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Originally Posted by Alex698
I am having a problem with some LED's that I am using for a backlight (they draw less power for my project). The LED's are powered by a 5V regulator then into a 10 ohm resistor then paralleled together with a common ground. The LED's work fine for about seven hours then they begin to blink (fail). Any ideas or solutions?
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What color light are the LEDs? That's important.
As a first guess, even if they are white or blue, your 10 Ohm resistor is not enough. You are overpowering the LEDs, causing them to fail.
Asuming 3.5 volt operating voltage at 20 mA, you need to drop (5.0 - 3.5 = 1.5) volts. To do that, R = V/I = 1.5 / 0.020 = 75 Ohms. I'd use the next size larger, for just under 20 mA. You can re-do the calculations with the manufacturer's specs (voltage, current) for the LEDs you're using. (Or just go to the Panasonic site and find something equivalent).
Don
For fun, someone ought to spread out a bunch of petri dishes or something all over a regional and see what you bring home with you. Or not. - KathieK [more] 
14-06-2006, 19:10
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