A cold cathode audio visualizer


Finally, cold cathode lights can be used for much more than illuminating the inside of your computer or making your whip look like it can hover. [James] discovered if he varied the voltage going into the inverter, only a certain amount of the tube would light up. Give a hacker an interesting observation and enough time, and eventually he’ll come up with something really cool. In this case, it’s a cold cathode audio visualizer, powered by fluorescent tubes doing unexpected things.

The build details are a little scant, but we were able to coax an imgur album of [James]‘ build. He’s using these 20″ CCFL lights with the stock digital inverters replaced with TDK CCFL inverters.

The digital control of this build is provided by an Arduino Mega and a custom shield. We’re guessing the graphic EQ is provided by an MSGEQ7 chip, and the inverters themselves are powered through the Mega’s PWM pins. It’s a lot like an IN-9 Nixie graphic EQ, only much, much bigger. [James] is planning a larger version of this build, dubbed the Mega speKtrum and we can’t wait to see that build along with a proper writeup.


  1. r0r0 says:

    This video is unavailable. sez yt.

  2. Nicholas says:

    Very cool. Reminds me of the old neon license plate frames. Similar effect.

  3. Matt says:

    Very very cool. Nicely done.
    I wonder how badly/quickly this damages the tubes.

    • ColdTurkey says:

      I don’t think it does. I have one of these in a PC case i bought about 10 years ago. it came with a board that had a mic and a variable pot and does exactly this, still works perfectly to this day! Has an awesome Borg-green look to it.

  4. mojojoe says:

    So why aren’t lightsaber models built like this?

  5. Hirudinea says:

    Is it just me or does anyone else think this would make a cool fireplace?

  6. Anonymous says:

    I have always wanted to do this, after I first found a CCFL that showed the ‘variable height plasma’ effect in a damaged monitor. Props to actually pulling it off!

  7. rue_mohr says:

    I knew about the effect, but I didn’t know it was that stable!
    great work!

  8. MrX says:

    Wow it is impressive how responsive it is.

  9. Sacha says:

    With hot cathode fluoros you should run them at full for about 100 hours first to migrate the mercury vapour to the cold spots. CCFLs should be fine.

  10. zibri says:

    Simply GREAT!

  11. I’ve seen something larger(112 tubes) with nixie coupled with a real Yamaha FM sound chip, but glowing blue of CCFL lights looks equally great… they all look amazing anyway.

  12. eucalyptux says:

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