VOLTAGE GENERATORS

摘要

1337750 Time-dependent function generators DEFENCE SECRETARY OF STATE FOR 21 March 1972 [21 Dec 1970] 60482/70 Heading G4G [Also in Division B1] A resistance network for obtaining a timevarying voltage comprises resistances R A , R B , R C in series with a source 10 of voltage E, the resistances R B , R C being linearly variable with time and the output being derived across the incircuit portion of R B . It is shown that if R A 2R C and 5R B R C 200R B (where all values are maximum values, the second relationship being approximate), the value of R A may be set to obtain functions of time which vary from linear through logarithmic to hyperbolic. The source 10 may be connected to the circuit through a commutator whereby the sign of the output may be reversed. Both resistances R B , R C may be associated with switches which enable the floating and live terminals to be reversed. The resistance R B may be shunted by a further resistance which prevents the value of R B falling below a certain value. All these details are illustrated in Fig. 2 (not shown) which gives typical values. In the mechanical arrangement of Fig. 3, resistances R B , R C are in the form of rotary potentiometers 40, 42 driven at identical speeds by a motor 100 through a gear chain 98, 94, 90, 88. Idler 96 couples gears 98, 94 and is fixedly mounted on an axially movable shaft 102. During operation of the circuit, shaft 102 is moved to the right by a tension spring 106, this movement being controlled by a follower 104 which engages wormwheel 92 mounted on the potentiometer shaft 84. At the end of the period of operation, the follower is disengaged from the worm-wheel and allows the shaft 102 to move to the left under the influence of compression spring 108 whereby the idler 96 is disengaged from the gears 98, 94 and the potentiometers decoupled from the motor. A modification is described (Fig. 4, not shown) in which the potentiometers are mounted on the same shaft coupled to the motor through a slippable friction drive.