Magic eye spectrum analyzer

its goddamned magic

 

If Nixies aren’t cool enough, maybe it’s time to step it up to magic eye tubes.

Magic eye tubes are, like Nixies and Dekatrons, display tubes. Unlike the alphanumeric characters of Nixies or rotating points of light in a Dekatron, Magic eye tubes are either bar graph or ‘Pac-Man’ displays that were used to show the signal strength of a radio station on very expensive radio sets.

After doing a few experiments with tubes, [sylvain] thought it would be cool to do something with magic eye tubes. He sourced eight vertical ‘bar graph’ magic eye tubes and built an audio spectrum analyzer.

One of the more difficult things to do was to compute the power levels for each frequency band. There are a few graphic equalizer ICs available, but [sylvian] decided to go the old-school, harder way by putting an FFT algorithm on an ATMega624.

An impressive piece of work that would look amazing next to a nice tube stereo system.

Comments

  1. Ryan says:

    Old school easy way would be to use a bandpass filter for each tube. No uC needed :)

  2. Jeff Nichols says:

    Am I the only one that thought the title referred to stereograms? http://en.wikipedia.org/wiki/Autostereogram

    I kept trying to unfocus my eyes and “see” the hidden spectrum.

  3. Alex says:

    Neat, I didn’t know these tubes came in a linear(?) variety. I’ve only ever seen the circular kind.

  4. masterburner says:

    Oh darn. I was so proud when I finished my stereo VU meter with EM84 tubes: http://www.youtube.com/watch?v=TIVUGsvTpVE

  5. n0lkk says:

    Not what I was expecting when I read spectrum analyzer, although it had me wondering hoe magic eye displays could be used as a spectrum analyzer. Something that display all the radio frequencies in a sample & their relative power level

  6. pyrobutters says:

    just need some bandpass filters and few analog electronics to call it oldskool… there tubes with uC ?! Overall, this cool, but it is disappointing to see a micro-controller, instead of the real deal analog. Whats wrong with analog? Seriously…. had to overclock the controller to make it work? That made me LOL. To each there own…

  7. NewCommentor1283 says:

    @sylvain
    i love the look, it’s slick
    the fact that you did NOT put LEDs under
    the tubes makes it look BETTER!
    you SHOULD get a greenish glow
    reflecting off of the case.
    these tubes arent all that bright
    and LEDs always drown em out.
    good job of letting the tubes do the lighting! :)

    PS:
    i agree with everyone else on the TYPO.
    im pretty sure H.A.D. meant …”decided to go the NEW-school”…

    could have been just simple capacitors, inductors, and resistors,
    all calculated with:
    Xc=1/(2pifc)
    XL=2pifL
    BW=Xc/RW (or is it BW=RW/Xc ?)
    and make it a double(pie) filter

    its still a good result though, theres nothing wrong with a uC.

    and yes these DID exist back in 1940, …
    they used them to help design stuff.
    they just costed about 20,000$ in today’s money
    and were as large as a suitcase and heavy.
    have pictures of one from 1940? you’r lucky. please post for all to see!!!

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