Arduino controlling an Philips MR16, dimming....

Hey guys!

I'm fairly new in the Arduino world but I just wanna run this through more experienced people (you guys :P)

I'm working on a lamp and I want it to have a bit of "intelligence". Depending on how you turn the knob it acts differently etc.

It's a 12V LED (Philips MR16 10w). The code it self I can figure out I think but with the electronics is a bit more of a confusion.

The controlling part is an encoder disc from a printer but I'm unsure about the output. What should I get? I have a driver with the right output but the controlling as a "limiting" the light.

Anyway, it should be fairly simple but, I would love some guidance here :)

http://www.youtube.com/watch?v=5avJVvrFedc

I was trying to find out what's inside these things to find out if there's already some circuity, and if there's a "fan" inside one, that means it needs direct dc 12v OR when you dim it, you also reduce the power to the fan and the LEDs.

A tip41 power transistor and PWM (analogWrite through a low pass filter) and a heatsink would probably pull off dimming, or a mosfet (logic level) instead of an NPN transistor.

I like TIP's 41 as it handles up to 4 amps with a regular heatsink and since it's a. cheaper than a mosfet and b. requires a lot less voltage to switch on and make the MR16 conduct.

But you can use analogWrite(PWMPin,value); to vary the brightness.

What about this fan?... is it going to have issues with PWM directly or some kind of capacitor to absorb the ripple?

Interesting... Though the one I'm planing to buy, I'm pretty sure that one didn't have any fan in it. Maybe this only occurs on really high powered ones?

How about if I already have a driver? Do I still need a MOSFET or simliar? Thought(hoping) I wouldn't... :)