R RacerGSR Junior Member Mar 10, 2003 4 0 0 Mar 10, 2003 #1 What size resistor should I use to step down the 5 volt from the power supply to a 5mm 3 volt LED???
P paco83 Member Nov 4, 2002 170 0 0 Mar 10, 2003 #2 depends on the current rating. If it's a 20mA rated LED, then it's (5-3)/.02 = 100 ohms