I'm modding my xbox jewel with five 5mm/2.1v/25mA/6.3mcd LEDS powered (in parallel) by the 12v HD power cable (yellow wire). What kind of resitors do i use? i've looked at several different tutorials/posts but they all say different things. does anyone know a definitive answer that actually fits ohm's law?

Why does everyone put the LED's in parallel???Just put 5 or 6 led's in serie ( + from one led to - from the next and so on.. ) So you won't need a resistor and the heat it produces is also gone.This is the best and simplest solution.
If you do want to do it with a resistor,a 330 Ohm would do for 12v,but use a 1/2 watt min.

japanwings, are they as bright in serial? every tut and old post ive read says to do them in parallel though they've never said why. anyone else no of parallel advantages?

QUOTE (madsciencetist @ Mar 3 2003, 11:34 PM)

every tut and old post ive read says to do them in parallel though they've never said why. anyone else no of parallel advantages?

i want to know this aswell!

if you put them in serie: 12 volts / number of leds=6 so you get 2 volts per led.2 volts or 2.1 volts ,you won't see a difference.Most leds are 1.8 volts anyway... Also this way you only have the power consumption of one LED.

The only advantage i can think off with parallel over series is if one goes when in series, they will all go off, as there is no power going to the others ( because of broken link )

In parellel, if one blows the rest will still work

I have mine in series and it works a treat

Like someone said earlier, there is a voltage drop across each LED while in series, so each one sees a smaller voltage on down the line. As long as you don't put too many in seriers, I doublt that you would see a difference. Although, you should make sure you are not exceeding the maximum voltage of the LED.

The advantage to doing them in parallel, is that each one will see the exact same voltage and if one goes out, it's much easier to find the one that is bad. Also, any resistors used would not be big enough to produce any noticable heat. I would personally wire them in parallel.

ok yellow is 5v red is 12v

heh

i think anyway?

and for using 5v yellow line u want 100ohm resistor on each led.

i believe the long leg is positive and shoret leg goes to ground. u wanna sodler the resistors to the long legs.

Unless the Xbox labels the colors of the wires different from a standard PC power supply, the yellow is 12V, red 5V.

oh ok. i jsut read soemwhere it was other way. my bad

Also, some power supplies are coded with orange and red wires; and I think in this case, orange is 12v, red 5v.

OK.. just so ppl dont' break their LEDs:

Yellow or Orange = 12V
Red = 5V

Read the rating on your LED and get an appropriate resistor (for parallel) and/or the appropriate number of LEDs (for series).

Have fun

blueinfinity you seem to know what youre talking about (at least in the way of resistors)

so if i do parallel, what resistors would i use for the 12v? (NOT THE 5v)

to all--

also would it be better just to get brighter LEDs and then use fewer-ohm resistors? maybe put a bunch on in series and not even use resistors at all? i know radioshack sells some really bright green ones--though i forget the specs on them, ill post them here later, i no they're different from the ones on radioshack.com

So if i used 6 of these:

http://www.radioshack.com/product.asp?cata...%5Fid=276%2D307

and hooked them up to the 12v wire coming off of the hdd than i dont need a resistor?

anybody? im goin to the store soon. and i dont kno if i should buy the risistors if i have 6 of the led's that were in my first post hook up to the 12volt.

You'll need a resistor on every LED. 100 Ohm if I remember correctly. . .

Oh, and using the 5v is DEFINITELY the safest way to go. Just tap into the 5v and stick a resistor on every LED and you'll be fine.

read earlier in the post. if i have 6 2.2volt led's that equals about 13.2 witch is about 12 if i hook them all up in a series (not parallel) then i hook them up to the 12volt than i dont need a risistor. right?

Yes you are right.. THe other way you don't need a resistor is if you buy 5volt LED's or 12Volt LED's.. Then there is no need.
Later
dave

Hey just hook them up in parallel using 75ohm resistors on each led you will get 20 ma going to each led since the leds are 20ma and put the resistors on the long leg on the led the short leg is the ground.