thanks for your reply Riva - but I'm not sure I follow. are you suggesting that I need to use external power to power the LED strip? as i said - i've had this working by powering it from the 5v on the arduino. my understanding is that the transistor up-converts the power to be enough for the strip. that said - i'm unclear how the board could be affected by trying to power the strip from the 5v, as there is no external power coming in?
thanks for your help!
claudia