Where to connect an external power source for an Arduino motor driver shield to? I have a BYJ48 stepper motor and an ULN2003A motor driver shield shield.

In many tutorials I read:


  do not to draw current from the 5V on the Arduino rail, but use an
  external power source, since the motor can draw quite some current


Which of these options to they mean by this?


  Connect an external power adapter to the Arduino and connect the
  ULN2003A board to the Vin pin and GND on the Arduino


or


  Connect the motor shield itself to an external power adapter and connect it to the + and - pin on the motor shield


or perhaps both are valid solutions?

The board I use is this one.
There are two things you need to do:


Prevent the motor drawing its power from the micro-controller board.
Make sure that all the grounds are connected but avoiding motor current return through the micro-controller board.








simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. A good wiring configuration. The heavy wires carry the motor current. 

Note that there is one ground connection between the micro-controller and the motor system. The return current for the 12 V supply does not pass through the micro-controller board.