Strip LED backlighting

Discussion in 'The Projects Forum' started by tonyamhr, Jan 23, 2012.

  1. tonyamhr

    Thread Starter New Member

    Jan 23, 2012
    2
    0
    Hi Guys,
    I would like to back light a 55" flat screen TV by placing strip LEDs around the rear of the cabinet to reflect off the wall where the TV is mounted. I have 4 one meter strips of sixty blue LEDs which should do the job. The strips were purchased from Hobby King and are labeled "Turnigy Power Systems". Each strip is rated with a VF of 12 volts and an IF of 400mA.

    I have successfully used these strips many times by cutting them in multiples of 3 LEDs, splicing, etc. for lighting model airplanes with great success, but I was usually working with one strip of 60 or less LEDs. My dilemma in this application is: Should I power each strip individually from a common 12 Volt supply capable of 1600 mA, or can I connect the strips in series from the supply? If I choose the latter (preferred), I'm thinking I need to increase my power supply to 48 Volts at 400mA.

    Is my thinking correct, or am I missing something? I would appreciate any comments or suggestions, and thanks in advance!

    Bob
     
  2. colinb

    Active Member

    Jun 15, 2011
    351
    35
    It's probably technically better to run the strips in series (48 V) because then there will be the same current through each LED, regardless of forward voltage (Vf) variations between the strips, which should mean good brightness matching. But, this might not be noticeably different from the parallel setup.

    Maybe the 120 Vac to 48 Vdc power supply can be more efficient??? But, I think a 12 Vdc power supply is much more common and easier to obtain.

    I would choose the topology (series or parallel) based on the power supply you have available or can obtain.
     
  3. tonyamhr

    Thread Starter New Member

    Jan 23, 2012
    2
    0
    Hey, thanks Colinb! I think if I understand you, you are saying that my thinking is correct and I'm on the right track...just simple ohms law DC circuit. You're right....a 48 volt PS may be a challenge and it needs to be small, like a wall "wart" transformer. I'll have to check around and see what I can come up with. Meanwhile, I'll lash them up parallel on my bench supply and see what happens. Thanks again

    Bob
     
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