New Guy Needs Advice

Discussion in 'General Electronics Chat' started by GreenasGrass, Aug 10, 2013.

  1. GreenasGrass

    Thread Starter New Member

    Aug 10, 2013
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    Hello folks, my first post, not sure how long I'll be here, seldom do I get into electronic builds and as the name says, I'm green as grass about a few of the newer technologies. Right now I am perplexed with regards towards LED's. I understand many of the older basics of electronics, I know a little about the newer stuff, but I need help.

    Please if you could point me in the right direction, I am attempting to learn about how to size drivers for LED strings. I have many questions.

    If given the all clear I will fire my questions here, if needed I can move to different sub.

    Thank you up front for any help you give me, regards, GaG
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,086
    3,025
    You should read this, and then come back with questions that it does not answer for you.
     
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  3. GreenasGrass

    Thread Starter New Member

    Aug 10, 2013
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    Thank you sir, I will look it over ASAP, my curiosity is killing me.:)
     
  4. #12

    Expert

    Nov 30, 2010
    16,247
    6,744
    That LED page by Bill Marsden has over 98,000 hits because it is so useful. (We, the local denizens, send beginners there regularly.) I say, let's attach some script to the page so the 100 thousandth visitor is greeted with fireworks and a gift certificate for a new dust bunny.:D
     
  5. wayneh

    Expert

    Sep 9, 2010
    12,086
    3,025
    I can supply the dust bunny! And his whole family...
     
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  6. GreenasGrass

    Thread Starter New Member

    Aug 10, 2013
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    A load of great technical information there, although I still find myself lacking.

    My first question would be:

    Can this driver be identified by markings, and if so is there a recommended replacement?

    http://imageshack.com/scaled/large/33/hx1w.jpg
     
  7. wayneh

    Expert

    Sep 9, 2010
    12,086
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    It appears to be a constant current supply operating in the voltage range shown. I think you should be able to find a similar 0.5A supply.
     
  8. GreenasGrass

    Thread Starter New Member

    Aug 10, 2013
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    Thank you for the reply. I searched looking for same but found no source, could you supply a link to a vendor?
     
  9. LDC3

    Active Member

    Apr 27, 2013
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    I believe this will replace it.
     
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  10. GreenasGrass

    Thread Starter New Member

    Aug 10, 2013
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    Thank you very much for the source.
     
  11. GreenasGrass

    Thread Starter New Member

    Aug 10, 2013
    13
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    Thank you all for your help, I have been somewhat enlightened, it feels good to learn and understand new technologies. I found this driver which should work perfectly as a replacement.
    http://www.ebay.com/itm/75W-LED-Dri...d=100011&prg=8016&rk=4&rkt=5&sd=390640155850&

    I believe that I now have a firm grasp on the workings of string LED's. I do however have another question that I have been unable to resolve through web searches, I'm hoping that I might find the answer here.

    At question is the swapping of LED's of different colors. I would like to replace several 3w red LED's with 3w white LED's. The red LED's have a driven voltage of 2.2 to 2.4, the whites have a driven voltage of 3.2 to 3.4, can these lights be swapped without further modifications, or must the resistor be changed too? Driven current on both is 550mA.
     
  12. wayneh

    Expert

    Sep 9, 2010
    12,086
    3,025
    The increased voltage drop across the string means that, to achieve the same current, the supply will operate at a slightly higher voltage. That should be no problem for the driver you linked. It will increase voltage to maintain current.

    Now, the driver you linked is a 680mA driver while you just said you need 550mA. That raises an eyebrow.
     
  13. GreenasGrass

    Thread Starter New Member

    Aug 10, 2013
    13
    0
    Thank you Wayne for your reply, once explained it becomes easy to comprehend.

    Also, I was looking at the 680mA as a replacement only, I will be using the 550mA that came with the string for now, your concern with regards towards the increased amperage is noted and I will continue to search for correct replacement.

    Thank you once again for the help.
     
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