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