LED'S AND GPO, HOW LONG WILL IT LAST?

redmage · Post by **redmage** » Fri Feb 27, 2004 8:39 pm

I am using a MX2 (LK202-24-USB) I got in. And I'm trying to hook up some LED's. I Bought a single LED from radio shack, a 3.7 Volt (4.5 Volt Max) with a foward current of 20mA, 30mA Max.

Now, I know the low power GPO's are 5 Volts, I read that in this forum. So I Asked the RadioShack guy what resistor I needed. So I end up with a 10k-Ohm, 1/4 Watt, 5% Tolerance resister.

I used a SPDIF lead wire, cut it in half (for two LED's) plugged then into GPO 4 and 5, then turned on the GPO's. I then held the resister to one end of the LED and then I touched the wires quickly to see if it would light up.

Well, it did! Yay! However, not very brightly, it's a 2600 mcd rating, which I was told was pretty bright. So, cursing my curious nature, I took the resistor out of the equation and boom, it lights up! And very brightly. I was expecting it to blow out after .05 seconds but it didn't.

My main question is, how long will it light up until it blows out, because it's getting too high of voltage, right?

tjones965 · Post by **tjones965** » Fri Feb 27, 2004 9:41 pm

A 47ohm resistor should put you safely in the led's voltage range. And it should be nice and bright.

Miles · Post by **Miles** » Mon Mar 01, 2004 9:38 am

Hello...

Please see the following link for a thorough explanation oh how to determine a satisfactory resistor value...

http://www.lcdforums.com/forums/viewtopic.php?t=1527