LED Resistor Guide

This information was posted over at the RPF by David Moeller. It's been copied here for the convenience of the NEG, and to preserve it, should it ever fall off of the RPF.

This is a simple, easy to follow guide to finding the right resistor for your LED wiring needs.

  1. You take the voltage, 9v in this case.
  2. Take the LED voltage drop (this means how much does it use up) easy, it states it on the package!!! For white LED's probably 4v.
  3. Subtract them!!! 9-4=5 Easy so far, right?
  4. Take the LED current rating (it says this on the package too) for White, to be safe we will say 20mA which is .020A but it can be higher.
  5. Divide the two 5 /.020 = 250
  6. Resistors come in standard values so pick the nearest standard value which is greater, for us it will be 270 ohms.
  7. The resistor % just means how accurate it to the stated value, 5% or 10% is fine, what ever you can find.
  8. The wattage is for how much power will go through it, so anything small 1/4w or 1/2w is fine.
  9. HOOK it up! It does not matter what side the resistor is on. It It does matter what side of the power the LED is hooked up to, the long lead on the LED is ALWAYS positive. (unless someone cuts it!)
  10. Enjoy your lighting!!!

Other useful information from that same thread:

costuming/ledresistors.txt · Last modified: 2010/04/18 20:42 (external edit)