The duty cycle of the train of pulses produced by the controller 14 and which are fed to the base of electrodes of transistors Q1 and Q2, is determined by {HEAD ~ the sense voltage} produced on {TAIL ~ line} 17 
produced on
The duty cycle of the train of pulses produced by the controller 14 and which are fed to the base of electrodes of transistors Q1 and Q2 , is determined by { HEAD ~ the sense voltage } produced on { TAIL ~ line } 17
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL OTH