A large selection of transistor equivalent circuits is available for use in transistor circuit analysis. In particular, those equivalent circuits which fit one of two general types are especially useful. These are the mesh-derived T and the nodal-derived pi equivalent circuits;Cascaded transistor circuits present no particular problem when circuit reduction of the active networks is employed. This method consists of obtaining a T or pi equivalent circuit to replace two or more transistors. It is very versatile and can be used with series, parallel, or both series and parallel feedback. Feedback need not be limited to one stage but may involve any number of stages. Of most significance, after the cascaded circuit has been reduced, the analysis is identical to single stage analysis. All methods and formulas applicable to single stage circuits are applicable to reduced cascaded circuits. (Abstract shortened by UMI.)