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