I'm in need of a power supply for a finished project. If I read the docs correctly a 5V power supply is not enough and should be minimum 7V. I have room for a small open frame power supply but am having trouble finding a cheap one. I looked at Jameco and they don't show a 7V open frame. 12V is pushing the limit according to the docs. Should I just take a wall wart and cut it open and mount it inside the project? I don't want to use a wall wart outside the project because the it also needs line voltage and I don't want two cords to plug in. So it is best for me to include a power supply inside. Any tips on good power supplies?
7 volts is needed for the on board regulator, if you get a regulated 5 volt supply you can attach it to the 5 volt and ground point on the board
or you could crack open a wall wart
These are good and pretty small, I use them a lot.
Either 5V direct to 5V pin on the power header, or 7.5V to the barrel jack.
Switching DC Wall Power Adapter 5V / 2A - dipmicro electronics 1A version available too
Switching DC Wall Power Adapter 7.5V / 1A - dipmicro electronics
You could also just use a USB adapter and plug it into the USB-port on the arduino. Works fine for me.
I think that you can also use 4 NiMH batteries in series directly into the 5V and GND pins (mind polarity). NiMH batteries are about 1.2V each. Powering the Arduino with a 9V battery is a waste (even though I do that) because...
*You give the Arduino 9 volts, only to let the voltage regulator drop it to 5V; 4/9 of the energy wasted
*9V batteries have poor current capability
*They have low capacity (about 0.5Ah) while NiMH batteries have about 2Ah
*They are expensive