I've built some small prototypes powered by usb so far. I've two questions:
I) As they are stand alone-objects, I'm going to power the board by a 9v-battery (connecting to 9v + gnd pin).
Do I need to change the resistors ore does the arduino board "calculate inside" everything on a 5V base? (does the board "turn down" the voltage to 5V if the power comes from the 9V-pin). [sorry for my bad explanation]
II) Do I need to change the Jumper to "external", even if the power doesn't come from the dc power jack, (but from the 9v-pin as I connect the battery to the pin)?
Thanks a lot for your help, bluma*