GB909899A - Improvements in magnetic switches - Google Patents

Abstract

909,899. Circuits employing bi-stable magnetic elements. INTERNATIONAL BUSINESS MACHINES CORPORATION. June 26, 1959 [June 30, 1958 (2)], No. 22083/59. Class 40 (9). In a magnetic switch comprising a number of cores, each with a single output winding and various input windings, a pulse is induced in one output winding in response to the selective energization of one half of the total number of input windings, these windings being so arranged that in a group of four cores the state of one core only is reversed by combined input energizations, while the remaining cores receive equal and opposite input energizations so that no spurious outputs are induced in the respective output windings. As shown in Fig. 1, magnetic cores are arranged in two groups 10-16 and 18-24 and are energized from input circuits by way of NPN transistors 18a, 18b-24a, 24b and input windings 26a, 26b- 32a, 32b arranged in pairs. Each winding of a pair such as 26a, 26b or 28a, 28b passes through the cores in the opposite sense to the other winding, and the four pairs of windings are so arranged that energization of one winding of each pair, e.g. 26a, 28b, 30a, 32b causes a " 1 " magnetizing state to be set up in a single core such as core 12 in one of the two groups. The other cores in the group each receive opposing and equalizing energizations so that no flux changes occur and no spurious outputs are induced in the respective output windings 34a-34d. The selected core is restored to state " O " by current applied by a transistor 39 to a winding 38. Opposing and equalizing energizations are also applied to all the cores of the second group, except for that core, e.g. core 20 which is the counterpart of the switched core 12. This core is driven from its remanent " O " state into saturation in the same sense and produces a small spurious pulse. An alternative arrangement is described, Fig. 4, in which groups of four cores such as 40-43 are arranged in a 4 x 4 matrix, each core being associated with column and row input windings, each set of windings being arranged as previously described. The column and row windings are selectively energized over transistors 56a-59b and 60a-63b respectively to cause coincidences switching of a single core, and the cores are normally biased well into the " O " saturation region by current in a winding 64. Due to the bias, automatic restoration of a selected core from state " 1 " to state "O" takes place when the input signals terminate. Rapid restoration of a switched core may also be effected by transferring the input signals to the other half of the windings.