I have a Arduino Duemilanove. My power source is the 5V regulated output of a normal computer ATX power supply. Seeing as though the Arduino needs at least 7V when using VIN, I can't plug it in there.
Where can I connect the 5V from the power supply to?
And also, would the Arduino automatically select the power source when using an external power supply? (The description mentions automatic power source selection between VIN and USB). Just worried that I might fry something when using an external supply at the same as powering the board using USB.
I am not the expert with powering with usb plugged in, From what I gather its best to disable usb power usually by modification of the cable
as far as regulated 5v you can plug it into anywhere on the arduino you would normally get 5v out of it (the + 5 pins) as it is already past the regulator
To power a Arduino board with an external regulated +5vdc, I like to take a old USB cable and hack off the PC end, locate the + & - leads and power the board through the on board USB connector. That way the auto-voltage circuit still functions as designed and you get to utilize the on-board USB thermofuse.
Lefty