Looking for Newbie Help with an LED Project

OneFlash · Apr 7, 2005

I have an LED. For argument sake let's call this LED a brand no-heat-generating 14000mcd LED. I know it powers up on 7.5 volts (3 AA batteries). What is the best resistor to use to get maximum LUX for say, 1 hour, without blowing the puppy up. What process do I use to calculate this?

LED-FX · Apr 8, 2005

Guess on 20mA ,
3 * AA are 1.5V alkaline = 4.5V no 7.5V remember ;-)

Try http://linear1.org/ckts/led.php

HTH
Adam

HarryN · Apr 8, 2005

That is a nice calculator - Here I was always doing this in long hand. /ubbthreads/images/graemlins/smile.gif

BTW- in case you do not know the Vf of your LED - you can guess at 3.5 - 4.0 and be reasonably safe for blue, green, and white LEDs.

Looking for Newbie Help with an LED Project

OneFlash

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LED-FX

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HarryN

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