Patent GB-701038-A (GB)
Title: Non-linear transformers
Inventor: LAWRENCE WALTER
IPC: H03K17/81
Filed: 1950-06-27
Abstract: 701,038. Digital electrical calculating apparatus. NATIONAL RESEARCH DEVELOPMENT CORPORATION. June 13, 1951 [June 27, 1950], No. 16068/50. Class 106 (1). [Also in Groups XXXV, XXXVIII and XXXIX] A saturable reactor comprises a number of coils embracing different numbers of laminations, forming pairs of magnetic circuits, each pair having a limb of reduced cross-section. Two sets of E-shaped laminations 1, 2, Fig. 1a, are interleaved, the set 2 being provided with notches 4 to make the magnetic circuit more easily saturable. The magnetic circuits are shown at 6-10, Fig. 2b, and the coils A, B, G, H embrace one or more of the laminations. The simple device of Fig. 4, in which a saw-toothed current is supplied to winding W1 and a steady current to winding W2 produces pulses in winding W3, the shape and duration of which vary with the circuit constants. Typical input current, flux and output voltages are shown in Fig. 5 (d), (e), (f), the negative output pulses being eliminated by the use of a rectifier. To reduce the tendency of the notch 17 in Fig. 4 to act as an air-gap, a modified notch and winding, Fig. 6, may be used. Complex wave-forms such as Vx, Vy, Fig. 7 (a) may be synthesized by a saturable reactor of the type shown in Fig. 2 (b), the circuit elements being shown schematically in Fig. 8. The wave forms are analysed into pulses as shown in Figs. 7 (b), (c), the separate pulses being produced between terminals Vx, Vy and earth. A polarizing current Ip is applied to windings 27- 33 corresponding to the B windings of Fig. 2b and a sawtooth current is applied to coil 26 of the type G. The output coils 34, 40 are of B type and produce the required positive and nega- - tive pulses in response to the saturation of the appropriate magnetic circuits by the alternating current in coil 26. The wave form, Vx, Vy shown in Fig. 7 are used for tracing the number 2 on an oscilloscope screen. For tracing numerals 1, 2 or 3 as desired, control current normally applied to terminals Ic1, Ic2 and Ic3, Fig. 9, is cut off from the appropriate terminal. A single control current Ic, Fig. 10, cancels the effect of one of an additional set of polarizing windings 47-49 to trace a number on an oscilloscope. By enlarging the apparatus to trace any one of the arabic numbers and providing several control windings such as 46, the device can be made to add numbers and trace the answer. By passing a control current Ic, Fig. 11 (c) through coils having appropriate numbers of turns and a saw-tooth drive current id through a coil 26, a waveform Vo, Fig. 11 (a), can be obtained from coil 50 in which the positive and negative half cycles are generated by the left and right-hand magnetic circuits. The magnitude of each pulse is determined by the cross-section of each lamination and the time position of each pulse by the control current Ic. Coils 51-54, 59 and 55- 58, Fig. 12, are driven respectively by currents I sin wt and I cos wt. Output coil 60 produces positive pulses at 72‹, 144‹, 216‹, 288‹ and coil 62 a negative pulse at O in each cycle. Selector switch.-A polarizing current is applied to winding 66, Fig. 13, and its effect is opposed by control current Ic applied to winding 65. As the current Ic is increased the magnetic field due to winding 66 is progressively cancelled and replaced by that in the winding 65 so that the input winding 64 which may be modulated by speech is coupled in turn to each of the ten output windings L0-L9. Binary encoding.-A control current Ic varying incrementally and applied to winding 78, Fig. 16, produces positive or negative pulses in outputs 1, 2, 3 according to the value of the control current, the outputs being arranged on a binary basis. Thus no current produces negative pulses at all outputs, a current of 10 ma produces a + ve pulse at output 1 and negative pulses at 2 and 3, while a current of 70 ma produces + ve pulses at all outputs. Adjustment of control current.-A "click plate" device, Fig. 17, may be used to adjust the control current automatically to the correct value; feed back being used to provide stability. A. common polarizing current Ipp is applied to progressive windings 81, 83 in the click plate and switch respectively. The click-plate also has input and output windings 84, 85 of H-type, the output being rectified, amplified and fed to control windings 80, 82. By injecting suitable pulses into the winding 82 the control current and hence switch output can be changed from one of the stable positions shown by the intersections of curves A and B to another in either direction and by any number of steps at one time. Fig. 18 shows a store for a single hinary digit. -A positive or negative pulse applied to coil 90 enters one or zero. A positive reading pulse applied subsequently to coil 92 induces the entered pulse to be repeated across coil 91, A store for a 4, digit binary number is shown in Fig. 20, the number being entered by the application of positive and/or negative pulses to coil 96 at. the same time as a staircase wave form is applied to coil 98 whereby switch 93 enters the number into windings 99-102. The number is read out over coil 107 digit-by-digit when four standard pulses are fed to coil 108 at the same time as a stair-case wave-form is applied to coil 110.