Building a sound reactive EL panel and learning something in the process

We’ve seen a lot of builds using electroluminescent wire, usually in the realm of costumes and props. Unfortunately, most electrical engineers don’t deal with blinking and dimming EL wire and panels and any tinkerer trying to control electroluminescence doesn’t have a lot of resources on how to control EL stuff. [ch00f] wanted to fill this knowledge gap, so he build a sound reactive EL panel driver and learned a lot in the process.

Nobody really knows how electroluminescent wire and panels work on a molecular level, but [ch00f] did know that changing the direction of an electric field will cause the EL material to glow. Changing the frequency of this electric field will change the EL material’s brightness, so all [ch00f] had to do was make a variable-frequency EL driver – something that’s a lot harder than it sounds.

We won’t bore you with the details because we  couldn’t do [ch00f]‘s write up any justice. We will skip to the end and tell you [ch00f] was able to make a sound reactive EL panel after a month of work that included making his own transformers and doing a whole bunch of math. You can check out the video of [ch00f]‘s [Tony Stark]-esque EL panel after the break.

Comments

  1. Chris says:

    Awesome write-up. It’s also a great tutorial on winding your own flyback transformers, which can be useful even if you have no interest in EL panels.

  2. Erik Johnson says:

    I thought EL had a “harmonic” frequency for peak efficiency which does vary brightness, but beyond that it’s just PWM. The sound-activated drivers I have tested vary the voltage, fixed frequency… No noticeable tone change with brightness change.

    • Ch00f says:

      Usually, EL wire is driven with a resonant power supply because they are cheap and highly efficient. You can switch them on and off easily with a TRIAC, but once you start switching fast enough to utilize persistence of vision, you’ll run into issues.

  3. sirus20x6 says:

    ~Nobody really knows how electroluminescent wire and panels work on a molecular level

    A moving electric current boosts valence electrons to higher states. photons are produced when they fall back down to their resting state.

    • Alvie says:

      ~~Nobody really knows how electroluminescent wire and panels work on a molecular level.

      ~A moving electric current boosts valence electrons to higher states. photons are produced when they fall back down to their resting state.

      So didn’t you just describe how it works at the atomic level not the molecular level?

  4. conundrum says:

    IIRC EL wire based on ZnS:Mn:Cu is the one which changes colour with frequency.

    I often wonder if someone should make an RGB wire using this effect, but using barium sulphide instead of zinc sulphide as the luminescent material.
    Just alternately coat segments with different materials and then use insulated rather than uninsulated wire with enamel removed from sectors where a connection is required.

    Another interesting idea, make the “cores” out of gallium tin alloy so that the tape can stretch out without breaking.

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