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Would a LED short itself?

Discussion in 'Electronic Basics' started by Mr. Man-wai Chang, Jun 27, 2013.

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  1. Any professor/PhD level explanations? :)

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  2. Tom Biasi

    Tom Biasi Guest

    It wouldn't. Someone would have to do something to it.
     
  3. Is it nothing more than a light bulb?

    Would you use a current-limiting resistor when you use traditional light
    bulb? :)

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  4. OK, are there 20mA fuses? Isn't a fuse safer than a resistor? :)

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  5. And a traditional light bulb could be powered by 110/220 V AC... isn't
    it extremely dangerous not to use a current-limiting resistor? :)

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  6. Tell me something I dunno! :)

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  7. Tom Biasi

    Tom Biasi Guest

    An LED is not a light bulb, it's a diode. Light bulbs (as understood to
    be incandescent by the tone of this conversation)are resistive and
    designed to operate at certain voltages.
     
  8. Tom Biasi

    Tom Biasi Guest

    May I suggest that you examine the function of those two devices?
     
  9. I think you need the newsgroup that's even lower than basics.

    An incandescent lightbulb uses a relatively high resistance wire, power
    put through that wire causes it to light up. If that lightbulb goes bad,
    it would generally open up. The only way it could short is if the
    filament collapses on some of the lower wire in just the right way, but if
    the bulb was on at the time, the power would just burn out the wire that
    remained, too much current going through regular wire.

    An LED is a solid state device. There may be instances when they might
    short out, but generally they'd just expire, leaving an open circuit.

    The resistor that all LEDs need (except for the LEDs that have some
    current limiting inside the package) is because the LED is a current
    device, it needs a certain amount of current to light up (so long as the
    voltage is higher than it's threshold, and lower than the maximum it can
    take). If too much current goes into the LED, it can "blow up". It is
    different from an incandescent bulb.

    Sometimes people do use resistors in series with incandescent bulbs. They
    want to limit the current surge through the bulb before the resistance
    goes up as it heats up. Or, to limit the actual light out of the bulb,
    though there are better ways to do that.

    Michael
     
  10. What exactly are those instances?

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  11. You meant I should use both a limiting resistor as well as a 20mA fuse? :)

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  12. Tom Biasi

    Tom Biasi Guest

    No, I mean you should learn what those devices are for.
     
  13. Guest


    Yes! I like it! Henceforth we must call all incandescent light bulbs Light Emitting Resistors!

    Oh, wait, by that definition some electric space heaters would also qualify as Light Emitting Resistors, huh.
     
  14. Guest


    Rimshot!
     
  15. Waste of my time...

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  16. SO an LED could never be used as a light-emitting fuse?

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  17. FYI, the video could also waste your time. :)

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  18. By just applying 3V over the LED, it would draw whatever current needed?

    Summarizing the replies from the answers, most said that the LED might
    **NOT** always just blow like a fuse. And that's the main reason of
    using a current-limiting resistor.

    If LED would always die like a fuse without shorting itself, then there
    should not be a need for a resistor.

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  19. Tom Biasi

    Tom Biasi Guest

    With all due respect this thread is going nowhere fast. You have
    received enough information to realize that your logic is severely
    flawed and that you need to do some research.
    Now I'm suspecting troll activities.

    Tom
     
  20. OK, let's end this thread! I will use current-limiting resistor. :)

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