GB993904A - Bistable transistor circuit - Google Patents

Abstract

993,904. Transistor bi-stable circuits. INTERNATIONAL BUSINESS MACHINES CORPORATION. Dec. 6, 1962 [Dec. 19, 1961], No. 46155/62. Addition to 884,275. Heading H3T. A bi-stable circuit comprises a supply circuit connected to pass current to two supply terminals 14, 15; two pair of transistors 10, 20 and 11, 21 connected such that conduction of one of a pair excludes conduction of the other, the transistors 10, 11 having collector load circuits connected to apply switching signals to transistors 21, 20 respectively; and two input transistors 45, 46 having their emitter-collector paths connected in parallel with those of the transistors 20, 21 respectively. Assume initially transistors 11 and 20 are conducting and transistors 10, 21 are cutoff. If a negative triggering pulse is applied to the base of transistor 46 it becomes conductive taking over the constant current from source 18 via resistor 19 switching off transistor 11. The rise in collector potential of transistor 11 causes transistor 20 to switch-off and the current supplied via resistor 16 transfers to transistor 10 which switches on, resulting in the second stable operating state with transistors 11, 20 cut-off and transistors 10, 21 conducting. Application of a negative triggering pulse to the base of transistor 45 will reset the circuit to its first state.