Hi I have been trying to control a servo with a 5k potentiometer, it worked really well when I used the Gnd and the 5V of the board, but when I used an external 9V battery to give the servo more power, the potentiometer went kinda crazy and was changing values all the time, it would sometime drop from 1023 to 700 without touching it. So I decided to connect the potentiometer to the Gnd and the 5V of the board, and the motor to the 9V battery, but nothing worked, they apparently need a common ground.
Is there a way to just use the potentiometer as an analogue input and use that input to control a servo that is powered by a different power source?
Sorry for the stupid question, I'm a noob. (Yes I did google the question)