Hello,
I'm new to the forum. I figure this is a really simple thing to do although I can't quite seem to figure out which component I would need, any advice would be greatly appreciated. I recently purchased a 'Micro Fiber Optic Illuminator' off of Ebay. This person already put together a high powered LED with the correct resistance and soldered on some connectors. What I'd like to do is put something in between this LED and the 9V powersource I will be connecting that can sit on the breadboard and be controlled via a PWM out on my UNO to fade the LED on and off. Obviously a potentiometer would achieve this but then I would manually be twisting the component with my hand to fade, whereas I would like to write some code that controls a component instead. Thank you in advance.
[u]Here is a solenoid driver circuit[/u]. You can use a similar circuit, but since the LEDs are not inductive, you can leave out the diode.
A MOSFET will work in place of the transistor, but you need "logic level" MOSFET in order to drive it from the Arduino's 5V output.
Or, if you need to drive more than one of these things, a [u]ULN2803[/u] should work.
BTW - I don't see a link to a datasheet, but I don't think those are "high power" LEDs. High-power LEDs are usually one Watt or more, and they are normally driven by a switchmode constant-current source, rather than applying a constant voltage and using a current-limiting resistor. A standard LED usually runs at about 20mA and 40-50mW.
You can probably drive them directly from an Arduino output (probably with a different resistor value for about 20mA).