Let’s deal with the problems of the various powering modes for the most famous Arduino boards, in order to overcome doubts users may have and to provide useful advices.
When you want to use an Arduino board in stand-alone mode, the first problem to face is the one of how to power it, once it is disconnected from the computer’s USB port. Unfortunately, a faulty knowledge of the theme of powering sometimes leads people to make unforgivable mistakes, since the first result is often that of seeing the board go up in smoke and almost always irremediably, since from that moment it will not work any more.
In the premise it is good to point out that the article will deal with the powering modes of the Arduino boards operating at 5 V (UNO, MEGA, Duemilanove); a short, specific note will be dedicated to Arduino YÚN, that is still a 5 V board, but with features that are different from the other ones.
Sourced through Scoop.it from: www.open-electronics.org