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Basic Electricity 101 question?

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Old 03-04-2009, 08:13 PM
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Default Basic Electricity 101 question?

I need to use a single l.e.d. light on a 12v. power supply. As an example, If the light has a max rating of 3.6v how do I figure what resistor to use? I'm sure there must be a simple formula. Thanks for your help.
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Old 03-04-2009, 08:18 PM
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http://www.kpsec.freeuk.com/components/led.htm

http://www.llamma.com/xbox360/mods/H...20an%20LED.htm


http://ledcalc.com/
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Old 03-04-2009, 09:46 PM
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V=i*r
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Old 03-05-2009, 12:00 AM
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Most LED's have a 1.6 to 2.5Vdrop by themselves.....but usually only handle 5ma to 50ma max. Sounds like there may be a resistor in there already? Do you have a Part Number or something?
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Old 03-05-2009, 09:57 AM
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R = (12V - 3.6V) / 0.02A = 400 ohm resistor


Go with a 500 OHM 1/4 watt
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Old 03-06-2009, 09:43 AM
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Thanks for everyone's help.
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