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Thread: Dimming a Red LED

  1. #1

    Default Dimming a Red LED

    I got a B/B/R tri-cree and I'm trying to get periwinkle/indigo out of it (blue side of purple). I've been playing with tons of resistor combinations, but almost no matter what I do I can't seem to make the red dimmer. Everything is on the red side of purple or what looks like "bubble gum" pink. Is there something inherent to red that makes it difficult to resist?

  2. #2

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    What resistors + resistor combos have you tried using?
    I've made a more blue-ish purple before by using a 1.2ohm 3w resistor and a 3.3ohm 5w resistor both on the red die. If I had a higher ohm resistor on me I would've tried that but that was the best solution at the moment.
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  3. #3

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    I've tried combinations of 1ohm/2 watt, 3.3 ohm/1 watt, dyna-ohm, doubling resistors. There are several more I haven't mentioned. According to the resistor calculator I used, the 3.3 ohm/1 watt resistor should have put the red LED at minimum lux. That one seems to shut it off entirely. Everything else seems to have little effect at all.

  4. #4

    Default

    The 3.3ohm/1watt shuts it off completely?
    That's surprising, I just checked and the red on my tri-cree has a 3.3ohm/5watt resistor on it.
    I was going to suggest you wire the 1ohm/2watt and 3.3 one after another to see if that achieves the shade you want.

    Do you have any other resistors lying around? If you do you could double/triple up on them to try to achieve that shade of purple.
    Why did Isendra die? Tell me the truth!

    That it is beyond your abilities does not mean it is beyond mine. I learned the lesson of Isendra's death. But I was given my power for a reason, and it is my burden to use it.
    I will use it, not fear it as you do, High Councilor Valthek

  5. #5

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    Yeah, I've got lots of little resistors sitting around and nothing seems to do the trick. I can get the blue to dim, but the red is being a jerk.

  6. #6

    Default

    Quote Originally Posted by CET View Post
    Yeah, I've got lots of little resistors sitting around and nothing seems to do the trick. I can get the blue to dim, but the red is being a jerk.
    So, what you're really saying is resistance is futile, huh?
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  7. #7

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    Quote Originally Posted by Forgetful Jedi Knight View Post
    So, what you're really saying is resistance is futile, huh?
    It had to be said.

  8. #8

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    Sorry...I had to.
    If you think you've had an original question, you probably haven't read enough...

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