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