The Nixie Tube Killer That Never Was

With the wealth of Nixie projects out there, there are points at which Hackaday is at risk of becoming Nixieaday. Nixie clocks, Nixie calculators, Nixie weather stations, and Nixie power meters have all graced our pages. And with good reason – Nixie tubes have a great retro look, and the skills needed to build a driver are a cut above calculating the right value for a series resistor for an LED display.

But not everyone loved Nixies back in the day, and some manufacturers did their best to unseat the venerable cold cathode tubes. [Fran Blanche] came across one of these contenders, a tiny cathode ray tube called the Nimo, and after a long hiatus in storage, she decided to put the tube to the test. After detailing some of the history of the Nimo and its somewhat puzzling marketing — its manufacturer, IEE, was already making displays to compete with Nixies, and seven-segment LEDs were on the rise at the time — [Fran] goes into the dangerous details of driving the display. With multiple supply voltages required, including a whopping 1,700 V DC for the anode, the Nimo was anything but trivial to integrate into products, which probably goes a long way to explaining why it never really caught on.

If you happen to have one of these little bits of solid unobtanium, [Fran]’s video below will go a long way to bringing back its ghostly green glow. You might say that [Fran] has a thing for oddball technologies of the late 60s — after all, she’s recreating the Apollo DSKY electroluminescent display, and she recently helped a model Sputnik regain its voice.

33 thoughts on “The Nixie Tube Killer That Never Was

  1. It might seem odd that LEDs competed with nixies.

    As for driving a nixie-tubes – this will seem even more odd –

    We actually had 74xx series TTL chips to drive 90volt nixie-tubes (open collector with Vce of around 90 Volts).

    There were other TTL chips for nixies to like 74141, 74142.

    Also 1700Volts (1.7kV) seems high today. A pentode’s anode cap was normally around 800Volts. A small TV tube would be in the 12kV range and a large TV tube would be 25kV to 27kV

    1. Early LED numeric displays were tiny and expensive, so there were a lot of competing ideas for displays that all made sense for a time. Nixies, 7-segment neon (panaplex), incandescent filaments (Numitron), and LEDs all existed at pretty much the same time. Gas pumps used panaplex displays into the ’90s because of their daylight readability.

  2. interesting material, mostly because of the required support hardware to get it going. I wonder what the designers of this tube were thinking. Though all these requirements are easily forgotten when observing the pretty green glow…
    If this would have caught on I’m sure that they would have made them in other colors also.

    Thanks for posting.

  3. You could also use a meter, the digital output summed via weighted resistors. I’m not sure if that ever made commercial equipment, but it was shown in hobby circles, kind of expensive, except in the late sixties/early seventies, there were lots if cheap meters around, intended for tuning indicators and “vu meters” in consumer equipment, where trend is more important than exact.

    Of course, you could be really cheap and have a bulb or later led for each binary output, 1-2-4-8. Add them together to get the number. Not too bad for BCD display, where there were four indicators for each decade. But a straight binary counter would mean adding up a string of numbers for the total count.

    RCA published a hobby manual about 1971, when a lot of this was still relatively new, and I think they had Nixie circuits along with Numitron or one of those later readouts. They might have shown the meter scheme, I’m not going to dig out the book, but I think it came just before cheap led readouts, so those were lacking


    1. For a tube of this size I’d guess 750V is more like it. I made a thing using similarly sized 3LO1i tube (look up Zloshnik) and it was about 750V. But maybe these tubes need more volts because they do not scan a thin beam, but project it all at once.

        1. Sorry, didn’t watch the video.

          I also searched for datasheets though and found that some of the Nimos require even higher anode voltage, so yeah, it’s pretty high. But doable. If we were flooded with these, powering them would be as easy as powering nixies.

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