Patent GB-715662-A (GB)
Title: Improvements in or relating to electric pulse generators
IPC: H03K3/53
Filed: 1952-05-20
Abstract: 715,662. Pulse generating circuits. GENERAL ELECTRIC CO., Ltd., BRISCOMB, D. W., and FAITHFULL, P. J. F. May 20, 1953 [May 20, 1952], No. 12788/52. Class 40 (6) In a pulse generator of the type in which a delay-line pulse-forming network is charged from a D.C. source via an inductor and is discharged periodically into a load on firing of a triggered discharge device, the duration of the pulses is varied by switching in or out additional sections of the delay line at its distance end and interrupting the application of trigger pulses to the discharge device. The Figure shows a pulse generator in which the delay-line 2 is resonantly charged from a D.C. supply 4 via inductor 5 and hold-off diode 6 and is periodically discharged via a load 3 when thyratron 1 is triggered by a pulse from trigger unit 11. The duration of the pulses generated may be varied by change over of contacts A1, B1 of relays A, B and the trigger pulse supply may be interrupted at contacts Cl of relay C the trigger pulses having a repetition frequency which is changed in steps in accordance with the changes in duration of the generated pulses. When contact B1 changes-over inductor 8 is connected in series with inductor 7 and the rate of build-up of the leading edge of the generated pulses in reduced which lessens the possibility of thyratron 1 being damaged due to the short duty cycle. The relays A, B and C are controlled by a remote switch 12 which, when its position is changed, causes a self-interrupted step-by-step rotary switch to operate which comprises solenoid 16 and interrupter contact 17 and drives a switch having banks of contacts 18 and 19 to a corresponding position. A further bank (not shown) alters the repetition frequency of the trigger pu'ses applied from unit 11. With the switches as shown relay A is energized and relays B and C are released so that the delay-line 2 has 4 sections to be charged and inductor 8 is shorted. When the switches are moved one position forward (clockwise), relays A and Bare both energized and the complete delay line is in circuit and the short is removed from inductor 8. In the next two positions of the switch neither relay A nor B is energized so that only the first 2 sections of the delay network are in circuit. Relays A and B are not fast acting so that when they are released the connections A1, Blare not changed until after the operation of relay C so that the network 2 has time to charge fully and no arcing takes place on breaking the contacts between its sections. When contact C1 is closed the supply of trigger pulses to thyratron 1 is interrupted for a longer time than the release time of relays A and B so that thyratron 1 cannot be triggered until the switching operations are completed. The interruption of trigger pulses may be effected by applying bias to the control grid of a pentode valve, Fig. 2 (not shown) included in the trigger unit 11, for a pre-determined time after closure of the contacts the delay being determined by the time constant of a resistorcapacitor network in the control-grid circuit. The pentode valve may constitute one valve of a multivibrator the frequency of operation of which determines that of the trigger pulses. Specifications 708,012, [Group XL (b)], and 708,021 are referred to.