I've got a ton of power adapters laying around the house, and I've been powering my Arduino with a 12v 1a adapter with no problems whatsoever. I've got a motor with a project I need to power with 9v and 2a -- And I have just such an adapter. I was planning on splitting the power -- one to the motor and one to the Arduino.
My question is this -- can the Arduino Duemilanove handle the 9v 2a power supply? I know the 9v will be fine, but I don't know if the 2 amp current will burn anything out.
The 2A rating on a power supply like that is the maximum current it can deliver. Actual current depends on the load. The supply does not force 2A through the load no matter what. The Arduino will draw as much current as it needs, which is only 40-50mA, from either supply.
Awesome. Thanks, Jack. It's been 20 years since I've done anything like this and my EE memories are foggy at best. I'll follow your advice and do some catching up.