A train of positive going pulses is fed to the base electrode of transistor Q1 by {HEAD ~ controller} 14 via {TAIL ~ line} 15 
A train of positive going pulses is fed to the base electrode of transistor Q1 by { HEAD ~ controller } 14 via { TAIL ~ line } 15
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL OTH