US3085162A - Electrical selector circuit arrangements - Google Patents

Description

April 9, 1963 B. J. WARMAN ETAL 3,085,162

ELECTRICAL SELECTOR CIRCUIT ARRANGEMENTS Filed Nov. 27, 1959 s Sheets-Sheet 1 CUPW swam INVENTORS BLOOMFIELD JAMES WARMAN WILLIAM BERNARD DELLER April 9, 1963 B, J. WARMAN ETAL 3,08

ELECTRICAL SELECTOR cmcurr ARRANGEMENTS Filed Nov. 27, 1959 '5 Sheets-Sheet 2 DPVE 1 DIP/V52 DP/VE 1] l DP/VE 2 INVENTORS BLOOMFIELD JAMES WARIMN WILLIAM BERNARD HELLER April 9, 1963 a. J. WARMAN ETAL 3,085,162

ELECTRICAL SELECTOR CIRCUIT ARRANGEMENTS Filed Nov. 27. 1959 3 Sheets-Sheet 3 CURRENT DRWE STEERING PULSE Y 'E DRIVE 1 PULSE 1! 1 cumzam' 5155mm 1 x EARTH 1 T l EARTH L i i i' z EBTL- i BLOOMFIELD JAMES VIARMAN WILUAM BERNARD HELLER BY unc -m United States Patent 3,985,162 ELECTRICAL SELECTOR CIRCUIT ARRANGEMENTS Bloomfield James Warman, Charlton, London, and William Bernard Deller, Mottingham, London, England, assignors to Associated Electrical industries (Woolrich) Limited, London, England, a British company Filed Nov. 27, 1959, Ser. No. 355,715 Claims priority, application Great Britain Nov. 28, 1953 3 Claims. (Cl. Shh-8) This invention relates to electrical selector circuit arrangements.

It is applicable both to circuits for random selection and also to cyclic switching circuits. Circuits employing electro-magnetic relays or electronic discharge tubes are well known for this purpose. However, such arrange ments employ apparatus which is comparatively bulky and requires appreciable power for actuating when employed for purposes such as computers.

The main object of the invention is to provide improved apparatus employing miniature components which is capable of high speed operation.

According to the present invention a selector switching circuit arrangement comprises a plurality of two-state magnetic cores each controlling an associated load circuit and each core having a set winding, a drive winding and a current steering winding, whereof each of the current steering windings is on one side connected to a current steering terminal and on the other side connected to the emitter of a common base transistor having its collector connected to the associated load and the arrangement being such that it a selected core is set, then, when a pulse is applied to the drive windings the selected core only will be re-set thereby inducing an in its current steering coil which is in the forward direction of the associated transistor emitter base junction and so that the end remote from the emitter base junction will be negative to earth, which end is connected to the current steering coil circuits of the other cores, whereby if a current steering pulse is then applied within the duration of the drive pulse current will flow in the current steering winding of a selected core only and hence in the associated load only.

The term load" is intended to include any suitable apparatus which may be current or voltage operated and includes static or dynamic means for supplying information only. The term terminal" is also intended in a broad sense to include any common connection. The term two-state core implies a magnetic core capable of assuming either one of two stable states of opposite polarity magnetism.

An important application of the invention is to a cyclic circuit in which case the cores would be arranged in two groups each with its own drive source and the two drives will be operated alternately so that first a core of one group and then a core of the other group will be successively operated.

In order that the invention may be more clearly understood reference will now be made to the accompanying drawings, in which:

FIG. 1 shows a selector circuit employing current steering.

FIG. 2 shows a cyclic counting circuit employing the same principle.

FIG. 3 illustrates graphically the operation of the circuit of FIG. 2.

FIG. 4 shows a circuit for applying current steering pulses in the arrangement of FIG. 1 or FIG. 2, and

FIG. 5 illustrates graphically the voltage changes which occur in the circuit of FIG. 4.

3,085,162 Patented Apr. 9, 1963 "ice In FIG. 1 there are shown three two-state cores A, B and C of the kind having two stable magnetic states of opposite polarity, i.e. a set state and a re-set state. Each of the cores has a set winding a, a current steering winding [1 and a drive winding 0. The set windings a are controlled from a suitable selector arrangement so arranged that the set winding of any selected core may be energised. The current steering windings b of the cores are, at their left hand ends, connected to the current steering terminal and at their right hand ends are connected to the emitters of their associated common base transistors, the collector circuit of which transistors are connected to loads indicated by the references RA, RB and RC respectively. These may either be current actuated or, in some cases, a voltage pulse may be derived from terminals PA, PB or PC, as indicated in dotted lines.

it will be appreciated that only one of the cores will be set at any one time. Assume for purposes of explanatlon that the core A is selected and has been set by a current through its set winding a. If now a positivegoing pulse is applied to the drive terminal the core A will be re-set, the remaining cores being unafiected. The re-sctting of core A will induce an E.M.F. in the current steering winding 11 which is in the forward direction of the emitter circuit of transistor T2, i.e. so that the left end of the winding will tend to have a negative potential relative to the right hand end. The negative potential developed at the left end of winding b will be applied to the common drive terminal and hence through all the other current steering windings to the emitters of their associated transistors and this will tend to hold them cut oil.

It now, during the drive pulse a positive going pulse is applied to the current steering terminal this would constitutc an EM. F. in series with the induced in the winding [2 of core A so that the common point connested with the current steering terminal will tend to remain negative relative to earth and this negative potential will, as above explained, he applied to the emitters of TB and TC. The net result will be that current will pass to earth through the low impedance winding b of core A and the low impedance emitter-base circuit of TA but will not flow through the other current steering windings. This will in turn cause current to flow through the collector circuit and the load RA. The collector circuit will in contradislinction to the emitter have a high impedance to earth. it will be appreciated that the Ell LP. developed across the current steering winding b and the negative potential applied to the other current steering circuits will not be allected by conditions in the load circuit RA since this will be isolated from the current steering winding by the transistor.

It will be appreciated that the positive end of current steering winding b should be connected to a circuit having a low impedance to earth when passing current and also it should not be effected by conditions in the load circuit. The transistor satisfies these requirements to an appreciable extent.

It will also be appreciated that the drive pulse should be applied so as to commence before the current steering pulse so that the E.M.F. across the current steering winding of a selected core is already present when the drive pulse is applied. Preferably also the external current steering circuit (not shown) includes an appreciable resistance.

As above mentioned, the selection of the cores may be effected in any suitable manner and there may be either random selection or cyclic selection.

FIG. 2 shows the invention applied to a cyclic counting circuit.

In the arrangement shown there are six load circuits R1R6 which are actuated in sequence. Each of the load circuits is actuated by an associated two state drive core indicated by the references I-VI. Each of the drive cores is shown with a set winding (1, current steering winding b and drive winding 0 whilst in addition there is a priming winding d. It will be observed that the cores are arranged in two groups, the cores I, III and V are arranged in the first group and all their drive windings c are connected to the first Drive 1. Similarly, the cores II, IV and VI are arranged in a second group and their drive windings c are driven from Drive 2. At the same time all the current steering windings are connected to a common drive source, indicated as Drive 3. In the drawing there are two drive 3 terminals shown; this is purely to simplify the drawing and in actual practice both ter minals would be commoned.

In order to understand the operation of the circuit, it will be assumed that initially the core I has been set by means of the priming winding d, the remaining cores being in the re-set" state. It now a pulse is passed through Drive 1, core I will be re-set. This will induce an E.M.F. across its steering winding b in such a direction that the left hand end tends to be negative with respect to the right hand end, i.e. it will be in the forward direction of the emitter circuit of T2 but at the same time the negative potential at the left end of the winding will be applied to all the other current steering windings and will tend to back them oil? so that if new a positive going pulse is applied through Drive 3 current will pass through the winding 1) of core I only and will be held off from passing through the other current steering windings of the other cores.

The developed across winding b of core I will render the transistor T2 conductive and cause current to flow through the set winding a of the core II and at the same time it will apply a pulse to the load circuit R2.

As explained in connection with FIG. 1. the right hand end of the current steering winding b, i.e. the positive end, is clamped to earth through a low impedance which is unaffected by the current through the collector circuit and the load R2 and, therefore, a relatively high negative potential can be developed at the left hand which backs off the other current steering windings and prevents current flowing through them when a current pulse from Drive 3 is applied to them. Furthermore, the voltage developed across the winding [2 is independent of the voltage developed across R2 due to current flow through the collector circuit of T2. Hence, the backing off of the other transistors is in no way impaired by the voltage developed across the load circuit R2.

This feature is of considerable importance since it ensures accuracy of operation of the circuit and permits appreciable output load signals to be obtained whilst at the same time avoiding faulty operation due to inadequate backing off of the unwanted cores.

Reverting to the sequence of operations the current flowing through the winding a of the core II and load circuit R2 will set the core II so that when a pulse is now applied through Drive 2 the core II will be re-set. This in turn will cause a current pulse to pass through current steering winding b of core II and hence by way of transistor T3 to set the core III and pass a pulse through load circuit R3. The next pulse from Drive 1 will now re-set core III and set the core IV. Eventually, when core VI is re-set this will once again set the core I, it being appreciated that the points marked X indicate a common point, the intervening connections being omitted for the purpose of simplifying the drawing.

FIG. 3 shows the sequence of operations graphically and it will be observed that positive pulses are applied to Drive 1 and Drive 2 alternately. The pulses applied to Drive 3 occur simultaneously to Drive 2 pulses. However, the Drive 3 pulses are shorter in duration than the Cit 2' Drive 1 and Drive 2 pulses and start later and terminate earlier than the Drive 1 and Drive 2 pulses.

Whilst in FIG. 1 there are shown only three load circuits and in FIG. 2 only six load circuits these are by way of example only as clearly there may be any suitable number of load circuits.

In some cases provision may be made for adjusting the timing of the Drive 3 steering pulses (FIG. 3) relative to the Drive 1 and Drive 2 pulses.

FIG. 4 shows a circuit for applying the current steering pulses. This circuit essentially comprises a current steering transistor TCS the output of which is connected through a resistor R with the current steering line.

In FIG. 4 it is intended to show the current steering pulses applied to the circuit of FIG. 1 and the connections to core A only are shown. FIG. 4 is, of course, also applicable to FIG. 2.

FIG. 5 shows graphically the voltage changes occurring in the circuit of FIG. 1. Initially at time 1 a positive going drive pulse is applied; this is effective to reverse the core A and induce an EMF. in the coil 12. Shortly afterwards at time r a negative going pulse is applied to the base of current steering transistor TCS. This produces a large positive going voltage pulse at the point X and a voltage pulse of reduced amplitude at Y. At the point Z, i.e. at the emitter of transistor TA, a small positive going voltage step occurs at time t; and then a large voltage pulse at 1 What we claim is:

1. An electrical selector circuit arrangement comprising a plurality of two-state magnetic cores, an associated load circuit controlled by each core and each core having a set winding, a drive winding and a current steering winding, each of said current steering windings being on one side connected to a current steering terminal and on the other side connected to the emitter of an associated transistor having its base grounded and its collector connected to the associated load, means whereby if a selected core is set, when a pulse is applied to the drive windings the selected core only will be re-set thereby inducing in its current steering coil an EMF. which is in the forward direction of the associated transistor emitter-base junction, and means for applying a current steering pulse to the current steering windings applied within the duration of the drive pulse, current will flow in the current steering winding of a selected core only and hence in the associated load only.

2. An electric selector circuit arrangement comprising a plurality of two-state magnetic cores arranged in two groups adapted for sequential operation, in a sequence in which cores in one group alternate with cores in the other group, each core having a setting winding, a drive winding and a current steering winding, an associated transistor connected to each of said current steering windings and driving a respective load circuit, a connection between each load circuit and the setting winding of the core in the alternate group next to operate in the sequence, means for applying re-setting currents to all the drive windings of the two groups alternately and means for concurrently applying current steering pulses to all the current steering windings so that a current steering pulse flows only in the current steering winding and associated transistor of a core which is being reset.

3. An electric selector circuit arrangement comprising a plurality of two-state magnetic cores arranged in two groups adapted for sequential operation in a sequence in which cores in one group alternate with cores in the other group, each core having a setting winding, a drive winding and a current steering winding, an associated transistor connected to each of said current steering windings and driving a respective load circuit, a connection between each load circuit and the setting winding of the core in the alternate group next to operate in the sequence, means for applying rc-setting currents to all the drive windings of the two groups alternately and a current steering circuit including a transistor adapted to apply current steering pulses through a resistor to all the current steering windings concurrently with the re-setting current so that a current steering pulse flows only in the current steering winding and associated transistor of a 5 core which is being reset.

References Cited in the file of this patent UNITED STATES PATENTS Lawrence Feb. 2,

Claims (1)

1. 3. AN ELECTRIC SELECTOR CIRCUIT ARRANGEMENT COMPRISING A PLURALITY OF TWO-STATE MAGNETIC CORES ARRANGED IN TWO GROUPS ADAPTED FOR SEQUENTIAL OPERATION IN SEQUENCE IN WHICH CORES IN ONE GROUP ALTERNATE WITH CORES IN THE OTHER GROUP, EACH CORE HAVING A SETTING WINDING, A DRIVE WINDING AND A CURRENT STEERING WINDING, AN ASSOCIATED TRANSISTOR CONNECTED TO EACH OF SAID CURRENT STEERING WINDINGS AND DRIVING A RESPECTIVE LOAD CIRUIT, A CONNECTION BETWEEN EACH LOAD CIRCUIT AND THE SETTING WINDING OF THE CORE IN THE ALTERNATE GROUP NEXT TO OPERATE IN THE SEQUENCE, MEANS FOR APPLYING RE-SETTING CURRENTS TO ALL THE DRIVE WINDINGS OF THE TWO GROUPS ALTERNATELY AND A CURRENT STEERING CIRCUIT INCLUDING A TRANSISTOR ADAPTED TO APPLY CURRENT STEERING PULSES THROUGH A RESISTOR TO ALL THE CURRENT STEERING WINDINGS CONCURRENTLY WITH THE RE-SETTING CURRENT SO THAT A CURRENT STEERING PULSE FLOWS ONLY IN THE

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