# Basic LED circuit, 9v battery, what resistors to use?

by alh1987
Tags: basic, battery, circuit, resistors
 P: 3 Hi all, im a new guy to the forum, glad to meet you all. iv been doing a little rc project and now need to wire up some lights. iv never done circuit work before but im willing to gain knowledge on how to. the main problem is that no matter how much i read or calculate, i cannot work out what resistors i will need or if my circuit is even possible. i want to run 3x 2 led circuits off one 9v power supply. is this possible? here is a quick sketch of what i was thinkin..any info is much appreciated. thanks Attached Thumbnails
 P: 3 Also, would i be better off using 2 circuits of 3 leds? i would need a red, white and UV on one circuit which would add up to 9v exactly, would i need to run a resistor or not, would it even work? iv drawn that many diagrams im starting to confuse myself so sorry for the 'novice' questions
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P: 25,505
hi alh1987! welcome to pf!

(btw, never reply to your own first post, it takes you off the "No replies" search )
 Quote by alh1987 … i want to run 3x 2 led circuits off one 9v power supply. is this possible?
the way you've drawn them, in parallel, you'll be putting 9v through each pair (4.5v through each individual one), and they're only rated 2.5v to 3.5v (is that each, or per pair?) …
will that damage them?
if you're trying to keep the voltage drop across each the same as the rated voltage, you need to put each one in series with a resistor, or to put them all in series with each other and a resistor

(I = 9/∑R, V1 = IR1 etc)

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## Basic LED circuit, 9v battery, what resistors to use?

Thanks Tim, thats was something i wasnt sure of, thought it was best to check with you guys first. is there any chance u could draw me up a little diagram and list of components please, i just dont get which way to go about it.
should i run a resistor to each LED?