GB1019141A - Improvements in or relating to multi-aperture magnetic core devices - Google Patents

Abstract

1,019,141. Circuits employing bi-stable magnetic elements. MULLARD Ltd. May 1, 1963 [June 29, 1962], No. 25065/62. Heading H3B. A laddie has one of its rungs divided into two flux paths by one or more apertures and a winding arranged in a figure-of-eight manner to pass through the aperture or apertures and around the rung so that in operation when a disturb flux is produced in the two flux paths there is generated in the winding opposing e.m.f.'s which substantially cancel each other out. In the embodiment of Fig. 1 (not shown) the aperture takes the form of a slot which divides the last rung along its longitudinal magnetic axis. Alternatively the slot may be replaced by a single small hole or two small holes, Figs. 2, 3 (not shown) through which the output winding is passed. Normally maximum noise occurs when the first hold rung of the laddic is not held because the set pulse causes a large disturb pulse, generated by driving the core further into saturation, to swing around the rung of the core around which the output winding is wound and set up a noise voltage in it. However, with the arrangement shown the disturb flux generates opposing e.m.f.'s in the output winding and since the aperture lies on the magnetic axis the resultant output winding voltage is zero. When all the rungs having hold windings are held then, during the drive pulse, there will be half-a-unit of flux switched around the last rung in the path between the window and the aperture and thus produced a signal in the output winding. Any signals produced by disturb fluxes will cancel each other out. By arranging the geometry of the apertured rung so that a proportion of the drive signal switches flux in the outer part as well as the inner part of the rung a delayed signal may be obtained. The laddies arranged as in Figs. 1, 2, 3 may have an aperture provided in the first rung, Fig. 4 (not shown).