Patent GB-773165-A (GB)
Title: Improvements in or relating to magnetic switching circuits
IPC: F02C7/277
Filed: 1955-04-27
Abstract: 773,165. Digital electric calculating-apparatus. WESTERN ELECTRIC CO., Inc. April 27, 1955 [April 27, 1954], No. 12155/55. Class 106 (1). [Also in Group XXXIX] In a circuit employing one or more magnetic cores, one or more advance windings are connected in series with the load which is shunted by a circuit containing one or more output windings, the latter circuit being capable of being blocked by outputs from said output windings to permit the advance pulse. to be effective in the load. In an OR circuit, Fig. 1, the core can be set by either of the input windings 21, 22. If the core is not set then the shunt circuit including the output winding 27 and the diode 28 has low impedance and shunts the load 30 and its diode 31. If the core is set, however, winding 27 produces a pulse which back-biases diode 28 so that the shunt has a high impedance and the advance pulse is effective in load 30. The disposition of the diodes ensures that no spurious output can be obtained due to the pulsing of winding 27 during setting. Likewise, if the advance pulse source has a high impedance, no spurious effects can be obtained through the advance coil 25. Such circuits may, therefore, be directly cascaded. A "joint-denial" circuit is also described, Fig. 2 (not shown) in which the field due to the advance winding is in the same direction as that due to the input windings, a further reset winding being provided. In the AND circuit; Fig. 3, the inputs are fed to windings 45 on separate cores, both advance windings 46 are connected in series with the load 30 which is shunted by both output windings 47, both of which must be pulsed before the advance pulse can be effective in the load. A binary adder operating in accordance with the principle illustrated in Fig. 8 is described. The input digits a, band the carry digit c are combined to form the respective functions a+b+c, abe and ab +bc + ac. The inverse of the latter, viz:-(a<SP>1</SP>+b<SP>1</SP>)(b<SP>1</SP>+c<SP>1</SP>) (c<SP>1</SP>+a<SP>1</SP>) is formed at D and combined with the first two functions to form the binary sum S=[abc+(a+b+c)](a<SP>1</SP>+b<SP>1</SP>)(b<SP>1</SP>+c<SP>1</SP>)(c<SP>1</SP>+a<SP>1</SP>). The output from the inverter is also re-inverted to reproduce the carry digit ab+bc+ca which is fed back to the first stage. Fig. 9 gives a detailed circuit for effecting this. Three advance pulses having phases #1, #2, #3 are used, the a and b digits being fed on to cores 66, 67 and the carry digit on to core 65 in phase #3. On the application of the phase #1 advance pulse with the output windings 76 serially connected to form a shunt path for the load, the latter receives the function a+b+c and since the load in this case is the input coil for core 79 that core is set accordingly. The output coils 85 each form a shunt for the second load which in this case is the input coil to core 88 so that this core receives the function abc. Finally, with the output coils 92 connected in pairs to form shunt paths for the third load which is the input coil to core 96, the latter receives the function (a+b)(b+c)(c+a)=ab+bc+ca. Advance pulse #2 feeds the inverse of the function on core 96 to both cores 88 and 75. The former is, therefore, now set in accordance with abc+ (a<SP>1</SP>+b<SP>1</SP>)(b<SP>1</SP>+c<SP>1</SP>)(c<SP>1</SP>+a<SP>1</SP>) and the latter with (a<SP>1</SP>+b<SP>1</SP>)(b<SP>1</SP>+c<SP>1</SP>)(c<SP>1</SP>+a<SP>1</SP>). The outputs of cores 88 and 79 are connected as in Fig. 3 in an AND circuit, resistance 119 being the load which is pulsed in accordance with the required function S. At phase #3 core 75 is pulsed to produce the inverse of its setting, viz:- ab+bc+ca which is fed back as a carry to core 65. A somewhat simpler binary adder, Fig. 10 (not shown), is constructed in accordance with the output function taken in the form S=(a+b+c) (a<SP>1</SP>+b<SP>1</SP>+c)(a+b<SP>1</SP>+c<SP>1</SP>)(a<SP>1</SP>+b+c<SP>1</SP>). Accordingly, six cores are provided for generating the functions a,al, b,bl, c,c<SP>1</SP>, output windings from appropriate cores being connected in series in accordance with the expressions in the brackets, the four circuits so formed being connected in shunt with the output load. The carry function is generated as in Fig. 9 and placed directly on to a further core from which the carry is then taken when required.