[sdiy] voltage and LEDs

[ASSI]

On Tuesday 16 February 2010, David G. Dixon wrote:
> > > I now see lm317 regulators can be set up as constant current
> > > source..
> 
> Well, why not?  Slap a resistor on a voltage regulator, and voila! 
> Constant current source.

Yes, I've done years ago hat to make a NiCd loader which still works - 
only I have no NiCd batteries anymore.  Driving an LED with the same 
contraption can yield interesting results with the nonlinearities in 
the LED characteristic.  There's a reason that linear LED drivers 
exist and not just two pages added to the application notes of voltage 
regulators.

http://www.infineon.com/cms/en/product/channel.html?channel=ff80808112ab681d0112ab6b15d7070e
http://www.maxim-ic.com/solutions/hb_led_drivers/

At the power Dennis is suggesting I'd rather look for a switched mode 
LED driver.  1A DC BTW is way too much for that LED, even 500mA could 
be too much depending on how you cool it.


Achim.
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