How to distinguish between LEDs

Discussion in 'General Electronics Chat' started by gabrieldesloz, May 9, 2016.

  1. gabrieldesloz

    Thread Starter New Member

    May 9, 2016
    1
    0
    Hello,

    I want to know what kind of tests can be done to distinguish between two leds of the same color, but with different characteristics (like luminous flux, for example).


    Thank you.
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,875
    996
    What are you trying to do?
    For luminous flux you would power both LEDs with the same fixed current and measure which is brighter..

    When powered you can also determine the forward voltage rating of each by measuring the drop across the LED..
     
  3. #12

    Expert

    Nov 30, 2010
    16,863
    7,518
    When I needed a measurement of light intensity, I used a Minolta SLR camera.
    I had to weasel my way through some references to translate F-stops into lumens, but it's possible.
    On the other hand, you can probably get a light meter a lot cheaper than buying a whole camera.:D
     
  4. dannyf

    Well-Known Member

    Sep 13, 2015
    2,196
    420
    Light them up?
     
  5. ScottWang

    Moderator

    Aug 23, 2012
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    785
    If you want to get a more accurate value of Luminous Flux then you can buy the Luminous Flux Meter, or you just want to do a general judge not that accurate, you can using a LDR + voltage divider + op amp positive amplifier.
     
  6. wayneh

    Expert

    Sep 9, 2010
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    3,417
    Put all your test LEDs in series with a current-limiting resistor. They'll all have the identical current. Then just look at them.
     
  7. ScottWang

    Moderator

    Aug 23, 2012
    5,075
    785
    Ha ha, just look at them, you got the good eyes ... :D
     
  8. wayneh

    Expert

    Sep 9, 2010
    12,611
    3,417
    If you can't see a difference, who cares?
     
    #12 likes this.
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