”http://www.youtube.com/watch?v=2D1hQq77dlU&feature=youtube_gdata”
5mm or 10mm LEDs will work just fine for most projects, but if you really want to light up a room, consider using some of the high-power variety. With forward currents up to a full amp, you’ll need a way to dissipate heat — but the results are very much worth the extra effort.
