Arduino and high power leds.

HI all,

So I have been doing some reading and I am looking to power a few high power leds. Just asking as a clarification that there is no other way to do it?..if I want to power some cree leds or other high power leds and run different patterns on them (say a blinking or an array chasing pattern) I need to use an LED driver? Such as this one? http://www.instructables.com/id/Circuits-for-using-High-Power-LED-s/

What are my other options? If say I have 8 or 10 these high power leds?.i know arduino will probobly be able to power only one. Should I use an led driver that will act as a relay? In other words, I'll get my power source from my 12v car battery and just use arduino as a switch indivially for each one? Spill some info please

Thanks,

Roman

i know arduino will probobly be able to power only one

No it can power no high power LED.

What are my other options?

For high power LEDs you need a constant current driver, there are lots of them about. That circuit you posted is not a particularly good one. It is much better to have a IC specifically designed for constant current rather than a fudge like this. see:- http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1234273497 http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1258412419 and the links off it.

It really depends how many LEDs and how powerful.

If you are only driving one or two LEDs say 1W each, then you can use the fact that you have a stable 5V reference and just use something like a BD139 transistor with 270R from the arduino to the base to switch the transistor on with the LED and a resistor, to limit the current (I'll let you do the Ohm's Law and power law bit).

This isn't a great way to do it, but it does work.

A better design is to use a LM317 in constant current configuration (Google it), and have a transistor to pull the reference pin down to turn the LED off. Then the voltage of your LED supply is far less critical and you can use an external supply. You can even chain two or three LEDs in series that way.

And now the plug! I cover all of these techniques in my book.

www.arduinoevilgenius.com

are you talking about RGB or single color leds? 350mA or 700mA? how many do you want to control?