100 led parallel!

Discussion in 'General Electronics Chat' started by kapitenio, Mar 15, 2010.

  1. kapitenio

    Thread Starter New Member

    Mar 14, 2010
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    helo!! I have a problem with the brightness of led.sto making a parallel connection of LED 100, but the very first 3 LED work perfectly and the others are low.ho put 3 green LEDs in parallel with 180 ohm resistors, the voltage shall be 12 v.i love all LEDs in illumination perfectly, perhaps, that some error in welding I say?
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    Welcome to the forums.

    If that is 33 strings of 3 green LED's in each, then there must be something that additionally limits current in the last 30 strings. How are the connections made? Individual wires, or on a printed circuit board? Can your 12 volt source supply slightly over one ampere of current?
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    I think that you meant to say that you have strings of three green LEDs in series with 180 Ohm resistors, and you have 33 of these strings in parallel, plus one more LED with a different resistor value.

    It would help if you posted a schematic as to how you have the LEDs and resistors wired.
     
  4. kapitenio

    Thread Starter New Member

    Mar 14, 2010
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    [​IMG]all LED strings are green. r 180 ohm. 3 leden first are good.other leds are pale..any help?
     
    Last edited: Mar 15, 2010
  5. SgtWookie

    Expert

    Jul 17, 2007
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    Oops - you have the resistors in series, and the LEDs in parallel. That's why it is not working correctly.

    Connect them like this:

    [​IMG]
     
  6. retched

    AAC Fanatic!

    Dec 5, 2009
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    Instead of having a full voltage BUSS that each resistor can pick off of,
    You are reducing it with each resistor to the next set.

    In Sgt.Wookies drawing, you can see the line at the top has 12v all the way across.

    The way you have it, it is only 12v until the first resistor. Then it drops. Then it hits the second resistor and drops more...so on and so on.
     
  7. Wendy

    Moderator

    Mar 24, 2008
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  8. kapitenio

    Thread Starter New Member

    Mar 14, 2010
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