And if Vc is initially too low, then {HEAD ~ less current} would flow through {TAIL ~ Q2} to increase Vc 
flow through
And if Vc is initially too low , then { HEAD ~ less current } would flow through { TAIL ~ Q2 } to increase Vc
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH