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Topic: Making LEDs go super super bright (Read 609 times) previous topic - next topic

nate890

is there a way, such as hooking up more voltage to an LED (I've tried, doesn't work) to make it go more bright?

abrookfield

#1
Jul 23, 2012, 01:17 am Last Edit: Jul 23, 2012, 01:21 am by abrookfield Reason: 1
over-driving a high powered led certainly does make it go super-bright... followed by super dim of you keep over-driving it

Think strobe-lights
www.reeftopper.com

nate890

I've compared 5V to 1 LED to 20V to 1 LED and there was no difference

marco_c

#3
Jul 23, 2012, 01:54 am Last Edit: Jul 23, 2012, 01:57 am by marco_c Reason: 1
LEDs are fixed voltage. The brightness varies by the current you pass through until they burn out.

If you have resistors in series you can reduce the resistance to get more brightness (ie, more current for the same voltage). Arduino pins can drive about 40mA, LEDs are generally operated at 20mA or less to be safe. The higher the current the lower the LED life.

If you want super bright LEDs you need to buy them specified that way rather than overdrive standard LEDs.
Arduino libraries http://arduinocode.codeplex.com<br />Parola for Arduino http://parola.codeplex.com

tmd3

#4
Jul 23, 2012, 04:44 am Last Edit: Jul 23, 2012, 04:46 am by tmd3 Reason: 1
You don't say why you want your LED brighter.  If it's part of a multiplexed array, it might be too dim because it's only on for a relatively short time, compared to the cycle time of the array.  If that's why, look here:  http://www.gardasoft.com/uploads/APP930%20Overdriving%20LEDs.pdf.  It'll tell you how to overdrive LEDs when you operate them at low duty cycles.  Be warned, though, that LEDs have maximum ratings that are peculiar to the particular device, and you probably have no way of knowing which LED you're using.  You'll have to make educated guesses if you use this method.  You'll also want to be pretty careful during development - if your program fails to turn an LED off, that LED will fail.

If you just want a continuously lit LED to be brighter, you can run the current up to the maximum for the LED, which is typically 20mA.  If that's not enough, you're stuck with buying a high-brightness LED.

nate890

I was just curious.. Thanks guys, will keep this all in mind ^.^

focalist

TMD, that is an interesting pdf.  Wish more info was provided.. Seen other that is similar though.

I am currently overdriving some 10watt rated LEDs at about 12watts (feeding 1.2a rather than 1A), but as the pdf says, I only do that pulsed, for photography.  Even then, 20% over isn't a huge deal.. Shortens life, but life is 50k hours....

Going higher, the main concerns are heat and melting the internal connections with the current pulse..
When the testing is complete there will be... cake.

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