High power amplifier with inductive load for e.g. voltage transformer - receives square wave input and consists of Darlington cascade with third transistor to tap on prim. winding

摘要

The amplifier, e.g. a 12 volt D.C. to 220 volt A.C. converter consists of three transistors, two diodes and the primary winding of a transformer which serves as an inductive load. An input square wave is fed to the base of the first transistor (3) which is also connected to a first side of the primary via a first diode (12). The first two transistors (3,4) are connected in a Darlington arrangement and the Darlington pair collector output is connected to a tap on the primary minding. The emitter is connected to the base of a third transistor (1). The emitter of the latter is connected to ground while its collector is connected to the first end of the primary. As second diode (11) is also connected between the first end of the primary and ground, in opposition to the third transistor. Pref. a dual symmetrical arrangement is used which receives antiphase signal inputs to either side and has a common connection of the second ends of the primaries.