Patent GB-900954-A (GB)
Title: Improvements in or relating to counting circuits employing multistable state magnetic core arrangements
IPC: H03K25/00
Filed: 1958-12-18
Abstract: 900,954. Counters. PHILIPS ELECTRICAL INDUSTRIES Ltd. Dec. 18, 1958 [Dec. 21, 1957], No. 40874/68. Class 106 (1). [Also in Group XXXIX] Quantised pulses step a core incrementally towards saturation in one direction by energizing one winding on the core and on attainment of saturation cause the operation of a bi-stable trigger circuit to switch the pulses to a second winding to step the core incrementally in the opposite direction, the quantised pulses comprising a first positive portion followed immediately by a second negative portion there being a time interval between the negative portion of one pulse and the positive portion of the next pulse. The arrangement avoids cumulative error. As shown in Fig. 1, a winding 6 or a winding 6<SP>1</SP> on a core 5 receives input over a transistor 24 or 24<SP>1</SP> depending on the state of the transistor trigger pair 10, 10<SP>1</SP>. Transistor 24 gates positive pulses induced in a secondary winding 3 of an input core 1 when transistor 10 conducts, while transistor 24<SP>1</SP> gates positive pulses from secondary winding 3<SP>1</SP> of input core 1 when transistor 10<SP>1</SP> conducts. Input core 1 is switched back and forth by each input pulse of a train, such as shown in Fig. 3, which is applied to winding 2; the positive part of an input pulse inducing a positive pulse in winding 3 and a negative pulse in winding 3<SP>1</SP> followed immediately by a negative pulse in winding 3 and a positive pulse in winding 3<SP>1</SP> in response to the negative part of the input pulse. With transistors 10 and 24 gating winding 6, the positive parts of the input pulses step the core 5 by way of secondary winding 3. Supposing the fifth pulse drives core 5 to saturation, then transistor 10 is cut off and 10<SP>1</SP> conducts so that the negative part of the fifth pulse immediately reverts the core 5 by one step since the positive pulse in secondary winding 3<SP>1</SP> is gated over transistor 24<SP>1</SP>. The negative parts of subsequent input pulses now step the core back to saturation the other way and when saturation is reached transistor 10<SP>1</SP> is cut-off and 10 conducts but, since secondary winding 3 has a negative pulse induced in it at this time, core 5 remains accurately at saturated remanence even if the pulse producing saturation persists for a while beyond saturation. As the fifth pulse in winding 6 gates its negative portion immediately to winding 6<SP>1</SP> only four pulses are necessary to return the core home and, in general with equal valued input pulses, the arrangement counts an odd number. By disturbing the ratios of windings 6 and 6<SP>1</SP>, or 3 and 3<SP>1</SP>, the count may be made asymmetrical, a step taken by way of winding 6 being unequal to a step taken by way of winding 6<SP>1</SP>. By this means a core cycle may count odd or even numbers. The number of pulses counted in a cycle can be varied by adjusting the distance or orientation of a small permanent magnet with respect to either the counting core 5 or the input core 1, the former arrangement decreasing the count while the latter increases it with increasing bias. Specification 780,884 is referred to.