SE314101B - - Google Patents

Abstract

1,209,665. Circuits employing bi-stable magnetic elements. TELEFONAKTIEBOLAGET L. M. ERICSSON. 11 Jan., 1968 [12 Jan., 1967], No. 1743/68. Heading H3B. In order to attenuate overshoot effects of drive current pulses in a matrix drive wire the drive current pulses are fed to one end of the matrix drive wire via the primary winding of the transformer, the secondary winding of which is connected between the other end of the drive wire and earth. In the arrangement of Fig. 4 pulse source I emits a voltage pulse U which appears across the primary and secondary windings of transformer T and since the capacitance to ground is uniformly distributed along the drive wire and the primary and secondary windings have equal numbers of turns a voltage distribution symmetrical to ground will be obtained. The overshoots of the drive current pulses due to the distributed inductance and capacitance to ground of the drive wire will be largest at the point A and since distributed capacitances and inductances of only half the drive wire are contributing to the production of overshoots the latter are reduced in magnitude. By connecting the drive wire as shown reverse voltages in the secondary winding induced at the end of the drive pulse are eliminated which voltages would otherwise produce a disturb pulse in the drive wire. Fig. 5 shows how a plurality of arrangements of Fig. 4 may be connected in series a disadvantage being that the voltages in the transformers T1, T2, T3 are successively decreasing. This may be overcome by using the arrangement of Fig. 6 in which transformer T is used in the same way as in Fig. 4 and toroidal cores Q1, Q2, Q3, Q4 are connected between sections of the matrix drive wire. Each section has one fifth of the voltage appearing across it and the voltages across the toroidal cores acting as single winding transformers are equal.