GB863621A - Electronic pulse generating apparatus - Google Patents

Abstract

863,621. Transistor monostable circuits. INTERNATIONAL BUSINESS MACHINES CORPORATION. Aug. 30, 1957 [Sept. 4, 1956(2)], No. 27372/57 Class 40(6) In a circuit comprising two transistors 10, 1<SP>1</SP> of the same conductivity type, the emitters are coupled together and to a first potential with coupling between the collector of transistor 10 and the base of transistor 11, these electrodes being connected to a different potential. An input signal applied to the base of transistor 10 changes its state to generate an output signal, the circuit restoring after a predetermined time. Assuming diode 12 and transistor 10 to be conducting, the collector potential is held sufficiently positive to bias off transistor 11 at the base, the emitter being held near earth potential due to diode 59 conducting. Due to the use of the potential divider 16, 17 the emitter of transistor 10 is held sufficiently positive to ensure its conduction. A positive going input signal applied over capacitor 15 drives the base positive and the transistor 10 cuts off. The resulting fall in collector potential lowers the base potential of transistor 11 so that it passes to the conducting state. The fall in emitter potential is transmitted through the divider 16, 17 and associated capacitor 20 to lower the emitter potential of transistor 10 and hold it cut off. The fall in emitter potential of transistor 11 is fed to the base of normally cut-off transistor 54 which conducts to provide a positive-going output pulse. The output pulse is fed back over inductor 57 which causes a delay, to drive the base of transistor 11 positive so that it cuts off and the circuit is restored to its initial condition.