The IR sensors worked fine, but I found the ultrasonic sensors act up when powered by a separate power supply, returning bogus numbers (im using SRF01's). I used a benchtop 5V supply to power the sensors (grounds tied of course) and left the Arduino on USB. Everything worked well initially but once I added all the sensors, I think we were overloading the USB port as the 5V rail was only giving around 4.25-4.5V.
I have a project using a bunch of Sharp IR distance sensors and some ultrasonic range finders with a Mega 2560.
I've searched but haven't found a totally clear answer on this.
How can I safely power the Arduino through the 5V pin and utilize the USB connection?
