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adren1l1ne
09-26-2006, 06:45 PM
Ok I have done quite a bit of forum searching reading ETC. and have yet to find any real advice or answers. Now my problem is this. I know next to nothing of resistors, and the like. I know the one you choose is based on your power supply. Is there a simple easy way to determine what you need. I looked at the calculater that is on line and as I said I know nothing of this type of wiring so the calculator did me no good.
Thanx

xwingband
09-26-2006, 06:58 PM
I moved it here since it definatly applies more here.

For the resistor you need to know a few things first: 1) Your batteries voltage 2) The forward voltage of the LED 3) what amperage you want to run your LED at

2 and 3 you'd get by looking up the specs of the LED. For a Luxeon there is a topic on that here. If it's not stickied I'll do it right after I post this (EDIT: it's in the LED Q&A forum). If it's for a decrative LED you'll have to look at the package.

The generic formula for the resistor is:

(battery voltage - forward voltage)/amperage = resistor value

That formula will give you the exact value to get that amperage. Sometimes it an odd number and you'll have to "over-resistor" it. Using an online calculator will do this automatically for you and round it to the closest standard resistor made.

987654321a
09-26-2006, 07:33 PM
dangit.... i had a website but i forgot it, it tells you exactly which resistor your should get depending on your voltage/amperage.

james3
09-26-2006, 08:01 PM
Dang we have gone over this snitz a million times :roll:

OK here is a nice and easy way to do it since that seems to be what everyone wants.

Get a 2.2ohm 5w resistor and the 4aaa or aa batt pack. use that with a 3w LED and you will be good to go.

Do-Clo
09-26-2006, 09:30 PM
James at least 100 times :)