LED Resistor Question

[Nox]

Hi, I'm trying to put some LED's on my box but I keep popping them. Where do I go to find an easy calculator to figure out the resistance I need to push down the incoming 5V to an acceptable 3V?

I used Ohm's Law R=E/I whereas resistance equals voltage divided by current. Since my LED is 35mAh and I am putting it on a 5V line, then my calculation should be ?=5/0.035 which is equal to about 152 for the value of my resistor. I found two resistors that I combined to make that value and my output voltage never changed. It remained at 5.31. I am using a digital multimeter to find values for my resistors and for my output voltage on my psu.

Any idea what I'm doing wrong?

Thanks!

[FyR]

http://led.linear1.org/1led.wiz

http://led.linear1.org/led.wiz

these should do the trick :)

[Nox]

Found what I was doing wrong Fyr, I was trying to limit the voltage output straight off the PSU without taking the voltage draw from the LED's in mind.
Basically I was trying to choke the 5v line into a 3v line, then run it to a power block to spread the lines around - I ran it in series off the 12v line and it works just fine, no dead lights.
Thanks!