Led aquarium lighting - wiring advice

Discussion in 'General Electronics Chat' started by stuuitjc, Jun 25, 2016.

  1. stuuitjc

    Thread Starter New Member

    Jun 25, 2016
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    Hi there,

    This is my first attempt at wiring LED's and need some advice on what driver to use to power them. I have purchased 12 3W LED's of eBay that I was hoping to wire in series.

    I have 4 white LED's with forward voltage of 3-3.9V and current IF=700-750mA

    4 red LED's with forward voltage of 2.2-2.6V and current IF=750mA

    4 blue LED's with forward voltage 3-3.7V and current IF=750mA

    I am very confused by all the numbers. Is it going to be possible to wire them in a series of they have varying voltages?

    What kind of driver would I need if I am using mains power?

    Any advice would be greatly appreciated
     
  2. DickCappels

    Moderator

    Aug 21, 2008
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    If you run them in series, you won't need to worry about the individual voltages, but the total voltage will be of concern. If you run them in series they will all be driven by the same current.

    Your LEDs will last a lot longer if you heatsink them well and run well below the maximum allowable current. The output of the driver should be isolated from the mains.
    I think the one at the URL below would work well.
    http://www.ebay.com/itm/AC-85V-265V...609082?hash=item1eb3442f3a:g:4dQAAOSwmmxW2OKM
    Also note the product label in the image below.
    [​IMG]
     
  3. stuuitjc

    Thread Starter New Member

    Jun 25, 2016
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    Thanks so much for replying. So when it says (1-3) x 1W does that mean 1 driver will only be able to power 1 3W LED?
     
  4. stuuitjc

    Thread Starter New Member

    Jun 25, 2016
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  5. DickCappels

    Moderator

    Aug 21, 2008
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    The example I cited outputs s constant 350 ma for any load from 2v to 12v; the voltage adjusts automatically to keep the current constant.

    If you use a power supply you cited supplies a constant voltage and would require additional circuitry (the mimimum being a resistor) to limit the current through the LEDs.

    You can use either approach but I think you would have less trouble with a constant current supply.
     
  6. bertus

    Administrator

    Apr 5, 2008
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  7. stuuitjc

    Thread Starter New Member

    Jun 25, 2016
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    Thanks Bertus. I see that the APC 16-700 outputs 9-24v @ 700mA whereas the 16-350 outputs 12-48v @ 350mA

    I was under the impression that the total forward voltage could not be higher than the max voltage output of the driver. Would it be better to go for the 16-350 seeing as I have a total forward voltage of 33v ?
     
  8. BobTPH

    Active Member

    Jun 5, 2013
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    Yes, the sum of the voltages of the LEDs you put in series must be less than the max the driver can output. Both of the ones recommended by people here were inappropriate for this reason.

    Bob
     
  9. stuuitjc

    Thread Starter New Member

    Jun 25, 2016
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  10. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    300 to 500 milliamp is a good safe, long life giving current for a LED with 700mA max limit.
    If your heatsink mounting is not perfect or loses contact with age cycling, running at max current will kill the LED'S by overheating.
    The data sheet will show irradiation vs current. You won't lose much running lower, but WILL extend lifespan.
    Besides, they are Chinese made and Spec'd. Exaggeration is not a rare thing in certain data sheets.
     
  11. stuuitjc

    Thread Starter New Member

    Jun 25, 2016
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    Excellent thanks so much.. I'll get the 16-350 since I made my own heatsink. I wouldn't wanna run them too hard and risk failure
     
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