Hi, I'm working on a project that will require 6 servos running at 5v (each one using around 200-300mA at no load). I have an external power supply built from an old computer AT supply. I can get up to 25A on the 5V rail :) In addition, I have a DC motor running from the external power supply's 5V rail as well.
Anyways, I know that to get the servos working properly, the grounds of the Arduino and the external power supply have to be connected together. So my question is: since the Arduino and External Power Supply grounds are connected together, is there any chance that back current from the DC motor can damage the Arduino? Will noise on the ground signal caused by all the motors be an issue as well?
I was thinking of using 4N25 optoisolators to completely isolate the Arduino circuits and the external power supply circuits, but the optoisolator's output is inverted, so I'm trying to figure out if this will be an issue with the PPM signal to servos.