Strange nano & servo behaviour


I have a servo connected to a Nano & I downloaded the Sweep program from the Arduino site.

If I use the 5v pin on the board to power the servo it moves with a nice smooth action.

However if I use the power directly from my bench supply the motion becomes very slow and the steps are really noticeable. It is also accompanied by the flashing of all the LEDs on the board (which doesnt happen when power by the Nano's 5v supply)

This is obviously going t be an issue when I want to run more than one servo.

Anybody any idea why this is happening?

Thanks Nic

Have you got the ground from the PS to the servo AND to the Arduino ground? See pic attached, source: zoomkat.

(Btw, it’s bad practice to power a servo from the Arduino.)


Yes they all have a common ground.

I dont really want to run the servo from the Nano's 5v pin but at the moment its the only way that makes the servo act as expected.


Do you know your PS is good?

If you have a holder for 4xAAs, try running the servos off that?

Works fine off a battery :smiley:

Must be the PS is flakey?

Strange the supply has always seemed stable in the past.

add your biggest capacitor to the 6V supply
avoid that both units are connected to grounded wall sockets