Arduino Uno works fine on USB but resets on 12v power supply ?

Other Hardware General Electronics
1

Hi everyone, Arduino and general electronic-voodoo noob here, please bear with me.

So, I have an Arduino Uno, with a 28BYJ-48 stepper motor plugged to it (via its ULN2003 driver board, connected to pins 8 to 11, powered by the 5V pin, ground to GND), and a bit of strip LED to make it pretty, directly powered via the VIN pin, ground to GND.

The code is simply the Stepper One Revolution tutorial code, so nothing too crazy going on there.

When I power it via USB, the motor works fine. (Obviously the LED strip doesn't light up, being powered through VIN).
But when I plug the Arduino to my 12V/3.0A power supply, everything works fine for ~10-15 seconds, and then the Arduino seems to reset every few seconds.

Could it just be my cheap power supply being difficult ? Or is there something crazy stupid I'm doing ? Please send help, and thank you! :wink:

2

Could be the 5V regulator overheating and going into thermal shutdown, cooling off, resetting, overheating ...
It's next to the barrel jack - see if it's getting hot.

3

If you are running power to the motor through the 5V regulator on the board from 12V Vin, that's quite
a lot of power.

You should really avoid powering motors from the logic 5V rail if possible - try a 7805 external regulator
bolted to a small heatsink, or a small DC-DC buck converter to derive 5V for the ULN2003/motor direct
from 12V without stressing the Arduino's on-board regulator.

4

Thanks MarkT. You saved my day. I got same issues while connecting 12v solenoid value

5

The obsolete tutorials on the Arduino site and others imply that the largely ornamental "barrel jack" and "Vin" connections to the on-board regulator imply that this is a usable source of 5 V power.

This is absolutely not the case. It is essentially only for demonstration use of the bare board back in the very beginning of the Arduino project when "9V" transformer-rectifier-capacitor power packs were common and this was a practical way to power a lone Arduino board for initial demonstration purposes. And even then it was limited because an unloaded 9 V transformer-rectifier-capacitor supply would generally provide over 12 V which the regulator could barely handle.