GB1261409A - Improvements in or relating to transistorised amplifiers - Google Patents

Abstract

1,261,409. Transistor amplifying circuits. TELEFUNKEN PATENTVERWERTUNGS G.m.b.H. 15 May, 1969 [24 May, 1968], No. 24893/69. Heading H3T. An amplifier comprises a plurality of transistors connected in a bridge circuit in which the two bridge halves are formed by two pairs of complementary transistors 1, 2 and 3, 4 respectively, the collectors of each pair of complementary transistors being connected together, means for connecting an output load, e.g. loudspeaker 9 in the bridge diagonal between the connection points 7, 8 of the collectors of the complementary transistors, and means for applying supply voltage - U B between the ends of the other bridge diagonal; wherein at least one transistor, e.g. transistor 2 of only one of the pairs is driven by the signal to be amplified and each of the transistors 3, 4 in the other pair has its control electrode and its collector connected across at least a part of the load. In the embodiment the bases of transistors 3, 4 are driven from the slides of an adjustable potentiometer 10 connected across the load 9. The arrangement may be driven from an emitter-follower stage 11, negative feedback being provided by a network comprising resistors R x , R y . The Specification also describes a simplified embodiment (Fig. 1, not shown).