NPN Working

For NPN When current is flowing through the base( it is high voltage), VCE is 0,=> VC=0V,=>V(R49-R50 node)=16.7V(dictated by R49-R50 voltage divider) When current is not flowing through the base( it is low voltage), VCE is high impedance(open),=> VC=24V R65 value to be decided by the amount of current the base can handle(circuit is signal to base->base->emitter->Gnd)