Cheap LED problem

Discussion in 'Off-Topic' started by Interitus, May 15, 2010.

  1. Interitus

    Thread Starter Member

    Nov 8, 2009
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    I bought some RGB 5mm 8kmcd LEDs off ebay, arrived in the mail friday. They have a viewing angle of 25 degrees. Got it hooked up and realized how cheap they were. Each color points off in a different direction. With the LED sitting on the table, the color spots on the ceiling are about 2-3' feet from center to center between blue and green, red in the middle. With a color fading script on the arduino-based controller "Ardweeny", the colors don't blend at all, except for where the color spots intersect. But its not a clean mix like I've seen in videos on youtube, and the separation of color is really obvious in fog.

    Somehow, I need a cheap solution to getting the LED to point in a single direction, and have the colors mix evenly. Right now my best idea is to use a reflector, like out of the older style flashlights, something fairly narrow. Of course I cant find any, so my only thought is to melt and form plastic from plastic bottles into the appropriate shape, maybe get a mold of some sort to help. But I'm thinking attempting to melt the bottles aint the best idea, even if I do it outside. And of course I dont mean melt into a completely liquid shape, but soft enough to mold.

    I'd need about 50 reflectors or whatever, and I don't want to spend a whole lot of money on this. I'm trying to get a nice clean spot beam effect, that shows up nicely in a fog. Does anybody have any ideas that could help?
     
  2. retched

    AAC Fanatic!

    Dec 5, 2009
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    Why LEDs? Why not a few spot lights? After all, thats what they are designed to do.
     
  3. Interitus

    Thread Starter Member

    Nov 8, 2009
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    This is basically just for a custom RB2 drumkit... low power and cheap. Actual spotlights cost way too much. These LEDs do have a good beam in fog, if just pointing in the wrong direction. And with LEDs I can get them to flash and fade however I want, controlled by the microcontroller.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    1,728
    I don't know how much fooling around you want to do, but here's a possibility:

    [​IMG]

    Just the general idea, mind you.

    If you do attempt to use MEK or lacquer thinner, be aware of the hazards (fire/flammable chemicals, absorption through skin, breathing, etc.) involved. Wear proper protective attire, including rubber gloves and eye protection, and use only in a well-ventilated area.

    Just a small drop of MEK should be enough to dissolve the plastic enough in order to form a permanent and clear joint. Too much, and you will likely ruin the LED.

    If you use a Plexiglas/Lucite rod that is smaller in diameter than the LED, the light will be even more focused.

    It'll take some fiddling around, but it'll be cheap, too.
     
  5. mik3

    Senior Member

    Feb 4, 2008
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    Buy new leds to make a good and neat work.
     
  6. Interitus

    Thread Starter Member

    Nov 8, 2009
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    well I certainly dont want to be cutting up the leds. or dealing with hazordous materials.

    I talked to a guy in IRC that does a lot of LED work, and he says the problem is pretty common. one of his suggestions was to sand the lens of the led. I've done this, I lose a little brightness and the spotlight effect, but the colors blend a lot better. I just grouped 3 sanded LEDs together rather messily, and in a small tube of white paper, I get a bit of the spotlight back, and the color blends pretty well. I just think I'll have to give up on my idea of having big strong spotlight beams like you'd see on a stage show.
     
  7. retched

    AAC Fanatic!

    Dec 5, 2009
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    Why not just use RGB leds that have all 3 colors in 1 led?

    You get color blending in the LED and then you dont have to do anything else.
     
  8. maxpower097

    Well-Known Member

    Feb 20, 2009
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    What about using a diffuser.
     
  9. SgtWookie

    Expert

    Jul 17, 2007
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    Did you read the very first sentence in the OP's problem statement? They ARE RGB LEDs, you goofus!
     
  10. retched

    AAC Fanatic!

    Dec 5, 2009
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    Wow. ...wow...

    Talk about putting my mouth in gear before putting my brain in gear.

    And the really bad thing is, when I read it, I read it as "I bought Red, Green, and Blue LEDs off ebay..."

    Sorry. Ill take my push ups.
     
  11. Markd77

    Senior Member

    Sep 7, 2009
    2,803
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    If you polish up the bottom of a coke can it makes a very good reflector. (You can start fires with them in good sunlight).
     
  12. bundick

    Active Member

    Dec 19, 2007
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    1
    Can you connect some small Fiber optic rods to the LED plastic cover?
    Sort of using Sgt Wookies idea, but plugging the rods in and redirecting the output end of the rods.

    Reflectors cut from Toy parts or old High Reflective light bulb reflectors. Tedious. But once you get the first one made, the rest are just factory work assembly.
     
  13. Interitus

    Thread Starter Member

    Nov 8, 2009
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    I have no idea where to get that kind of thing. And I've already exceeded my original budget a few times over, so if I were to buy anything, it'd have to be dirt cheap or free.

    I think my plan is going to be constructing some boxes, white on the inside, with an acrylic diffuser from a fluorescent fixture. should look decent.
     
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