Help with LEDs

[RacerGSR]

What size resistor should I use to step down the 5 volt from the power supply to a 5mm 3 volt LED???

 

[paco83]

depends on the current rating. If it's a 20mA rated LED, then it's (5-3)/.02 = 100 ohms

 

[iZero]

bit-tech's LED calculator

 

[RacerGSR]

Thanks guys. That really helped.