GB931745A - Improvements in or relating to transistor relay circuits - Google Patents

Abstract

931,745. Transistor comparator circuits. GENERAL ELECTRIC CO. Ltd. Feb. 23, 1961 [Feb. 26, 1960; July 26, 1960], Nos. 6829/60 and 25962/60. Class 40 (6). A transistor comparator circuit comprises two transistors having their base and emitter electrodes directly cross-connected and having a pair of relatively variable unidirectional signals of the same polarity connected respectively between the emitters and a common point, the circuit being such that when the signals are equal neither transistor conducts but when one is larger than the other a corresponding one conducts, means being provided which is responsive to a predetermined conduction of each transistor. In the Figure, the base and emitter electrodes of transistors 1 and 2 are directly non-connected so that when the unidirectional input signals applied to transistors 12 and 13 are equal the bases and emitters are all at the same potential and neither of transistors 1 and 2 conduct. If the signals are unequal, one transistor will conduct and when the conduction exceeds a certain value the corresponding circuit 8 or 9 will operate a relay 10 or 11. In an alternative circuit (Fig. 1, not shown), transistors 12 and 13 are replaced by triode valves.