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