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