how much watt LED should i get

Discussion in 'General Electronics Chat' started by indianhits, Mar 22, 2013.

  1. indianhits

    Thread Starter Active Member

    Jul 25, 2009
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    0
    Hello Guys i am trying to do a project where i need to put my indicator outside so it should be visible to people in 5-10 meters it should be pretty bright and i am using this battery 12 V, 5.0 Ah(i got this from my old motorbike) config for this work.

    The same battery also connects to a bulb with 12 V, 35W & few other minor circuits.

    i want an LED which does not drain the battery much but it must produce bright light.So, it must be optimum one!

    Thank You! :)
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,058
    3,820
    Another thing to consider is ther viewing angle. Some small indicator lights (20 ma) will easily send a very narrow beam 5 meters - it will have to be viewed directly in front of the LED. Other LEDs will have up to 180 degree (spherical) viewing angle. These LEDs will have to be more powerful to be seen at 5 meters (with reasonable brightness).
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,770
    970
    define bright?
    really any 20ma LED can be seen from 10 meters.
    try a nice 10mm 20ma LED and appropriate current limiting resistor
     
  4. indianhits

    Thread Starter Active Member

    Jul 25, 2009
    86
    0
    and yeah i forgot to mention that this LED also blinks so...

    @GopherT i need a >45 degrees viewing angle LED sorry i was not clear before.

    and it must also be visible during daytime

    Thanks!
     
  5. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,770
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    go buy a few 20ma LED's and see if they are acceptable to "you" for "your" application.
    If not find a brighter one. Manufacturers datasheets will always have brightness and viewing angle specs.
    square/round/rectangle/through hole/smt/red/white/blue/orange/green/yellow,etc.. lots of choices for YOU

    The more current it requires the faster the battery is drained. YOU need to determine whats an acceptable level of brightness and battery drain
     
  6. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    You can also add a reflector. With a reflector, a fairly small led can be seen over a long distance.
     
    Last edited: Mar 22, 2013
  7. crutschow

    Expert

    Mar 14, 2008
    13,016
    3,235
    Use a high-brightness type LED. They can be quite bright will less current then a standard LED.

    You can make it visible in daylight for a longer distance if you mount the LED in a small cavity or box and paint the cavity flat black.
     
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