I am currently working with a servo and an external power source. I am using an Arduino Nano Every. The external power source is 7 volts so I used a buck converter to convert it to 5 volts before directing it to the main circuit. Sometimes the circuit works, but sometimes the whole circuit just stops working. Resetting the Arduino doesn't work and repowering would result in a dimly lit Arduino as if there were a short somewhere. But when i plug my arduino to the computer, most of the critical components work fine. Does anyone know what the problem is? Here's my current circuit: enter image description here

The two big rectangles are buck converters, the pins on the most right are pins for power sources. The pins up top are for sensors. the pins on the bottom left are actuator pins. Im currently connecting the battery to the circuit board using female male connectors. I've tested it a few hours ago and it worked, but when i tested it now, the whole circuit board doesn't work. Not to mention the arduino's led is just dimly lit.

  • 1
    \$\begingroup\$ You forgot to show us the circuit. \$\endgroup\$
    – Mitu Raj
    Jun 2, 2021 at 9:49
  • \$\begingroup\$ you can supply the 7 V to the Vin pin of Nano Every (VIN min-max 7-21V) \$\endgroup\$
    – Juraj
    Jun 3, 2021 at 4:54

1 Answer 1


If it works when powered from USB, but not when powered using the buck converter, then there is most likely a problem with insufficient power of the buck converter.

It is quite hard to read the circuit from the board layout (maybe add a real schematic). What is the "buck converter" you use? Is it a device somewhere on the board or the build-in converter on the Arduino board (\$V_{IN}\$ pin)?

Arduino's converter is not powerful enough to power the servo. It can't keep the voltage at that current, voltage will drop, which results in unstable behavior of the microcontroller.

By the way, the regulator on the Arduino board is linear, not buck converter (that refers to switching supply).

Try measuring the voltage on 5V pin when the thing is running (servo is turning), if it is significantly below 5V, you definitely need a better 5V supply.

  • \$\begingroup\$ I also answered a (probably similar) question on 3D printing forum here. The problem was Arduino's onboard 5V converter overloaded by other 5V devices connected to it. \$\endgroup\$ Jun 2, 2021 at 21:10

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