can i use one resistor on 11 leds?
Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=123190
Printed Date: May 11, 2024 at 10:34 PM
Topic: can i use one resistor on 11 leds?
Posted By: CutDog504
Subject: can i use one resistor on 11 leds?
Date Posted: August 20, 2010 at 9:03 PM
I'm trying to convert the dash bulbs in my cluster to LEDs. I have 11 tiny bulbs that I need to replace with LEDs. The bulbs all share the same power circuit and ground. So I'm trying to find out if I can just put one resistor in the main power feed of the bulb circuit. If the resistor calculator I found online is correct, I can use one 1/2 watt 47 ohm resistor. The LEDs I'm using are 3.5volt 20ma. So would this work using only one resistor, or will I have to put a 470 ohm on each and every LED soldered on the board??
Replies:
Posted By: CutDog504
Date Posted: August 21, 2010 at 11:04 PM
ANYBODY?
Posted By: oldspark
Date Posted: August 22, 2010 at 3:04 AM
You can do it with one resistor for the lot, BUT - if you lose too many LEDs, you'll blow the rest.
V=IR => R = V/I = 10V/(11x20mA) = 10/.22 = 45R = 47 Ohms or 56 Ohms for a bit of margin.
P = I^2 x R = I x I x R = .22 x .22 x 47 = 2.27 => 5W.
So a 5 Watt 47 (or 56) Ohm resistor.
Posted By: CutDog504
Date Posted: August 23, 2010 at 9:53 AM
thanks
Posted By: djbori1980
Date Posted: December 15, 2010 at 12:14 PM
here is a goo sight to make your own leds. I do use if from time to time to make sure i get the correct resistance
https://metku.net/index.html?path=mods/ledcalc/index_eng
if you scroll down it will give you all types of ways to connect your leds with including the calculator
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