Patent GB-610306-A (GB)
Title: Improvements in and relating to thermionic valve circuit arrangements
IPC: G05F1/52
Filed: 1944-03-16
Abstract: 610,306. Electric indicating systems. MORRIS, D. G. O., and METROPOLITANVICKERS ELECTRICAL CO., Ltd. March 16, 1944, No. 4966. [Class 40 (i)] [Also in Groups XXXV and XL (c)] In a thermionic valve circuit arranged for input between the grid and the negative end of a cathode impedance to give cathode follower operation, and having an anode impedance and a grid-anode coupling capacity, there is provided means for interruption of the input circuit and means for deriving an output dependent on anode current which is normally dependent on the input, but changes only with a large time constant upon interruption of the input circuit. In a system for indicating the position of a remote object, Fig. 2, of the type claimed in Specification 609,705, a D.C. motor 20, having constant field excitation 20a and driving a movable system (not shown) into a position corresponding to the position of a remote object, is supplied from a metadyne generator 21, the centre-tapped control winding 22 of which is energized by the output of an amplifier 23, which may be of the type described in Specification 577,801, [Group XL], the input to which, when ganged switches 27a-e are in their third position, is from apparatus 31 producing as in Specification 609,705 voltages, between conductors 32, 33, and conductor 34, the difference of which is dependent on the magnitude and sense of deviation between the movable system and the remote object. A D.C. source 3, 3 centre-tapped at 9 provides H.T. for amplifier 23 and a network 43 provides smoothing, anti-hunting and time derivative components of control. A voltage obtained from a potentiometer 38 connected across the output of a bridge circuit associated with the armature of motor 20 as in Specification 580,005, [Group XXXV], is accurately proportional to motor velocity and is fed back in opposition to the input of amplifier 23 so that the velocity of motor 20 is dependent on the magnitude of deviation between the movable system and the remote object. When manual control of motor 20 is desired, switches 27a-e are moved either to their first position, in which case speed setting is by a reversing potentiometer 28, across D.C. source 3, 3, the output of which is opposed to the voltage from potentiometer 38 and applied as input to amplifier 23, or to their second position, in which case the output of a manually-operated position control system, the transmitter and receiver portion of which is represented by 29, is opposed to the output from potentiometer 38 and applied as input to amplifier 23 so that motor velocity is dependent in magnitude and sense on misalignment of the movable system and a hand control member (not shown). When, with switches 27a-e in their third position, the signal from apparatus 31 is less than a predetermined minimum, means within apparatus 31 affect the potential of a conductor 48 to render a triode 47 sufficiently conductive to operate, through coil OCRL, relay contacts RL and RL1, RL2 which move from the position shown to respectively, disconnect an input from potentiometer 38 to a circuit associated with a triode 1 and to connect the output from a cathode potentiometer 4 of that circuit in opposition to the output of a potentiometer 44 supplied from potentiometer 38 as input to amplifier 23. The circuit associated with triode 1 normally gives an output dependent on the input but, by virtue of a condenser 10, it has the property of maintaining the output unchanged and substantially constant for a time after the input is removed. The setting of potentiometer 44 is such that the velocity of motor 20 is also unchanged during these conditions. This " ratelocking " may be obtained by manual operation of a switch RLS when switches 27a-e are at either their second or third positions or may be obtained at any time by movement of switches 27a-e to their fourth position. If the movable system is driven by a non-electric motor or an electric motor without constant excitation, a tachometer generator may provide the voltage proportional to speed, suitable means being provided to control the motor from the output of amplifier 23.