern kit is much more reliable (at a component level at least), and much less expensive in real terms ($3 – 10 was a lot more then than it is today). It also packs a lot more functionality into much less space. The result is that it’s inherently more difficult to repair. Manufacturers have learned that we value functionality and size over repairability, so that’s what we get.

  2. I visited this place when i was in Columbus a few months ago (Early Television Museum). A heck of a collection of very old TVs, nearly all functional ad running. What made me think of it was the mention of putting a magnifying glass in front of the CRT. There were quite a few commercially sold devices from way back when on display doing exactly that, making a small display look a bit larger though pretty obviously distorted. Well, thats what they had to work with i suppose. https://www.earlytelevision.org

    1. I never saw a magnifier as a kid but I remember seeing the 3 color transparency overlay that made you think you had Color TV. It was a family visit to friends or relatives in a nearby city and their TV looked weird and I asked my dad why and I learned the truth. This would have been in the first few years of color’s debut.

      1. I vaguely recall that Pong for tv had an overlay, but maybe a different game or I’m imagining things.

        Early tv was mechanical, a wheel with a neon bulb.

        After color tv arrived, there were schemes to add color to b&w sets. So something mechanical that fit iver tge screen.

    2. Oddly enoguh keeping the computer museum at InfoAge is one on broadcast technology. There are quite a few TV sets there. And the greeter always wants to discuss who really made the technology work. And there’s a crowd of them at the American Museum of the Moving Image, at the oldest known still working movie studios.

  3. As a kid, I remember going into a shoe store, and looking down at my feet through a cheap-looking x-ray machine with a stamped metal exterior and a tiny CRT display on top. This tech application didn’t last for long.
    I’m glad that I didn’t make use of it to see my skeletal little tootsies more than a couple of times.

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