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LEDS Answered

I am wondering if you run a led at full voltage and amps then as you add more resistance light output goes down here is my question 1 led at 20ma or 2 led at 10ma do not 2 leds give more light than 1. Like is light output a linear taper to amount of current applied or is it more of an audio taper?

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luxstar

4 years ago

Check out this page on candlepowerforums:

http://www.candlepowerforums.com/vb/showthread.php?89607-White-LED-lumen-testing

There are multiple charts showing current vs lumens per watt. The charts may look misleading. The brightness goes down as the current goes down but the decrease is very non linear from 0 to about 8 ma. Also the LEDS are slightly more efficient at 10 ma than at 20 ma. Most of the LEDS tested are most efficient (peak) at about 6 - 7 ma. So if the data is correct, two LEDS at 10 ma should be slightly brighter than one LED at 20 ma. There is a possible added benefit to running 2 LEDS at less than 20 ma. They may last longer.

I hope this was illuminating.

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mpilchfamily

4 years ago

As current to the LED drops the light emitted drops exponentially. But do some of you own testing. Connect 2 LEDs in series and see how they compare to a single LED. Be sure to use the same resistor on both setups.

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iceng

4 years ago

LED = Light Emitting Diode ... and a diode is non-linear photon to current.