12 led heat sink/board

Discussion in 'The Projects Forum' started by ctwistedpair, Sep 13, 2014.

  1. ctwistedpair

    Thread Starter New Member

    Jan 14, 2013
    25
    2
    Hi. I'm trying to figure out the whys of this board. It holds 12 high power led's in series. When I soldered the led's to the board and apply 18vdc, only 6 led's light up. The red traces are the power path (confirmed by meter). All of the led's work individually. Any ideas?
    PS I bought these from China and there is no other data available. (at least not in English)
    Thanks for any words of wisdom.
     
  2. LDC3

    Active Member

    Apr 27, 2013
    920
    160
    Can you find the current?
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    You need a constant current power supply and you need a voltage higher than the sum of the forward voltages of all the leds in series..
     
  4. ctwistedpair

    Thread Starter New Member

    Jan 14, 2013
    25
    2
    Thanks, i thought that none of the leds would light if the v was too low. I put 4-9v batteries in series, BINGO.
    Thanx for your help
     
  5. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    And what are you using to limit the current to the LEDs?
     
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