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  • EEVblog #362 – LED Tube Lighting Install & Theory

    Posted on October 2nd, 2012 EEVblog 12 comments


    Installing LED fluorescent tube replacements in the EEVblog LAB with before and afetr measurements.
    Bonus theory material on fluorescent startup and LED tube design and dangers.
    With Doug Ford from Doug Ford Analog Design:
    www.dfad.com.au

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    • William

      Anyone else notice some strange noises in the audio starting at about 28:55 once the LED tubes are turned on?

      • Goophy629

        Yea, some long and raising beeps…disappeard after the big bang…

      • Worf

        Heard those – thought it’s some RF interference with the LED tubes. Once the tubes burn in it tends to disappear quite quickly.

        Seen it with some LED bulbs where they’d interfere with FM radio for a bit, but once they’ve been installed awhile it goes away.

    • http://www.techartblog.com Rob

      Magic Smoke, I remember my boss setting a cap off in a VCR once and it was a spectacular acid plume, must have reached about 4 foot into the air.

      • Rick

        I used to supervise a test department where, among other things, IBM CRT terminals were built and tested. These units had two huge electrolytics in the power supply and one day a tech defeated the safety cover interklock on the functional test station so he could troubleshoot the board.

        He learned the hard way WHY the interlock and safety cover were in place. One of the caps was reversed and (no lie–I was there) blew off the board and shot through the ceiling tile above the test station. No vents on top of the cap so that’s just the way this one blew. Never did see that cap, again, but a hole in the ceiling tile remained as a valuable to my techs to not defeat interlocks.

        • http://www.eevblog.com EEVblog

          Ah, the pre-vent days!

    • Worf

      Instead of using white LEDs – how are using arrays of red/green/blue LEDs? Compensating for the differences in brightness and whatnot – do they give better color and all that?

    • Salas

      Dave, was it a fully satisfying upgrade after all? Maybe it takes even more light for impressing the eye VS what was installed before. Surely a good economy move, regarding consumption and longevity at least.

      • http://www.eevblog.com EEVblog

        Another video uploading now that hopefully shows the difference. Yes, it’s a massive difference. I’m now using more power because of the 2x20W 3m strips + 2x60W diffused panels.
        Hard to catch the differences on camera though.

    • Wartex

      This is the 2nd time you botched the starter explanation. This is how starters look like http://i.imgur.com/hfPlK.jpg

      The GDL (gas discharge lamp) is normally OPEN. Also the bimetal is INSIDE the GDL and is integral part of it, there is nothing connected in series. At first the gas inside the GDL is ionized which heats up the bimetal and causes it to close. This is called “preheating stage”. As soon as bimetal closes, the filaments glow and heat up the gas inside the fluoro tube. The bimetal opens as the gas cools down inside GDL and the ballast dumps the energy into the main tube, this is called a “strike”. Now you have the current flowing from filament to filament and there is not enough current flowing via GDL to heat up the gas enough to short the bimetal again.

      Jeez, get it right already.

      • f4eru

        Yep, right.

        You could represent it as paralell tube and switch, electrically at least.

    • Warren

      Dave,
      You need to scoot those LED tubes all the way to the wall to get the best lighting for that dark corner.
      Then install one under the first shelf of your bench!
      -Warren