* GB785548 (A)

Description: GB785548 (A) ? 1957-10-30

Improvements in and relating to milling machines

Description of GB785548 (A)

PATENT SPECIFICATlON 785,548 Inventors 8:-JOHN VALENTINE THOMAS HOWARD and JOHN EWART PERKINS. Date of filing Complete Specification: Dec 7, 1955. Application Date: Dec 8, 1954 No 35515/54. Complete Specification Published: Oct 30, 1957. Index at Acceptance -Class 83 ( 3), K 2 B, K 3 (C 3: G 2: H 10: Ill: HX: L 5: N: R), W 7 (B 3 D: B 7: B 15 A: BX: C: 02: 03). International Laasification:-B 23 c. COMPLETE SPECIFICATION. Improvements in and relating to Milling Machines. We, WESTLAND Ai RCRAFT LIMTED, of Yeovil, in the County of Somerset, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to milling machines. The shaping or machining of workpieces where the surface to be shaped has a contour the angle of which varies from place to place along its length presents a problem a simple solution of which constitutes the main object of the present invention. The invention consists in a milling machine embodying a pivoted cutter head and means for automatically varying the tilt of the cutter in correspondence with the desired varying angled contour of a workpiece as the latter is traversed in the machine, wherein said tilt varying means comprise rollers on the cutter head adapted to abut fixed abutment surfaces on a template rigidly associated with the workpiece. The invention also consists in a milling machine as set forth in the preceding paragraph including also means for manually varying the cutter tilt, e g before abutment of said rollers with the template has

taken place. The invention also consists in a milling machine as set forth in either of the two preceding paragraphs, wherein said rollers are mounted eccentrically in relation to the cutter axis and means are provided for adjustment for the purpose of predetermining the depth of cut. The invention also consists in a milling machine as set forth in the second of the three preceding paragraphs wherein said tilt varying means comprises a hydraulic or lPrice 3 s 6 d l pneumatic ram attached to the cutter head and adapted to be operated manually. The invention also consists in a milling machine as set forth in any of the four preceding paragraphs wherein the work and template are adapted to be traversed in the machine by a friction wheel engaging a surface on the template. The invention also consists in a milling machine as set forth in any of the five preceding paragraphs wherein the drive for traversing the workpiece embodies an epicyclic speed-reduction gear of high ratio, e g. 1. The invention also consists in a milling machine as set forth in the preceding paragraph wherein slipping-clutch means are provided in said drive to enable the speed of traverse to be varied. The invention also consists in a milling machine as set forth in any of the seven preceding paragraphs wherein the cutter is driven by way of a flexible shaft. The invention also consists in a milling machine substantially as hereinafter described and as shown in the accompanying drawings. Referring to the accompanying diagrammatic drawings: Figure 1 is an elevation of a milling machine embodying the present invention. Figure 2 is an end view of the same. Figure 3 is a plan view of the same. Figure 4 is a sectional view of the canting head. Figure 5 is a sectional view of the gear box; and Figure 6 is a sectional view on the line VI /VI of Figure 5. In carrying the invention into effect according to one convenient form, a pedestal 7,5 So i 785548 A is provided on the back of which is mounted a vertical slide assembly B which carries a sliding head C and this in turn carries a cutter head assembly D Slidably mounted on the top of the pedestal A is a table E and on this is located a jig F, embodying operative faces 21 and 31, which jig holds a workpiece G, from the face of which metal is to be removed. Bolted to the underside of the table E is a gearbox H and secured on the output shaft a of the gearbox H is a head faced with friction

material pressed against a serrated strip 4 in a slot in the jig F by two adjustable tensioning rollers c. The vertical slide B is raised or lowered by means of a hand wheel d and locked in position by levers e The sliding head C is forked at its forward end and carries the cutter head assembly D on swivel pins f, levers y being provided to lock the sliding head in any desired position. A hydraulic or pneumatic ram J is attached to a bracket h fixed to the sliding head C and its ram rod head is attached to a bracket 17 fixed to the cutter head D, the cutter head being driven by a flexible shaft z from an electric motor mounted preferably overhead. On the front of the table E is mounted a bracket 1 carrying an operating hand wheel or lever m the table being adapted to be locked in position by a lever, as A C-shaped body is provided as the cutter head having on either side support bearings o and the attachment, bracket 17 Vertically through this head is mounted a driving shaft assembly carrying a cutter K The shaft assembly is composed of two components 41, 2, for carrying the cutter K, threaded on a long central bolt or shaft 3 which by tightening up a nut 23 clamps the assembly together, the nut 16 clamping parts 5 and 2 together. The head of the shaft 3 is threaded for attachment to a flexible drive the outer casing of which screws onto part 13 Also on this end of the shaft is formed a square s adapted to engage a similar square in the shaft assembly 41 This shaft assembly revolves as a unit in three roller bearings. ,0 On this and bearing on parts 4 and 5 are -disposed eccentric bushes 7 and 6 carrying ball bearings 19 and screwed on fixed sleeves 8 and 9 are knurled locking rings 11 which on being tightened up clamp flanges t of the a 5 bushes 6 and 7 against the sleeves 8 and 9, so preventing the bushes from turning. The flanges 10 of the bushes 6 and 7 are engraved in Iaoa inch for setting to pointers 21. Is I An epicyclic gearbox H (Fig 5) is provided for reducing the speed of an electric motor down to the required speed of operation embodying a casing 29 rotatably supported in a bearing 91 in the main framework 94V 3.5 which supports the gearbox as a whole. On an internal flange of the casing 29 are cut 60 teeth of a gear wheel 'a. Within the casing 29 and supported on a bearing 90 is located a second internally toothed gear wheel 30 having 59 teeth and 70 meshing with these two are three pairs of planetary gears, each pair being made from one piece of material and having 20 and 19 teeth respectively These revolve in bearings 87 and are arranged equidistantly in a pair 75 of frames 85 which are locked together by means of three bolts 89

with distance pieces 88 These frames are mounted and revolve one in a bearing 86 in the casing 29 and the other in a bearing 86 in the hub of the Sit second gear wheel 30. Within the frames 85 is a driving gear shaft 27 with 20 teeth supported on two ball bearings 107 and in mesh with the 20 toothed wheel of the planetary gears 28 85 Bolted to the hub of the second gear 30 is the output shaft a to which is fixed a friction driving wheel b Also on the second gear wheel 30 is bolted a bevel gear 31 meshing with a further gear 32 for remote hand 9 P operation by a hand wheel x. Surrounding the casing 29 is a friction clutch or brake band (not shown) which may take the form of a contracting band or pair of contracting shoes, the tensioning of which l 3 is controlled from a hand wheel y or foot pedal. In operation, a jig F of a suitable shape to contain the component to be machined is located on the table E and may slide or be lb E revolved thereon and is retained at a position opposite the cutter K by the friction driving wheel and tensioning wheels c The cutter K is revolved by a flexible shaft z connecting a remotely located electric motor with 10. spindle 3. To commence operation, the table E is fed forward and when the face of the jig F contacts the lower ball bearing 19 of the cutter assembly D, as this is free to revolve 110 in bearings o, the cutter assembly will tilt until the upper ball bearing 19 contacts the face 3 of the jig F Normally this position is held throughout the operation so that as the jig F containing the component G is fed 115 past the cutter K, the ball bearings 19 being held in tight contact with the faces 21 and 31 will roll along these faces which are shaped to conform to the required finished shape of the component G, and the revolving cutter 1320 K will remove metal from the face of the component until-it takes on the conformation of the faces 2 and 3. Throughout the operation the sliding head C is locked in a suitable position by levers g 123 as also the vertical slide assembly B by its locking levers e Alternatively, however, it may be desirable to operate the sliding head as well during the operation. Should it be found undesirable or difficult ':3 f drive, can be allowed to slip, thereby varying the rate of reduction of speed. Bolted to the second internally-toothed gear wheel is a bevel gear wheel 31 meshing 65 with another bevel 32 which is remotely operated by a hand wheel or lever x so that the drive can be operated by hand, or when driven by electric motor, additional load against rotation can be imposed by hand to 70 cause the gear assembly to slip in the brake band and so vary the speed at which the spindle a is driven.

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* GB785549 (A)

Description: GB785549 (A) ? 1957-10-30

Improvements in or relating to magnetic amplifiers

Description of GB785549 (A)

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BE535294 (A) CH359753 (A) DE1140976 (B) FR1120616 (A) US2777073 (A) US2827603 (A) US2827608 (A) BE535294 (A) CH359753 (A) DE1140976 (B) FR1120616 (A) US2777073 (A) US2827603 (A) US2827608 (A) less Translate this text into Tooltip

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The EPO does not accept any responsibility for the accuracy of data and information originating from other authorities than the EPO; in particular, the EPO does not guarantee that they are complete, up-to-date or fit for specific purposes.

PATENT SPECIFICATION 785,549 Date of Application and filing Complete Specification Jan 13, 1955. No 1081/55. Application made in United States of America on Feb 26, 1954. Application made in United States of America on May 24, 1954.

Complete Specification Published Oct 30, 1957. Index at Acceptance:-Classes 40 ( 1), N 1 A 5 A; and 40 ( 4), F 9 J. International Classification: -GO 8 c H 03 f. COMPLETE SPECIFICATION Improvements in or relating to Magnetic Amplifiers We, LIBRASCOPE, INCORPORATED, a Corporation organised under the laws of the State of California, United States of America, of 1607, Flower Street, Glendale, California, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:The present invention relates to magnetic amplifiers and more particularly to an apparatus for accelerating the response of such amplifiers and enabling the cascading of stages thereof without a response lag which occurs in the resetting type of amplifier of a number of cycles proportionate to the number of stages cascaded. The present invention provides a magnetic amplifier having a reversible cycle of operation, each cycle corresponding in duration to a half cycle of the line current supplied thereto, comprising at least one pair of saturable cores, cyclically operable means for alternately saturating both of said cores first in one direction and then in the opposite direction by simultaneously exposing said cores to flux produced by an alternating line current, means for effecting a temporal separation of the saturations of said cores during particular cycles of operation by exposing at least one of said cores to flux produced by a signal current during such cycles of operation, and means operating in synchronism with saturation of at least one of said cores during the particular cycles of operation and upon each saturation thereof for controlling the delivery of output current from said amplifier within the particular cycles of operation and during the temporal separation in core saturations in such cycles and without any transfer of memory in the cores from the particular cycles of operation to the next cycles cf operation as represented by flux in the cores. The invention also relates to magnetic amplifiers which provide an improved power efficiency over amplifiers now in use and which lPrice 3 s 6 d l cannot draw excessive current from the power source even with considerable variations in line voltage Furthermore, magnetic amplifiers constructed in accordance with the invention are prevented from becoming excessively heated even with considerable variations in line voltage. In certain fields of technology, a fast and sensitive response to electrical signals is required For example, the res'ponse of an automatically aimed gun or cannon to such signals must be very quick

and sensitive, especially when the target is itself moving in an elusive path Servo mechanisms have been devised to perform such work As a part of such servomechanisms, means are employed to amplify a relatively weak output signal so that a relatively strong signal can be employed to control the operation of successive components of the system and finally the gun itself. In the field of magnetic amplifiers the basic characteristics of such devices may be best described with reference to the hysteresis loop. The parameters and shape of this loop characterize the magnetic material employed and the configuration of the core structure It is usual to express the ordinate or vertical axis in terms of flux density (gausses) and the abscissa or horizontal axis in terms of magnetomotive force (oersteds). With reference to the ordinate axis, the flux density measured in gausses is directly proportional to the number of volt-seconds per turn of winding per square centimetre of core cross-sectional area Once the cross-sectional area of the core and the number of turns per winding have been fixed, then the ordinate value may be expressed in volt-seconds Likewise, once the effective length of the magnetic path and the turns per winding for a given core have been fixed, then the abscissa value may be represented in ampere units. Et will thus be perceived that "voltseconds " is the time integral of the applied alternating voltage, which is, of course, the area under the voltage vs time curve It similarly becomes apparent that the rate of 785,549 change of volt-seconds is voltage, which hereinafter may be referred to as " rate ". With reference to the hysteresis loop, positive saturation is reached where the upper portion of the curve levels off, and negative saturation occurs where the curve approaches the level in the lower portion The core at saturation will exhibit no further increase in voltseconds The only effect of attempting to increase the volt-seconds beyond saturation is to increase the current The same is true in respect to saturation in the opposite polarity or direction In the upper half of the hysteresis loop, the level or paint of maximum voltseconds is termed " positive saturation ", and in the lower half of the loop the level or point of maximum volt-seconds is termed "negative saturation ". The volt-seconds required to change the magnetic state of a core from positive saturation to negative saturation or vice versa will of course, vary according to the cross-sectional area of the core and the magnetic material of which it is made, and may be conveniently referred to as the " volt-seconds capacity " of the core. Core materials for magnetic amplifiers should be selected with the object of obtaining a relatively sharp differentiation between the

impedance exhibited in the unsaturated and saturated states, respectively, and minimizing the current required to effect saturation In general materials having rectangular hysteresis loops are satisfactory for these purposes; materials identified by the trade names "Supermnalloy ", " MO-permalloy ", and "Deltamax being examples thereof. Earlier magnetic amplifiers have in general been subject to slow response; that is, a time lapse of several cycles of applied alternating voltage occurs between a signal input and its resulting output In this manner a useful gain is achieved in magnetic amplifiers through memory or what might be termed the process of integration " Memory" results from the fact that energy in one half cycle of alternating voltage is retained for use in successive half cycles of alternating voltage The " process of integration " sometimes occurs because small amounts of energy may be retained in successive half cycles and may be stored on a cumulative basis to control the ultimate production of an output pulse. Later developments produced a magnetic amplifier generally known in the art as the so-called " fast response " or " reset " amplifier The operation of this type of amplifier is best described with reference to two periods; consecutive half cycles of line voltage, of opposite polarity defining two periods characteristic of its operation One period is the " resetting " or " signal input " period and the other period is known as the " power period ". At the end of the power period, corresponding to the beginning of the next reset period, two cores are saturated in the same direction, e g, are positively saturated During the succeeding reset period the cores in the absence of any signal are reset substantially equal amounts toward regative saturation by the resetting 70 voltage With reference to a hysteresis loop, such resetting is effected by introducing voltseconds to the cores to change their magnetic states so that they are represented by points on the loop between positive and negative 75 saturation The introduction of a signal during this interval accelerates the resetting of one core and proportionally decelerates the resetting of the other core During the succeeding power period, both cores advance toward the -0 original or positive saturation state at th same rate As a result of the differential resetting of the cores, one necessarily reaches positive saturation prior to the other, and in the interval of time between such positive saturation 85 of one core and such positive saturation of the other, power is delivered to a load Subsequent to saturation of the second core no power is delivered to the load, and the cycle is complete when the succeeding reset period begins 90 If a greater power gain is required than can be achieved with a single stage amplifier of this reset type, resort must

be had to cascaded stages In such cascaded reset amplifiers the power period of the first stage corresponds to 95 the reset period of the second stage, and similarly for additional stages Therefore, each additional stage employed results in an additional half cycle delay between the input to the amplifier and the resultant output obtained 100 therefrom. The operation of magnetic amplifiers embodying the present invention may be described with reference to a single period; not more than a single half cycle of the applied 105 line voltages defining the entire period characteristic of its operation The input and resulting output therefrom occur successively within this same period Two associated cores proceed from one saturated state to the other 110 saturated state (e g, from positive saturation to negative saturation) within the same period. During the succeeding period these cores reverse and proceed to the original (positive) saturation state The signal is introduced when 115 both cores are proceeding from either saturated state toward the other saturated state and prior to the saturation of either core This is known as the signal input interval Both cores proceed toward saturation at substantially the 120 same rate in the absence of a signal However, the introduction of a signal during the input interval increases the rare as which one cor: proceeds toward saturation, and reduces th. rate at which the other core proceeds 125 toward the same state of saturation. As a result of the tem-poral separation of the core saturations, power is delivered to a load in the interval of time between the saturation of the cores The introduction of 130 voltage from becoming overloaded even with considerable variations in the amplitude and frequency of the line voltage For example, the line voltage may vary as much as 15 volts above or 15 volts below a normal value of 115 volts 70 without any overloading of the voltage source. Such elimination of overloading is important in preventing excessive heating of the amplifier and the voltage source and in maintaining its eptnurimu operation, i e, complete satura 75 tion of certain cores within each half cycle and very near the end of each half cycle of line voltage. In this embodiment of the invention a first pair of saturable cores forms a main amplifier 80 and a second pair of saturable cores forms a switching amplifier Line windings are wound on the cores in the switching amplifier and in the main amplifier for the introduction of line voltage from a source In addition to the line 85 windings on the cores, input windings are disposed on the cores in Whe main amplifier and are differentially connected to produce magnetic fluxes of

opposite polarities in their cores. Pairs of differentially connected output wind 90 ings are also disposed on the cores in the main amplifier and in the switching amplifier An output circuit including rectifiers and a load is connected to the output windings in the main and switching amplifiers 95 The cores in each pair are so associated with the windings on the cores that one of the cores in the switching amplifier saturates first when a line voltage is introduced to the magnetic amplifier After the core in the switching 100 amplifier has saturated, both cores in the main amplifier saturate simultaneously when no input signal is introduced to the input windings in the main amplifier, and the cores saturate at different times upon the introduction 105 of an input signal to the input windings An output signal is produced across the load during the time in each half cycle of line voltage when one of the cores in the main amplifier becomes saturated and until the time that the 110 other core in the amplifier becomes saturated. As disclosed above, one of the cores in the switching amplifier and at least one of the cores in the main amplifier become saturated towards the end of each half cycle of line volt 115 age Subsequently in the half cycle, current flows through the output winding disposed on the unsaturated core in the switching amplifier This current is in a direction to prevent the core from becoming saturated Since the 120 core remains unsaturated, it presents a high impedance to the line voltage and limits the current flowing from the source of line voltage through the line windings In this way, the source of line voltage cannot become over 125 loaded even with considerable variations in the amplitude and frequency of the line voltage, and the voltage source and amplifier cannot become excessively heated Thus, the two cores in the switching amplifier not only per 130 the signal is the cause of such temporal separaiicn and hence controls the resulting output. As a general rule the signal voltage tends to establish load current However, if this were permitted, the amplifier would provide practically no power gain The present invention stablishea high impedance path between the signal input and the load to power transfer during the signal input interval without affecting the signal influence on the temporal separation of the times of core saturation During the power output interval, the high impedance path becomes a low impedance path to power transfer thereby enabling power gain. Since the entire cycle of operation of the amplifiers in accordance with the present invention is completed within one half cycle of the applied line voltage or, as a matter of fact, within a small portion of the half cycle starting at the beginning of the half cycle, it is possible to cascade several stages of amplification, the output at each stage occurring within the signal input interval of the following

stage; all within the same half cycle Consequently, a signal input to the first stage during the early part of the half cycle will produce a resultant output from the last stage within the given half cycle, this output being independent of signals introduced prior to the given half cycle. The operation of magnetic amplifiers in accordance with the present invention may be considered as being reversible because a complete cycle of operation of the amplifier may be effected as the cores proceed either from positive to negative saturation or from negative to positive saturation A cycle of amplifier operation is completed when the cores are moved from one to the opposite state of saturation during one half cycle of applied line voltage Another cycle of amplifier operation may be completed immediately thereafter when the cores are moved from said opposite state back to the original state of saturation; this, of course, occurring during the succeeding half cycle of line voltage Also, during the half cycle of line voltage causing the cores to pro; ceed from one to the other state of saturation, the signal input takes effect prior to saturation of either core and the temporal separation of core saturations is effected in the manner hereinbefore explained, enabling a power output subsequent to saturation of the first core and prior to the saturation of the second core. Since a high impedance path is established between the signal input and the load to power transfer during the signal input interval, and since the high impedance path becomes a low impedance path for power transfer during the power output interval, then it may be seen that signals of either polarity or " alternating current " signals may be amplified. In addition to the foregoing features, the magnetic amplifier also includes self-regulatE 5 ing features which prevent the source of line 785,549 785,549 form a switching function but also a regulating function in preventing the source of line voltage from becoming overloaded. With the foregoing in mind, among the objects of the present invention are the following: The provision of a magnetic amplifier capable of executing an entire cycle of amplifier operation within the interval of one half cycle of applied line voltage; the provision of a magnetic amplifier capable of outputs at higher voltage levels for a given line voltage than heretofore achieved; the provision of a magnetic amplifier capable of a plurality of stages of amplification with a total time delay of less than one half cycle of applied line voltage; the provision of a multi-stage magnetic amplifier wherein each stage receives its input during the output period of the preceding stage, all successively effected within one half cycle of applied line

voltage; the provision of such a multi-stage magnetic amplifier affording an increased gain per unit time delay, the provision of a magnetic amplifier for maintaining a substantially optimum operation even with considerable variations in the amplitude and frequency of a line voltage and for producing a desirable output signal even with such variations in the line voltage; the provision of a magnetic amplifier having self-regulating features for preventing the amplifier and the source of line voltage from becoming overloaded and excessively heated even with considerable variations in the amplitude and frequency of the line voltage; the provision of a magnetic amplifier in which the self-regulating features operate to insure that an output pulse is produced in each half cycle of line voltage regardless of considerable variations in the amplitude of the line voltage and in the same half cycle as that in which the input signal is introduced; the provision of a magnetic amplifier including means for reducing power dissipation in the magnetic amplifier and in the line to a minimum, especially when no signal is introduced to the amplifier for amplification; the provision of a magnetic amplifier for increasing the operating efficiency of the amplifier so that an output pulse of optimum amplitude can be produced by the amplifier upon the introduction of an input signal; the provision of a magnetic amplifier requiring a minimum number of components to obtain the advantages disclosed above; the provision of a magnetic amplifier of the above character in which adjustments can be made in the amplitude of output signal and in the relative time during each half cycle in which the output signal is produced, and the provision of a method of regulating the operation of a magnetic amplifier to prevent a source of line voltage and the amplifier from becoming overloaded and excessively heated even with considerable variations in the amplitude and frequency of a line voltage. Other and further objects of the invention will become apparent to those skilled in the art from a reading of the following detailed description when taken in the light of the accompanying drawings, wherein:Figure 1 is a circuit diagram of a half wave 70 type magnetic amplifier operative in accordance with the principles of the present invention; Figure 2 is a pictorial representation of suitable saturable core structures having associated windings thereon in accordance with the 75 circuit diagram of Figure 1; Figure 3 shows a typical hysteresis loop for either of the cores of Figures 1 or 2; Figure 4 is a modified circuit diagram of a half wave type magnetic amplifier which may 80 embody the principles of auto-transformer action; Figure 5 is a circuit diagram of a bridge type magnetic amplifier operative in a manner similar to the half wave type amplifier of 85 Figure 4; Figure 6 is a circuit diagram of a full wave

type magnetic amplifier also operative in accordance with the principles of the present invention; 90 Figure 7 a shows a typical wave form for the applied line voltage; Figure 7 b is one representation of a signal voltage wave form; Figure 7 c is a voltage wave form indicating 95 the relative state of saturation of one of the cores of a given pair with respect to the signal and line voltages; Figure 7 d is a voltage wave form indicating the relative state of saturation of the other 100 core of the pair with respect to the signal and line voltages; Figure 7 e is a voltage wave form showing the output cf a load with respect to the line and signal voltages; 105 Figure 8 is a circuit diagram of a full wave bridge type magnetic amplifier operative in accordance with the principles of the present invention: Figure 9 is a three-stage magnetic amplifier 110 employing szages of the full wave type and illustrated as a control amplifier in a servo loop; and Figure 10 is a circuit diagram of a specific embodiment of the present invention with 115 legends indicating the circuit parameters of the particular embodiment disclosed. Figure 11 is a circuit diagram illustrating a further embodiment of a magnetic amplifier incorporating the self-regulating features of 120 the invention; Figure 12 A to 12 C, inclusive, are representative curves illustrating voltage waveforms at terminals in the amplifier shown in Figure 11 wrhen a relatively high line voltage and no 125 signal voltage are introduced to the amplifier; Figures 13 A to 13 C, inclusive are representative curves illustrating voltage waveforms at the terminals upon the introduction of a relatively low line voltage and no signal voltage; 130 785,549 Figures 14 A to 14 D, inclusive, are representative curves illustrating voltage waveforms at the terminals for the case where a relatively high line voltage and a relatively large signal voltage are introduced to the amplifier; Figures 15 A to 15 D, inclusive, are representative curves illustrating voltage waveforms at the terminals when a relatively low line voltage and a relatively high signal voltage are introduced to the amplifier; and Figure 16 is a hysteresis loop for a typical wound core as used in the magnetic amplifier shown in Figure 11. The principle of operation of the device in accordance with the present invention is most easily understood from the simplified circuit diagram of Figure 1 The operation of the circuit of Figure 1 will first be described in connection with its application as a magnetic amplifier for alternating currents and secondly as a d c magnetic amplifier, these terms denoting, respectively, merely a signal of reversing polarity and a signal of single polarity A first saturable core 11 is illustrated in accordance with electrical symbols in Figure 1, one suitable configuration being the toroid 11 shown in

Figure 2 The core configuration is, of course, not restricted to the illustrated toroidal shape but the toroid does represent one convenient structure providing a magnetic path for establishing mutual coupling between a plurality of windings wrapped thereabout. A second core 13, generally exhibiting similar magnetic characteristics to the first core, is also shown in the shape of a toroid in Figure 2 A line winding 15 is wrapped about the first core 11 and a further line winding 17 about the second core 13, the line windings being in series by way of a connection 19 It should be pointed out that although the line windings 15 and 17 are shown as separate windings, it will be apparent hereinafter that effectively the twrso windings in series comprise an equivalent single winding having turns wrapped about both of the cores 11 and 13. A pair of leads 20 and 21 extends respectively from the windings 15 and 17 to line input terminals 23 and 25, voltage absorbing means shown as the resistor 28 being connected in the lead 20 Signal windings 27 and 29 are respectively disposed on the cores 11 and 13 and are connected differentially, i e, in series opposing relation A pair of leads 31 and 33 extends from the vindings 27 and 29 to signal input terminals 35 and 37, respectively A protective impedance, shown as the resistor 39, is connected in lead 33 to limit current flow through the signal circuit, particularly after one or both cores are saturated Although the resistors 28 and 39 are represented as separate components, it is to be understood that they may represent the resistance of windings with which they are in series. A pair of output windings 43 and 45 is conrncc d diffe entially, i e, in series opposing relation with respect to the induced current flow therein occasioned by line current The output windings 43 and 45 are respectively disposed on the cores 11 and 13 in the manner of the signal windings 27 and 29, the output 70 windings having terminals 47 and 49, respectively. The pictorial representation of Figure 2 shows the direction of wrapping of each winding on the cores 11 and 13 with respect to the 75 other windings thereon In reality the windings overlap and each winding may textend about the entire periphery of the toroids, but for simplicity of representation the windings are shown slightly spaced apart about the 80 toroid nerimeters. A load for the magnetic amplifier of Figure 1 is represented by the resistor 51 connected between amplifier output terminals 53 and 55. A lead 57 is connected between the output 85 terminal 49 associated with output winding and the amplifier output terminal 55 and a further lead 59 extends from amplifier output terminal 53 via a switch represented as a rectifier 61, to output terminal 47 of the other out 90 put winding 43.

A suitable line voltage is represented in Figure 7 a as the a c wave 71, illustrated as symmetrical about the axis 73, although such symmetrical distribution about the axis is not 95 essential according to the present invention. The horizontal axis 73 is measured in time and the vertical axis in voltage so that point on the axis 73 represents the end of one half cycle of line voltage measured from point 100 77, and point 79 indicates the end of one cycle of line voltage Regarding the a c wave 71, the prior art reset amplifier previously dis cussed relies upon the time interval between point 77 and point 79 to effect its cycle of 105 operation, whereas in the ultra-fast amplifiers herein disclosed, the entire cycle of operation is effected within a half cycle or less of the a.c wave 71, i e, at least between the points 77 and 75 In the ultra-fast magnetic amplifier 110 shown in Figure 1 and hereinafter referred to as an amplifier of the half wave type, the operation is such that an output is provided during the intervals measured between the points 77 and 75 and also between the points 115 79 and 81 when an a c signal of one phase with respect to the line voltage is applied between terminals 35 and 37 An a c signal of opposite phase will enable an output during the intervals 75 to 79 and 81 to 82 There 120 fore, the half wave designation is with respect to a c signals However, when a d c signal is introduced between the input terminals 35 and 37, an output may be derived during each of the intervals 77-75, 75-79, and 79-81, 125 etc. The operation of the amplifier of Figure 1 will be explained with reference to its application as an a c power amplifier of the half wave type, the a c signal (signal of reversing 130 785,549 polarity) being introduced between signal terminals 35 and 37 and an a c line voltage such as that represented at 71 in Figure 7 a being introduced between amplifier input terminals 23 and 25 Assuming that the alternating current wave 71 is traversing the half cycle between points 79 and 81 (Figure 7 a) and that this polarity is indicated by a positive sign at terminal 23 and a negative sign at terminal 25, then the direction of current flow through line windings 15 and 17 is shown by arrows 91 and 93 If a signal, for example represented by the wave 95 show in Figure 7 b, is introduced between signal input terminals 35 and 37 such that the signal wave is traversing the interval between the points 97 and 99, the terminal 37 is marked by a positive sign and the terminal 35 by a negative sign, the direction of current flow through the signal windings 27 and 29 being represented by the arrows 101and 103 which point in opposite directions. The direction of current flow here is the basis for stating that the signal windings 27 and 29 are connected differentially or in series opposing fashion, the currents flowing in the signal windings having

opposite effects upon the cores 11 and 13 However, it will be noted that the current flow through signal winding 27 produces an effect on core 11 aiding that produced by the current flowing through line winding 15 whereas the effect produced on core 13 by the current flowing through signal winding 29 opposes that produced by the line current flowing through line winding 17. Returning now to the hysteresis loop of Figure 3, the point 111 on the ordinate axis 113 represents the maximum number of voltseconds in the upper or positive direction for the hysteresis loop which is an ordinate measure of positive saturation and the point on the ordinate axis 113 in the negative direction indicates the maximum number of volt-seconds on the hysteresis loop which is negative saturation, the hysteresis loop being regarded as a typical loop for either of the cores 11 or 13 As has been stated previously, both cores are moved from positive to negative saturation, or vice versa, during each half cycle of the a c input wave 71 Since an arbitarary point ( 79 in Figure 7 a) was assumed as a starting point to enable description of the operation, this point will be taken to correspond with point 111 on the hysteresis loop of Figure 3 It will be appreciated that during the interval between point 75 and point 79 on the a c wave 71 of Figure 7 a, the cores 11 and 13 were moved from a state of negative saturation indicated by the ordinate point 115 in Figure 3 to a state of positive saturation indicated by the point 111. As the line voltage, indicated by the wave 71 in Figure 7 a, proceeds from point 79 toward point 81, the cores 11 and 13 follow the hysteresis loop from an ordinate level indicated by the point 111 downwardly in the direction of the left-hand arrow toward negative saturation indicated by the ordinate point An increasing number of volt-seconds is transferred from the line windings 15 and 17 70 into the cores 11 and 13 because the area under the a c wave 71 increases with time during the half cycle measured between the points 79 and 81. In the absence of any signal voltage at ter 75 minals 35 and 37, the cores 11 and 13 saturate at the same time as is indicated at the left in Figures 7 c and 7 d X which respectively show the shape of the voltage across the line winding (El) and the voltage across the line wind 80 ing 17 (E,,) The voltage rise across winding is indicated at 121 and the voltage rise across winding 17 at 123 in Figures 7 c and 7 d, respectively; the signal voltage (Es) being zero during this time interval as is shown in Figure 85 7 b The cores are usually substantially uniform and the turns generally equal so that the voltage divides substantially evenly across the windings 15 and 17 and equal numbers of volt-seconds are applied to each of the cores 90 11 and 13 The line winding voltage waves 121 and 123 follow the shape of the applied line voltage wave 71 until saturation occurs at which time

the impedance of the windings and 17 drops so that the winding voltages 95 fall to approximately zero and follow the axis and 127, respectively, of the wave-shape diagrams of Figures 7 c and 7 d, the line voltage during this interval being absorbed across the resistor 28 Also, in the absence of signal volt 100 age at terminals 35 and 37, the cores proceed to saturation (from ordinate point 111 to ordinate point 115) at substantially the same rate as is apparent from a comparison of Figures 7 c and 7 d 105 The usual or ordinary situation above discussed is predicated upon the condition of zero output for zero input In the event that an output is desired when the signal input is zero, the cores may be made dissimilar in 110 material, configuration, or the number of turns in windings 15 and 17 may be made unequal. The application of a signal voltage to the signal windings 27 and 29 affects the cores 11 and 13 differently due to the differ ntial con 115 nection of the signal windings For a given time interval, and assuming the polarity of Figure 1, a greater number of volt-seconds are transferred into core 11 than are transferred into core 13 and so core 11 saturates first 120 This is represented at point 131 in Figure 7 c; the shape of the voltage wave 121 across line winding 15 prior to saturation being represented at 1211 The voltage wave 121 ' rises to a higher value than the voltage wave 121 125 because of the increased number of voltseconds transferred to core 11 due to the signal current Therefore, core 11 saturates in less time in the presence of signal voltage than in the absence of signal voltage, as is indicated 130 785,549 by a comparison of the lengths of time axis beneath the wave shapes 121 ' and 121. Expressed another way, the rate of moving the core 11 from ordinate level point 111 on the hysteresis loop to ordinate level point 115 (i.e, from positive to negative saturation) has been increased. The opposite effect is produced in core 13 because a comparison of the direction of current flow through signal windings 29 and line winding 17, as indicated by the arrows 103 and 93, makes it apparent that the effect of the signal current is opposing the effect of the line winding current with respect to the state of the core 13. Resort may also be had to the hysteresis loop of Figure 3 to explain this action in terms of the core characteristics When the current flow through signal winding 27 is in the same direction as the current flow through line winding 15, the effect is an increase current in so far as the state of core 11 is concerned. Hence, considering the illustrated hysteresis loop, core 11 moves to the left of the loop, i e, establishes a different or wider hysteresis loop because of the effective current increase as seen along the abscissa 135 expressed in a quantity proportional to amperes Core 13

moves to the right to establish a narrower hysteresis loop (within the area enclosed by the illustrated loop) due to the eflective decrease in current As core 11 moves to the left it also moves faster downwardly (toward negative saturation) because its rate of movement along the hysteresis loop has been increased, whereas core 13 moves to the right and downwardly at a decreased rate If sufficient current is supplied to the signal windings it is actually possible to reverse the direction of movement of core 13 along the loop Particularly this is important in multi-stage amplifier action. The operation may also be expressed mathematically in terms of the following voltage relation: E,,+El,=E where E,, represents the voltage across line winding 15, E,7 is the voltage across line winding 17 and E,, is applied line voltage appearing between terminals 23 and 25 (assuming a negligible voltage drop across resistor 28 due to magnetizing current) This is also apparent considering that prior to saturation of either core, the impedance of windings 15 and 17 is so high that the effect of resistor 28 may be neglected. Since the windings are represented as having equal numbers of turns, the line voltage may divide substantially evenly between the line windings However, due to the nature of saturable cores the voltage across these windings may fluctuate in an uneven distribution For zero signal input the uneven voltage distribution causes an induced voltage across signal windings 27 and 29 The resultant current flowing in the signal circuit automatically reduces the magnitude of the voltage unbalance. Once core 11 saturates, a voltage determined by the relationship between the load windings and resistor 28 appears across line 70 winding 17 to drive core 13 to saturation within the same half cycle of line voltage that caused saturation of core 11 This is indicated, in time, at point 139 on the time axis of Figure 7 d where the voltage wave 1231, across line 75 winding 17, shifts to its maximum value indicated by the upper curved portion 141 which follows the shape of the applied line voltage curve 71 At the time indicated by point 139, a voltage is induced across load winding 45 80 (according to transformer principles) with a polarity corresponding to the polarity of the voltage produced in the winding 17 by the line voltage EAC Since the voltage EAC has a positive voltage at its upper terminal in Figure 1 85 a positive voltage is produced at the upper terminal of the winding 17 in Figure 1: This causes a voltage to be induced in the winding 46 such that the potential at the upper terminal of the winding is positive with respect 90 to the potential on the lower terminal of the winding This induced voltage is operative to provide a current flow in the load circuit in the direction of the arrow 143 This current passes through the load represented by the 95 resistor

51, since the rectifier 61 permits the current flow in this direction The current flowing through the load 51 and the rectifier 61 has an amplitude limited substantially only by the load The reason for this is that the 100 winding 45 serves as a generator and the winding 43 has a low resistance because of the prior saturation of the core 11 The purpose of the rectifier is to prevent current flow, through the load during the signal input 105 interval However, at point 145 on the time axis of Figure 7 d core 13 becomes saturated because the increased line voltage across line winding 17, effective during the time interval between points 139 and 145 (power output 110 interval), transfers sufficient volt-seconds to core 13 to drive it to negative saturation indicated by orinate level point 115 in Figure 3. The resulting output produced in the time interval between saturation of core 11 and 115 saturation of core 13 is shown in Figure 7 e as a pulse 147 of load voltage E,. During the signal input interval (time integral of curve 121), the current supplied by the signal source is relatively small, since only 120 incremental changes in the magnetizing current are necessary to produce the temporal separation between saturation of the cores prior to saturation of either core, assuming ideal rectifiers in the load circuit Hence, the 125 actual signal input power is small After core 11 saturates the number of volt-seconds delivered to load resistor 51 will be equal to the volt-seconds difference between the cores at the time of saturation of core 11 The 130 785,549 differential volt-seconds are delivered to load resistor 51 between core saturations The power to the load is the instantaneous voltage squared divided by the load resistance, and the load is made small compared to resistor 39 in order to achieve power gain. For the circuit shown in Figure 1, a signal polarity opposite to that indicated will result in no temporal separation of the cores because the signal voltage during the signal input interval appears across output winding terminals 47 and 49 Normally the rectifier prevents current flow during the signal input interval, but for the opposite signal polarity, current will flow through the rectifier and the load therefore signal voltage is substantially dissipated across resistor 39. Considering the operation of the circuit of Figure 1 as an amplifier of d c signals, if during the next half cycle of line voltage (points 81-82, Figure 7 a), signal voltage of the same polarity as was impressed during the first half cycle is impressed between signal terminals 35 and 37, the cores are subjected to the action outlined except that they are moved from negative to positive saturation, and core 13 saturates first. From the above description, it will be evident that the cores 11 and

13 are a pair ol saturable cores Windings 15, 17 and the leads extending therefrom to the source of alternating line current can be included in the term "cyclically operable means " A means for effecting temporal separation of the saturation of the cores 11 and 13 will include the socalled signal windings 27 and 29, as well as the source of signal energy connected thereto. To continue, the output circuit embracing the windings 43 and 45, as well as the rectifier 61, (all functioning in the manner indicated supra to control the output currtnt from the amplifier), can be considered as included in the expression " output current controlling means ". The foregoing is intended to be purely exemplary and in no sense limiting the invention claimed to the Figure 1 embodiment. In Figure 4 there is shown a modified type half wave magnetic amplifier The structure of Figure 4 includes a pair of saturable cores 151 and 153 having effectively a single winding shown as the series connected windings 155 and 157 wrapped thereabout The line voltage is adapted to be applied to these windings between terminals 159 and 161, which terminals are connected by way of leads 163 and trapped into windings 155 and 157 in the manner of an autotransformer The windings and 157 are connected together through voltage absorbing resistors 167 and 169 and also -through a voltage divider comprising a pair of impedances herein represented as resistors 171 and 173 Between the junction of the resistors 167 and 169 and resistors 171 and 173 there is connected a rectifier 175 and a load shown also in the form of a resistor 177. A pair of terminals 179 and 181 is connected across the rectifier 175 to serve as signal input terminals The impedances 171 and 173 have equal values so that the junction point 183 70 thereof is effectively at the electrical midpoint of the a c applied line voltage introduced between terminals 159 and 161 Obviously, a centre tapped transformer could replace the resistors 171 and 173 The signal voltage 75 applied at terminals 179 and 181 causes a current to flow through windings 155 and 157 in such a manner as to aid the line current through one of these windings and oppose the line current through the 80 other winding, thereby effecting the temporal separation between the times of core saturations As a result of the temporal separation of the times of saturation of the cores a power interval is established and cur 85 rent is caused to flow through the load 177 in the same manner as was explained in detail in connection with the description of Figure 1. The circuit diagram of Figure 4 may be regarded as a quasi-bridge type circuit and, as 90 shown in Figure 5, may easily be converted for bridge operation by substituting a winding (similar to winding 157 and

located about the core 153) for the resistor 171 and a winding 187 (similar to winding 155 and located 95 about the core 151) for resistor 173 The voltage absorbing resistors 167 and 169 are then combined as a single resistor 189 in series vwith the line input terminals 191 and 193, a signal voltage being applied between terminals 100 and 197 disposed across rectifier 199. When either core saturates prior to the saturation of the other as a result of the differential application of signal voltage in the manner hereinbefore described, current flows through 10; the windings of the saturated core to deliver power to the load 177, assuming proper polarity with respect to current flow through rectifier 199 Load current is established when signal input terminal 195 is negative regardless 110 of the line polarity at terminals 191 and 193. It may now be appreciated that suitable switching means for preventing current flow into the load (resistor 51, Figure 1) during the signal input interval and permitting current 115 flow during the power output interval would permit signals of either polarity to produce corresponding outputs The circuit of Figure 6 represents an arrangement capable of effecting the foregoing The components in the por 120 tion of the circuit corresponding to the circuit of Figure 1 are identified by the primes of the numbers used in the description of Figure 1. For this portion of the circuit the operation is the same as previously described The added 125 components perform the switching function. Specifically it is desired to present a high impedance between the output winding terminals 47 ' and 49 ' and the amplifier output terminals 531 and 55 ' during the signal input 130 785,549 interval and a low impedance during the power output interval For a signal input of a given polarity, the rectifier 61 of Figure 1 serves this purpose In the circuit of Figure 6 the foregoing is accomplished regardless of the polarity of the signal input. An additional pair of saturable cores 201 and 203, usually similar to the cores 111 and 131, are respectively provided with line windings 205 and 207, and output windings 209 and 211 connected in the same manner as the corresponding windings on cores 11 ' and 131. The line windings 205 and 207 are connected in series across input terminals 23 ' and 251 through a further voltage absorbing resistor 213 usually of the samne value as resistor 28 ' A full wave rectifier bridge 215 has its d c terminals 217 and 219 connected between terminals 221 and 223 of output windings 209 and 211 through a dummy load represented by the resistor 225. The a c terminals 227 and 229 of the bridge 215 are connected between terminal 47 ' of the output winding 431 associated with core 11 ' and

amplifier output terminal 531. The operation of the circuit of Figure 6 will be first described with a signal voltage applied to terminals 351 and 371 of the polarity assigned on the drawing (+ or 371) During the signal input interval the signal voltage appearing across the signal windings 271 and 291 appears across output windings 431 and 451 The same voltage also appears between terminals 221 and 223 in the polarity indicated because of the current flow through rectifier 231, dummy load 225 output windings 211 and 209 in the direction indicated by the arrows 233 and 235, rectifier 237 and load 511 This current is the incremental magnetizing current for cores 201 and 203 because these cores are in the same relative states as cores 111 and 13 ' Since during the signal input interval the cores 201 and 203 are also unsaturated only incremental magnetizing current can flow and therefore windings 209 and 211 present a high impedance across terminals 471 and 491 Therefore, the signal source (not shown) need only provide incremental magnetizing current for core pair 11 ' and 131, assuming ideal rectifiers, as in the case of Figure 1 and also incremental magnetizing current for core pairs 201 and 203 The voltage drop across thle load and dummy load is small compared to the voltage between terminals 221 and 223 As a result of the same signal voltage appearing across the pair of windings 271 and 29 ' and the pair of windings 209 and 211 and the opposite effects produced upon the associated cores by the current through the differentially connected windings, the rates of saturation of cores 201 and 203 are eftected differentially in the manner of cores 111 and 131 so as to cause one of the cores 201 and 203 to saturate at the same time that one or the cores 111 and 131 saturates. For the polarity shown, this is core 203 and core 111 Subsequent to the saturation of the core 203, the induced voltage across winding 209 is of the polarity to cause current flow through the bridge from terminal 217 to 219 70 effecting a low impedance path between a c. terminals 227 and 229 of the bridge This effect is maintained until core 201 saturates. Also, when core 203 saturates, core 111 saturates so that the induced voltage across wind 75 ing 45 of core 13 ' establishes current flow to the load 511 since the low impedance path is effected between bridge terminals 227 and 229. For the same line pvolarity indicated in 80 Figure 6, the application of a signal of opposite polarity to that indicated would cause core 131 to saturate prior to core 111 thereby providing current flow through the load 511 of polarity opposite to that indicated During the 85 signal input interval, the voltage across terminals 471 and 491 would also be reversed from the polarity indicated The path of the

resulting current would be through the load 511, rectifier 243, dummy load 225, output 90 windings 209 and 211 in the same direction as produced by signal of the former polarity (indicated direction) and through rectifier 245. Therefore, core 203 saturates at the same time as core 131 for this situation 95 When the line voltage polarity is reversed, the direction of signal current flow through windings 209 and 211 remains unchanged, so core 201 saturates first in the event of a signal voltage of either polarity effecting the 100 low impedance path between a c terminals 227 and 229 as before For this condition if the signal polarity is reversed, only the order of saturation of cores 11 ' and 13 ' is affected to change the polarity of the output across 105 load 511. The circuit of Figure 8 shows a magnetic amplifier of the full wave type incorporating the bridge circuitry of Figure 5 and otherwise operating in accordance with the full wave 110 operation explained in connection with the circuit of Figure 6 A pair of cores 301 and 303 are provided with line windings 305 and 307 wrapped about core 301 and line windings 309 and 311 disposed on core 303 in the 115 manner of the windings and cores illustrated in Figure 5 A second pair of cores 313 and 315, respectively, have line windings 317 and 319 wrapped about core 313, and line windings 321 and 323 wrapped about core 315 to 120 perform the function of the windings on the cores identified at 201 and 203 in Figure 6. A full wave bridge rectifier 325 has its d c. terminals 327 and 329 connected by way of leads 331 and 333 across the bridge circuit 125 formed by the windings on the saturable cores 313 and 315 at points 335 and 337 and by way of a dummy load 339 The a c terminals 341 and 343 of the rectifier bridge 325 are connected across the bridge circuit comprising 110 the windings on the cores 301 and 303 at points 345 and 347 by way of a load illustrated as a resistor 349. Line voltage is introduced to a line transformer 351 at terminals 353 and 357, the primary winding 359 supplying a secondary winding 361 which provides the line input to the bridge circuit associated with cores 301 and 303 at input terminals 363 and 365 by way of a voltage absorbing resistor 367 The other bridge circuit associated with cores 313 and 315 receives its line input at terminals 369 and 371 by way of a voltage absorbing resistor 373 and a pair of connections 375 and 377 which extend directly to the transformer input circuit As in the case of the signal windings 27 ' and 291 of the circuit of Figure 6, the signal is introduced differentially into the circuit of Figure 8 by way of signal input windings 381 and 383 which extend to signal input terminals 385 and 387 by way of the so-called protective impedance or resistor 389 As a result of the differential rate established in the

core pair 301 and 303 caused by the application of the signal, a similar differential rate is induced in core pair 313 and 315 in the same manner as described in connection with the circuit of Figure 6 Consequently, at the time of the saturation of the first core in pair 301 and 303, one core in the pair 313 and 315 will saturate The saturation of the first core in pair 313 and 315 acts in the manner hereinbefore explained to provide a low impedance path between the a c terminals 341 and 343 of the rectifier bridge 325 to permit power tranfer to the load 349 Also, as was set forth in connection with the description of Figure 6, the amplifier of Figure 8 will accept signals of either polarity applied between terminals 385 and 387 during the signal input interval of either half cycle of line voltage introduced across terminals 353 and 357 to deliver output across load 349 Hence it may be appreciated that in the circuit of Figure 8 a bridge type magnetic amplifier is used to provide the switching function for a second bridge type magnetic amplifier enabling the second amplifier to operate in the manner of a full wave amplifier. In the circuit of Figure 9 there is shown a magnetic amplifier having three stages generally indicated, respectively, at 401, 403 and 405 Each of the stages operates in accordance with the principles explained in connection with the description of Figure 6 except that the output from stage 401 is now used as the input to stage 403 and the output from stage 403 becomes the input to stage 405 As has been mentioned, this action occurs within one half cycle of the line voltage and will occur during each consecutive half cycle in the presence of the signal. The input interval for stage 403 is of greater time duration than the input inrerva for stage 401, and the input interval for stage 405 is of greater time duration than the input interval for stage 403 This is because the output interval for stage 401 must necessarily correspond in time with at least a portion of the input interval for stage 403, and this is 70 true for each succeeding stage regardless of the number of stages. It has been previously pointed out that the output interval of a given stage of amplification immediately succeeds the input interval 75 for that stage This sequence of operation enables an output from stage 401 to be effective as an input to stage 403 and similarly with respect to successive stages. Assuming an input signal applies between 80 terminals 407 and 409, a temporal separation is effected between the times of saturation of cores 411 and 413 due to the differential application of signal energy by way of signal windings 415 and 417 A similar 85 temporal separation is established between the saturation times for cores 419 and 421 One of the cores in the pair 419 and 421 saturates at the same time that

saturation occurs in one of the cores 411 and 413, this time being 90 established relatively early in any half cycle period of line frequency This action may be expressed in terms of volt-seconds supplied by the line voltage applied at terminals 423 and 425 Since the line voltage must be 95 sufficient to cause all of the cores of the multi-stage magnetic amplifier to be driven to saturation during each half cycle only a portion of the volt-seconds is used in causing saturation of the cores of the first stage This 1 W O is usually a relatively small portion of the totai line volt-seconds per half-cycle When one of cores 419 and 421 saturates, a low impedance path is provided between output windings 427 and 429 of stage 401 and the input 105 windings 431 and 433 of stage 403, the fugl wave bridge rectifier 435 functioning in the manner heretofore described as a result of the saturation of one of the cores 419 and 421 and the induced voltage appearing across one 110 of the associated output windings 437 and 439. The input windings 431 and 433 for stage 403 are connected to affect the cores 441 and 443 differentially so as to effect a temporai 115 separation in the saturation times of these cores, since neither of cores 441 and 443 has reached saturation during the operation above described The same temporal separation i, effected between the times of saturation of 120 cores 445 and 447 When saturation of one of the cores 441 and 443 occurs due to the output of stage 401 being applied as the input to stage 403, saturation is established in one of the cores 445 and 447 to effect a low imped 125 ance path to the input windings 449 and 451 (by way of rectifier bridge 452) for stage 4 GC associated with cores 453 and 455 Sinc -. at this time in the half cycle, neither of these cores is saturated, the delivered signal is cap 130 785,549 terminals, signal input terminals, and load terminals of Figure 9 have been applied, and legends have been applied to the several circuit components giving their specific characteristics 70 The resistances of the resistors corrseponding to those appearing in Figure 9 are indicated in ohms in Figure 10 The power rating of certain of the indicated resistors is indicated in watts The various coils cor 75 responding to those shown in Figure 9 ar identified by legends indicating the wire size and number of turns, e g, number 42 indicating wire of 42 Brown and Sharpe gang and the legend " 250 OT" indicating 2503 80 turns of this wire.The magnetic cores designated " No. 5233-Si " are cores of one mil " Supermalloy " having an O D of 1 500 inches; an I D. of 1 000 inches; and a height of 0 375 inches; 85 and are of a minimum weight of 37 0 grams. The cores designated " No 5340-51 " are of an O D of 750 inches, an I

D of 0 500 inches; and a height of 0 125 inches; and have a minimum weight of 3 09 grams The 90 cores designated "No 50041-4 A" are of 4 mil " Orthonol" and have an I D of 2 000 inches; an O D of 2 500 inches; and a height of 1 000 inches. Since it is inconvenient to make the small 95 first stage of this amplifier operate on a conventional line voltage of the order of 115 volts a c 60 cycles because to do so would require a great many turns of extremely small wire, the circuit diagram of Figure 10 pro 10 o vides for the application of a smaller voltage ( 36 volts a c 60 cycles) to the first stage This smaller voltage is obtained from additional windings 500 applied to the switching cores of the last stage corresponding to the cores 105 457 and 459, respectively, of Figure 9 These windings simply serve as a step-down transformer to provide a lower line voltage to the first stage with no degrading of the other functions of the last stage cores 110 Bt-cause small differences in characteristics between cores create a tendency to emit an a.c output in the absence of any a c input, means are provided in tile circuit of Figure for correcting such core unbalance This 115 is accomplished, as shown in Figure 10, by the insertion of resistors shunting the sign l windings corresponding to the windings 413 and 415 of Figure 9; the effect of these resistors being to introduce an a c signal of the 120 proper amplitude and phase to cancel the unwanted output Inserting one of these resistors, if it is made to have a sufficiently small impedance, will introduce an a c output; the smaller the resistance, the larger the 125 output Inserting the other resistor will have the same effect except that the induced a c. output will be of the opposite phase Both i:sisters may be inserted and the ratio of their resistances adjusted to cancel a small a c 130 able of effecting a temporal separation in the times of saturation of the cores 453 and 455. Again at about the same time that one of th; cores 453 and 455 saturates, one of the cores 457 and; 459 is driven to saturation to provide a low impedance path via rectifier bridge 460 to amplifier output terminals 461 and 463. The output of the multi-stage amplifier of Figure 9 appearing at terminals 461 and 463 is dependent upon the input applied at terminals 407 and 409 and occurs during the same half cycle of line voltage It is noted that this output is independent of any input applied to the amplifier during the preceding half cycle of line voltage. Many factors are capable of determining the time of saturation of the cores in each stage. These factors include the cross-sectional ar a of the core structure, the number of turns comprising the line windings, and the saturation characteristics of the core material used.

For example, the cross-sectional dimensions of the cores may increase in successive stages, thereby enabling saturation to occur at later points in a given half cycle. The magnetic amplifier illustrated in Figure 9 is shown applied as a control amplifier for a servo loop wherein the output appearing across t Wrminals 461 and 463 is applied to the control phase (indicated at terminals 471 and 475) of a two-phase motor 477 supplied with line voltage at terminals 479 and 481 A mechanical connection is indicated by the dotted line 483 between the rotor (not shown) of thbt two-phase motor 477 and a rotatable shaft 485 of a control transformer 487 The control transformer is supplied with electrical input from a synchro-transmitter 489 such that the output of the control transformer a. terminals 491 and 493 will be zero if the angular orientation of the rotatable shaft 485 corresponds to the angular orientation of the input shaft 495 of the synchro-transmittzr 489 Otherwise, an error voltage appears across terminals 491 and 493 and is applied as the input to the multi-stage magnetic amplifier across terminals 407 and 409 The resultant amplified output applied to the control phase at terminals 471 and 475 will cause an angular rotation of the rotor of the twophase motor 477 and a corresponding angular rotation of the control transformer rotatable shaft 485 in such a direction as to cause the output voltage of the control transformer at terminals 491 and 493 to decrease A resonant circuit 500 is included in the servo loop for anti-hunting purposes following conventional practice. Figure 10 is a circuit diagram of an embodiment of the present invention which has been actually constructed and successfully operated In this figure, which corresponds with the embodiment of Figure 9 with the exceptions hereinafter indicated, the primes of the reference numerals applied to the line voltage. 11 l 785,549 785,549 output If both resistors are inserted and both resistances made small, the input impedance of the magnetic amplifier will be reduced, and hence the gain will be reduced However, greater stability of output against changes of temperature and the like will be achieved Typical values for the resistors designated R-3 and R-4 in Figure 10 range from 4000 ohms to 20,000 ohms. Due to slight differences in the back impadance of rectifiers and to differences in characteristics of cores, a small d c output will sometimes be observed in the absence of any d c. input This may be corrected by shunting the highest impedance rectifier by a resistance such as that designated R-1 or R-2 in Figure 10 For greater stability against variations of rectifier back impedance, both R-1 and R-2 may be inserted and the ratio of their resistances adjusted to give approximately zero d c output for zero d

c input. The smaller these resistors are made, tile greater the stability and the less the gain will be Typical values for the resistors R-1 and R-2 range from 0 1 to 0 5 megohms. It will be understood that in cases of extreme differences between core characteristics and between rectifier characteristics, resistors may be inserted in the second and thid stages in the same manner as the resistors R-1, R-2, R-3 and R-4 are illustrated as applied to the first stage It will likewise be tnderstood that the advantages gained from the insertion of these resistors can well offset the disadvantages, since performance never can be quite as good from a poorly balanced magnetic amplifier as from one that is well balanced. In the embodiment of the invention illustrated in Figure 11, a source of alternating line voltage 511 is provided As will be disclosed in detail hereinafter, the line voltage ordinarily has a value of 115 volts and a frequency of 60 cycles One object of the present invention is to maintain ultra-fast and efficient operation over a wide range of supply voltage variations For example, with a frequency of 60 cycles, the voltage may increase to a value as high as 130 volts and may decrease to a value of 100 volts or less Or, when the voltage remains at 115 volts, the frequency may vary between 52 and 68 cycles. Or the voltage and frequency may both vary from their mean values to produce total variations of + 13 % or more. Resistances 512 and 514 having values of approximately 55,000 and 45,000 ohms, respectively, are connected in series with the voltage source 511 The particular values chosen for the resistances and the function of the resistances will be disclosed in detail subsequently A pair of line windings 516 and 518 which ate the line wrindings of the switching magnetic amplifier are in series across the resistance 512 A pair of line windings 520 and 522 which are the linm windings of the main magnetic amplifier arin series across the resistance 514. As a particular example, the windings 516 and 518 may each be formed from 6 C O turns 70 of No 23 wire (Brown & Sharpe) The windings 516 and 518 are respectively wound on cores 524 and 526 having saturabik:nag netic properties The windings 516 and 518 may be wound separately on the cores 524 75 and 526 or the cores may be stacked and each of the windings may be wound around bot cores By way of illustration each of the cores 524 and 526 may be toroidal in shap and may have an inner diameter of approxi 80 mately 2 inches, an outer diameter of approximately 22 inches and a height of approximately 1 inch. The cores 524 and 526 may be made from material known as " Orthonol " The core 85 material is composed of approximately 50 -. nickel and 50 % iron and is made from material which is rolled only in

a particular direction and which is annealed in hydrogen to grain orient the material 90 Input windings 528 and 530 are shown as being wound on th cores 524 and 526, respectively The windings are shown as being diiierentially connected to a source of direct voltage, such as a battery 532 through a manu 95 ally operated switch 531 and a rheostat 533. Because of such differential connections the winding 528 produces magnetic flux in one dfraction in the core 524 and the winding 530 produces magnetic flux in the opposite direc 100 tion in the core 526 The windings 528 and 530, the switch 531, the battery 532 and the rheostat 533 need not actually be included in the magnetic amplifier shown in Figure 11, for reasons hereinafter explained 105 A pair of output windings 534 and 536 are also respectively wound on the cores 524 and 526 Each of the windings 534 and 536 may be wound around both of the cores 524 and 526 in the stacked relationship of the cores 110 if the windings 516 and 518 are not so wound. Othenvise, the winding 534 is usually individually wound around the core 524, and the winding 536 is usually individually wound around the core 526 By way of illustration, 115 each of the windings 534 and 536 may be formed from approximately 2,600 turns of No 26 (Brown & Sharpe) wire. The line windings 520 and 522 are respectively wound on cores 538 and 540 (main mag 120 netic amplifier cores) corresponding in composition and construction to the cores 524 and 526 As an example, each of the windings 520 and 522 may be formed from approximately 462 turns of No 22 (Brown & Sharpe) 125 wire Each of the windings may be wrapped individually about its associated core or lt may be wrapped about both of the cores 538 and 540 in the stacked relationship of the cores 130 be an electrical motor or other suitable means for utilizing the amplified signal. As noted previously magnetic cores produce a changing magnetic flux when a voltage is applied to a winding supported on the core 70 If a voltage is applied to the winding for a sufficient period of time, the core may become magnetically saturated The core becomes negatively magnetically saturated when a voltage of a first polarity is applied to the wind 75 ing on the core for a particular period of time. The core becomes positively saturated when the same voltage of the opposite polarity is applied to the winding for the same length of time 80 During the time that a core is not saturated, it produces increased amounts of magnetic flux, as a voltage of one polarity is applied For certain core materials such as that used in the cores of this embodiment, 85 small increases in current may cause large increases in the rate of change of magnetic flux Since increases in rate of change of flux are equivalent to electromotive force-in other

words, voltage-a large increase in volt 90 age can be produced by a small increase in current (incremental magnetizing current) when the core remains unsaturated This may be sever by the steep sides of the curve show-n in Figure 16, such sides being desig 95 nated as 570 and 572 Because of the large increase in voltage required to produce a small increase in current, the impedance presented by the winding may be relatively large during periods of core unsaturation For example, 100 each of the output windings 534, 536, 548 and 55 G may have impedances of approximately 100,000 ohms when their associated cores remain unsaturated. Wh 1 en a core becomes magnetically satu 105 rated, increases in current through its associated winding produce substantially no increase in magnetic flux Because of the lack of any increase in flux in the core, no voltage is induced in the winding This may be seen 110 by the horizontally flat portions 574 and 576 in the hysteresis loop shown in Figure 16. G 3 ince impedance is represented by the ratio between the voltage and the current, the winding has substantially zero impedance when its 115 associated core becomes saturated For example, the winding 536 presents a very low impedance when the core 526 becomes saturated. The performance of a magnetic core at any 120 instant is dependent upon certain characteristics of the core For example, the performance of the core is dependent, among other factors, upon the cross-sectional area of the core and the magnetic material from which it 125 is made The characteristics of the core in turn determine how long a period of time is required to change the core from a negative saturation to a positive saturation or vice versa when a particular voltage is imposed on 130 Input windings 542 and 544 are wound on the cores 538 and 540, respectively Each of the windings 542 and 544 may be formed from approximately 150 turns of No 26 (Brown & Sharpe) wire The windings 542 and 544 are connected in series with a source 546 of signal energy and a manually operated switch 547 to introduce energy differentially to the cores 538 and 540 In other words, the winding 542 introduces energy of one polarity from the source 546 to the core 538 and the wvinding 544 introduces energy of opposite polarity to the core 540. The cores 538 and 540 also have output windings 548 and 550 wrapped around them. Each of the windings 548 and 550 may be formed fronm approximately 2,000 turns of No 26 (Brown & Sharpf) wire The windings 548 and 550 and the windings 542 and 544 may be wound around both of the cores 538 and 540 when the windings 520 and 522 are individually wound on their associated cores Otherwise, the windings 542 and 544 and the windings 548 and 550 are individually wrapped around their associated cores.

The lower terminal of the winding 534 in Figure Ul is connected to the lower terminal of the winding 536 Because of such an interconnection, the windings 534 and 536 are differentially responsive such that the winding 534 produces magnetic flux in an opposite direction to that produced by the winding 536 A connection is made from the upper terminal of the winding 534 to one terminal of a dummy load 552 having a relatively low impedance For example, the dummy load 552 may be a resistance having a value of approximately 1,000 ohms. The other terminal of the dummy load 552 is connected to the plates of two diodes 554 and 556 The cathodes of the diodes 554 and 556, respectively have common terminals with the plates of diodes 558 and 560 The cathodes of the diodes 558 and 560 are in turn connected to the upper terminal of the winding 536 as seen in Figure 11 ?bh diodes 554, 556, 558 and 560 may each be four series-connected germanium diodes. The lower terminals of the windings 548 and 550 are connected together in a manner similar to that disclosed above for the windings 534 and 536 In this way, the windings 548 and 550 operate differentially to produce magnetic fluxes in opposite directions in their respective cores 538 and 540 Connections are made from the upper terminal of the winding 548 to the plate of the diode 558 and from the upper terminal of the winding 550 to one terminal of a load 562 having a relatively low impedance The other terminal of the load 562 is connected to the plate of the diode 560 By way of illustration, the load 562 may be a resistance having a value of approxiLrly 1,CJ 3 ohms Actually, the load may 785,549 785,549 the winding associated with the core. Increases in voltage result in a decrease in the time required to change the polarity of core saturation Similarly, increased periods of time are required to saturate a core for decreases in voltage applied to the associated winding. The combination of voltage and time required to convert a core from one polarity of saturation to the opposite polarity of saturation has been defined as the " volt-seconds capacity" of the core The term "voltseconds" can bee mathematically described as the integral of voltage with respect to time. Thus. At volt-seconds= 5 Vdt, where V= the voltage at any instant; and dt= an infinitesimal increase in time from that instant. Since the volt-seconds level of a core at any instant is dependent upon the value of the volt-seconds which have been applied through an associated winding previous to that instant, the curve shown in Figure 16 represents the relationship between current and volt-seconds. The value of the current is represented along the horizontal axis and the amount of voltseconds is represented along the vertical axis.

As will be seen in Figure 16, the portions 570 and 572 are relatively steep and the portions 574 and 576 are relatively flat such that a response curve approaching a rectangle is produced Such a response curve is desirable for reasons which will become apparent in the subsequent discussion. During alternate half cycles, the source 511 of Figure 11 has a positive voltage on ith upper terminal and a negative voltage on its lower terminal, such a voltage relationship being hereinafter referred to as a positive half cycle During such periods, magnetizing current flows downwardly through the windings 516, 518, 520 and 522 This magnetizing current is relatively small and produces in the cores 524, 526, 538 and 540 magnetic fluxes in a downwardly direction These magnetic fluxes move the volt-second level of the cores in a downward direction on the hysteresis loop shown in Figure 16. If a voltage should be applied by the battery 532 to the windings 530 and 528 through the rheostat 533 as shown, current would flow downwardly through the winding 530 and upwardly through the winding 528 The current through the winding 530 would cause the winding to produce a magnetic flux in the core 526 in the same direction as that produced by the winding 518 However, because of the differential action of the windings 528 and 530, the winding 528 would produce a magnetic flux in the core 524 in the opposite direction to that produced by the wlinding 516 The resultant rate of change of flux in the core 526 would thus be greater 65 than the rate of change of flux in the core 524. Since the core 526 has a greater rate of change of flux at any instant than the core 524, a greater voltage is instantaneously applied by the source 511 to the winding 518 70 than to the winding 516 The application of a greater voltage to the winding 518 than to the winding 516 causes the core 526 to become saturated before the core 524 since the core 526 receives a greater amount of volt-seconds 75 per unit of time than the core 524. Since the line winding 518 has a greater voltage than the line winding 516, the output winding 536 has a greater voltage than the output winding 534 This results in voltage 80 being applied to the rectifiers 554, 556, 558 and 560 in the back or non-conducting direction Consequently, the voltage source 532 must only supplyv incremental magnetizing current to the cores 524 and 526 and low back 85 current to the rectifiers. As disclosed above, only magnetizing current initially flows through the windings 516, 518, 520 and 522 This magnetizing current is relatively small since the cores 524, 90 526, 538 and 540 are unsaturated and the cores are operating in the region 572 of Figure 16 During this time, the voltage across the windings 520 and 522 is of

the same order of magnitude as ile voltage across the windings 95 516 and 518 This results from the fact that the resistances 512 and 514 have values ot the same order of magnitude, thereby causing a voltage to be produced across the resistance 512 of the same order of magnitude as the 100 voltage across the resistance 514 The voltage produced across the windings 516 and 518 is illustrated at 580 in Figure 12 C and the voltage across the windings 52 G and 522 is illustrated at 578 in Figure 12 B These voltages 105 are produced as a result of the application ot a substantially sinusoidal voltage from the source 511 as illustrated at 581 in Figure 12 A. When the core 526 becomes saturated, substantially no voltage is produced across the 110 winding 518 This results from the fact that the core 526 is operating in the substantially flat portion (Figure 16) of its response curve and causes a negligible impedance to be produced in the winding 518 Since no voitage 115 is produced in the winnding 518, the voltage from the source 511 must be redistributed in the windings 516, 520 and 522. On first thought, it would appear that a voltage would be produced across the wind 120 ing 516 of the same order of magnitude as the voltage across the windings 520 and 522 when the core 526 becomes saturated It would appear that this voltage relationship would occur because of the values of the resis 125 tances 512 and 514 However, if any voltage of the polarity normally produced by the source 511 were to appear across the line 52 and the diodes Since the current flows ipwardly through the winding 534 in Figure 11, it produces flux which opposes the flux )btained by the flow of current through the winding 516 from the source 511 Because 70 of this opposing action, the core 516 cannot become saturated in the half cycle of line voltage. The voltage producing the flow of current through the dummy load 552 has a positive 75 polarity at the upper terminal of the winding 534 and an opposite polarity at the lower terminal of the winding As will be seen, however, the battery 532 produces a more positive polarity at the lower terminal of the winding 80 528 than at the upper terminal of the winding. This causes volt-seconds to be produced by the flow of current through the dummy load 552 in an opposite direction to the voltseconds produced by the battery 532 Thus, 85 the florw of current through the dummy load 552 provides a stabilizing action in maintaining the operation of the amplifier as disclosed above. The above discussion relates to the operation of the magnetic amplifier when a post 90 tive voltage is applied from the source 511 to the winding 516 and when no signal is produced by the source 546 However, the amplifier operates in a similar manner upon the application of a positive voltage from the 95 source 511 to the

winding 522 (hereinafter defined as a negative half cycle) and the application of no voltage from the source, 546. Under such a set of conditions, current flows upwardly through the windings 522, 520, 518 100 and 516 This current produces flux in the core 524 in the same direction as the flux produced in the core by the flow of current from the battery 532 The flux produced in the core 526 by the application of voltage from 1 5 the source 511 opposes the flux produced in the core by the application of voltage from the battery 532 This causes the core 524 to become saturated before the core 526. When the core 524 becomes saturated, the 110 full voltage from the source 511 is applied across the windings 522 and 520 This voltage causes the cores 538 and 540 to become simultaneously saturated and the full line voltage to be subsequently impressed across the 115 winding 518 Since the lower terminal of the winding 518 has a more positive voltage impressed upon it than the upper terminal ot the winding, the voltage induced in the winding 536 is more positive at the lower terminal 120 than at the upper terminal This voltage is in a direction to produce a flow of current through the dummy load 552 and the diodes in a manner similar to that disclosed above. Thus, the magnetic amplifier operates in a 125 similar manner during both halves of each voltage cycle from the source 511. The characteristics of the magnetic amplifier ate chosen so that the amplifier will operate in a manner similar to that illustrated in 130 winding 516 and hence the output winding 5 534, a very large current would flow through 1 the resistor 552 and the rectifirs 554, 556, 558 and 560 in the forward direction of the rectifiers-in other wcrds, the direction of low N rectifier impedance This current from the output winding 534 would necessitate an 1 equivalent current through the line winding 516 as a result of normal transformer action. l-wever, the current through the line winding 516 would also have to flow through line vvindings 518, 520 and 522. Since no load current can flow through the windings 520 and 522 when they are unsaturated, only magnetizing current can flow through the winding 516 The impedance presented by the winding 516 to the magnetizing current is relatively low since a relatively low impedance is presented to the winding by the circuit including the output windings 534 and 536, the load 562 and the diodes Because of the relatively low impedance presented to the winding 516 and the relatively small current through the winding, practically no voltage is produced across the winding This is illustrated at 582 in Figure 12 C This causes the full voltage from the source 511 to be applied across the windings 520 and 522, as illustrated at 584 in Figure 12 B. The application of the full line voltage across the windings 520 and 522 causes a considerable amount of volt-seconds to be fed into the

cores 538 and 540 such that the cores become saturated relatively quicldy In the absence of a signal current, the cores 538 and 540 become saturated at substantially the same instant since they have similar voltsecond caparities and the same amount of volt-seconds are fed into the cores When the cores become saturated, the impedances presented to the windings 520 and 522 become relatively low and the voltages produced across the windings become negligible This is illustrated at 586 in Figure 12 B. Upon the saturation of the cores 538 and 540, the core 524 is the only core remaining unsaturated This causes the full line voltage from the source 511 to be impressed across the winding 516, as illustrated at 588 in Figure 12 C The large voltage across the winding 516 causes a considerable current to flow through the winding and a large voltage to be induced in the winding 534 Since the voltage induced in the winding 534 has the same polarity as the voltage applied to the winding 516, the upper terminal of the winding 534 in Figure 11 is at a more positive potential than the lower terminal of the winding The large voltage across the winding 534 in turn causes a load current to flow through the circuit including the dummy load 552, the diodes and the windings 534 and 536. This current is relatively large because of the low impedance presented by the dummy load 755,549 is Figures 12 A to 12 C inclusive, when a maxirnum voltage such as 130 volts is produced by the source 511 and when no signal is p -:duced by the source 546 As -wvill h seen Figure 12 C, the core 524 saturates relatively late in the first half cycle and in alternate half cycles thereafter and tihe core 526 saturates relatively late in the second half cycle and in alternate half cycles thereafter. j I The saturation of either the core 524 ot the core 526 at a relatively late time in each half cycle causes the full linae voltage from the source 511 to be applied to the windings 520 and 522 for only a relatively short time in each half cycle before the cores 538 and 540 saturate This is seen by the relatively short duration of the curve portion 584 in Figure 12 B Since the cores 538 and 540 become saturated at almost the end of each 2 half cycle, the full line voltage is oniy applied in alternate half cycles across the vwinding,130 for relatively short periods of time, as illustrated at 588 in Figure 12 C Similarly, the full line voltage is applied to the winding 516 for only a relatively short period of time in alternate -half cycles of voltage Because of this, the volt-seconds produced in the wind-ings 516 and 518 by the current flowing through the dummy load 552 is relatively low. As has been previously disclosed, the line voltage from the source 511 may 7 vary considerably For example, before work is commenced in factories in the morning, the voltage may be relatively high since not

much pcower is being consumed Late in the day, the voltage may decrease considerably since not only factories are consuming considerable power but people require electricity to light their homes Thus, the voltage from the source 511 may ovary from as high a value as volts to as low a value as 100 volts The low line voltage from the source 511 is illustratzd at 589 in Figure 13 A. When the line voltage from the source 511 is relatively high, each of the switching magnetic amplifier cores 524 and 526 receives a considerable amount of volt-seconds The core remaining unsaturated at the end of each half cycle receives a considerable amount of volt-seconds during the half cycle This causes the unsaturated core to be at a position approaching saturation in the hysteresis loop shown in Figure 16 For example, the core 524 would have a volt-second level corresponding to the position 590 in Figure 16 at the end of each positive half cycle (i e, upper terminal of source 511 is positive) As will be seen, the position 590 is not far from the flat portion 576 representing the negative saturation of the 'core 526 at such times. Upon a decrease in the voltage applied to the windings from the source 511 the voltseconds applied to the cores 524 and 526, 538, 540 decrease As will be disclosed in detail hereinafter, the volt-seconds are still sufficient to produce a saturation of one of the cores 524 and 526 and oi both cores 538 and 540 during each half cycle when no tsignal is applied from te source 546 However, the care remaining unsaturated is not as close to 70 saturation as it is when the line voltage is h Ligh For example, the core 524 would have a volt-seconds i Lvel corresponding only to the position 592 in Figure 16 at the end of alternate half cycles (i e, positive voltage from 75 tee source 511 - shen the line voltagz is only volts) As will be seen, the position 592 g s mnuch further away than the position 590 from GS hale negative saturation represented by ifat portion 576 80 A zeduction in the line voltage from the source 511 causes the Barlhausen effect to becomev temporarily predominant in the op:razion of tht magnetic amplifier when the source 532 is not present The Barkhausen 85 eacot relates to the phenomenon that cores do not always operate in the same way at differZ.i=es For example, the molecules in the core may not be magnetically aligned as well at one instant under a particular set of 90 conditions as at another instant under the saime set of conditions This causes the flux produced,by the core to be less at one instant than at the other As -w Yill be s en, each core has a random voltage variation from a norm 95 in accordance with the Barkhousen effect. The Barlthausen effect will now be considered in relation to the pair of switching cores 524 and 526 The effect will also be considered in positive half cycles when cur 100 rent flows downwardly through the windings 516, 518, 520 and 522 as a result of a positive voltage on

the upper terminal of the source 511 Under these conditions, the Barkhausen effect produces a random distri 105 bution of voltage between the windings 516 and 518 and consequently between the windings 534 and 536 Since the windings 534 and 536 are connected differentially, the voltage across these windings in series tends to 110 fluctuate 'from positive to negative rapidly in a tandom manner. If the random differential voltage produced by the Barkhausen effect were positive (upper terminal of winding 534 positive), it would pro 115 duce a filow of current through the dummy load 552, the diodes and winding 536 This current would flow upwardly through the winding 534 and downwardly through the winding 536 in a direction to produce flux iii 12 C opposition to that resulting from the Barkhausen effect As a result, the Barkhausen effect can never build up to an appreciable differential voltage of positive polarity However, a negative differential voltage as a result 125 of the Barkhausen effect will only generate low current because of the high impedance presented by the diodes 554, 556, 558 'and 560 Therefore, negative differential voltseconds can accumulate 13 C 785,549 785,549 As a result of the Barkhausen effect, the core 524 at the end of positive half cycles of line voltages changes from the position 590 to the position 592 in Figure 16 when the line voltage decreases Since the core 524 has a volt-second level corresponding to the position 592 at the end of positive half cycles for low line voltages, it has only to travel from the position 592 to the flat portion 574 in the subsequent half cycles to become positively saturated As a result, the core 524 requires less volt-seconds to become saturated upon the imposition of low line voltages than upon the imposition of high line voltages This causes the core 524 to become saturated earlier in the ntgative half cycle for low line voltages than for high line voltages This may be seen by comparing the duration of curve portions 593 and 594 in Figures 13 B and J 13 C with the duration of the corresponding curve portions 578 and 580 in Figures 12 B and 12 C Similarly, the core 526 becomes saturated relatively early in positive half cycles. Upon the saturation of the core 526 in positive half cycles, substantially no voltage is produced across the winding 518 For the saine reasons as disclosed above in the discussion of high line voltages, the voltage across the windings 516 and 518 have a negligible value, as illustrated at 595 in Figure 13 C When the windings 516 and 518 have a negligible voltage, the windings 520 and 522 hav e the full line voltage imposed across them, as illustrated at 596 in Figure 13 B. Because of the low line voltage, the cores 538 and 540 require a longer time to become saturated after the<y receive the full line voltage than in the case where the line voltage is high This is illustrated by the relatively long duration of the curve portion

596 in Figure 13 B Both of the cores 538 and 540 bcome saturated at the same time since they both have similar characteristics and receive the same amount of volt-seconds. The saturation of;the cores 538 and 540 causes the voltage across the windings 520 and 522 to edrep to a negligible value, as illustrated at 598 in Figure 13 B When this occurs, the full line voltage is applied across the winding 516 This is illustrated at 600 in Figure 13 C The r sultant flow of current through the dummy load 552 and the diodes is in a direction to stabilize the operation of the magnetic amplifier, as fully disclosed above Thus, one of the cores 524 and 526 r,;mains unsaturated during each half cycle of line voltage even when the line volt, age drops to a relatively low value such as 100 volts. The operation of the nsagnetic amplifier as disclosed above has proceeded on the basis of no signal from the source 546 It has been -hewn by such disclosure that the magnetic amplifier can never draw excessively large currents from the source 511 even with considerable variations in line voltage The operation previously described is modified, however, when ia signal is introduced to the windings 542 and 544 from the signal source 70 546, since the purpose of the magnetic amplifier is to amplify such signals. When the signal source 546 has a more positive voltage at its lower terminal than at its upper terminal, current flows downwardly 75 flhrough the winding 544 in Figurp 11 and upwardly through the winding 542 This current produces a flux in the core 540 in the same direction as the flux produced by the line current through the winding 522 when 80 the line currsnt flows downwardly through the winding However, the flux produced in the core 538 by the signal current from 'the source 546 is in opposition to the flux produced in the core by the line currnnt from the 85 source 511 This causes the core 540 to receive more volt-seconds than the core 538 and to become saturated before the core 538. During the time that all of the cores 524, 90 526, 538 and 540 are unsaturated, the voltage across the windings 516 and 518 is of the same order of magnitude as the voltage across the windings 520 and 522 This is shown by tei curve portion 602 in Figure 14 C for 95 the voltage across the windings 516 and 518 and by the curve portion p 504 in Figure 14 B for the voltage across the windings 520 and 522 It results in part from the fact that the resistances 512 {and 514 are of the same order 100 of rnagnitude It also results in part from the fact that the signal from the source 546 appears across the windings 534 and 536 in a manner similar to its appearance across the windings 548 and 550 As will be seen, the 105 voltage produced by the signal source 546 acro'ss the windings 536 and 550 is in a direction to aid the flux produced in the cores 526 and 540 by the line voltage The voltage

produced by the source 546 across the wind 110 ings 534 and 548 is in a direction to oppose the flux resulting from the line current. The instantaneous voltage relationships in the different line windings for an unsaturated state of the cores 524, 526, 538 and 540 tan 115 be expressed by the following four linear equations when there are substantially eqi-ll turns ratios between the various windings in the switching amplifier and the corresponding windings in the main amplifier: 120 e 1 +?e, + e, + e 4-e L ( 1) ( 2) e e, where ( 3) e,+e, Resistance 512 ( 4) 03 + e 4 Resistance 514 Cl =tthe voltage across the winding 516; e,=the voltage across the winding 518; th = he voltage #across the winding 520; e =ithe voltage across the winding 522; 785,549 e L=the line voltage from the source 511 and C,=the signal voltage from the source 546. After positive volt-seconds have been applied to the cores for some time the core 526 becomes saturated and ithe impedance of the winding 536 becomes relatively low The core 526 becomes saturated first for the same re'asons as disclosed above for the case where no signal voltage is produced by the source 546 However, the core 526 becomes saturated at an earlier time in the half cycle than in the case where no signal voltage is produced by the source 546 This results from the action of the signal source 546 in changing the voltage relationships across the different line windings so as to produce an increase in the volt-seconds applied to the core 526 above that ordinarily received by the core from the line source 511. Upon the saturation of the core 526, the voltage across the winding 516 drops to a negligible value in a manner similar to that disclosed above The voltage drops to a negligible value provided that the signal voltage from the source 546 has disappeared If a signal is still being produced by the source 546, the voltage across the winding 516 actually drops to a negative value This may be seen by making e 2 = 0 in the above equations and solving the equations for e 1 since equation ( 4) is no longer valid As will be seen from equation ( 2), e, then equals -es The voltage produced across the winding 516 is illustrated at 606 in Figure 14 C for the situation where the source 546 is still producing a signal voltage after the core 526 has bscome saturated. The solution of the above equations for the situation where e,= O indicates that c 3 =-; and ( 5) ( 6) 2 The total voltage across the windings 520 and 522 is e L+e S, as illustrated at 608 in Figure 14 B As will be seen from equations ( 5) and ( 6), the core 540 is receiving a greater number of volt-seconds than the core 538 after the saturation of the core 526 Furthermore, the core 540 had received a greater amount of volt-seconds 'than the core 538 before the saturation of any core because of the differential action produced by

the windings 542 and 544 on the voltage from the signal source 546 This causes the core 540 to become'saturated before the core 538. When the core 540 becomes saturated, the impedance presented to the winding 522 becomes relatively low and the voltage across the winding becomes negligible Since the cores 524 and 538 are now the only corts remaining unsaturated, approximately half of the voltage from the source 511 is impressed across the winding 516 and the other half is impressed across the winding 520 These voltages are respectively illustrated at 610 65 and 612 in Figures 14 C and 14 B. During the time that the cores 526 and 540 are saturated, current flows through a circuit including the winding 534, and dummy load 552, the diodes 554 and 558 and the diodes 70 556 and 560 and;the winding 536 This current is relatively large since the impedance presented by the dummy load 552, the diodes and the winding 536 is relatively low. Because of this current, the voltage on the 75 plate of the diode 558 is substantially equal to the voltage on the plate of the diode 560 This results from the fact that the voltage drops across the diodes 554 and 556 are essentially equal 80 Since the plates of the diodes 558 and 560 have substantially equal voltages, the impedance between these members must be relatively low This causes the voltage generated across the winding 548 to produce a flow 85 of current Through a circuit including the diode 558, the winding 536 the winding 534, the dummy load 552, the diode 556, the load 562, the winding 550 and the winding 548. This current produces an output voltage 90 across the load 562, as illustrated at 614 in Figure 14 D. After the core 54 G has become saturated, volt-seconds are still applied to the core 538 since approximately half of the line voltage 95 from the source 511 is impressed across the winding 520 during this time This causes the core 538 to become saturated some tinie after 'the saturation of the core 540 Upon the saturation of the cores 538 and 540, the 100 voltage across the windings 520 and 522 becomes neg,,ligible, kis illustrated at 616 in Figure 14 B This causes the full voltage from the source 511 to be impressed across the winding 516, as illustrated at 618 in 105 Figure 14 G The core 524 cannot become saturated at any time during the positive half cycle of Sine voltage for the same reasons as disclosed above for the case where no signal is produced by the source 546 110 In the next ihalf cycle of line voltage, the core 524 becomes saturated before the core 526 in a manner similar to that disclosed above Furthermore, the core 1538 bcomes saturated before the core 540 because of the 115 differential volt-seconds introduced to the cores from the source 546 ussuming voltage from the source 546 remains the same polarity When the cores 524 and 538 become saturated, currents flow through the 120 dummy load

552 and the load 562 in a manner similar to that described above This results from the induction of more positive voltages at the lower terminals of the windings 536 and 550 than at the upper terminals 125 is opposite polarity However, as has been previously disclosed, the Barldkhausen effect has the same action as the battery 532 Therefore, the battery 532, the rheostat 533, and the windings 528 and 530 on switching amplifier 70 cores 524 and 526 do not have to be included in the amplifier. The apparatus disclosed above has several important advantages It provides a relatively strong output pulse during each and every 75 half cycle of line voltage and during the same half cycle of line voltage in which a signal voltage is introduced to the amplifier The amplifier produces in successive half cycles output pulses corresponding in amplitude and 80 polarity to the amplitude and polarity of the signal voltage Furthermore, such output pulses are completely independent of input signals (source 546) and output pulses occurring any prior half cycle 85 The amplifier also has the advantage that it operates efficiently such that excessive currents are never drawn from the line source 511 even with considerable variations in the line voltage from the source 511 For example, with the 90 values disclosed for the different components at the beginning of the specification, the line voltages may vary between 100 and 130 volts without materially affecting the operation of the amplifier 95 Since variations in voltage are equivalent to variations in frequency in determining the total volt-seconds during each half cycle of line voltage, it should be appreciated that the amplifier will also operate reliably with con 100 siderable variations in the frequency of the line voltage Furthermore, it is believed that a person skilled in the art would understand from the above disclosure how to adjust the circuit parameters so that the amplifier 105 operates efficiently with even greater swings in voltage than 100 to 130 volts. Since the magnetic amplifier disclosed above is capable of producing large output signals, it can be used as the last stage in a sequence 110 of cascaded stages Prior stages in such a cascaded arrangement may be similar to those disclosed in Figures 9 and 10. The magnetic amplified disclosed above is especially adapted to be used as the last stage 115 in a cascaded arrangement because of its delivery of output power towards the end of each half cycle of line voltage Since each stage provides some delay between the time that it receives an input signal and delivers 120 an output signal, stages prior to the last stage will have time in each half cycle to operate properly when the last stage in the cascaded arrangement delivers an output signal towards the end of each half cycle of line voltage 125 As may be seen from the above disclosure, the amplitude of the output

signal is dependent upon the amplitude of the input signal. This may be seen from the fact that the current flowing through the load 562 is depen 130 of the windings The current flows through the load 562 until the core 540 becomes saturated. It will thus be seen that an output pulse is produced across the load 562 in each half cycle of line voltage when a positive signal is produced on the lower terminal of the source 546 relative to the voltage on the upper terminal of the source It can be further shown by a discussion similar to the above that an output voltage of opposite polarity is produced across the toad 562 in each half cycle of line voltage when the signal voltage is more positive art the upper terminal of the source 546 than at the lower terminal of the source. Thus, an output pulse is produced in each and every cycle of line voltage when any signal is produced by the source 546 And, the polarity and amplitude of the output pulse is determined by the polarity and amplitude of the input pulse during the same half cycle. The curves shown in Figure 14 relates to the situation where a relatively high voltage, such as 130 volts, is produced by the source 511 and a relatively large signal voltage is produced by the source 546 The curves shown in Figure 15 illustrate the case where a low line voltage such as 100 volts is produced by the source 511 and a large signal is produced by the source 546 As will be seen, the curves shown in Figure 15 are similar to the curves shown in Figure 14, except that the relative times at which various cores become saturated may be somewhat different because of the differenct in line voltage. It is desiriable that one of the cores 524 and 526 saturate before either or both of the coars 538 and 540 In order to insure this sequence, the resistances 512 and 514 are respectively connected across the windings 516 and 518 and across the windings 520 and 522 The resistance 512 is also provided with a slightly greater value than the resistance 514 so that the cores 524 and 526 will receive slightly more volt-seconds than the cores 538 and 540 during 'the time at the beginning of each voltage half cycle in which all of the cores are unsaturated. It has been shown that current flows through the windings 534 and 536 and the dummy load 552 towards the end of each half cycle of line voltage whether a low or a high voltage is applied to the magnetic amplifier from the source 511 It has been further shown that current flows through the windings 534 and 536 and the dummy load 552 in each half cycle of line voltage whether or not a signal voltage is applied to the magnetic amplifier from the source 546 and whether the signal voltage is of one polarity or the other. This current produces in the core 524 or the core 526 a change in the volt-second level equivalent to that produced in the cores by the flow

of current from the battery 532 through the windings 530 and 528, but of -785,5549 1 t 9 785,549 dent upon the voltages across the windings 548 and 550, and the voltages induced in the windings 548 and 550 are dependent upon the amplitude of the signals applied to the windings 542 and 544. The relative time at which the output signal is produced in each half cycle is dependent upon the current flowing through the dummy load 552 and the windings 534 and 536 As disclosed previously, this current controls the relative time in each half cycle in which one of the cores 524 and 526 becomes saturated. Since the cores 538 and 540 cannot generally become saturated until one of the cores 524 and 526 becomes saturated, an output pulsecannot be delivered in each half cycle until after one of the cores 524 and 526 has become saturated In this way, the relative timing -in other words, the phase-of the output o signal can be controlled by adjusting the amplitude of the signal applied to the windings 528 and 530 The signal applied to the windings 528 and 530 may be adjusted in amplitude by varying the positioning of the movable contact on the rheostat 533 so as to change the effective resistance in the circuit. Since both the phase and the amplitude of the output signal can be controlled, the magnetic amplifier disclosed above can be used to accurately control the operation of certain devices such as motors The operation of the motor can thus be varied by adjusting the phase and the amplitude of the output signal.

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* GB785550 (A)

Description: GB785550 (A) ? 1957-10-30

A typewriter including means for double letter space typing

Description of GB785550 (A)

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PATENT SPECIFICATION 7 Date of Application and filing Complete Specification: Jan 27, 1955. 9 No 2530/55. Application made in Germany on Jan 27, 1954. Complete Specification Published: Oct 30, 1957. Index at acceptance:-Class 100 ( 4), C 20 (B 2 A: GIA). Index at acceptance:ication:-B 41 j. COMPLETE SPECIFICATION A Typewriter including means' for Double Letter Space Typing We, OLYMPIA WERKE A G, of Wilhelmshaven, Germany, a German Body Corporate, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and, by the following statement: - The invention relates to a typewriter comprising an actuating mechanism for obtaining double letter-spacing. A known mechanism of this kind effects a double step of the escapement for the double letter-spacing by varying the stroke of the loose dog which' is formed, like a slide The variation of the stroke is effected by means of a special control device actuated by the double letter-spacing key. It is the object of the invention to devise an arrangement for the double letter-spacing key which is particularly advantageous and reliable in service, and which, if the key is depressed, actuates the control device for effecting the double letter-spacing, locks this device in its position, and' again releases this device for normal typing by a repeated downward's movement of the key so that, in contrast to systems known hitherto, it is not necessary to impart to the double letter-spacing key a movement in an, additional direction

for the locking of the key in its depressed position, or for the release of the locking device. To this end, a typewriter with single letterspacing step and with double letter-spacing step and a key in the key board for the changing of the steps of typing, which key is operationally connected with the letterspacing mechanism through a linkage, is characterised according to the invention in that the linkage comprises a locking lever, which, when the letter-spacing key is depressed and the linkage is shifted to change the letter spacing step, locks the linkage in the shifted position, and that the linkage comprises links, constituted by a pin within a guide slot, so as to allow, after the locking has been effected' a partial, return movement of the key lever whereby this lever comes into a position to engage the locking lPrice 3 s; 6 d l lever, and, when, depressed a second time, engages the locking lever to move it into its 50 release position According to a preferred construction, the said' linkage comprises a link lever pivotally mounted near the key board of the machine; one arm of the said, link lever is connected 55 to the letter spacing mechanism through rods and levers linked together, one link consisting of a pin moving in a slot; to the same arm of the said link lever a locking lever is linked by means of a pin-and-slot link and a spring 60 urging the pin to move towards one end of the slot, wherein the locking lever has a notch for engaging a rigid abutment of the machine; near to the end, of the other arm of the said link lever the key lever is linked 65 which is guided for a substantially vertical movement by another link linked to a rigid member of the machine; and the key lever has a lateral projection which is positioned to engage a lateral projection of the locking 70 lever when the latter is in the locking position, so that, when the key lever is depressed a second time, it causes the locking lever to move out of its, locking position. Further details of the construction accord 75 ing to the invention will now be explained with reference to the accompanying drawings, wherein Fig 1 is a schematical representation of the double letter-spacing key in connection with 80 the actuating mechanism leading to the escapement, Fig la is a perspective front view of the key, Fig lb shows part of the actuating mech 85 anism for effecting double letter-spacing, Fig 2 illustrates the double letter-spacing key in its normal' position, Fig, 3 shows the double letter-spacing key in its depressed position for effecting double 90 letter-spacing, Fig 4 shows the double letter-spacing key in the double letter spacing position, Fig '5 represents the double letter-spacing key at the instant of changing over to normal 95 typing. 85,550 As shown, a paper carriage 2 with a platen 3 is mounted in the usual manner in the rear part of the typewriter frame 1 The keylevers,

not shown, are guided within a comb-shaped keylever guide 4, fastened to the frame 1 of the machine The keylevers are connected in a manner known per se with sublevers 6 'by means of pull 'wires 5 The sublevers 6 are supported in a known manner in a sublever bearing 6 c and are provided with arms 6 a and 6 b Each sublever 6 is connected through a pull wire 7 with the associated typebar, not shown The arm 6 b of the sublever 6 actuates, when a key has been struck, a universal bar 8 which in turn actuates the escapement device and the ribbon-feed mechanism. A transverse rail 9 is disposed at the rear part of the frame 1 of the machine and is fastened to the lateral walls thereof, and this rail 9 carries holding brackets 11 fastened by means of screws 10, which brackets serve for the support of a rotary shaft 12 A fork 13 is fastened by means of screws 14 to the shaft 12, which fork is formed, by an upwards extending projection 13 a provided with a slot 13 b (Fig lb) The shaft 12 also carries an actuating lever 34 which is fastened to the shaft and has a bent portion 34 ia extending to the left (as shown in Fig 1) 'which influences the escapement device for effecting double spaced step by engaging a pull rod 35 forming part of the escapement device. A bearing 151 is fastened to, and extends laterally from, the universal bar 8, and linked to the upper end 15 a of the bearing is an actuating bar 16 This actuating bar 16 is provided at its rear end with a projection 16 a which engages the slot 13 b of the fork 13. The lateral wall of the frame 1 of the machine also carries a lever 18 pivotally mounted about a pin 17 The portion of the lever 18, -which extends to the left, is provided with a slot 18 a which serves for the suspension of a wire 19 which connects the lever 18 with the actuating bar 16 The lower part of the lever '18 is operationally connected through an actuating wire 20 with the double letter-space key device according to the invention. This device consists of a double letter-spacing key 21 adapted to move in a vertical direction and provided in a known manner with a key button 22 The keylever 21 forms one member of a quadrilateral link, the latter comprising in addition to the keylever 21, a link bar 23 > a link lever 24 and a locking lever 25. The double letter-spacing keylever 21 has a projection 21 a extending to the left which serves for guiding the double letter-space keylever in a slot provided in the comb-shaped keylever guide 4 in the same manner as the other keylevers, The projection 21 a has at its left hand lower end a bent lug 21 b which serves as a stop. The link bar 23 is articulated on the one hand to an upwards extending projection of the portion 21 a of the double letter-spacing lever 21 by means of a screw 26, and on the other hand to the keylever guide 4

by means 70 of a pin 27 The bar 23 is cranked to a small extent (Fig, la), so that it can be guided in the same slot 46 of the comb-shaped keylever guide 4 as the extension 21 a of the keylever 21, i e both levers are positioned one 75 above the other. The lower end of the double letter-spacing keylever 21, is articulated with the link lever 24 by means of a screw 28 It is supported by the sublever bearing 6 d by means of a pin 80 29 which is located substantially at the centre of the link lever 24 The left-hand end of the link lever 24 has an upwardly bent portion 24 a which carries two pins 30 and 31. Thle pin 30 serves as a link for the actuating 85 wire 20 which actuates the double-step mechanism. The pin 31 extends into a slot 25 a of the locking lever 25 Thus the locking lever 25 is operationally connected on the one hand 90 with the link lever 24 by means of its guide slot and the pin 31, and, on the other hand, is guided in a special slot 4 c of the keylever guide 4 At its centre the locking lever 25 has a projection 25 b which serves for fastening a 95 tension spring 32, the other end of which is linked to a finger 24 b of the link lever 24. The locking lever has at its central lower part a downwards extending projection 25 c the purpose of which will be explained here 100 inafter The locking lever 25 has at its upper right-hand part a notch 25 d. An extension 24 c of the link lever 24, which projects beyond the link betveen this lever and the keylever 21, serves for fastening a 105 tension spring 33, the other end of which is connected to a projection 21 c of the double letter-space key 21. The described arrangement operates as follows: 110 For typing with double letter spacing, the loose dog, not shown in the drawing, which is formed as a slide, has to be displaced in such a manner that the escapement effects a double step For this purpose it is necessary 115 to shift downwards the pull rod 35 associated with the escapement This operation is performed in such a manner that on depressing the key lever button 22, the link lever 24 is angularly displaced about its pivot 29 in 120 a clockwise direction, as shown in Fig 1, with the result that the actuating wire 20 is pulled to the right and the lever 18 is rotated about its pivot 17 in an anti-clockvise direction, whereby the pull wire 19 moves down 125 wards by gravity Accordingly, also the actuating bar 16, which is linked to the said pull wire 19, moves downwards The projection 16 a of the actuating rod 16, which is guided within the slot 13 &, engages thereby the fork 130 785,550 1 A typewriter with single letter-spacing step and with double letter-spacing step and a key in the key board for the Ithanging of the steps of typing, which key is operationally connected with the

letter-spacing mechanism through a linkage, characterised in that the linkage comprises a locking lever, which, when the letter-spacing key is depressed and the linkage is shifted to change the letter spacing step, locks the linkage in, the shifted position, and that the linkage comprises links, constituted by a pin within a guide slot, so as to allow, after the locking has been effected, a partial return movement of the key lever whereby this lever comes into a position to engage the locking lever and, when, depressed a second time, engages the locking lever to move it into its release position'. 2 A typewriter according to claim 1, wherein the said linkage comprises a link lever pivotally mounted near the key board of the machine; wherein one arm of the said link lever is connected to the letter spacing mechanism through rods and levers linked together, one link consisting of a pin moving in a slot, wherein to the same arm of the said link lever a locking lever is linked by means of a pin-and-slot link and la spring urging the pin to move towards one end of the slot, wherein 'the locking lever, has; a notch for engaging a rigid abutment of the machine, wherein near to the end of the other arm of the said link lever the key lever is linked which is guided for a substantially vertical movement by another link linked to a rigid member of the m'achine, and wherein the key lever has a lateral projection which is positioned tol engage a lateral projection of the locking lever when the latter is in the locking position, so ithat,, when the key lever is depretsed a second time, it causes the locking lever to move out of its locking position, 3 A typewriter comprising a double step mechanism substantially as described with reference to and as illustrated in the accompanying drawings. For the Applicants, IMATTHEWS, 'HADDAN & CO, Chartered Patent Agents, 31 '32, Bedford 'Street, Strand, London, W C 2. 13, which in turn causes the shaft 12 to rotate. The actuating lever 34 fastened to the shaft 12 is then caused to rotate in the same direction, and' it pulls; with its projection 34 a the pull bar 35, downwards Now the task is to maintain this position for the time during which double-step typing is desired, Therefore, it is necessary to lock the double letterspace key in its lower position This locking is effected in the following manner: When the key lever 21 is depressed and the link lever 24 is rotated thereby in a clockwise direction, the locking lever 25 is moved to the right by the pin 31 of the link lever 24 The upper edge of the locking lever 25, which is guided in the special slot 4 c of the key lever guide 4, then moves along the upper edge of the said slot '4 c up to the notch 25 d of this locking lever 25 The spring 32 pulls the lever 25 to some extent upwards and, causes its notch 25 d to engage the key-lever guide 4 so that the double letter-spaced key now remains

locked in its lower position (see Fig 3) However, the slot 25 a of the locking lever 25 allows the link lever 24 and the key lever 21 to carry out a return movement ito a small extent which makes it possible for the lug 21 b of the double-space key lever 21 to pass past the bent portion 25 c 'of the locking lever to assume a position above this bent portion 'o of the locking lever 25. If after the double step typing normal typing is to be restored, the double letter-space keyiever is again depressed, whereby, its lug 2 lb presses down the 'bent part 25 c of the locking lever 25 and causes a rotation of the locking lever about its, pivot 311 in a clockwise direction until the lug 2 '1 b and the bent part 25 c are disengaged, The link lever 24 'is now free to move in an anti-clockwise direction and causes through the actuating wire an angular displacement of the lever 18 in a clockwise direction, whereby the actuating rod 1,6 is released and a normal stepping action of the escapement is restored. The invention is not limited to the described constructional example, but may 'be applied with, advantage to all those typewriters where the locking and subsequent release of the double letter-spacing key is required.

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* GB785551 (A)

Description: GB785551 (A) ? 1957-10-30

Method and apparatus for generating magnesium vapour in the interior of amolten metal or alloy using magnesium oxide

Description of GB785551 (A)

PATENT SPECIFICATION Date of Application and filing Complete Specification Feb 18, 1955.

No 4944/55. Complete Specification Published Oct 30, 1957. Index at Acceptance:-Class 82 ( 1), A 9 C 1 (A: B: D: i G), A 9 (C 2 B: D 5), 14 B. International Classification: -C 22 b, c. COMPLETE SPECIFICATION Method and Apparatus for Generating Magnesium Vapour in the Interior of a Molten Metal or Alloy using Magnesium Oxide I, FREDRIK J 6 RGEN ORDING HURUM, a turnings in order to achieve a high Norwegian subject, of Dronningensgt, 50, specific gravity so that the briquettes may Trondheim, Norway, do hereby declare the more or less submerge into the molten invention, tor which I pray that a patent may metal The use of lead results in be granted to me, and the method by which it poisonous fumes while the use of iron 50 is to be performed, to be particularly described turnings is attended only by partial subin and by the following statement: mersion with a poor recovery of The addition of magnesium to a molten magnesium. metal or alloy having a melting point which is 2 Submerging briquettes in the molten above the temperatures at which magnesium metal by meanes of an inverted cup This 55 boils, involves a number of difficulties cup acts as a trap for magnesium vapour Unalloyed magnesium has a low specific and makes handling difficult and results gravity and consequently will float on top of uncertain. the molten metal or slag where it will readily 3 Fastening briquettes to an iron rod by be attacked by the atmosphere, forming oxides means of which the briquettes are kept 60 or nitrides besides being oxidized by the slag forcibly submerged in the metal This The most common method in use today for method has yielded very good results proadding magnesium to a molten metal such as vided a suitable " filler " or " moderator " for instance cast iron, steels and alloys consists is used such as dead burnt Mg O, finely in adding the magnesium as part of an alloy ground coke or ferrosilicon However 65 with a heavier metal, such as nickel or copper such briquettes have the disadvantage of Such alloys which usually contain no more igniting when exposed to the atmosphere than 20 % Mg have an increased specific at high temperature such as may be the gravity compared with pure magnesium and case when the briquettes are kept suswill sink through the slag and partly submerge pended in a pre-heated ladle into which 70 into the metal below the metal is poured. Alloys of magnesium with silicon or ferro The purpose of this invention is to furnish silicon are also useful for the above purpose a method utilising a briquette of such a but the resulting low specific gravity is a great rfractory nature that it will not ignite or handicap become partly destroyed when exposed to the 75 The difficulties mentioned are aggravated atmosphere at high temperature

or to the by the fact that the magnesium evaporates with sputter of metal over a prolonged period of a certain violence and forces any lumps of time such as may be the case when pouring alloys containing magnesium to the surface of a big charge of metal into a pre-heated ladle the metal, the magnesium passing into the or other vessel or when collecting the metal 80 atmosphere as fumes of Mg O from two or more furnaces into a common ladle Such methods which consist of the addition or particularly when collecting the metal from of lumps of a magnesium-containing alloy to a cupola furnace to fill a big ladle The a metal in the spout of the furnace or in the briquette according to the invention may be runner will permit only a low recovery and be kept in a fixed position in a pre-heated ladle 85 a source of hazards or furnace for the desired length of time withA number of methods have been invented out any danger of ignition or destruction such based on the use of briquettes including as will be present when the briquettes contain magnesium as a component, such as: magnesium in the metallic state or in the form 1 Briquetting magnesium with lead or iron of an alloy 90 lPice 3 s 6 d l iI; 1 Furthermore the unused remnants of the briquettes may be used again for one or more additional treatments after the ladle has been emptied of its contents. According to the invention, calcium silicide and burnt magnesium oxide are used as reacting agents in briquette form and the briquettes are fixed so that the magnesium vapor generated and the slag formed will rise and float unhindered to the top of the surface of the metal the remnants of the briquettes being held securely fixed while progressively brought to reaction Such briquettes may be stored for any length of time and will not ignite or become attacked by the atmosphere at high temperature When however submerged in a metal having a temperature above that of the boiling point of magnesium, a reaction will begin whereby magnesium is emitted as a vapour while calcium silicide is transformed to a calcium silicate This reaction is progressive and without violence and its rate will depend on the flow of heat from the metal into the interior of the briquette and also to some extent on the composition of the briquette It is an a Ivantage that such a briquette-if of large size-should be given a special shape which will permit the metal to penetrate into the interspace between two adjoining surfaces and thereby facilitate the flow of heat to the interior of the briquette It is furthermore advantageous that the calcium silicate formed on the surface of the briquette shall be free to rise to the top of the metal as a slag and not obstruct the flow of heat from the metal by forming a protective coating on the surface of the briquette For that purpose the briquette may be given a composite shape in having a flat cylindrical portion and an inverted truncated conical portion any slag which is formed being thereby permitted to

move upwards without being trapped. It is furthermore an object of the invention to furnish a briquette which is not too highly refractory, but which will begin to fuse at a temperature somewhat below that of the molten metal As fusion begins the reaction will be facilitated and the magnesium ivpour formed will be instrumental in causing disruption or disintegration of that part of the briquette which is in the state of partial fusion and the reaction may thereby be accelerated as it proceeds from the outside of the briquette towards the interior For that purpose such fluxes as Ca F 2, Na F, Nak Si F 6, Na CI and other salts may be used as an addition to the reacting agents, i e Mg O and calcium silicide The Mg O may be replaced by burnt dolomite to the extent desired The composition of the briquettes may be such that a 3 lag of a basic character will result as the reaction proceeds and for that purpose oxides of the alkali-earth metals may be added A basic slag thus formed may be helpful for the removal of magnesium sulphide and other compounds from the metal, because this slag will protect the sulphides against reversal of the process such as wili take place it the oxygen in the atmosphere is alloyed to attack the suiphides in the presence ot metallic iron 70 W'tine such iluxes as mentioned above may De useful to tne reaction, by initiating fusion at a lower temperature, it may also be uselul to add sucn metals and alhoys as will likewise initiate fusion at a lower temperature, 75 such as for instance aluminium in linely powderd or granulated corm or a finely crushed alloy of aluminium or ierrosiiicon may be mixed into the briquetue as required tinely ground coke may also be added as a useful ace reacting component of the briquette. 1 he method according to the invention will however be more clearly understood by reference to the accompanying drawings of apparatus winch is at present preferred tor the 85 purpose. in these drawings:Pigure 1 is a central vertical section through a furnace ladle; Pigures i and 3 illustrate different forms 90 ot briquettes and the manner in which they are mounted. Figure 4 shows an arrangement for enabling the briquettes to be pre-heatea prior to their introduction into an induction furnace; 95 figures 5 and 6 sllow mocitied arrangements of tie briquettes. The ladle I is only partially filed with metal Zs as is normal for instance when the ladle is to be used for collecting metal trom a cupola 100 wurnace, several tappmgs oeing required. Extending from a bracket j hixeci with the ladle 1 is an overhanging suppoit arm 10 which carries at its tree end a depending rod 4 for supporting briquettes 3 and 6 respectively, the 105 upper part of the rod being clad with a series ot abutting sleeves 7 of refractory material serving both as spacers for clamping the briquettes and for

protecting the rod 4 Only the lower series of briquettes 3 are submerged 110 in the molten metal and as shown in Figure 2 these are in part cylindrical ( 8) and in part -of truncated conical form ( 9) This shape permits the molten metal to enter the space 11 between each pair of adjacent briquettes and 115 facilitates the flow of heat thereto The truncated conical surfaces being lowermost the slag formed on the surface of the briquette is thus allowed to rise to the top of the metal without becoming trapped 120 The briquettes 6 as shown are not yet submerged but are exposed to the heat and sputter of the metal, and are pre-heated while the metal is filled into the ladle Reaction does not take place however until these briquettes 6 are 125 actually submerged in the molten metal The flat cylindrical briquettes as shown in Figure 3 may alternatively be used. Since the briquettes referred to above may be strongly pre-heated without initiating any 130 785,551 so that the magnesium vapor generated and the slag formed will rise and float unhindered to the top of the surface of the metal the remnants of the briquettes being held securely fixed while progressively brought to reaction.

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* GB785552 (A)

Description: GB785552 (A) ? 1957-10-30

Improvements in and relating to fasteners

Description of GB785552 (A)

PATENT SPECIFICATION Invue'nor: PETER HENRY GAY ALLEN A' Date of Application and filing Complete Specification: March 14, 1956. No.7993/56.

Complete Specification Published: Oct 30, 1957. Index at acceptance:-Class 44, BE 13 X. International Classification:-FO 6 b. GCOMPLETE SPEC Is FICATION Improvements in and relating to Fasteners We, THE BRITISH THOMSON-HOUSTON COMPANY LIMITED, a British i Company having its registered office at Crown House, Aldwych, London, W C 2, do, hereby declare the invention, for which we pray that a patent may be grranted to us, and the method by which it is to be performed, to be particularly described in land by the following statement: - This invention relates to means for fixing apparatus, such as electronic units, to slotted angle or channel members from which racks for mounting such apparatus is often constructed. The object of the present invention is to provide a quick acting fastener which nevertheless cannot be accidentally disengaged. According to the invention there is provided a fastener comprising a bolt member having a rectangular head, the bolt shank standing perpendicularly off one of the long sides of said head, the root of said shank being of a square cross-section having a side dimension equal to the width of the head, the remainder of the shank being of a cylindrical cross-sec-tion, ra helical spring positioned on the cylindrical part of the shank and means for retaining said helical spring on the shank situated at the free end of the shank. The invention will be more readily understood from the following description reference being made to the accompanying drawing in which Fig 1 shows' 'a fastener according to the invention mounted in a panel or side-walll of a chassis or the like, and Figs 2 a and 2 b which show more clearly the construction of the bolt member. In Fig 1 the bolt member 1 is shown positioned in a circular hole in part of a sheet member which may well be the wall of a chassis The bolt member has, as is more clearly shown in Fig 2 b a rectangular head 2 of dimensions such ithat is will pass through the slots in the angle or channel members of the racks. The shank of the bolt is in the form of a square, root portion 3 which changes to cylindrical form for the remainder 4 of its length. lPrice 3 s 6 d l The end of the shank is machined as by threading, drilling or grooving to' receive a, form of retaining means against which a helical spring 7 when mounted on the shank, will bear As shown, the end of the shank has a circumferential groove 5 therein Dino which is fitted a spring clip 16. In use, a chassis, or panel 8 fitted with the fastener is presented to the rack on which it is to be mounted The head 2 of the bolt member passes through one of the longitudinal slots in the angle or 'channel and is then pulled against the spring,7 to draw the square pottion of the shank clear of the slot When thus positioned, the bolt is rotated

through 90 and released, The root portion being square and being of a size such as, so fit snugly the width of the slot, the bolt member holds the supported apparatus firmly. To release the apparatus the bolt head 2 is gripped, pulled against the action of spring 7 and rotated; to allow the head to pass through the slot. The invention provides all the elements of a simple fastener for the applications envisaged for it The bolt may be machined from a single piece to withstand the considerable forces which heavy equipment may impose on the head.

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