Hi, old thread here but just wondering, i picked up the 4 wire sensor utrasonic with no regulator so,can I just hook up ping and echo to the white signals on EZB-v4 but the +5v and ground separately to a 5 volt battery external,do I need to attach another ground also to EZ-B? Or just leave it absent? (signals ony)

edit.....So I tried it out with no other ground than the 5 volt ac adapter on the sensor with the radar window,it is showing multiple red dots near bottom but hand in front of sensor then shows a red ping further to top of radar window and motors go into obstacle turning so I guess I can just run the sensor with it's own battery and nothing but signal wires to white ports EZ-B?will his cause any future harm if no extra ground to EZ-B?

next edit.....so since I was getting crazy random pings everywhere,thought I would add the ground wire on eZ-B and then $$bingo all the random pings stopped,now i was getting accurate steady red dot line showing the roof as my sensor was facing the roof and when I put my hand in front of sensor it showed up a red dot on radar closer to bottom,think that's it ,working good!

Yes, this is a very common oversight/mistake for folks newer to robotics and electronics, you always need interconnected grounds or "commons". This is the return path for electronics, with out a shared common connection for the ground the circuit would not be complete.

Good job solving your own question @RoboRad

Also (you already appear to know this) but as a reminder, do not exceed the 5volts for your ultrasonic sensor or you will damage it.