Originally Posted By: mlord
Originally Posted By: tfabris
I think that long-term, if the Arduino Mega board is going to be my 3.3v source, then I need a 7v power supply instead of a 5v power supply.

Just use 5V through the USB connector. It is simpler for probably everyone, since most cars have more 5V sources than 12V sources these days, and those that don't can be updated with a simple plug-in dual 5V thingie

I suppose you must be thinking about the boot/trunk area here, where you'll likely be tapping into some existing 12V wires? In which case, yeah, you can use the 5V Pololu PSU you have, but I would still wire it to a USB cable and then plug that into the Arduino's USB port.