595,509

PATENT SPECIFICATION

Application Date: May 12, 1945. No. 11985/45

(Patent of Addition to No. 535,778 dated Oct. 3, 1939.)

Complete Specification Left: May 10, 1946

Complete Specification Accepted: Dec. 8, 1947.

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PROVISIONAL SPECIFICATION

Improvements in or relating to Electric Oscillation Generators

We, ELECTRIC & MUSICAL INDUSTRIES LIMITED, a British Company, of Blyth Road, Hayes, Middlesex, ERIC LAWRENCE CASLING WHITE, a British Subject of "St. Boniface", Richings Way, Iver, Buckinghamshire, and DOREEN WALKER, a British Subject, formerly Doreen Blumlein, of Lanheren, Lescudjack, Penzance, Cornwall, legal representative of ALAN DOWER BLUMLEIN, deceased, late a British Subject of 32, Ardley Road, Ealing, W.5, do hereby declare the nature of this invention to be as follows:-

This invention relates to modifications of the electric oscillation generators described in the Specification of parent Patent No. 535,778.

In this specification various forms of electric oscillation generators or multi-vibrators are described comprising a first and second electron discharge valve each having a cathode, a control electrode and an output electrode, the valves being retro-actively coupled together so than in operation said valves conductor alternately and generate relaxation oscillations, each cycle of which has two portions, wherein coupling is effected through a first network between the output electrode of the first valve and the control electrode of the second valve and through a second network between the cathodes of said valves, the duration of each of said portions being determined by the time constants of circuits associated with said valves. With such a construction the valves conduct alternately and even though the first valve may be controlled by the application of suitable controlling impulses, said valve will nevertheless, change from one state to the other even though a controlling pulse is absent. The circuits described in the said specification possess many advantages over oscillation generators know at the date of said patent, but for certain purposes it may be de3sired to employ an oscillation generator in which a change from the stable to the unstable state can only be effected on application of a controlling impulse and it is the object of the present invention to provide modifications of the circuit arrangements claimed in the specification of Patent No. 535,778 in which such a change can be effected.

According to the invention there is provided a modification of the electric circuit arrangement claimed in any of the Claims of the specification of Patent No. 535,778, in which instead of the duration of each of said portions of each cycle being determined by time constant circuits, the duration of one of said portions is arranged to be controlled independently of the time constant of a circuit associated with said valves so that one of said portions is rendered stable. With such a construction the generator, according to the present invention, instead of having two unstable states has one stable and one unstable state, so that when the generator has been triggered from the stable to the unstable state and returns to the stable state, a change from the stable to the unstable state can only occur as a result of the application of a controlling pulse.

In order that the said invention may be clearly understood and readily carried into effect, it will now be more fully described with reference to the accompany drawings, in which:-

Figure 1 illustrates a circuit arrangement embodying one form of the invention,

Figure 2 illustrates curves showing the voltages of various electrodes of the valves shown in Figure 1,

Figure 3 is a circuit arrangement of a further embodiment of the invention,

Figure 4 illustrates curves showing the voltages of various electrodes of the valves shown in Figure 3,

Figure 5 is a circuit arrangement of the embodiment shown in Figure 3, including modification, and

Figure 6 illustrates curves shown the voltages of various electrodes of the valves shown in Figure 5.

Referring first to Figures 1 and 2 of the accompanying drawing, it will be seen that the circuit disclosed in Figure 1 is similar to the circuit of Figure 2 of the parent specification, elements in Figure 1 of the accompanying drawings which correspond to the elements of said Figure 2 having been given the same reference characters. In the circuit shown in Figure 1 the resistance $ has been omitted and between the cathodes of the valves 1 and 2 a unilaterally-conducting device 3 in the form of a diode is connected, the anode of the diode being connected to the cathode of the valve 1 and the cathode of the diode being connected to the cathode of the valve 2. The circuit shown in Figure 1 operates in a manner analogues to the second type of operation described in the parent specification, and it is arranged that the bias potentials are such that when the valve 1 is conducting the diode 3 is also conducting. When the valve 1 is rendered non-conducting on the application thereto of a negative triggering pulse the diode 3is also rendered non-conducting and the valve 2 rendered conducting, the operation of the circuit thereafter being similar to the described operation of the circuit of said Figure 2 as will be appreciated from the curves shown in Figure 2 of the accompanying drawings until the valve 1 is again rendered conducing. At this stage the cathode potential of valve 2 commences to drift downwardly and as describ3ed in the parent specification this downward drift continues until valve 2 becomes conducting. However, in the present invention due to the presence of the diode 3 the downward trend in potential of the cathode of valve 5 is arrested when this potential falls to a valve such that the diode 3 is rendered conducting, which thus effectively prevents the valve 2 being rendered conducting. Thus, the valve 1 is maintained conducing and the circuit remains in such stable condition until the valve 1 is again rendered non-conducting on the application of a triggering pulse. The duration, therefore, of that portion of the cycle of operating during which the valve 1 is conducting is not determined by the time constant of R4 and C. If desired the valves 1 and/or 2 and the diode 3 may be arranged in a single envelope.

Figure 3 of the accompanying drawings illustrates a circuit arrangement similar to that shown in Figure 3 of the parent specification which is intended to operate in a manner similar to the first type of operation referred to in the parent specification.

In this case, in order to maintain the valve 1 conducting until it is rendered non-conducting on the application of a triggering pulse, the difference in bias applied to the control electrodes of the valves 1 and 2 is made so great that the ratio of the two portions of each cycle is effectively infinite. Figure 4 illustrates the voltages of the control grids of valves 1 and 2 when triggering pulses of the form shown in the Figure are applied to the grid of valve 1. If desired, the grid leak R1 associated with the valve 1 to which the triggering pulses are applied may be shunted by a unilaterally-conducting device shown as a diode 4 in Figure 3, so as to ensure that the valve 1 is only rendered non-conducting by the application of triggering pulses of a desired polarity.

Figure 5 of the drawings illustrates a circuit similar to that shown in the accompanying Figure 3, in which the stability of the period of the unstable portion of the cycle of operations is improved by biassing the control electrode of the valve 2 through a unilaterally-conducting device shown as diode 5. The lower end of the grid leak R2 if connected to a point of lower potential than the anode of the diode 5. With this construction the diode 5 can be arranged to conduct after the change of valve 2 to the non-conducting state, in order to discharge condenser C1 as quickly as possible so that the circuit is again sensitive to a triggering pulse sooner than would otherwise be the case. Figure 6 illustrates the voltages of the grids of valves 1 and 2 of Figure 5 and it will be observed that, due to the operation of the diode 5, the duration of the negative kick in potential of the grid of valve 2 when this valve is rendered non-conducting is reduced compared with the kick shown in Figure 4 which allows the valve 2 to be rendered conducting by the next triggering pulse if desired very shortly after the return to the stable state.

In the circuits described in Figures 1, 3 and 5 output pulses may bed taken from either the anode of the valve 1 or the anode of the valve 2. In the example shown in the drawings in which the anode of the valve 1 is coupled to the grid of the valve 2, the anode of the valve 2 can have any impedance in series therewith, particularly if the valve is a tetrode or pentode. In Figure 5 of the drawings it will be observed that the valves 1 and 2 are shown as pentode valves. In this case, if it is desired to generate pulses of a shorter duration than the unstable period of the generators, a short-circuited delay network may be included in the anode circuit of the valve 2, as indicated at 6 in Figure 5, the anode potential of the valve 2 then varying as shown in Figure 6.

Dated this 11th day of May, 1945.

F. W. CACKETT,

Chartered Patent Agent

COMPLETE SPECIFICATION

Improvements in or relating to Electric Oscillation Generators

We, ELECTRIC & MUSICAL INDUSTRIES LIMITED, a British Company, of Blyth Road, Hayes, Middlesex, ERIC LAWRENCE CASLING WHITE, a British Subject of St. Boniface, Richings Way, Iver, Buckinghamshire, and DOREEN WALKER, a British Subject, formerly Doreen Blumlein, of Lanheren, Lescudjack, Penzance, Cornwall, legal representative of ALAN DOWER BLUMLEIN, deceased, late a British Subject, of 32, Ardley Road, Ealing, W.5, do hereby declare the nature of this invention and in what manner the same is to be performed, to be particularly described and ascertained in and by the following statement:-

This invention relates to modifications of the electric oscillation generators described in the Specification of parent Patent No. 535,778.

In this specification various forms of electric oscillation generators or multi-vibrators are described comprising a first and second electron discharge valve each having a cathode, a control electrode and an output electrode, the valves being retroactively coupled together so that in operation said valves conduct alternately and generate relaxation oscillations, each cycle of which as tow portions, wherein coupling is effected through a first network between the output electrode of the first valve and the control electrode of the second valve and through a second network between the cathodes of said valves, the duration of each of said portions being determined by the time constants of circuits associated with said valves. With such a construction the valves conduct alternately and even though the first valve may be controlled by the application of suitable controlling impulses, said valve will nevertheless, change from one state to the other even though a controlling pulse is absent. The circuits described in the said specification possess many advantages over oscillation generators known at the date of said patent, but for certain purposes it may be desired to employ an oscillation generator in which a change from one state to the other can only be effected on application of a controlling impulse and it is the object of the present invention to provide modifications to the circuit arrangements claimed in the specification of Patent No. 535,778 for this purpose.

According to one feature of the present invention there is provided an electric circuit arrangement comprising first and second electron discharge valves each having a cathode, a control electrode and an output electrode, said valves being retroactively coupled together so that in operation said valves conduct alternately and generator relaxation oscillations, each cycle of which has two portions, wherein coupling is effected through a first network between the output electrode of the first valve and the control electrode of the second valve and through a second network between the cathodes of said valves, the duration of one of said portions being determined by the time constant of a circuit including capacity in said first network whilst the duration of the other of said portions is arranged to be controlled independently of said time constants that one of said portions is rendered stable, said second network including an impedance of impedances so disposed in the cathode circuits of said valves and of such value or values that in operation the flow of current between the cathode and control electrode of each valve is substantially prevented.

According to another feature of the invention there is provided an electric circuit arrangement comprising first and second electron discharge valves each having a cathode, a control electrode an output electrode, said valves being retroactively coupled together so that, in operation, said valves conductor alternately and generator relaxation oscillations, each cycle of which has two portions, wherein coupling is effected through a first network between the output electrode of the first valve and the control electrode of the second valve and through a second network between the cathodes of said valves, said second network including resistive impedances so disposed in the cathode circuits of said valves and of such value or values that in operation, the flow of current between the cathode and control electrode of each valve is substantially prevented, and the duration of one of said portions is determined by the time constant of a circuit including the resistive impedance in the cathode circuit of one of said valves and capacity connected between said cathodes and the duration of the other of said portions is determined independently of the time constant of said capacity and the resistive impedance in the cathode circuit of the other valve so that the last mentioned portion is rendered stable.

With such a construction the generator, according to the present invention, instead of having two unstable states has one stable and one unstable state, so that when the generator has been triggered from the stable to the unstable state and returns to the stable state, a change from the stable to the unstable state can only occur as a result of the application of a controlling pulse.

In order that the said invention may be clearly understood and readily carried into effect, it will now be more fully described with reference to the drawings accompanying the Provisional Specification, in which:-

Figure 1 illustrates a circuit arrangement embodying one form of the invention,

Figure 2 illustrates curves showing the voltages of various electrodes of the valves shown in Figure 1,

Figure 3 is a circuit arrangement of a further embodiment of the invention,

Figure 4 illustrates curves showing the voltages of various electrodes of the valves shown in Figure 3,

Figure 5 is a circuit arrangement of the embodiment shown in Figure 3, including a modification, and

Figure 6 illustrates curves showing the voltages of various electrodes of the valves shown in Figure 5.

Referring first to Figures 1 and 2 of the drawings, it will be seen that the circuit disclosed in Figure 1 is similar to the circuit of Figure 2 of the parent specification, elements in Figure 1 of the drawing which correspond to the elements of said Figure 2 having been given the same reference characters. In the circuit shown in Figure 1 the resistance R of the circuit of Figure 2 of the parent specification has been omitted and between the cathodes of the valves 1 and 2 a uni-directionally conducting device 3 in the form of a diode is connected, the anode of the diode being connected to the cathode of the valve 1 and the cathode of the diode being connected to the cathode of the valve 2. The circuit shown in Figure 1 operates in a manner analogous to the second type of operation described in the parent specification, and it is arranged that the bias potentials are such that when the valve 1 is conducting the diode 3 is also conducting. When the valve 1 is rendered non-conducting on the application thereto of a negative triggering pulse the diode 3 is also rendered non-conducting and the valve 2 rendered conducting, the operation of the circuit thereafter being similar to the described operation of the circuit of said Figure 2 as will be appreciated from the curves shown in Figure 2 of the drawings until the valve 1 is again rendered conducting. At this stage the cathode potential of valve 2 commences to drift downwardly and as described in the parent specification this downward drift continues until valve 2 becomes conducting. However, in the present invention due to the presence of the diode 3 the downward trend in potential of the cathode of valve 2 is arrested when this potential falls to a value such that the diode 3 is rendered conducting, which thus effectively prevents the valve 2 being rendered conducting. Thus, the valve 1 is maintained conducting and the circuit remains in such stable condition until the valve 1 is again rendered non-conducting on the application of a triggering pulse. The duration, therefore, of that portion of the cycle of operation during which the valve 1 is conducting is not determined by the time constant of R4 and C. If desired the valves 1 and/or 2 and the diode 3 may be arranged in a single envelope.

Figure 3 of the drawings accompanying the Provisional Specification illustrates a circuit arrangement similar to that shown in Figure 3 of the parent specification which is intended to operate in a manner similar to the first type of operation referred to in the parent specification.

In this case, the bias potentials applied to the control electrodes of the valves 1 and 2 are such hat vale 2 is normally non-0cnoduting and vale 1 conducting, the latter valve remaining conducting until the cycle is commenced on the application of a triggering pulse which renders the control electrode of valve 1 sufficiently negative to render the valve 1 non-conducting. If desired the grid leak R1 associated with the valve 1 to which the triggering pulses are applied may be shunted by a unidirectionally-conducting device shown as a diode 4 in Figure 3, so as to ensure that the valve 1 is rendered non-conducting by the use of a triggering pulse of positive polarity. Figure 4 illustrates the voltages of the control electrodes of valves 1 and 2 when the diode 4 is connected in the manner shown and when positive triggering pulses of the form shown in the Figure are applied through the input condenser shown to the control electrode of valve 1.

if the diode 4 is omitted the triggering pulses instead of being of positive polarity as shown in Figure 4 will required to be of negative polarity.

The arrangement shown in Figure 3 can be employed as a frequency divider for fairly low division-rations, e.g., 2:1, the circuit operating in a manner similar to that described in the Specification of Patent No. 456,840.

If desired the resistance R2 may be replaced by a valve which is normally arranged to be conducting, the circuit being then triggered to cause valve 1 to be rendered non-conducting by monetarily interrupting the current passed by the valve which replaces the resistance R5 by the application of a negative triggering pulse to its control electrode.

Figure 5 of the drawings accompanying the Provisional Specification illustrates a circuit similar to that shown in the Figure 3 of the drawings accompanying the Provisional Specification, in which the stability of the period of the unstable portion of the cycle of operations is improved by biassing the control electrode of the valve 2 through a unidirectionally-conducting device shown as a diode 5. The lower end of the grid leak R2 is connected to a point of lower potential than the anode of the diode 5. With this construction the diode 5 can be arranged to conduct after the change of valve 2 to the non-conducting state, in order to discharge condenser C1 as quickly as possible so that the circuit is again sensitive to a triggering pulse sooner than would otherwise be the case. Figure 6 illustrates the voltages of the grids of valves 1 and 2 of Figure 5 and it will be observed that, due to the operation of the diode 5, the duration of the negative kick in potential of the grid of valve 2 when this valve is rendered non-conducting is reduced compared with the kick shown in Figure 4 which allows the valve 2 to be rendered conducting by the next triggering pulse if desired very shortly after the return to the stable state.

In the circuits described in Figures 1, 3 and 5 output pulses may be taken from either the anode of the valve 1 or the anode of the valve 2. In the example shown in the drawings in which the anode of the valve 1 is coupled to the grid of the valve 2, the anode of the vale 2 can have any impedance in series therewith, particularly if the valve is a tetrode or pentode. In Figure 5 of the drawings it will be observed that the valves 1 and 2 are shown as pentode valves. In this case, if it is desired to generate pulses of a shorter duration than the unstable period of the generators, short-circuited delay network may be included in the anode circuit of the valve 2, as indicated at 6 in Figure 5, the anode potential of the valve 2 then varying as shown in Figure 6.

Having now particularly described and ascertained the nature of our said invention and in what manner the same is to be performed, we declare that what we claim is:-

  1. An electric circuit arrangement comprising first and second electron discharge valves each having a cathode, a control electrode and an output electrode, said valves being retroactively coupled together so that in operation said valves conduct alternately and generate relaxation oscillations, each cycle of which has two portions, wherein coupling is affected through a first network between the output electrode of the first valve and the control electrode of the second valve and through a second network between the cathodes of said valves, the duration of one of said portions being determined by the time constant of a circuit including capacity in said first network whilst the duration of the other of said portions is arranged to be controlled independently of said time constant so that one of said portions is rendered sable, said second network including an impedance or impedances so disposed in the cathode circuits of said valves and of such value or values that in operation the flow of current between the cathode and control electrode of each valve is substantially prevented.
  2. An electric circuit arrangement comprising first and second electron discharge valves each having a cathode, a control electrode and an output electrode, said valves being retroactively coupled together so that, in operation, said valves conduct alternately and generate relaxation oscillations, each cycle of which has two portions, wherein coupling is effected through a first network between the output electrode of the first valve and the control electrode of the second valve and through a second network between the cathodes of said valves, said second network including resistive impedances so disposed in the cathode circuits of said valves and of such value or values that, in operation, the flow of current between the cathode and control electrode of each valve is substantially prevented, and the duration of one of said portions is determined by the time constant of a circuit including the resistive impedance in the cathode circuit of one of said valves and capacity connected between said cathodes and the duration of the other of said portions I determined independently of the time constant of said capacity and the resistive impedance in the cathode circuit of the other valve so that the last mentioned portion is rendered stable.
  3. An electric circuit arrangement according to Claim 1, wherein said valves have a common cathode impedance and the difference is the bias potentials applied to said valves is so great that said portion is rendered stable.
  4. An electric circuit arrangement according to Claim 2, wherein said capacity is arranged in parallel with a uni-directionally-conducting device which is arranged to conduct at an appropriate time to render said portion stable.
  5. An electric circuit arrangement according to Claim 1 or 2 substantially as described and as shown in Figure 1, 2 or 3 of the drawings accompanying the Provisional Specification, or substantially as described.

Dated this 9th day of May, 1946.

F. W. CACKETT,

Chartered Patent Agent.

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Leamington Spa: Printed for His Majesty’s Stationery Office, by the Courier Press. - 1948.

Published at The Patent Office, 25, Southampton Buildings, London, W.C.2, from which copies, price 1s. 0d. each (inland) 1s. 1d (abroad) may be obtained.