Adafruit motor shield external power

I am trying to control 12v 350mA stepper motor with Adafruit motor shield with Arduino UNO. Will this adapter work for providing external power to the shield? 12V/2A AC-DC Power Adapter
Is Battery pack a better option?

Sure. Don't forget you'll also need external power to the dc jack on the arduino if you don't have a USB cable connected.

raschemmel:
Sure. Don't forget you'll also need external power to the dc jack on the arduino if you don't have a USB cable connected.

Thanks. Yes I am using USB to interface Arduino. Is there a difference if I use external power to arduino or to motor shield? Or do I have to use both?

The little jumper on the motor shield connects the USB +5V to the Motor shield +5V. If you don’t have the USB connected the L293 has only one other source for that +5V and that is the arduino onboard regulator (which is a different +5V source than the USB) which receives power from the arduino ext. dc power jack.
Option A: USB plugged in and jumper installed.
Option B USB DISCONNECTED, jumper installed, Motor ext. pwr connected (greater than 7Vdc)
Option C USB DISCONNECTED, jumper installed, arduino ext. dc power jack supplied by 9V dc.
Option D USB DISCONNECTED, jumper NOT installed,Motor ext. pwr connected (greater than 7Vdc) AND arduino ext. dc power jack supplied by 9V dc.

If you remove the jumper and only supply pwr to the motor shield ext pwr terminals, you will see there is no voltage on the Arduino Vin, hence no +5V to either the arduino or the L293 VCC1 (pin-16). The jumper connects the ext motor pwr terminals to the arduino Vin allowing you to run everything off that power , if and only if it is high enough voltage to supply the arduino +5V and the L298 +5V. If the jumper is removed and you supply motor power and then supply power to the arduino ext dc power jack , you will see that the ext dc power jack supplies the arduino Vin and hence the L298 VCC1.
Those are your options.
Hope that’s not too hard to follow.

I am working on a project and trying to remove the jumper, but dont know how this is done. Do we do this by not allowing the 3 and 5V pins to connect between the motor shield and the Arduino board? Also when plugging in the 12V power source into the motor shield, do we use the Vsrc and gnd terminals for the motor?

Any guidance would be greatly appreciated.
Thank you!