I have an arduino Uno with a motor shield attached I would like to drive 2 12 volt dc motors. Can I just attach a 12 volt power supply to the arduino Uno?

I ask because if I can attach a 12 volt power supply to the uno, I would like to also try and drive some leds from the Uno as well. I remember that the VIN jumper needs to be connected if connecting a power supply through the Arduino uno. There is also a pin labeled VIN.

If I can connect a 12 volt power supply to the arduino uno, can I power the leds from the vin pin.

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2 Answers 2


Possibly. It depends exactly what it is you want to drive.

When you connect 12V to the barrel jack you get about 11.3V out of the VIN pin. This is because there is a diode in series with the barrel jack to protect against reverse polarity connections. This loses some voltage (could be as much as 0.7V).

Also that diode is rated at 1A maximum. So you can't drive anything that would need more than 1A (including the current needed by the Arduino and shield components).

  • Thanks for the info. As mentioned I plan to drive an oled strip and it requires at least 10V. Sep 5, 2018 at 3:58
  • It's all a question of the current. You need to total up the currents of everything - motors included - and make sure it stays below 1A.
    – Majenko
    Sep 5, 2018 at 9:02

That depends on the motor shield - for some motor shields you have to cut a circuit path (or unset a jumper) to separate the power for the motors from arduino's power!

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