When transistor Q1 is driven to a conducting condition, current flows from the voltage source Vs, via {HEAD ~ line} 11, through {TAIL ~ the lower winding L1} of the primary of transformer T to ground via the now conducting transistor Q1 
through
When transistor Q1 is driven to a conducting condition , current flows from the voltage source Vs , via { HEAD ~ line } 11 , through { TAIL ~ the lower winding L1 } of the primary of transformer T to ground via the now conducting transistor Q1
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 REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH