{HEAD ~ A set up circuit} is coupled to the sensor, the power source, and {TAIL ~ the wire feeder} 
{ HEAD ~ A set up circuit } is coupled to the sensor , the power source , and { TAIL ~ the wire feeder }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL