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