Patent GB-856444-A (GB)
Title: Improvements in or relating to magnetic core circuits
IPC: H03K19/16
Filed: 1958-02-05
Abstract: 856,444. Controlled non-linear inductors. SOC. D'ELECTRONIQUE ET D'AUTOMATISME. Feb. 5, 1958 [Feb. 5, 1957; Jan. 4, 1958], No. 3752/58. Class 40 (9). A magnetic-core switching arrangement comprises a common pulse input circuit 6 which is connected to a number of loads through main windings 7 of controlled non-linear inductors, and a pulse Io is selectively applied to a load by simultaneously applying a signal to a control winding 8 which magnetizes the associated core to a point well beyond saturation, the input pulse acting on the core fluxes in a sense opposite to that of the control signal. The arrangement may employ cores having rectangular hysteresis loops or cores having negligible hysteresis. Basic arrangements are shown in Figs. 3 and 4 in which cores 1-4 in either a normal remanent condition " N " or unsaturated, depending on the core material, are selectively magnetized to beyond saturation in the " N " direction by control current in windings, 8 to provide a low impedance path for an input pulse IO to a resistor 5. The basic Fig. 3 arrangement may be used to provide column and row switches for a magnetic core storage matrix, Fig. 5. The Fig. 4 arrangement comprising main windings connected in series may be used in a combined decoding and switching circuit, Fig. 6, in which cores 10 are controlled by coded signals constituted by direct and complementary currents in selected control windings 8. The number of cores may be reduced, Fig. 8, by providing a plurality of main windings on each core. When cores of rectangular hysteresis loop are used, they may be provided with reset windings 14, Fig. 9, which are energized in the intervals between control signals, rectifiers 15 being connected in series with the main windings 7 to suppresss induced reset pulses. When switches including rectifiers are used with a storage matrix, Fig. 13 (not shown), each storage core has its column and row windings duplicated to provide for both read and write operations. Alternatively two switching arrangements for opposite directions of input currents Io, I1 may be connected in parallel as shown in Fig. 14. In Fig. 10, the input current Io may be of either polarity. As shown, two switching cores such as 1, 21 have respective " N " reset and " P " reset windings 14, 16 and control windings 8, 18 which are " P " and " N " magnetizing. In operation, the two cores 1, 21 are driven to opposite magnetic states well beyond saturation by a control signal acting in both windings 8, 18 so that an input pulse Io is able to pass in either direction, and the path is re-opened by applying a resetting pulse to windings 14 and 16. A method of improving the signal to noise ratio is shown in Fig. 16 in which windings 34 common to all the switch cores provide a low impedance path to ground for induced switching transients. An alternative is illustrated in Fig. 17. A further modification is shown in Fig. 18 comprising a saturable inductor 46 connected in parallel with the switch to overcome possible seizure after repeated switching operations due to progressively smaller changes of the core flux. The switching arrangement shown in Fig. 3 may also be used in a tree-type decoder, Fig. 22.