Resistor Question

[crazyl69]

         To begin, I'm new to this forum and this is my first time posting. I'm working on a friends psp (trigger mod) and would like to use red led's. I understand that red led's are of lesser voltage (2.4) than the blue led's of (3.5,5.0) volts. What number ohm resistor can I use in order to properly power up the low voltage red led's with out having to worry about burnning them out.        Edit: would the 10 ohm resister still be good enough or a higher ohm be necessary. Any help would be highly appreciated. Thanks...

[Azie139]

i think 10 ohm should be good

[l0rdnic0]

10 might be good but when in doubt look up LED Calculator on Google....  You just need to know your supply voltage (5volt on a PSP in most spots) and you fwd current.. in your case 2.4 and the miliamps your led opperates at..

 

http://ledcalc.com/

or

http://www.hebeiltd.com.cn/?p=zz.led.resistor.calculator

[BABYGOAT]

86.666 Ohm resistor.

Input voltage  minus forward voltage for led =

5.0V - 2.4V = 2.6V

Answer divided by LED current = resistor value

2.6 divided by (usually 30 mA) 0.03 = 86.666 Ohm

Done!!!

Someone correct me if i am wrong?