GB765974A - Improvements in or relating to transfer circuits for electric signals - Google Patents

Abstract

765,974. Non-contact-making relays. SOC. D'ELECTRONIQUE ET D'AUTOMATISME. June 2, 1954 [June 3, 1953], No. 16364/54. Class 40 (4). An arrangement for transferring trains of rectangular pulses from one circuit to another under the control of a D.C. signal comprises a pair of annular magnetic cores 1, 2 each having substantially rectangular hysteresis loops and supporting input and output windings and a control winding, each input winding 3, 4 being energized by pulse trains which are complementary to the pulses applied to the other input winding while the output windings 7, 8 are connected in series opposition with a load 9. By providing a number of core pairs I, II, III having common input circuits, Fig. 1, and selectively energizing the control windings 5, 6 of a single pair, the input pulse trains are transferred to only one of a number of loads which may comprise separate recording heads of a magnetic drum. All the cores are initially magnetized to saturation in the N direction, and since pulses in the input windings 3, 4 are also N-magnetizing, signal transfer does not take place. If, however, a D.C. signal I, is applied to the control windings 5, 6, both cores are magnetized to saturation in the P direction. As the amplitudes of the complementary pulses I c , I c 1, Fig. 2 (not shown), applied to windings 3 and 4, change between zero and I o , N-magnetizing forces are produced in the respective cores which alternate from one core to the other. Induced currents +i a , - i a are thus produced in the output windings which act alternately in opposite directions due to the opposed connections. The rectangular magnetizing-characteristic determines the uniform amplitude of the induced currents and the output pulses are a replica in form of the input pulse train, provided that the duration of each pulse lies between a minimum and a maximum value. As each core in turn is changed to an N condition by energization of its input winding, the resultant induced current acting in the load circuit and the output winding of the idle core restores that core to a P-condition in readiness for the next pulse. Signal transfer ceases on termination of the control signal. In order to speedily restore both cores to their initial N-magnetizing condition the input currents I c , I c 1 are applied simultaneously to their respective windings. Alternatively an N-magnetizing current may be applied to auxiliary windings (not shown), mounted on the cores.