Patent GB-883017-A (GB)
Title: Improvements in or relating to magnetic trigger circuit arrangements
IPC: H03K3/45
Filed: 1958-06-20
Abstract: 883,017. Circuits employing bi-stable magnetic elements. PHILIPS ELECTRICAL INDUSTRIES Ltd. June 20, 1958 [June 21, 1957], No. 19844/58. Class 40 (9). A magnetic trigger circuit comprises two cores A, B of rectangular hysteresis-loop material having respective windings WA, WB connected in series to an A.C. supply GR, and the application of a negative or a positive control pulse to a control terminal SET initially establishes a relatively unidirectional magnetic state " 1 " or " 0 " in both cores with the result that one of the cores changes its state continuously in response to the A.C. supply, while the other core remains in the control-selected state. The cores are identical, but are provided either with a dissimilar number of winding turns, Figs. 3 and 5, or bias windings, Fig. 6, so that one core must completely reverse its state in response to a pulse before the pulse current rises to a value sufficient to act on the other core. As shown in Fig. 3, rectifiers G1, G2 direct alternate half-angles of current from the A.C. supply through respective series paths comprising windings WA1, WB1 and WA2, WB2, the windings WB1, WA2 having the lesser number of turns. If the cores are initially set to state " 1 " by a positive control pulse passed through WA1, WB1, then core A remains in this state as its winding WA1 is state " 1 " magnetizing and its winding WA2 has a lesser number of turns. The magnetic state of core B on the other hand is alternated by the supply pulses, and high and low currents are obtained in the series paths comprising rectifiers G2 and G1 respectively. Direct and inverted outputs are obtained across resistors R2 and R1 at terminals UA and UB respectively. The reverse conditions are obtained when both cores are set initially to state " 0 " by a negative control pulse. The circuit includes provision for storing the signal applied to the terminal SET without the need for continuous application of the A.C. supply. The cores A and B have respective additional windings WA3, WB3 connected in series opposition for this purpose, the windings being connected over a rectifier G3 and switch CS to a gate PS. When the switch is closed, the gate is opened by a negative potential induced in one of the additional windings. This condition arises when both cores are brought to the same (initial) magnetic state determined by the control pulse, and the same dynamic conditions are therefore obtained when the gate is subsequently reopened. In a modified circuit. Fig. 5, only the core A has two windings WA1, WA2, and the windings WA1, WB, WA2 on the two cores have progressively lesser number of turns is that order. The mode of operation is the same as previously described, the output being taken from a terminal UB. In a further arrangement, Fig. 6, only one path comprising identical windings WA1, WB1 on cores A and B respectively is connected to the A.C. source GR. The additional windings WA2, WB2 which control the gate PS also serve to apply biasing current from a source GB to the cores, the bias acting on the two cores in opposite respects to a degree less than that necessary to reverse a core state. According to the direction of initial polarization of the two cores, one of the cores is able to reverse its state before the energizing current rises to a sufficient value to act on the other core. The arrangement therefore operates in the manner previously described, and an output is obtained at terminal UB in the condition when core B continuously reverses its state. In all the arrangements described, outputs may alternatively be obtained from auxiliary windings on the cores.