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UV LEDs die fast?

Discussion in 'Electronic Basics' started by John Bokma, Apr 13, 2005.

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  1. John Bokma

    John Bokma Guest

    Out of a batch of 50 UV LEDs two have "died" somehow. With the first one I
    thought it was a bad connection, so I re-soldered the LED, and it worked.
    When I turned the circuit off for some time, same problem. So again I
    thought: "cold" connection, re-heated it, and worked...

    But when the circuit got cold again, same problem. I replaced the LED, and
    no problems for hours.

    Two days ago, however, another LED stopped working, same problem. Heating
    it, it works again. This time I was able to "see" (indirectly, UV LEDs can
    harm your eyes) what happened: the three LEDs in series started to flicker
    for some time, and then all went off. Heating it -> works.

    Does anyone have an idea why this is happening? Just 2 bad LEDs out of 50?

    See http://johnbokma.com/pet/scorpion/detection-using-uv-leds.html for the
    circuit diagram.

    Also: I use most of the time 9V to feed this circuit, so I doubt it has
    anything to do with overloading the LEDs.

    TIA,
     
  2. John Bokma explained :
    look at the traces leading to the led. Is a pad lifted? or has a crack
    in the board developed?. reheating is the key common factor.. I'd look
    for external faults before the led.
     
  3. John Bokma

    John Bokma Guest

    2 more leds have died. I bought a digital meter, and am going to do some
    measurement. I got more and more the impression that the shop sold me
    garbage. (Especially since I use 9V to run the circuit, not 12).
     
  4. Should you determine that it is the LEDs, could you tell us what brand
    these LEDs are?

    - Don Klipstein ()
     
  5. John Bokma

    John Bokma Guest

    I have no idea about the brand, but I ordered them from LSDiodes.com.
    They seem to have a good reputation, but I am amazed that I manged to
    kill 4 UV LEDs, especially since I thought they would last for thousands
    of hours.

    I'll check it out next week.
     
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