hey guys. i need some help figuring out what resistor i need to make my DIY LED underbody light work. heres the deal .... they will run off of a 9volt battery .... the led's i picked up at radio shack are ...
5 mm high brightnes
intensity: 2850 mcd ( typical )
chromaticity coordinates: x=.334,y=0.197 ( typical )
viewing angle: 30 degrees
fw current: 30mA
fw supply:3.5v ( typical ),4.0v (max)
thats all the info on the bag the leds came in. i know if we touch them right to the 9v batt they burn up ... ( tried it .. lol ) so what size resistor would i need to run these off a 9v batt ?? thanks guys,scott