The controller generates {TAIL ~ an error signal} that PWMs {HEAD ~ the switch} thereby controlling the heating element 
The controller generates { TAIL ~ an error signal } that PWMs { HEAD ~ the switch } thereby controlling the heating element
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH