Everyone Needs a Nixie-Tacho!

Sure, the video is ten minutes long, or approximately 15 times your average attention span for anything (… SQUIRREL!!!). But let me be clear – you need to watch it. Here’s why:
a) It’s a Holden/Isuzu Gemini wagon with a nixie-tube based tachometer.
b) See above.
Write-up is here. I love the internet sometimes.

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  1. jerjozwik Avatar

    i got a nixie clock for my phone… thats almost as cool… right?

  2. Feds_II Avatar

    I read it as "Nixie Taco" which I assumed was some kind of double entend-treé.

    1. Alff Avatar

      Me, too. Was wondering who Nixie is, and if she is good looking..

    1. njhoon Avatar

      I must say that this link cost me hours of time and an account ot Instuctables. Thank you. Every once in a while playing the 'Follow the link' is actually useful and fun.

  3. Dutch Avatar

    The last time I saw any of these was in the '70s (pre video). There used to be a drag racing arcade game where you sat in the seat and had to launch, row the four speed and keep the little Corvette from getting too crossed up. It had the same type of numbers in the time and mph display. Man, would I love to have one of those today!!!

    1. ZomBee Racer Avatar

      HA! I remember that game! Every year the fair came to town and I would head directly to the arcade to play the latest driving games. I still remember the clunky feel of the shifting lever and the metallic clank of the gas pedal.
      Unfortunately the arcade tent was always pitched precariously close to that satanic Zipper ride.

  4. Peter Tanshanomi Avatar
    Peter Tanshanomi

    Nixies are cool, yes. But I can't get excited about this application. Why?
    1) Exposing rare, fragile Nixies in the comparatively harsh environment of an automobile dashboard (especially when not firmly mounted) is just asking to have the worldwide population of functional Nixies reduced by a number between one and four. Unless the Ruskies start manufacturing them again, they aren't a renewable resource.
    2) Digital tachs are, generally speaking, a severely stupid concept. When the numerical values change rapidly enough, the result degrades into an imperceptible jumble of rapid flashes. Furthermore, the numerical value isn't what's important about engine speed, anyway. What's vital to know at a glance is where the current lies within the rev range, and the trend data (how quickly it's changing, and in what direction). Analog steam gauge needles and fluroscan-style or "thermometer" bars both illustrate these relationships quite elegantly.
    I've owned two digital tachs, and they are good for exactly two things: making carb adjustments that affect idle speed, and capturing peak engine speed in memory for recall later.

    1. cmdrfire Avatar

      Well said. Although as a project I am impressed, and I dig the Nixies themselves (I've built a clock which softly illuminates my room at night) the automotive environment may end up destroying them. Mind you, there's people these days who make Nixie watches, so this isn't the worst application I've seen.
      I like the OLED as well; back in engineering school I used the same (or a similar one) in a project I was doing. I can stand by that without any concerns.

    2. Rust-MyEnemy Avatar

      The diagnostic mode built into the a/c panel of old A4s (like mine) gives you various functions including a digital tach (which reads in 10rpm increments, e.g 150= 1500rpm). Even with so few significant figures available, mucho acceleration still meant an unreadable display, typically with at least two "8"s where every available LCD segment was lit for fractions of a second.
      Digital displays are hopeless for displaying transient values.

      1. skitter Avatar

        <img src="http://i615.photobucket.com/albums/tt237/jskitter/hooniverse/XJGauges.jpg&quot; width="500">
        Even my bicycle speedometer couldn't keep up with acceleration.
        Clearly, the only solution is to use digital displays of analog gauges.
        Wait, what?
        <img src="http://i615.photobucket.com/albums/tt237/jskitter/hooniverse/LFAGauges.jpg&quot; width="500">

  5. retro Avatar

    I agree that it's utterly pointless and impractical, but since when did that stop something from being cool?

  6. Black Steelies Avatar

    So would the tubes closer to the right, being more numerically volatile, wear out faster than the left tube?

  7. Van Sarockin Avatar
    Van Sarockin

    This is wonderful, in a steampunk, missile silo sort of a fashion. But as Tans said, hopelessly inappropriate for this application. I will add that not only are the right hand values changing too quickly to be correctly read, that the time lag in the neon elements mean that by the time a value is displayed, either the engine is at a stable rpm, or it has transited to another value. This makes the tach hopelesly unreliable for its crucial purposes: avoiding overrevving and picking shift points.

  8. Spockie-Tech Avatar

    Greetings Guys
    This is Spockie-Tech, the creator of the above Nixie-Tach.. nice to read your comments 🙂
    Some info for commentors (if theyre still around).
    The IN4 Nixie tubes used in this project are about the commonest nixie tube you can get. there are tens of thousands of them out there for about $1 each.. I have about 50 of them waiting for something to use them for.. Theyre not that popular because they are end-view (instead of side view) and they have the russian "reversed 2" instead of a 5, which makes the 5 look a bit weird, so rest assured I am not recklessly consuming a precious resource of tubes.. I have the much rarer IN18's and B7971's, but Im not putting them in a car..
    Despite that, they have been bumping around on the dashboard for over a year now and are still fine. They are handling the environment well.
    Wrt the usefulness of a digital tacho. This is not your average digital tacho.
    As I explained in the video and code, I went to a lot of trouble to implement what I called a "delta limiter" (or something like that) in the code, which stabilises the RPM readout enourmously, whilst still allowing very rapid and accurate response.. Most digital tachos update around once a second to remove the jittering of the last 2 digits.. this one updates around 20-50 times a second, yet thanks to the clever delta code, the last 2 digits are very stable and you can actually distinguish the difference between 750 rpm and 755 rpm easily.. very useful for tuning carbs and stuff if you want that sort of precision
    Sure, when you are winding up and down through the gears, the last few digits blur out, which is why is why (if you look at the video) it *also* has the Nixie bargraph on top.. It has both digital *and* Analog displays so it is useful for both.
    Shift points – got that covered too.. although not implemented in the video, each nixie tube has a seperately controllable blue backlight that can be programmed to activate at any point.. so each tube can light up with a funky blue glow, gicing you 4 lights for shift points or any other warning display you can think of.
    Finally, its not *just* a tacho. It also has the ability to display speed, temperatures, ignition advance or any other parameter I want. Its just when I made the video, I had only implemented the tacho function.. As soon as the currently underway project is functioning, then the nixie-tach's speed function will be used to trigger the umm. other projects function at 88mph. Does that give you a hint ? 😉

  9. Jim Avatar

    Very nice. I'm about to do – almost – exctly the same thing today, except the "long" way with an ICL7135 A/D converter and 1 of 10 decoders, and a frequency to voltage converter. One difference is that the least significant digit will only display 0 or 5. 50 RPM isn't much here or there and will limit the display jitter. What strikes me is the neon Russian bar display along the top. I have 2 which I'd love to use for temperature and fuel, but have had no luck driving them. I assumed they were current operated – I forget what voltage they struck at – but attempting to bench test them through about 82K and a pot, they got real hot and I was afraid of burning them up. Do you have any info on driving the bars?

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