Patent GB-784541-A (GB)
Title: Improvements in or relating to magnetic switching circuits
IPC: G06F11/08
Filed: 1955-04-27
Abstract: 784,541. Circuits employing bi-stable magnetic elements. WESTERN ELECTRIC CO., Inc.. April 27, 1955 [April 27, 1954], No. 12153/55. Class 40 (4). A magnetic switching circuit comprises a core having a plurality of input windings, some being arranged to produce fields in one direction and some in the other direction, so that according to the number of windings of each kind pulsed, the remanent magnetism does or does not change direction, a further winding being subsequently pulsed to produce or not produce a pulse in an output winding according to the direction of remanent magnetism. It is illustrated that if n input variables are possible and it is required to produce an output if k or more of the variables have the value " 1," then in a core having n input windings (n - k + 1) windings must be fed in a positive sense with their associated input variable, and the remaining (k - 1) windings must be in a negative sense with the complements of the associated variable (i.e. if the variable is " O," then " 1 " must be fed to the winding and vice versa). Fig. 1 illustrates a circuit for detecting the " implausibility " of a 2-out-of-5 coded signal (i.e. the presence of a number of elements other than 2). Core 11 is arranged to be " set " (i.e. its direction of remanent magnetism reversed) if three or more of the signals Xl ... X5 are equal to 1. Accordingly 3 of its windings are fed in positive sense with variables X1, X2 and X3, respectively, and the other two are fed in the negative sense with the complements X<SP>1</SP>4 and X<SP>1</SP>5 respectively. The core 10 is arranged to be set if less than 2 of the variables X1 ... X5 has a value " 1," i.e. if 4 or more of the complementary variables X<SP>1</SP>1 ... X<SP>1</SP>5 have the value " 1." Accordingly two of the complementary variables X<SP>1</SP>1, X<SP>1</SP>2 are fed in positive sense and three of the variables X3, X4, X5 are fed in the negative sense. Thus one or other of the cores is set if an implausible signal is received so that when subsequently the windings 19 are pulsed an impulse is delivered from one of the windings 21 to a work circuit 13. In a further embodiment, Fig. 2, an output pulse is delivered if the signal is plausible. Thus core 26 is arranged to be set if two or more variables are equal to " 1 " (XI ... X4 applied positively and X<SP>1</SP>5 negatively) and core 25 is arranged to be set if two or less of the variables are " 1 ", i.e. three or more of the complements are " 1 " (X<SP>1</SP>1 ... X'4 applied positively and X5 negatively). The work circuit 28 is arranged to be pulsed by the activating source 31, the pulse, however, being shunted by an output winding 32 if one of the cores is not set, i.e. the work circuit does not receive the pulse unless both cores are set and the signal is plausible. Fig. 3 illustrates a combined circuit giving signals to work circuits 50, 51, respectively, according as the signals are implausible or plausible. The cores 45 ... 48 are set if the number of variables equal to " 1 " are respectively #2, #2, <2 and >2. The output circuits employed are of the type described in Specification 762,930 in which the output coil 55 is connected in series with the activating coil so that its output pulse opposes the pulse from the activating source 54. Thus for implausible signals one of the parallelconnected windings 55 of cores 45, 46 does not produce an opposing voltage and the work circuit 50 receives a pulse. Likewise for a plausible signal neither of the series-connected windings produces an opposing voltage and work circuit 51 receives a pulse. The Specification includes a mathematical investigation on tolerances and optimum turns ratios for the positively and negatively connected windings.. Specifications 773,165 and 779,843 also are referred to.