Output equivalent circuit of transistor shunt voltage regulator

An incremental output equivalent circuit was suggested earlier by Zakarevicius for the transistor series voltage regulator. It is now shown to be equally valid for the transistor shunt voltage regulator. The parameters of this equivalent circuit can be determined almost by inspection. It leads to an easy evaluation of the regulation factor and output impedance of the regulator. A typical transistor shunt voltage regulator is used to test the validity of this equivalent circuit.