Hello, i'm completely new to the Arduino concept and to the forum, so please forgive my probably very obvious questions...
I'm trying to figure out how to create a pulsing (or breathing) light effect similar to the ibook one, but on a larger scale (for an art work). It seems that Arduino is the way to go, so I am about to place an order for a board. But first I wonder if anyone could tell me - is it possible to control LED spot bulbs (2.3 watt for instance) with arduino? After some reading in the forum it seems that an LED driver might be necessary - is this the case? And again the question, which i'm still not clear about - if I wanted to drive three separate bulbs, would I need three separate boards?
Thanks - and sorry again if i'm repeating questions that have already been asked a million times...
hi
yes you are on the right track. You need an LED driver to convert the relatively small signal from the Arduino to a higher powered one that can swtich the LED on and OFF. It will be driven by one of the PWM pins, to make it 'breathe'. There is a diagram somewhere in the 'playground'. Hope this helps.
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that's a big help already - thanks!
I am not an EE, but couldn't you just use a transistor to supply the leds with the right voltage?
I am thinking that connecting up the Base to the PWM pin, and the Emitter through a resistor to ground and the collector to the high wattage LED spots.
Nevertheless, charlotte_mg, the Arduino comes with 3 PWM pins so one board should be perfect for creating the effect you need, regardless of how the leds are driven directly.
That's more or less the idea, but with some resistors for base and collector current limiting... Here's a diagram for driving a few regular leds.
For higher current loads, the transistor would have to be something like a TIP102 or an appropriate MOSFET like anIRFZ20. The 2N2222 is the diagram is good for up to about .8A.
D