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Thread: Resistance without energy drain

  1. #1

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    Default Resistance without energy drain

    Just to clarify at the beginning of this post this is not a resistor calculation question. I know those are irritating and have already done the calculations.
    Now on to my question. I have ordered a Tri Cree Deep Red/Red Orange/Amber LED with 1.5 ohm, 1.2 ohm, and 1 ohm resistors respectively. Now the colors I chose I know are not the brightest LED's around. My question is am I ok to bump down to a lower resistance? I know it will wear on the battery a little but I am hoping to find a happy medium of energy saving and brightness in LED's. Would I be ok to place a 1 ohm on all LED's? Has anyone else done the same thing I am asking? Any help would be greatly appreciated.

  2. #2

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    I am not knowledgable enough to give you a good answer, so take it with a grain of salt.

    Are we talking XPE2?

    From what I gather it is pretty easy to burn out a Red or amber led. There are threads on FX-sabers about over driven LED's.

    If you have a huge heat sink (like the v3) and nice paste you might be able to pull it off. I used a 1.1 on red before.

    Or you can go Rogue and try and pipe in some sort of coolant, possibly at near absolute zero, to ensure the super-conducting electromagnet array stays cool enough to maintain the EM field envelope around the super-heated plasma beam.

    Wait, what was the question?

  3. #3

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    If you use a smaller resistor than what is required, then the LEDs can draw more current than you've calculated. This is commonly referred to as "overdriving" the LEDs. The LEDs will usually be brighter, run hotter, and have a shorter lifespan. The Cree LEDs are more resilient than some of the older LEDs we used to use. Overdriving a red P4 was a recipe for buying a new LED.

    If the LED draws enough current that it produces more heat than your heatsink can dissipate, you will cook your LED and it'll go *pop*.
    We all have to start somewhere. The journey is all the more impressive by our humble beginnings.

    http://led.linear1.org/1led.wiz for the lazy man's resistor calculator!
    http://forums.thecustomsabershop.com...e-to-Ohm-s-Law for getting resistor values the right way!

  4. #4

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    If you really want to maximize brightness, you should measure the actual forward voltage and use that. It'll give you the brightest LED without having to worry much about overdriving it too hard.

  5. #5

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    Quote Originally Posted by TheUnchosenOne View Post
    If you really want to maximize brightness, you should measure the actual forward voltage and use that. It'll give you the brightest LED without having to worry much about overdriving it too hard.
    This.

    I just measured the FV on my Tri-CREE Deep Reds and it came in at 2.8-2.9v. This can be dependent on the batch, manufacturer, etc...

    You can pick up a nice bench power supply for around $60 and I will be well worth it if you are building more than one saber (which you will). Erv Plecter has a YouTube video on how to measure FV that is a great resource.

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