led christmas lights

Discussion in 'General Electronics Chat' started by normbear, May 2, 2011.

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  1. normbear

    Thread Starter New Member

    May 2, 2011
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    I bought a bunch of LED christmas lights a couple of years ago because they were the cheapest LED's I'd seen, and I wanted to use them for ambient lighting. Some of them have been on for several hours daily for two years plus, with no problems, some have a couple of dark LED's, otherwise fine, and a couple of strings went totally dark. I decided to try to fix the dark strings, and I'm mystified by the circuit. The male plug on one end, female on the other, show continuity all the way through. The bulbs are wired in series, except the end ones have one wire going in, two coming out, and one of the wires coming out goes straight from one end bulb to the other, with the other one connecting all the LCD's. There's a fuse for each pole inside the male plug, but no resistor that I can find. The plugs are not polarized, and the ones that work light up no matter which way you plug them in. Any ideas about how these work?

    Thanks,
    Norm
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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  3. normbear

    Thread Starter New Member

    May 2, 2011
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    Thanks, Kermit. Great resource. This should keep me busy for a while.
     
  4. marshallf3

    Well-Known Member

    Jul 26, 2010
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    One wire is the duplicate hot lead that feeds the outlet on the end where you plug in additional strings.

    So on on one end you have a 120V outlet, then there's the LED string which can be nothing more than 50 - 70 LEDs all hooked in series so they'll run off 120V. An ohmmeter won't read through that many LEDs in series.

    The reason the work either way they're plugged in is because they're being fed AC, even though they're only using 1/2 of the cycle.
     
  5. bertus

    Administrator

    Apr 5, 2008
    15,646
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    Hello,

    According to the newly published ToS, the mains powerd leds are not allowed:
    Terms of Service
    Quote:
    6. Restricted topics. The following topics are regularly raised however are considered “off-topic” at all times and will results in Your thread being closed without question:

    • Any kind of over-unity devices and systems
    • Automotive modifications
    • Devices designed to electrocute or shock another person
    • LEDs to mains
    • Phone jammers
    • Rail guns and high-energy projectile devices
    • Transformer-less power supplies

    Bertus
    __________________
     
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