LED driver

Discussion in 'General Electronics Chat' started by 1-3-2-4, Aug 5, 2013.

  1. 1-3-2-4

    Thread Starter Active Member

    Dec 26, 2008
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    I have a project I'm thinking about doing with 6 bridgelux LED's at 350mA they provide 1220 Lm. They have a 27.2 VF rating anyways I'm wondering what driver rating do I need to drive 6 of them in series? I assume that a 27V 350mA out can drive all 6? They seem hard to find, you have some on ebay that have a wide operating output voltage but I don't know if they are adjustable.

    Driver has to have AC line input to DC.
     
    Last edited: Aug 5, 2013
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Is 27.2Vf per LED or the sum of all 6?

    If thats the sum then a driver is EASY to find.. If thats per LED then its MUCH harder as anything over 54V is more of a safety hazard and the available driver selection is MUCH smaller..


    And do you want dimming? If so potentiometer or PWM or analog voltage control?
     
  3. bertus

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  4. 1-3-2-4

    Thread Starter Active Member

    Dec 26, 2008
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    It's 27.2 for each LED and I don't need dimming.
     
  5. bertus

    Administrator

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    Hello,

    The given driver would be suitable to drive ONE led.

    Bertus
     
  6. 1-3-2-4

    Thread Starter Active Member

    Dec 26, 2008
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    I don't have the space for 6 drivers
     
  7. bertus

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  8. 1-3-2-4

    Thread Starter Active Member

    Dec 26, 2008
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    Opps I forgot to mention that I need AC line input to the driver not DC.
     
  9. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    How about 3 x 54V drivers?

    Finding a 120VAC input, 165VDC (350ma) output LED driver is almost impossible if not impossible.

    or run parallel strings with current mirroring or other method to prevent thermal runaway
     
  10. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    3 x Meanwell APC-25-350 will work just fine with 2 LED's in series on each.
     
  11. 1-3-2-4

    Thread Starter Active Member

    Dec 26, 2008
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    Here is an idea on the space I would have.. I don't know the true size of the LED so I tried to get as close as possible..

    [​IMG]
     
  12. mcgyvr

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    See my last post about the meanwell APC drivers.. Should fit easily there..
     
    1-3-2-4 likes this.
  13. 1-3-2-4

    Thread Starter Active Member

    Dec 26, 2008
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    Yep saw it.. and about the heatsinks.. Because it will have a cover over it I'm unsure how thick the heatsink should be or if I should have active cooling along with it.

    I also don't know how quick the temp will rise, more of an issue in the summer months but the winter not so bad.

    Then you have the cover with it's design I assume I wont need any Fresnel lens and it should be ok without a filter inside? And light spread.. not too too concerned about it, just more concerned about yard lighting and not spread.

    I assume those drivers you listed are adjustable right?
     
  14. mcgyvr

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    Thick really means nothing as far as heatsinks.. You need to know thermal resistances,etc.. for proper heatsink calculation.. Its more about surface area. Do NOT underestimate the need for adequate heatsinking on high power LED's.. Its NO joke. Fires will/do happen. There are numerous heatsinks on ebay for 10W-20W multichip LED's.. 1 per LED should suffice. (Or something with a thermal resistance of 5 deg C/W or less.

    If you need a lens or not is up to you..

    And what do you mean by "adjustable" drivers?? You said you don't want dimming.

    And you'd better find a way to get the heat out if you intend to enclose it all.
    You stick that in a box without proper ventilation and it could be a hot melted mess very shortly.
     
  15. 1-3-2-4

    Thread Starter Active Member

    Dec 26, 2008
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    I'm no stranger to 1 & 3 W LED's but not used to so many in a enclosed area..

    I might have to join a reef site since they are into building custom LED hood lights and they might know a thing or two about this
     
  16. mcgyvr

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    This is for a reef tank and not "yard lighting" ? big difference.

    If so what is the color temp of the LED's?
    What type of corals?
    Size/depth of tank?
    You want dimming too to prevent bleaching when you first start using the light over the tank. Or slowly lower it close to the water over a few weeks/months. And chances are you might want to simulate sunrise/sunsets when you pick up a reef controller.

    ps I am a reef site member (reef central) and have designed my own LED lighting for my tank. I'm actually running 4 x 50W LED's over my 120G Long tank now
     
  17. 1-3-2-4

    Thread Starter Active Member

    Dec 26, 2008
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    No this is for yard lighting I was just saying how reef tank users have a decent light setup but cooling is not that much of an issue because the heatsink is above the tank.

    So anyways with the aluminum flat bar being 3/4" thick and 5" by 6" I assume it can take a lot of heat but sooner or later the heat as to come away and I don't think passive cooling is going to be that much.. What I need is a real world test to see how 6 LED's at 350mA is going to be on a aluminum bar of that size.
     
  18. mcgyvr

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    consider using aluminum u channel vs flat bar.. Remember its all about surface area not thickness/mass.

    "best" would be to have the aluminum heatsink on the outside of the enclosure and possible forming the side or top or whatever with the LED's directly bonded to them.. But to enclose it all without any ventilation "could" cause issues.

    The "reef" guys more or less know what it takes to keep them cool over a tank inside BUT more or less know nothing about proper design for outdoor/exposed to elements fixtures.
     
  19. bwack

    Active Member

    Nov 15, 2011
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    Hi 1-2-3-4. What bridgelux LED model are you planning to use ? Is it the high CRI that you like to have ? It certainly looks good in the specs :)
    Maybe we can look at another LED model with lower total Vf.
    I was looking for the device in question here http://bridgelux.com/ .. but couldn't guess myself to what device you are looking at.
     
  20. Metalmann

    Active Member

    Dec 8, 2012
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    .." being 3/4" thick and 5" by 6""






    Way too big for that size LED, try something thinner like 1/16", 1/8", or even 1/4" thickness.
     
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