led n00b here, need a little help
hey guys i am new to electronics and figured id start with leds, my first project will be to make a torth from a penguin caffinated mints tin using some domestic batteries, some Super bright (17000mcd) 3v Green LEDs and 10 resistors only described as "Used to operate a 3.3v LED on a 5v Power Line.
" and the same for the 10 12v resistors. now can anyone tell me. when would i need a resistor in my circuit? (i know the one for the 12v line would be perfect for arraching to a car battery and not killing the led.) but the 5v resistors? when would i use them? when i make this torch i will be using 2 or 3 aa batteries, 2 aa batteries make 3v and these leds are meant for 3.3 so im assuming i wont need a resistor however if i used 3 aa (4.5v) would i need the 5v resistor or would it be to much?
im sorry im confusing