Powering a DC Motor with 5v 10amp dc External power supply.

Hello Everyone,

Please help, I am stumped here as a beginner.. I followed the attached diagram to a T and my DC motor powers on. Then I changed the Ground and 5v coming from the arduino uno to the negative and positive terminals on a DC Barrel terminal for my external power supply. I even added a 10volt capacitor to prevent spikes.. I then run the program and make sure to power the arduino via usb first and then power on the supply..

The DC motor no longer works as it did when i had the power coming from the arduino board. Although, I hear the motor is working.. just doesn't seem like enough electricity is reaching the motor?

Can anyone shed some light for me on what is going on here? Am I doing something wrong?

Oh . One last thing.. I connected the ground and 5v directly from the external supply to the motor and it works .. so there is something going on with the circuits.. I am guessing it could be the transistor..

Did you remember to connect the ground of the motor supply to the Arduino ground?


Nope.. I am hoping this is what is missing. Do I connect the arduino ground to the external power supply ground? will try it tonight thanks so much :slight_smile:

yup this was the answer thanks russellz