US3927365A

US3927365A - Switch operating device

Info

Publication number: US3927365A
Authority: US
Inventors: Koji Kodama; Yujiro Kasai
Original assignee: Tokyo Shibaura Electric Co Ltd
Current assignee: Toshiba Corp
Priority date: 1972-03-31
Filing date: 1973-03-28
Publication date: 1975-12-16
Anticipated expiration: 1992-12-16
Also published as: JPS5331350B2; JPS48101038A; USB345527I5

Abstract

A switch operating device comprising a driving transformer having the input side supplied with switching current, a plurality of switching transformers whose primary sides are connected in series to the output side of said driving transformer and a plurality of switching circuits connected to the corresponding secondary sides of said plurality of switching transformers.

Description

United States Patent Kodama et al.

[ Dec. 16, 1975 SWITCH OPERATING DEVICE Inventors: Koji Kodama, Tokyo; Yujiro Kasai,

Ohme, both of Japan Assignee: Tokyo Shibaura Electric Co., Ltd.,

Kawasaki, Japan Filed: Mar. 28, 1973 Appl. No.: 345,527

Published under the Trial Voluntary Protest Program on January 28, 1975 as document no. B 345,527.

Foreign Application Priority Data Mar. 31, 1972 Japan 47-32465 US. Cl. 323/48; 307/17; 323/25 Int. Cl. G05F 5/00 Field of Search 323/48, 6, 23, 25; 307/83,

CONTROL SWITCH -13 [56] References Cited UNITED STATES PATENTS 3,356,931 12/1967 Welty et a1. 323/48 3,601,690 8/1971 Judson et a1 323/48 Primary Examiner-Gerald Goldberg Attorney, Agent, or Firm-Oblon, Fisher, Spivak, McClelland & Maier [57] ABSTRACT A switch operating device comprising a driving transformer having the input side supplied with switching current, a plurality of switching transformers whose primary sides are connected in series to the output side of said driving transformer and a plurality of switching circuits connected to the corresponding secondary sides of said plurality of switching transformers.

8 Claims, 5 Drawing Figures FlGki PRIOR ART 1 1 CONTROL v SWITCH isb CONTROL SWITCH -13 Sheet 2 of 3 3,927,365

US. Patent Dec. 16,1975

FIG. 3

CONTRO SWITCH CONTROL SWITCH U.S. Patent Dec. 16, 1975 Sheet3 0f3 3,927,365

FIG. 5

CONTROL SWITCH -13 SWITCH OPERATING DEVICE I BACKGROUND OF THE INVENTION This invention relates to a switch operating device for quick simultaneous control of the operation'of'a plural ity of switching circuits, for example, for reading out data from elements constituting a computer memory and storing data in said elements. I

Generally, this type of switch operating device is widely applied, for example, in thosecircuits'for read ing out or storing signals having a plurality of bits which are used in the memory device of a data treating apparatus. Said device is provided with a switching transformer for each of a plurality of switching elements for their simultaneous operation. These switching trans transistor nonconducting, causing the switching circuit former are supplied with pulse current'to effect the for supplying driving voltage (+V) and one terminal 13A of a control switch 2 having the other terminal 138 grounded. One terminal on the secondaryside of each of said plural transformer 3 to 3,, is connected to the base of each of the transistors or the switching elements constituting switching circuits, for example, NPN transistors 4 to 4,, and the other terminal on the secondary side of the transformer is connected tothe' emitter of the switching element or NPN transistor." The collector and emitter of the transistorconstitute the output terminals of the switching circuit.

The conventional operating device of the abovementioned arrangement was operated in the following manner. When the control switch 2 was open, the potentials of the primary windings of the transformers 3, to 3,, and that of the terminal 13 were maintained at plus V volts while the potential of the terminal 138 was at ground potential. When the control switch 2 was closed, the potential of the terminal 13A dropped toward ground while the potentials of the primary windings were maintained at plus V volts. However, this transient voltage drop propagated from the tenninal 13A to one end of the secondary winding of the transformer 3n. Accordingly, a potential difference.

plus V was generated across the secondary windingof the transformer 3,, to cause a transient current flow therethrough while the potentials of the remaining: secondary windings 3 to 3,, remained at plus V volts, Similarly, the transient voltage drop propagated from; the secondary winding of the transformer 3, to that of the transformer 3,, and caused a transient current flow therethrough. Now assuming that thepropagation or delayed time of the voltage drop in each secondary winding is A t, the entire time delay of the transformer 3 to 3, will be n X A 2. Accordingly, When the control switch 2 was closed, a transient current appeared at the terminall3A and was propogated in the primary side of the transformers 3,, to 3, in the order mentioned and then pulse currents were induced in the s condary side of each transformer. The current pluses thus induced were supplied across the base-emitter region of the transistor to render said region conducting. When the control switch 2 was opened, the primaryside of the transformer was not supplied with current to render the to be turned off.

However, the prior art switch operating device raised a problem withzthe successively delayed operation of the respective switching elements. This originated with the fact that when the control switch 2 was closed, transient current was propogated to the respective transformer'3, to 3 in the order mentioned, namely, starting with the unit (3n) nearest to the control switch 2, causing the corresponding switching circuits to be actuated inthe'order' of 3,, to unit 3 in a successively ,delayed sequence. 'Similary when the control switch 2 was opened, the switching elements were cut off in succession, starting with the unit (4n) connected to the aforesaid transformer 3,, closest to the control switch 2. Such time delay become more prominent with the increasing number of transformers, posing an important question with a'switch operating device requiring an extremely short operating time (for example, a nanosecond) used in an apparatus like an electronic computer. Since there is recently made strong demand for the high speed operation of an electronic computer, it has become'indispensable to develop a switch operating device capable of eliminating such time delay as much-as possible.

I SUMMARY OF THE INVENTION This inventionhas been accompished in view of the above-mentioned circumstances and is intended to provide a-switch operating device easy of manufacture which" promi riently reduces the delay operation of a switching element and effects the simultaneous actuation of numerous switching circuits by means of a single circuit, thereby realizing the high speed operation of an apparatus like an electronic computer for which extremely quick work is demanded.

According to an aspect of this invention, there is provided a switch. operating device comprising a driving transformer having the input side supplied with switching current; a plurality of switching transformers having the primary sides serially connected to the output side of said driving transformer; and a plurality of switching circuits-connected to the secondary sides of the corresponding switching transformers.

According to another aspect of the invention, there is provided a switch operating device comprising a driving transfonner having the input side supplied with switching current; a plurality of switching transformers having the primary sides serially connected across one terminal onthe input side of said drive transformer and the terminal of a source of said switching current as well as to theoutput side of said driving transformer.

BRIEF DEscR PrIoN OF THE DRAWINGS DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS There will now be described by reference to the accompanying drawings the preferred embodiments of this invention. Throughout the embodiments, the same parts are denoted by the same notations.

Referring to FIG. 2 representing an embodiment of this invention, referential numeral 11 is a power supply terminal impressed with drive voltage (+V). This power supply terminal 11 is connected to one terminal on the primary side of a driving transformer 12 so as to supply pulse current to a plurality of the later described switching transformers 14 to 14,, The other terminal on the primary side of said driving transformer 12 is connected to one terminal 13a of a control switch 13 for generating pulse current, the other terminal 13b of which is grounded. When the control switch 13 is closed, a transient current propagates in the direction of the indicated arrow a. Both terminals on the secondary side of the driving transformer 12 are connected to both ends of a circuit consisting of the serially connected primary sides of a plurality of switching trans- ,forrners 14 to 14,, One terminal on the secondary side of each of said switching transformers 14 to 14, is connected to the base of each o'fa plurality of, for example, NPN transistors 16, to 16, constituting switching circuits 15 to 15 The collectors of said NPN transistors 16 to 16,, are connected to the output terminals 15 to 15,,a on one side of the switching circuits 15 to 15,.. The emitters of said NPN transistors 16 to 16,, are connected to the other terminal on the secordary side of each of the switching transformers 14 to l4, and also to the output terminals 15 to 15, on the opposite side of the switching circuits 15 to 15 To both terminals on the secondary sides of the switching transformers 14 to l4, are connected matching resistors 17, to 17,, respectively. The arrows b and c in FIG. 2 indicate the direction of a steady state current induced in thesecondary winding of the transformer 12. There will now be described the operation of a switch operating device according to this invention arranged as described above. First, the power supply terminal 11 is impressed with driving voltage plus V. When the control switch 13 is not actuated, no voltage is induced on the secondary side of the transformer 12 and no voltage difference appears across both terminals of the secondary side. Now, however, the control switch 13 is actuated. Upon said actuation, pulse current flows through the primary side of the driving transformer 12, and voltages of opposite polarity plus v and minus v are simultaneously induced on the terminals of the secondary side thereof. The transient voltage rise pluse v on the upper terminal of the secondary side propagates to the upper end of the primary winding of the switching transfonner 14 plus causing a first transient current to flow therein. At the same time, the transient voltage drop minus v on the lower terminal of the'secondary side of the transformer propagates to the lower end of the primary winding of the transformer 14,, thus causing a second transient current to fow therein. Hence, the transient voltage rise plus v propagated to the switching transformer 14 and the transient voltage drop minus v propagated to the switching transformer 14,, are simultaneously propagated to the switching transformers 14 and 14 respectively, and thus first and second transient currents flow simultaneously in the primary windings of the switching transformers 14,

and 14 in the same direction. Thus, the induced first transient current in the direction of the arrow 12 propagates through the primary sides of the switching transformers 14 to 14 in the order mentioned, namely, starting with the unit 14, whereas the induced second transient current in the direction of the steady state current propagates arrow c in the opposite way through the primary sides of the switching transformers 14,, to 14,, namely, starting with the unit 14,, Now assuming that the propagation or delay time of the transient voltage rise and drop in each primary winding of the switching transformers 14 to 14,, is At, the whole time delay therein will be N divided by 2 X A t. While said both induced transient voltages are propagates to the central one of a group of switching transformers 14 to 14,, another kind of current is induced on the secondary side of said switching transformers. If the switching transformer 14,, occupies the 25th order, then the transient voltage plus v induced in the direction of the arrow b is propagated through the switching transformers 14, to 14 starting with the unit 14 whereas the induced current voltage minus v is propagated in the opposite way through said switching transformers 14 to 14, starting with the unit 14 Accordingly, the switching transformer finally reached by both induced transient voltages plus v and minus v, substantially at the same time is the switching transformer 14 constituting the central unit of said group of switching transformers 14 to 14 Now, the time required for transmission of said induced transient voltages isdescribed. Let it be assumed that the time required for single induced transient voltages to pass through the individual switching transformers is represented by T. Then thetime required for single induced transient voltage to propagate through all the switching transformers startfrom the unit 14 is Tn. Where both of induced transient voltages propagate opposite directions from the transformers l4, and 14, toward the central unit, then the time required for both of induced transient voltages to reach the central transformer 14 is T'n/2. Namely, the switch operating device of this invention ehables energization of all the switching transformers 14 to 14,, twice as fast as that when a single stream of induced transient voltage is propogated way through all the switching transformers 14 to 14,,

Pulse currents carried through the switching transformers 14 to 14,, due to the induced transient voltages give rise to the induction of another kind of current on the secondary sides of said transformers 14 to 14,, Fresh current thus induced a second time is conducted across the base-emitter regions of switching elements, for example,

transistors

16, 16,, constituting switching circuits 15 to l5, connected to the secondary sides of the switching transformers 14 to 14 thereby actuating said transistors 16, to 16,, and in consequence the output terminals 15 45 to 15, -15 of the respective switching circuits 15, to 15,, When the control switch 13 is opened, the switching circuits 15 to 15,, are successively cut off, starting with both end units toward the central unit. This arrangement enables the switching circuits to be turned on or off in a far shorter time than possible with the prior art switch operating device shown in FIG. 1.

Further understanding of the present invention may be had by comparison of the operation of the circuitry of FIG. 2 of the present invention with the operation of the circuitry of FIG. 1 of the prior art. In FIG. 1, if control switch 2 remains open, those portions of all the terminals 1-l3a which include the primary windings of I the transformers 3 -3,, have a potential of while the potential of terminal 13b is zero. When the control switch 2 is closed under this condition, electric current 11 flows from terminal 13a to terminal 13b because of the potential difference of V between these terminals. Despite this current flow, the primary windings of all the transformers 3 -13 have their potentials preserved at +V.

As current i1 runs out from terminal 13a to terminal 13b, terminal 13a has its potential reduced to zero.

Accordingly, the potential defference of V comes into existence between terminal 13a and point 1 causing current i 2 to flow from point 1 to terminal 13a. In spite of this, the primary windings of allthe transformers 3 3, retain their potentials at +V.

As eurrent i2 runs out from point 1, the potential of point 1 is reduced to zero. This establishes a potential difference of V between the ends (i.e., points 1 and 2 of the primary winding of transformer 3,, This potential difference causes current i3 to flow from point 2 to point 1 until point 2 has its potential reduced to zero.

Similarly, a potential difference of V is produced between points 3 2 and so forth and currents i4- i7 flow successively.

If it takes time At for each current to flow through the primary winding of each of transformers 3 3,, a period of time substantially equal to n A t elapses between the closing of control switch 2 and the flow of current i7, assuming that the delay resulting from the currents through the portions of the transformers other than the.

primary windings is zero. In other words, the potential variation of +V to zero is shifted from terminal 13a to tenninal 1 step after control switch 2 is closed.

In applicants invention, as shown in FIG. 2, if control switch 13 is open, the potential at terminal 11, terminal 130 and the primary winding of transformer 12 is +V. When the control switch 13 is closed terminal 13a has its potential reduced from l-V to zero and the potential at point 1 is also reduced from +V to zero. Consequently, a potential difference of V appears between

points

1 and 2 and current i1 flows through the primary winding of transformer 12. This causes generation of a voltage E in the secondary winding of transformer 12. Thus, the ends (i.e., points 3 and 4 of the secondary winding assume potential differences of +E/ 2 and E/2.

At this moment, the primary windings of transformers 14 -14,, are at zero voltage causing current i2 to flow from point 3 to point 5 under a potential difference of +E/2 and causing current i3 to flow from point 6 to point 4 under a potential difference of +E/2. This means that a positive electric charge shifts-from point 3 to point 5 and a negative electric charge shifts from point 4 to to point 6 so that point 5 assumes a potential of +E/2 and point 6 assumes a potential of E/2. Once

points

5 and 6 attain the potentials +E/2 and 31 E/2, a potential difference of +E/2 is established between

points

5 and 7 and between points 8 and 6. Urged by the potential difference of E/2, currents i4 and i5 flow through the primary winding of transformer 14, and through the primary winding of transformer 14 respectively. Then, the potential of points 7 and 8become +E/2 and E/2, respectively. This causes currents i6 and i7 to flow through transformers 14 and 14,, respectively, and so forth.

Thus, the potentials +E/2 and E/Z caused by current i1 respectively at

points

3 and 4 are conveyed successively through points 3 5 7 9 and 4 6 -*8 10. If l4,-l4,, are equal in number to transformers 3 -3,, (FIG. I the period of time between the closing of control switch 13 and the pulsing of transformers 14, through 14,, is nearly half the time between the closing of control switch 13 and the pulsing of transformers 3 through 3,,

There will now be described another embodiment of this invention by reference to FIG. 3. The embodiment of FIG. 3 differs from that of FIG. 2 in that the driving transformer 22 consists of a balance-unbalance converison transformer, namely, a baluns (or balancing) transformer. According to this arrangement, the power supply terminal 11 is connected to one terminal on the input or primary side of said baluns transformer 22 and the other terminal on the input side, namely, one terminal on the secondary side of said baluns transformer 22 is connected to one terminal of the control switch 13. One terminal on the output side, namely, the other terminal of the primary side of said baluns transformer 22 is connected to one terminal on the primary side of the switching transformer 14,, and the other terminal on the output side, namely, on the secondary side is connected to one terminal on the primary side of a switching transformer 14,, When the control switch 13 is closed, two streams of induced transient voltages pulse V and minus V propogate through both output terminals of the baluns transformer 22. One stream of transient voltage propagates through a group of switching transformers, starting with one terminal in the primary side of the unit 14 toward the central unit of said series and the other stream of the voltage minus v propagates through the group of transformers in the opposite way, starting with an outer terminal on the primary side of the unit 14,, similarly toward the central unit. Accordingly, the transmission of both streams of transient voltages through all the switching transformers is completed in half the length of time required for a single stream of transient voltage to pass through the entire group of said switching transformers, thereby enabling the switching circuits 15 to 15 to be successively turned on or off with an extremely reduced time delay.

Referring to FIG. 4 representing still another embodime nt of this invention, both ends of a circuit consisting of the serially connect primary sides of a first group of switching transformers 14, to 14,, are connected between the power supply terminal 11 and one terminal on the primary side of the driving transformer 12. To both terminals on the secondary sides of the driving transformer 12 having the primary side connected in the aforesaid manner are connected both ends of a circuit consisting of the serially connected primary sides of a second group of switching transformers 14 to 14,,. The first group of switching transformers 14 to 14 and the second group of switching transformers l4,,, to 14,, are connected to a first group of switching circuits 15 to 15 and second group of switching circuits 15,,, to 15 respectively. (It will be noted that a number designated by m is equal to substantiallyone third of a number denoted by n.)

There will now be described the operation of a switch operating device arranged as shown in FIG. 4'. The power supply terminal 11 is impressed with driving voltage (+V) to actuate the control switch 13. Upon said actuation, two streams of transient voltages plus v and minus v are transmitted through the primary side of the driving transformer 12 simultaneously and are induced on the secondary side of said transformer 12. The transient voltage passing through the primary side of the transformer 12 propagates through the first group of switching transformers 14 to 14, in the order mentioned, namely, starting with the unit 14,, nearest to the driving transformer 12, thereby successively actuating the transistors 16, to 16, connected to the secondary sides of the switching transformers 14, to l4,,,. When the switch operating device of FIG. 4 commences operation, namely, at the moment two streams of transient voltage plus v and minus v begin to propagate through the primary side of the driving transformer 12, then similarly two streams of transient voltage propogate through the secondary side of the driving transformer 12. One stream of transient voltage is successively propagated through the second group of switching transformers 14,,, to 14,, in the order mentioned, namely, starting with the unit l4,,, and the other stream of transient voltage is successively propagated in the opposite way through the second group of switching transformers 14,, to 14 in the order mentioned, namely starting with the unit 14,,. Said both streams of transient voltages are propagated to the central unit l4,,, of switching transformers. As

the result, different types of transient voltages are induced on the secondary sides of switching transformers, thereby actuating switching transistors 16,,, to 16,, connected to the secondary sides of said switching transforrners14,,, to 14,,. When the control switch 13 is turned on, the induced transient voltage is simultaneously propagated to switching transformers 14, 14,,, and 14,,. The first group of switching transformers 14, to 14, connected to the primary side of the driving transfonner 12 have a number substantially equal to one half of that of the second group of switching transformers 14,,, to 14,, connected to the secondary side of the driving transformer 12. Accordingly, the transient voltages are finally propagatedto the switching transformers 14, 14,,,.,,,,,, substantially at the same time.

' Now let it be assumed that transient voltage propagates through each of the switching transformers 14, to 14,, in a time of T. Then the time required for the transient voltage to propagate through both groups of switching transformers in one way only from the unit 14, will be T'n. In contrast, where two streams of transient voltage pass through the first group of switching transformers 14, to 14, starting with the unit 14,,, and also through the second group of switching transfonners 14 to 14,, toward the central unit, starting with both end units 14,,, and 14 then the time required for both streams of transient voltage to flow up to the units 14, and 14 will be T'n/3. Namely the time required for said both streams of transient voltage to be propagate through the first and second groups of switching transformers 14, to 14 and 14,,, to 14,, is one third of that which is required for a single stream of pulse current to travel through said both groups of switching transformers in one way only from, for example, the aforesaid unit 14,, The induced pulse current is supplied to the base-emitter regions of the switching transistors 16, to 16,, connected to the secondary sides of the corresponding switching transformers 14, to 14,, so as to actuate said switching transistors 16, to 16,, When the control switch 13 is turned off, then switching circuits 15, to 15 constituting a first group are successively cut off, starting with the unit 15 and switching circuits 15,,, to 15,, constituting a second 8. group are also successively cut off toward the central unit, starting with both end circuits l5,,, and 15 With the switch operating device of this invention, therefore, the switching circuits 15, to 15,, are successively turned on or off with a prominently minimized time delay.

There will now be described by reference to FIG. 5 a further embodiment of this invention. This embodiment of FIG. 5 only differs from that of FIG. 4 in that the driving transformer consists of a balance-unbalance conversion transformer, namely, a baluns transformer 22. Between the power supply terminal 11 and one input terminal, namely, one terminal on the primary side of the baluns transformer 22 are connected both ends of a circuit consisting of the serially connected primary sides of a first group of switching transformers 14, to 14 having a number substantially equal to one third of the total switching transformers 14, to 14,, having a required number n. The other input terminal, namely, one terminal on the secondary side of said baluns transformer 22 is connected to one terminal of the control switch 13. One output terminal, namely, the other terminal on the primary side of said baluns transformer 22 is connected to one terminal on the primary side of a switching transformer l4,,, constituting one of the endunits of thesecond group of switchingtransformers l4,,, to 14,, The other output terminal, namely, one terminal on the secondary side of said baluns transformer 22 is connected to one terminal on the primary side of a switching transformer 14,, constituting the opposite end unit of the second group of switching transformers 14,,, to 14,,. As in FIG. 2, the above-mentioned arrangement of FIG. 5 causes two streams of transient voltages plus v and minus v to propagate through both input terminals of the baluns transformer 22. On the other hand, two more streams of transient voltages simultaneously propagates through both output terminals of the baluns transformer 22. The first stream of transient voltage propogates through the first group of switching transformers l4,,, to" 14, in the order mentioned, namely, starting with one terminal on the primary side of the switching transformer 14,,, The second stream of transient voltage passes through the second group of switching transformers toward the central unit, starting with one ter minal on the primary side of the transformer 14,,, The third stream of transient voltage is propagated through the second group of switching transformers toward the central unit, starting with the one terminal on the primary side of the switching transformer 14,,. Accordingly, the streams of transient voltages are collectively propagated through the whole series of switching transformers 14, to 14,, three times quicker than when a single stream of pulse current moves through said entire series of switching transformers 14, to 14,,. Therefore, the switching circuits are successively turned on or off with an exceedingly reduced time delay.

The polarity of the driving power source, the resultant direction in which the pulse current passes and the arrangement of the switching circuits are not limited to those described in connection with the foregoing embodiments, but may be obviously used in any modification, insofar as they do not depart from the object of this invention.

What we claim is:

1. A switch operating device comprising a driving transformer having the input side thereof supplied with switching current; a plurality of switching transformers having the primary sides thereof serially connected to the output side of driving transformer; and a plurality of switching circuits connected to the secondary sides of said switching transformers.

2. The switch operating device according to claim 1 wherein the driving transformer has a primary winding connected across the terminals of a power source through a control switch and a secondary winding connected to the serially connected primary sides of said plurality of switching transformers.

3. The switch operating device according to claim 1 wherein the driving transformer is a balance-unbalance conversion or baluns type having two input terminals connected between the terminals of a power source through a control switch and two output terminals connected to the serially connected primary sides of said pluarlity of switching transformers.

4. A switch operating device comprising a driving transformer having the input side thereof supplied with switching current; a first plurality of switching transformers whose primary sides are serially connected between one inout terminal of said driving transformer and the source of said switching current, a second plurality of switching transformers whose primary sides are serially connected between the output terminals of said driving transfomier; and a plurality of switching circuits connected to the secondary sides of said first and second plurality of switching transformers.

5. The switch operating device according to claim 4 wherein the driving transformer has a primary winding connected across the terminals of a power source through a control switch and the serially connected primary sides of a first group of switching transformers; and a secondary winding connected to the serially connected primary sides of a second group of switching transformers.

6. The switch operating device according to claim 4 wherein the driving transformer is a balance-unbalance conversion or baluns type having two input terminals connected across the terminals of the power source through the control switch and the serially connected primary sides of the first group of switching transformers; and two output terminals connected to the serially connected primary sides of the second group of switching transformers.

7. The switch operating device according to claim- 5 wherein the first group of switching transformers are chosen wherein the first group of switching transformers are chosen to have a number substantially equal to half that of the second group of switching transformers.

8. The switch operating device according to claim 6 wherein the first group of switching transformers are chosen to have a number substantially equal to half that of the second group of switching transformers.

Claims

4. A switch operating device comprising a driving transformer having the input side thereof supplied with switching current; a first plurality of switching transformers whose primary sides are serially connected between one inout terminal of said driving transformer and the source of said switching current, a second plurality of switching transformers whose primary sides are serially connected between the output terminals of said driving transformer; and a plurality of switching circuits connected to the secondary sides of said first and second plurality of switching transformers.

7. The switch operating device according to claim 5 wherein the first group of switching transformers are chosen wherein the first group of switching transformers are chosen to have a number substantially equal to half that of the second group of switching transformers.