Wiring LED's

Discussion in 'General Electronics Chat' started by Paulquinn, Aug 29, 2013.

  1. Paulquinn

    Thread Starter New Member

    Aug 28, 2013
    5
    0
    Hey guys quick question. Is it better to wire LED's in parralel or
    In series?
     
  2. #12

    Expert

    Nov 30, 2010
    16,348
    6,835
    If you put as many LEDs in series as the voltage supply will allow, you will use the least number of resistors, compared to installing a resistor for each LED.
     
  3. Metalmann

    Active Member

    Dec 8, 2012
    700
    223


    Most say in series, lately I've been using parallel with no noticeable side effects......
     
  4. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
    971
    Out of curiosity.. Do you have a "current limiting device" (or current mirror) for each series string in that parallel circuit or just hoping they will share the current equally?

    Have you read up on "LED thermal runaway" ?
     
  5. wayneh

    Expert

    Sep 9, 2010
    12,155
    3,061
    You need to define your meaning of "better".

    As #12 has noted, a series arrangement allows you to limit current through several LEDs with a single resistor (depending on your power source and LED voltage drops). So it is "better" because it uses less parts and wastes less energy.

    But if you need to light 20 LEDs and you only have a 5V supply, it cannot be done without a parallel arrangement. So then parallel is "better", since it's the only choice.

    I think the fast and simple strategy in most cases is to use as many in series as you can and then put more strings in parallel when you need to.

    One thing that does NOT work well is LEDs in parallel without individual current limiting. You can put current-limited STRINGS in parallel, but not un-limited LEDs themselves.
     
  6. Paulquinn

    Thread Starter New Member

    Aug 28, 2013
    5
    0
    Ok should have worded it better.
    I mean most efficient. If I have several LEDs
    Not enough so I would loose voltage by running in series
    Is it more efficient for the led to run parallel because each one has
    It's own resister? Alot of diagrams I've seen have shown a few LEDs
    In parallel.
     
  7. #12

    Expert

    Nov 30, 2010
    16,348
    6,835
    No. You got the right answers, even if it does seem a matter of luck.
     
  8. wayneh

    Expert

    Sep 9, 2010
    12,155
    3,061
    Just the opposite. Every path from "+" to "-" that includes an LED will have the same current, for example 20mA. This current is defined by the LED's specification. The power consumed in that path is the voltage of the supply times that current, for example 12V x 20mA = 240mW.

    This does not change if you add more LEDs in series. So adding as many LEDs in series as you can, and reducing the value of the current limiting resistor, gives more light without requiring any more power. It's therefore more efficient. Power that was dissipated by the resistor is instead used to make more light.

    Each string added in parallel to the first will consume another 240mW. If the strings are identical, the efficiency is unchanged.
     
  9. Metalmann

    Active Member

    Dec 8, 2012
    700
    223
    "Have you read up on "LED thermal runaway" ?"




    Certainly.
     
  10. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
    971
    and does each series string have current limiting?
    or do you hope they will keep sharing current..
    and how much variation have you seen in currents..
    I'm just interested...
     
  11. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
Loading...