# LEDs



## sinus_ (Oct 27, 2004)

hello,

i have just made simple "lighting" for my casing. just screwed a wall switch behind and the connected this red LED-looking (it is square) to the +12V connection of the PSU... it works but the red light is not bright enough... 

so i was wondering if i could create a series of LEDs. can anyone tell me how to connect at least 15 LEDs? with the resistors and stuff... i seemed to have forgotten from my previous lessons in highschool :sigh: 

thanks guys


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## merlin (Sep 25, 2002)

I think you have have to take supply voltage, subtract the LED voltage and then divide by current. That will show you what resistor you can use with your LEDs. 


_example_ 
supply voltage is 12V
LED is rated at 2V
Current 0.02A

so I think it goes : 
(12V-2V)/0.02A = 500ohm ? or the nearest greater. 
As with anything, don't quote me on this. Double check your work. Take pictures if you blow up anything :grin:


[update]
Here's a neato calculator for ya. If you're using more than 1 led, add up the voltages.
http://www.bit-tech.net/article/68/


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## semma (Oct 16, 2004)

the easiest way to connect multiple leds is with a resistor network. heres a good one from jameco. it will allow you to connect 15 leds all from the same voltage source. its 470 ohm which is good for 12 volts. if you want to use 5 volt line i thinks its 100-150 ohms

http://www.jameco.com/webapp/wcs/st...toreId=10001&catalogId=10001&productId=120099


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