Correspondingly, each time {HEAD ~ transistor Q2} is driven from a non conducting condition to {TAIL ~ a conducting condition} in response to the positive going pulses applied by the controller 14 via line 13, current flows from the voltage source Vs through the upper winding L2 of the primary of transformer T through transistor Q2 to ground 
is driven
Correspondingly , each time { HEAD ~ transistor Q2 } is driven from a non conducting condition to { TAIL ~ a conducting condition } in response to the positive going pulses applied by the controller 14 via line 13 , current flows from the voltage source Vs through the upper winding L2 of the primary of transformer T through transistor Q2 to ground
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL 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 OTH OTH OTH OTH OTH OTH OTH OTH