Patent GB-721669-A (GB)
Title: Improvements in or relating to magnetisable core circuits such as utilised in computing apparatus
Inventor: SPENCER ROLF EDMUND
IPC: H03K3/45
Filed: 1950-05-19
Abstract: 721,669. Non-contact-making relays. ELECTRIC & MUSCIAL INDUSTRIES, Ltd. May 21, 1951 [May 19, 1950], No. 12668/60. Class 40 (4). [Also in Group XIX] A magnetic core circuit for use in computing apparatus &c. comprises a magnetizable means for applying a magnetizing force of one polarity and of sufficient magnitude to saturate the core, means for applying a magnetizing force of opposite polarity to the core, the first and second means being such that the second magnetizing force is applied during the presence of the first magnetizing force, and means for deriving an output signal from such reversals. A magnetic core 10, Fig. 1b which may consist of a " clock spring " spiral or a flat annulus of thin magnetic material, carries a winding 11 having D.C. bias sufficient to saturate the core negatively, the magnetizing force being represented by o, bo, Fig. 1a; the resulting magnetization represents state " 0 ". Two other windings 12, 13 are connected to separate digit sources (IN)1, (IN)2 from either of which digit " 1 " would be received as a pulse sufficient to generate a magnetizing force exceeding bo, c which nullifies the negative magnetizing force caused by the D.C. bias and momentarily reverses the state of magnetization of the core to state " 1 "; a winding 14 provides an output pulse as the core is taken round a magnetization cycle. Thus the device can be employed as an " and " gate, an " or " gate, or a multiple coincidence gate. Moreover, by reversing one of the windings in Fig. 1b e.g. (IN)2, an anticoincidence gate is derived in which, when simultaneous pulses occur on the two input lines, no change of state of the core takes place; if, however, a pulse occurs at input (IN)1 only, then the core is taken round the magnetization cycle and an output pulse is delivered. To prevent undesirable coupling in this case, unilateral conducting devices such as rectifiers or biased chokes are preferably included in the coupling circuits. In another arrangement a pair of cores are connected symmetrically with coupling circuits reversed with respect to each other: this tends to nullify leakages. As applied to a pulse generator, two magnetic cores 21, 22, Fig. 4a are arranged with interconnected windings 27, 29, including rectifiers 28, 30, and are supplied alternatively in phases alpha and # with timed, negative-magnetizing pulses Palpha, P# at windings 25, 26. When an input pulse arrives at a winding 23 the core 21 is changed to state " 1 ", but this change does not affect the core 22 which is then in state " 0 ". The next Palpha pulse on winding 25 returns the core 21 to state " 0 " and, via connection 27, this causes the core 22 to change to state " 1 ". The following P# pulse on winding 26 returns the core 22 to state " 0 " and changes core 21 again to state " 1 " via connection 29. This cycle of operation is repeated until an inhibiting pulse arrives on winding 24. Output pulses can be obtained, e.g. from a winding 31. Alternative arrangements of input and output windings are suggested. Pulse generators having an initiation threshold of more than one could have a plurality of stimulating windings 23 or be preceded by a gate of the desired threshold. Other arrangements of gates with delayed output are described.