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Want to dim the LED lighting

By cigarman
Aug 2, 2009
  1. I want to dim by at least 50% the LED hard drive activity lights on two cases as well as on some 5 1/2" swap bay drive cradles installed in these cases. I'll probably want to dim the power LED lights as well for these units. Does anyone know of a gadget made to go in-line on the wiring to facilitate this, or, can anyone recommend a certain resistor that I could solder in the + (positive) lines to make this work? I assume it's the positive line that should be spliced into with a resistor, but if it's the negative one, please confirm. I don't want to burn the house down, so I would want a resistor that could take the load with no problem. They must have thousands of resistors for this and that, so I'm hoping someone with much more knowledge of electronics than me could specify what I could look for at a Radio Shack or hardware store. I guess I'm hoping someone out there has done this and could specify a resistor that will do the job--or another way to diminish the annoyingly bright lighting on cases and such. Thanks for your time.
     
  2. red1776

    red1776 Omnipotent Ruler of the Universe Posts: 5,219   +157

    I wonder if a potentiometer might be the answer you are looking for?
     
  3. strategic

    strategic TechSpot Paladin Posts: 1,020

    Just as red mentioned, you'll need a potentiometer (dimmer switch).
    OR
    To keep things to a minimum, you can always take a fine tip marker and cover over the lights 2-3 times to help dim it (paint with a fine tip brush would also work). I would try that 1st before getting into the wiring.
     
  4. captaincranky

    captaincranky TechSpot Addict Posts: 11,688   +1,879

    Actually you need to dust off the "Ohm's Law" page in an electronics text to determine the value of the "pot" required. An LED is a very low wattage device
    , so a miniature trimmer potentiometer likely will be all that's needed.

    It think Ohm's law is; "E" equals "I" over "R". But really look it up! Formulas and algebra go in one of my ears, and out the other.

    Or, and this is my favorite, 'cause it doesn't require much thought. Just use a fan controller pot, that should work just dandy!
     
  5. red1776

    red1776 Omnipotent Ruler of the Universe Posts: 5,219   +157

    yeah the HDD and activity lights are usually under 1w,
     
  6. captaincranky

    captaincranky TechSpot Addict Posts: 11,688   +1,879

    Edit Above; The variable resistor from a case fan may be just what the "butcher" ordered!

    Inset it in series with the positive lead to the LED,
    after wiring the center lead of the pot to either end.


    I hope I didn't state the obvious too blatantly, with that last effort.
     
  7. red1776

    red1776 Omnipotent Ruler of the Universe Posts: 5,219   +157


    I just threw my 2 cents in there because i work for an LED company :)
     
  8. captaincranky

    captaincranky TechSpot Addict Posts: 11,688   +1,879

    Do LEDs come in 24 volt models? If so, there's your answer! Of course we both know they only come in cases of 1000. ;)
     
  9. red1776

    red1776 Omnipotent Ruler of the Universe Posts: 5,219   +157

    If ya buy'em from me they do! :haha::p;)
     
  10. cigarman

    cigarman TS Member Topic Starter Posts: 33

    I would need a small potentiometer for each light I want to dim then? I was hoping I could just splice in a resistor in each + line I want to alter.
     
  11. captaincranky

    captaincranky TechSpot Addict Posts: 11,688   +1,879

    Well, then you need one potentiometer, to set the light level for the LED you want to change. I suppose after that, you could measure the resistance that is needed, then buy a fixed resistor(s) of that value to put in the line(s).
     
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