Beginner LED Project - Advice needed!

Hello forum, I am hoping some of you could point me in the right direction with my project...

I have had an arduino duemilanove sat on my desk for about a year now and am finally getting round to giving a project a go. I have created some basic sketches and circuits already with it so am familiar wiht the basics, just needed some advice on my project. Ok here goes....

I have 12 LEDs that I want to install in my closet, they would come on when the door to the room is opened and then power off when the door is closed. I would like the LED's to fade on when powered up and fade off when powered down.

My first question is does the arduino have enough power to light 12 LEDs or will I need to use an external power source?

My first question is does the arduino have enough power to light 12 LEDs or will I need to use an external power source?

That depends on how bright you want them to be, but yes, you probably need an external supply.

From all the reading I have been doing in the forum I had pretty much reached that conclusion! Ok my next questions is this...

I am using PWM to fade the LED's on and off. If I was to use an external power supply would I still be able to make use of the PWM feature?

Yes but you will need an external transistor or FET to do the switching.

Yes, but you must use something (like a logic-level FET) to drive the LEDs. Have a look over at the Playground for examples and circuits.

Thanks for the advice, i’m off to source a transistor :slight_smile: