Electronics Determining ratings for an led?!?

Discussion in 'Modding' started by Arcana, 5 Feb 2003.

  1. Arcana

    Arcana What's a Dremel?

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    How can I determine the ratings on an LED if I don't know its part num...I have some yellow led's I got from allelectronics.com that doesn't have any ratings on it...and I needs em.
     
    Arcana, 5 Feb 2003
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  2. acrimonious

    acrimonious Custom User Title:

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    connect one to a variable power suplly and turn it up until it blows out.
     
    acrimonious, 5 Feb 2003
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  3. Arcana

    Arcana What's a Dremel?

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    Arcana, 5 Feb 2003
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  4. RascalRusty

    RascalRusty What's a Dremel?

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    arrrr, sweet dude, just what im after, hey acrimonious do you know where on UK I can get LED like this, but in Green and Red, the clear version in 3mm super bright, maplin dont have anything near
     
    RascalRusty, 5 Feb 2003
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  5. acrimonious

    acrimonious Custom User Title:

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    maplin, rapid, everywhere!

    i'd say 1.5v is a safe bet then, if it looks too dim use 3v.
     
    acrimonious, 5 Feb 2003
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  6. RascalRusty

    RascalRusty What's a Dremel?

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    Ive tried Maplin loads, there dont do a Clear super bright Geen or Red in 3mm Clear, only diffused :waah:

    Will have to try Rapid
     
    RascalRusty, 5 Feb 2003
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  7. Arcana

    Arcana What's a Dremel?

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    my circuit is a 470 Ohm resistor off of 12V...think that'll hold it? I believe 2.4v is what that gives right?
     
    Arcana, 5 Feb 2003
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  8. ZapWizard

    ZapWizard Enter the Mod Matrix

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    Ok guys HOW to determine an LED's specs...

    First use a Diode Tester
    This will tell you the forward voltage drop.

    Now for the current rating:
    Normal LED = 5-10mA
    Ultrabright = 20-25mA

    Use the Bit-Tech LED calulator to figure out the resistor value.
    http://www.bit-tech.net/article/68/
     
    ZapWizard, 5 Feb 2003
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  9. Arcana

    Arcana What's a Dremel?

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    Nice....
     
    Arcana, 5 Feb 2003
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  10. cpemma

    cpemma Ecky thump

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    I've a couple of multimeters with diode test, but they both give very low Vf results, as the test current is so low. For example, a 2v red only shows 1.4v. So YMMV.

    Most yellows are around 2.1v at 10-20mA If.
     
    cpemma, 5 Feb 2003
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  11. ZapWizard

    ZapWizard Enter the Mod Matrix

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    Ah, if the multimeter doesn't put out enough current to make the LED light up than, ya it won't give an acurate number.
    Forgot about that.

    In the end I mostly assume 2.1 to 2.4volt drops at 20mA for superbrights, and 1.4-1.8 volt drops at 15ma for normal LED's
     
    ZapWizard, 5 Feb 2003
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  12. cpemma

    cpemma Ecky thump

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    It's "accurate", just not "real", ie typical of what gives at normal running currents. ;)

    [​IMG]
     
    cpemma, 5 Feb 2003
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