Thus, during a portion, Δ, of each period P, there is a dead zone during which both transistors {HEAD ~ Q1} and Q2 are in non conducting {TAIL ~ condition} 
in non conducting
Thus , during a portion , Δ , of each period P , there is a dead zone during which both transistors { HEAD ~ Q1 } and Q2 are in non conducting { TAIL ~ condition }
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 OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL