US2731203A - Saturable core circuits for counting and the like - Google Patents

Description

Jan. 17, 1956 J. G. MILES 2,731,203

SATURABLE CORE CIRCUITS FOR COUNTING AND THE LIKE 2 Sheets-Sheet 1 Filed May 24, 1951 STAGE I INVENTOR JAMES G. MILES FEEIDB 3 A C Z? WINDING O TRIGGIERAFWINDING ATTORNEY J. G. MILES Jan. 17, 1956 SATURABLE CORE CIRCUITS FOR COUNTING AND THE LIKE Filed May 24, 1951 2 Sheets-Sheet 2 A.C. POWER SOURCE INVENTOR JAMES G. MILES Isa/[W ATTORNEYS United States Patent SATURABLE CORE CIRCUITS FOR COUNTING AND THE LIKE James G. Miles, Minneapolis, Minn., assignor, by rnesne assignments, to Sperry Rand Corporation, New York, N. Y., a corporation of Delaware Application May 24, 1951, Serial No. 227,962

19 Claims. (Cl. 235-92) The present invention relates to magnetic core type circuits adapted for use in binary counting circuits and the like.

Several magnetic arrangements are presently known for performing electrical functions such as counting, amplifying, controlling or triggering in computing machinery and control systems. One such device is disclosed in United States Patent No. 2,519,513 issued to R. L. Thompson. Patent No. 2,519,513 discloses a circuit in which an electrical counting operation, theretofore performed by vacuum tubes, is accomplished by means of saturable core reactors. The arrangement of that patent is chiefly concerned with apparatus generally consisting of two sections each having two conditions of stability, the sections being cross-connected so as to provide an arrangement in which a change in the stability condition of one section will produce an opposite change in the stability condition of the other section. In this respect, the device disclosed in Patent No. 2,519,513 is a magnetic analogue of the well-known Eccles-Jordan flipfiop circuit. The Eccles-Jordan circuit essentially comprises two triode vacuum amplifiers regeneratively connected through resistors and condensers so that either one tube or the other tube is always conducting. The Thompson device may be said to resemble the Eccles- Jordan flip-flop circuit insofar as it is also a two-sided circuit with cross feedback, having two stable states, the susceptance state of each side of the circuit being determined by the state of the other side, and either one reactor section or the other conducting at any instant of stable operation.

The present invention differs from the above and other devices previously known by reason of its greater simplicity and economy of circuit elements and also in the manner of its operation. The present invention is characterized, for example, by provision of a single-sided magnetic circuit with relay action in which the stability condition is self-determining according to an arrangement by which a considerable amount of the output signal of each subsection, or stage, is positively fed back into the same stage. The use of the positive external feedback principle to obtain a plurality of conditions of stability is shown in United States Patent No. 2,027,312, issued to A. S. Fitzgerald. However, Patent 2,027,312 does not suggest any means for providing triggering and counting properties such as those which form important features of the present invention.

An advantage of the present invention is that it permits the utilization of a single-sided magnetic flip-flop that permits utilization of the attendant advantages of such single-sided flip-flop. One advantage of employing single-sided flip-flops is that there is no requirement for approximately equal loads to optimize operational characteristics as is required by balanced or Eccles-Jordan type flip-flops.

Another advantage of the single-sided flip-flop is that it utilizes fewer core windings and circuit components than do balanced or Eccles-Jordan type flip-flops. Singlesided flip-flops are therefore capable of significantly faster operation, which is yet another advantage in digital computer applications.

A distinguishing feature of the present invention is that the electrical condition of a magnetic amplifier may be caused to advance from one state of stability to the other by the application of unidirectional pulses to a trigger ringing circuit.

It is therefore an object of this invention to provide a novel triggering circuit in a magnetic flip-flop circuit.

It is a further object of this invention to provide a novel triggering circuit as described hereinafter, so constituted that its application to a conventional magnetic flip-flop circuit produces a device capable of performing a binary counting operation.

It is a further object of this invention to provide a magnetic flip-flop circuit in which the electrical equilibrium is altered by a change in the degree of core saturation of a magnetic element therein.

It is another object of this invention to provide a binary counting circuit in which greater reliability is attained through the employment of saturable core reactors in place of conventional vacuum tubes.

It is a further object of this invention to provide a binary counting circuit of the saturable reactor type utilizing fewer core windings than heretofore used.

Another object of this invention is to provide a binary counting circuit capable of more rapid operation than hitherto possible.

It is yet another object of this invention to provide a binary counter of single-sided circuit form in which either of two conditions of stability may obtain, such condition of stability being self-determined as hereinafter set forth.

A still further object of this invention is to provide a binary counting circuit in which the counter is advanced by means of a special trigger ringing circuit as described below.

Further objects and the entire scope of the invention will become further apparent in the following detailed description and in the appended claims. The accompanying drawings display the general construction and operational principles of the invention; itis to be understood, however, that said drawings are furnished only by way of illustration and not in limitation thereof.

In the drawings:

Figure 1 is a circuit diagram of a preferred form or embodiment of this invention.

Figure 1A is a circuit diagram of an alternative embodiment of the invention shown in Figure 1.

Figure 2 is a graphical representation of the relationship between the magnetornotive forces present in a trigger winding and an external feedback winding of a saturable core reactor element in the counter.

Figure 3 is a graphical representation of the waveforms present at certain specified points with reference to Figure l.

A preferred circuit embodying the various features of the present invention is shown in Figure 1. Figure 1 shows two stages of a magnetic binary counter, the stages being designated as I and II by legend in Figure 1.

Referring to Stage I, there is provided a toroidal core 10 composed for example of spirally-wound molybdenum permalloy tape. On this core there is disposed a trigger ringing winding 12, a reactance winding 14 and a feedback winding 16.

An input such as a pulse input is intended to be applied between a suitable ground connection and a terminal 18. The input may, if desired, be provided with a resistance 19 connected from terminal 18 to ground. From terminal 18 the input pulse is applied to the trigger winding 12 through a capacitance 20 connected in lead 22.

The reactance winding 14 is connected over a line 24 and through a decoupling capacitance 26 to a suitable source of alternating current power 28. The source 2% will preferably be an R. F. source, as will be explained more fully hereinbelow.

The feedback winding 16 is connected over leads 36 and 32 (and other circuit elements to be described below) to the direct current terminals 34 and 36, respectively, of a full wave rectifying circuit designated generally as The alternating current terminals 40 and 42 of the rectifier 38 are connected between ground at terminal 42 and at terminal 4-0 to a point in an alternating current circuit comprising the reactance coil 14 and power source 28.

The circuit as thus far described may function with the single core 10 by providing in the D. C. circuit between rectifier 38 and feedback coil 16 a suitable R. F. choke to block the flow of R. F. currents in this circuit. Also the circuit comprising the trigger ringing coil 12 may be provided with a suitable R. F. choke to block R. F. currents in that circuit.

A representative circuit utilizing chokes is shown in Figure 1A. This circuit closely follows either one of stages I and II as shown in Figure 1. it will be noted that the power source supplies alternating current through the capacitance 26 to the reactance winding 14. Connected to the opposite end of winding 14 is the bridge rectifier 38. The feedback winding 16 is connected at one end thereof to one D. C. terminal of bridge 33 as is the case in Figure 1. However, the opposite end of feedback Winding 16 instead of going to a coil on a companion saturable reactor is connected to a suitable choke 16' and from there proceeds to the second D. C. terminal of the bridge 38. Thus the alternating current which may be induced in the feedback winding 16 by transformer action from the reactance winding 14 is blocked in the feedback circuit. Similarly, whatever alternating currents which may be induced in the trigger winding 12 by reason of transformer action are blocked by suitable choke 12.

However, while chokes may be employed as mentioned in the immediately preceding paragraph, it is preferable, as shown in Figure 1, to employ a second toroidal core ltlA which is identical with core 10. About core 16A there are also provided windings 12A, 14A, and 16A which may be identical in all respects to the windings 12, 14, and 16 on core 10. The function of core 10A and the windings thereabout is to effectively cancel objectionable R. F. currents in the trigger ringing and feedback circuits and to thereby replace the previously mentioned chokes and with improved results. As indicated in Figure 1, the direction of winding of each of the respective trigger and feedback windings only corresponds on each of the cores so that the relationships of the M. M. F.s produced by each of the trigger and feedback windings on each core will be the same. Reactance windings are wound in opposition to provide the above-mentioned decoupling of the control and feedback circuits from the A. C. power supply circuit, as is well known in the art.

In addition to the use of two separate toroidal cores for cancelling out undesired alternating currents, there may be employed, for example, a single core of the following type: The core may be built up as by stacked laminations having two outer legs at the ends of the core with a third leg of considerable cross-section between the outer legs, this third leg being subdivided in its central portion to form two parallel sub-legs of reduced crosssection. This type of core construction has been previously known in the art as for example in Patent 2,027,312, referred to above. For use with the present invention, the two reactance windings will be each wound on one of the just-mentioned sub-legs and connected in 1 of the S series but wound in opposite directions. The trigger winding may then be wound completely about the central third leg. The feedback winding is also wound about the third central leg.

Those skilled in the art will understand from the foregoing description that alternating current in the reactance winding 14 will produce a predetermined alternating flux in the core 10. Also, the connection of terminal 40 of the rectifier 38 in a lead 44 leading from winding 14A, which latter is in turn connected over lead 46 with winding 14, will cause a direct current of predetermined value to flow through the feedback windings 16 and 16A which windings are connected in series with the direct current terminals 34 and 36 of rectifier 38. The arrangement is such that, assuming the current in winding 14 to be subject to a flux in an intermediate amplitude, a change in the inductive reactance of coils 14 and 14A will cause a change in the R. F. voltage at terminal 40 of rectifier 38 which will result in a change in direct current through coil 16 to alter the stability of the circuit in a manner to be described fully hereinbelow. As will become apparent, the windings 16 and 16A are in positive feedback relationship with the trigger windings 12 and 12A respectively when the trigger windings are conducting a positive impulse.

Continuing to refer to stage I of Figure 1, the capacitance 2t? and the inductive reactance of winding 12 and return impedance 19 form a series resonant circuit which can be shock-excited, or caused to oscillate electrically, by the application of a single impulse of electric energy as at terminal 18 across the impedance 19 to ground. However, because of damping due in part to the ohmic resistance of the winding 12, there can be but substan tially one positive and one negative surge of current. Thus by this arrangement there is provided a means whereby a succession of unidirectional input pulses such as counting pulses may produce critically damped ringing oscillations. As will be explained below, the just-mentioned surges of critically damped oscillating current through the winding 12 will contribute to altering the flux conditions within the core 10 (and the core 10A if .employed) to cause the circuit to assume one of two conditions of magnetic and electrical stability, that is, either relatively direct current saturation or relatively direct current non-saturation. Hereinbelow it will be assumed that two cores are employed.

Assuming that suitable values of frequency and voltage are applied to render the circuit operable, alternating current from the power source 28 passes through the re actance windings and the rectifier, and unidirectional (rectified) pulsating current then exists in the feedback windings. The feedback current causes the cores to be partially saturated. This degree of saturation, and other magnetic and electric effects to be described hereinafter, may be best understood with reference to the graph in Figure 2.

The graph in Figure 2 illustrates the relationship between the magnetomotive forces (M. M. Ffs) of the trigger windings and the feedback windings where the A. C. source voltage and frequency remain constant. The curve AKBMCDNEF forms a so-called 8 curve common to saturable core devices having excessive regenerative f edback, as will be well understood by those skilled in the The line ED is vertically tangent to the upper knee curve at point D, and the line CE is vertically tangent to the lower knee of the 3 curve at point C. The knees of the S curve represent the limits of the unstable region DC.

The previously mentioned feedback current in the feedback windings causes the cores to be partly saturated. It may be first assumed that the core is at a lower stable state of saturation at stability residual point M of the curve in Figure 2. As an approach is made toward saturation, as by adding saturating M..M. F. from the trigger ringing winding or any other means, the incremental permeability, the etfective inductance, and therefore the inductive reactance of the reactance winding '14 and the 1 feedback Winding 16 decreases in a manner well understood by those skilled in the art until a critical point C is reached. At this time the feedback current increases 5 sharply to excite the core proportionately further towards saturation, and the feedback M. M. F. rises along the path CE and thence along EF, where inductance is at -a low value and the feedback M. M. F. is sufiicient to keep the core in a state of upper or saturated stability. The upper position of stability is somewhere along the line DEF, preferably at N.

A lower or desaturated condition of stability will obtain if by some means there is induced an M. M. F. tending to partially cancel the feedback M. M. F. The cores will then become less saturated, feedback M. M. F. will decrease along the path FED in Figure 2 and the effective inductance and therefore reactance will increase until a critical point D is reached. From point D the feedback M. M. F. will fall off sharply along the line DB, thus going proportionately further into desaturation. The cores thereby stabilize at point M, the previously mentioned state of lower or desaturated stability at which the inductance is at a high value and the feedback M. M. F. is relatively small.

The manner in which the ringing oscillations are employed to effect a change in the just-mentioned magnetic equilibrium will now be explained in detail: If the cores are in an upper or saturated condition of stability at N along the curve DF the M. M. F. produced by the positive surge of the ringing current will merely drive the cores further into saturation. The ringing M. M. F. is represented in Figure 2 by the curve extending through the points G and H, this curve being characterized by swings to one side and then the other of a vertical line passing substantially mid-way between the critical points C and D. The swings to points G and H exceed the points C and D, as indicated.

While the positive surge including the point G will be ineffective in changing the state of the circuit, nevertheless, the negative surge passing through point H and therefore going below the point D will drive the cores into the lower or desaturated stability condition along the path NDBKBM. When the negative part of the trigger pulse is removed, lower stability will settle at M. If now another positive input pulse is applied the positive surge including point G will exceed point C and will drive the cores into a saturated condition along the path MCEF. While a negative surge including the point H will follow the positive surge this negative surge will not operate to immediately force the circuit back into the lower condition of stability. The magnetic inertia of the system as it snaps into the region of upper stability along the path CEF prevents the rapidly following negative surge H from forcing the cores back into the lower state. Circuits according to this invention have been built and operated extensively and function in the manner set forth herein.

From the foregoing description it will be clear that a so-called single-sided flip-flop is provided. While two cores 1i? and 10A are employed in the preferred embodiment, the device remains a single-sided flip-flop, inasmuch as the second core 10A is employed only for cancelling R. F. currents and is not interconnected with the first one 10 in any manner resembling a circuit analogous to an Eccles-lordan circuit.

While I have described my novel trigger ringing circuit as employed with a single-sided flip-flop stage according to the herein invention, it will be apparent that my trigger ringing circuit may also be employed to trigger two-sided flip-flop circuits as well.

A preferred means of obtaining an output signal from the flip-flop stage may be by sampling the voltage appearing across the alternating current terminals 40 and 42 of the rectifying circuit 38. The-forward impedance of the 75 rectifier is suflicient to load' the flip-flop stage itself. The voltage waveform appearing across the rectifier terminals 40 and 42 will be analogous to the wave form of an amplitude-modulated radio-frequency signal in that the voltage amplitude of this modulated alternating current wave form will be large when the flip-flop is in the upper region of stability and small when the flip-flop is in the lower region of stability.

Wave forms resulting from the operation of the circuits as thus far described may be fully understood with reference to Figure 3. In Figure 3, various wave forms are indicated in parts (a) through (h) of this figure, successive Wave forms occurring at times to through t4. Positive input pulses applied to terminal 18 are represented in part (a) of Figure 3. Figure 3 part (b) represents the ringing oscillations which occur in windings 12 resulting from the application of the input pulses, and part (c) represents the modulated wave form of the alternating voltage appearing at terminal 40 of the rectifier 38. Still referring to Figure 3, parts (a), (b), and (c) serve to make clear that an input pulse applied in terminal 18 at time t1 will cause the wave form envelope to be of maximum amplitude until the occurrence of the next input pulse at time t2 when the envelope will become reduced to small amplitude until the next input occurs at time t3 and so forth.

Inasmuch as the signal sampled across terminals 40 and 42 of rectifier 38 will be a modulated alternating voltage, a useful pulse output voltage may be readily obtained in the following manner: Continuing to refer to Figure 3 and also referring to Figure 1, detection may be accomplished by connecting terminal 40 of rectifier 38 over a line 48 to a clipping section comprising resistance 50 connected between line 48 and ground, a second resistance 52 also connected to ground, and a crystal diode 54 connected between line 43 and the ungrounded end of resistance 52. The function of the clipping section is to transmit only the lower or negative portion of the wave form envelope, as represented in part (c) of Figure 3. The lower negative side of the envelope as illustrated in part (at) of Figure 3 may then be demodulated by condenser 56 connected in parallel to ground with resistor 52. The action of capacitor 56 will be to eliminate the alternating voltage to produce a square wave form as represented in part (c) of Figure 3.

One use for the direct current output signal just described may be to generate a carry pulse to be used as an input pulse to a next succeeding flip-lop stage as in a binary counter. For this purpose a resistor-capacitor differentiating circuit comprising resistance 58 and capacitor 60 may be connected between the ungrounded side of capacitor 56 and ground as shown in Figure l to differentiate the output square wave shown in part e of Figure 3, producing first a negative and then a positive pulse for each square wave cycle. The resulting negative and positive pulses are represented in part (f) of Figure 3. Since only one pulse is required for each counting cycle in a binary counting circuit the positive pulse may be chosen arbitrarily to be clipped by a crystal diode 62 connected, as shown in Figure 1, in parallel to ground with the resistor 58. The remaining negative pulse as illustrated in part (g) of Figure 3 is the carry pulse from the counter stage. This carry pulse may be inverted and matched into the trigger ringing circuit of the counter stage II by means of an impedance matching pulse transformer 64, as shown in Figure l. The output of transformer 64 appears on line 66, which may be termed the carry line and this wave form is represented in part (h) of Figure 3.

Stage Ii of the counter may be in all respects identical with stage I, as shown in the drawings, and will in turn serve to produce an output pulse on its output line designated 66 for every other input pulse received over line 66. From the foregoing and with particular reference to Figure 3, it will be apparent that each stage will produce a single output pulse for every second input pulse and therefore the stages as interconnected Will perform as a binary counting circuit.

Magnetic binary counters with supply frequencies of 1.0 megacycle have been constructed and operated at rates as high as 60,000 counts per second and even this rate is not by any means a maximum rate.

While those skilled in the art will understand that a great many combinations of values of the various components of the circuits hereinabove described may be em- Power source 28: l megacycle Toroz'dal cres.-The cores should have the smallest possible amount of core material in order that their magnetic state may be changed rapidly with only a small amount of energy. Therefore, it is preferable that the cores of Figure 1 be made of a sensitive magnetic material, as for example, 4-79 molybdenum permalloy tape about /8 mil thick and about inches Wide. The tape may be insulated by a colloidal deposition applied by a cataphoresis method. Ten turns of the insulated tape may be spirally wound under tension on a ceramic mandrel to form a suitable core.

It will be understood that the foregoing values and speci ications are merely illustrative and it is not intended that the herein invention be limited to these values. Since other values and other embodiments of the invention will become apparent to others upon reading this specification, it is intended that the invention be limited only by the scope of the appended claims.

I claim:

1. In a device having a saturable core, a reactance winding and a feedback winding arranged on the core, means connected with the windings for supplying electric current thereto so that the device has first and second critical states of flux saturation in the core beyond which the device Will drive itself to first and second stable states, triggering means for shifting the circuit from either stable state to the other, the triggering means comprising a triggering winding on the core, the trigger-Winding being connected with a capacitance in a resonant circuit, and means for causing the flow of an oscillatory surge of electric current through the triggering winding, the oscillation being of sufiicient magnitude to drive the core flux beyond either one of the critical states and into the opposite stable state.

2. In a device having a saturable core, a reactance winding and a feedback winding arranged on the core, means connected with the windings for supplying electric current thereto so that the device has first and second critical states of flux saturation in the core beyond which the device will drive itself to first and second stable states, triggering means for shifting the circuit from either stable state to the other, the triggering means comprising a triggering winding on the core, the trigger winding being connected with a capacitance in a resonant circuit, and means for causing the flow of an electric excitation current oscillation consisting of a current surge in a first direction followed by a current surge in a second direction through the triggering winding, the surges being of sufficient magnitude to drive the core flux beyond either one of the critical states and into the opposite stable state.

3. In a device having a saturable core, a reactance Winding and a feedback winding arranged on the core, means connected with the windings for supplying electric current thereto so that the device has first and second critical states of flux saturation in the core beyond which the device will drive itself to first and second stable states, triggering means for shifting the circuit from either stable state to the other, the triggering means comprising a triggering winding on the core, the trigger winding being connected with a capacitance in a resonant circuit, and means for causing the flow of an electric excitation current oscillation consisting of a current surge in a first direction closely followed by a current surge in a second direction through the triggering winding, the surges being of sufficient magnitude to drive the core flux beyond either one of the critical states and into the opposite stable state.

4. In a device having a saturable core, a reactance winding and a feedback winding arranged on the core, means connected with the windings for supplying electric current thereto so that the device has first and second critical states of flux saturation in the core beyond which the circuit will drive itself to first and second stable states, triggering means for shifting the device from either stable state to the other, the triggering means comprising a triggering Winding on the core, the trigger winding being connected with a capacitance in a resonant circuit, and means for causing the flow of an electric excitation current oscillation consisting of a current surge in a first direction closely followed by a current surge in a second direction through the triggering winding, the surges being of suflicient magnitude to drive the core flux beyond either one of the critical states and into the opposite stable state, the time duration of the surges being sufiiciently short relative to the shifting time of the circuit to prevent reshifting of the circuit in response to a surge immediately following the shifting surge.

5. Apparatus as in claim 1 and further including means connected with the reactance winding for obtaining a signal indicative of the stable state of the circuit at any given time.

6. Apparatus as in claim 5 wherein the stable state indicating signal is an alternating current of one of two amplitude levels depending on the stable state at a given time, and wherein means are provided for clipping, demodulating and differentiating the indicating signal to derive a single carry pulse for every second excitation current oscillation in the trigger winding.

7. Apparatus as in claim 1 and further including means interconnecting the reactance and feedback windings for obtaining a signal indicative of the stable state of the circuit at any given time.

8. Apparatus as in claim 4 and further including means connected with the reactance Winding for obtaining a signal indicative of the stable state of the circuit at any given time.

n eluding means interconnecting the reactance and feedback windings for obtaining a signal indicative of the stable state of the circuit at any given time.

11. Apparatus as in claim 10 wherein the means interconnecting the reactance and feedback windings cornprises a rectifying circuit.

12. Apparatus as in claim 7 wherein the means interconnecting the reactance and feedback windings comprises a rectifying circuit.

13. Apparatus as in claim 1 and further including means for applying only unidirectional excitation pulses to the resonant circuit.

14. Apparatus as in claim 4 and further including means for applying only unidirectional excitation pulses to the resonant circuit.

15. A binary counting circuit made up of interconnected stages, each stage comprising a reactance winding and a feedback winding arranged on a saturable core, means connected with the windings for supplying electric current thereto so that the stage has first and second critical states of flux saturation in the core beyond which the circuit will drive itself to first and second stable states, triggering means for shifting the circuit from either stable state to the other, the triggering means comprising a triggering winding on the core, the trigger winding being connected with a capacitance in a resonant circuit, means for causing the flow of an electric excitation current oscillation consisting of a current surge in a first direction closely followed by a current surge in a second direction through the triggering winding, the surges being of suflicient magnitude to drive the core flux beyond one of the critical states, the time duration of the surges being sufiiciently short relative to the shifting time of the circuit to prevent reshifting of the circuit in response to a surge immediately following the shifting surge, means connected with the reactance winding for providing an alternating voltage envelope the amplitude of which indicates the stable state of the stage, means comprising means for demodulating the voltage envelope to obtain an indicating signal upon the occurrence of a transition of the stage, and means for interconnecting the just mentioned means of the first stage to the resonant circuit means of the next following stage to trigger said next stage in corresponding manner.

16. A circuit as in claim 15 wherein the means for obtaining an indicating signal also comprises diflferentiating and clipping means for producing a single unidirectional pulse for every second transition of the stage.

17. In a saturable core device having first and second stable states, triggering means for shifting the device from either stable state to the other, the triggering means comprising triggering winding means connected with capacitance means in a resonant circuit, the resonant circuit including parameters for damping same so that an excitation pulse applied thereto will cause substantially only a single oscillation in the triggering winding means.

18. In a binary counting circuit made up of interconnected stages of saturable core devices wherein each device has a reactance winding, an interconnected feedback winding and a damped resonant trigger winding circuit, means operatively connected with the reactance winding for obtaining an output in the form of an envelope of alternating voltage the amplitude of which indicates the stable state of the stage, and means for obtaining a carry pulse for operating the next stage, said carry pulse means comprising means to demodulate the alternating voltage envelope.

19. A circuit as in claim 18 wherein the carry pulse means further comprises means for differentiating the Wave form obtained by demodulation, and further comprises means for suppressing one of the diiferentiated pulses so as to provide a single carry pulse for every second transition of a stage.

References Cited in the file of this patent UNITED STATES PATENTS 1,862,211 Dowling June 7, 1932 2,010,610 Simpson Aug. 6, 1935 2,010,614 Suits Aug. 6, 1935 2,027,312 Fitzgerald Ian. 7, 1936 2,222,048 Stevens et al. Nov. 19, 1940 2,265,296 Lee Dec. 9, 1941 2,519,513 Thompson Aug. 22, 1950 2,524,154 Wood Oct. 3, 1950 2,591,406 Carter et al. Apr. 1, 1952 2,640,164 Giel et al May 26, 1953 OTHER REFERENCES Static Magnetic Storage and Delay Line, An Wang and Way Dong Woo; Journal of Applied Physics, volume 21, January 1950; pp. 49-54.

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