Help needed to hook up some LED's

[Brocken]

Help needed to hook up some LED\'s

I bought some of the following LED's (NSPW500BS 5600 MCD) and was going to use them in my solar powered garden lights as the led's in the two lights don't match very well for color and I thought white would be better than yellow. well the solar/batteries only put out 1.96V to light the LED's and the white ones I bought only glow a little so I thought as long as I have them I might as well make something out of them. I would like to hook 4 or 5 of them up to a 9V battery and was wondering how to calculate what resister would be needed. Thanks for any help or directions provided.

Dave

 

[kalengkong]

Re: Help needed to hook up some LED\'s

V = I * R
Voltage = current * resistor

hope this help

 

[whiskypapa3]

Re: Help needed to hook up some LED\'s

Hook two of them them up in series with a 56 ohm 1/8 or 1/4w limiting resistor, then use two or three of these pairs in parallel to get the output you want.

a. Led voltage drop at 20ma = approx 3.5v
b. Two in series = " 7.0v
c. Half used 9v batt = " 8.0v
d. Subtract b from c = 1.0v
e. Divide d by 20ma = 50 ohms (.05w, use => 1/8w)

Max power in Led with fresh battery (30ma load);
(9.0v - 7.0v)/50 *3.5 = 140 mw

or 20% over Nichia spec

use 56 ohm resistor

(9.0v - 7.0v)/56 *3.5 = 125 mw

Go for it !