US2526003A - Polar locking circuit - Google Patents

Description

Oct. 17, 1950 A. E. CANFORA POLAR LOCKING CIRCUIT Filed May 12, 1945 our/=07 WZN .l' 5/6/5441. I i WPUT :EOUTPUT iii INVENTOR. Aer/m f. CA/VFORA BY Patented Oct. 17, 195

2,526,003 POLAR LOCKING omourr Arthur E. Canfora, Brooklyn, N. Y., assignor td Radio Corporation of America, a corporation of Delaware Application May 12, 1945, Serial No. 593,502

2 Claims.

This invention relates to locking circuits.

More particularly my invention relates to a circuit arrangement of the type which employs a triode discharge tube and a pentode discharge tube suitably interconnected so that the triode tube may be held conducting or non-conducting by varying its grid voltage while the pentode tube is controlled by varying its screen grid voltage between positive andnegative values. The controlling input signal is preferably applied to the control grid of the pentode tube, either directly or through a suitable condenser. i

Locking circuits as heretofore known commonly employ two voltage dividers, one connected from the anode of a first tube to a point of potential below the cathode of the second tube, a tap being taken off of this voltage divider and connected to the control grid in the second tube. The second voltage divider is like the first except that it is connected between the anode of the second tube and a potential below that of the cathode in the first tube. A tap on this second voltage divider is connected to the control grid of the first tube. In such an arrangement the ohmic values of the resistors involved in the voltage dividers must be held within a close percentage of the prescribed values if the proper circuit operation is to be obtained. This fact, therefore, necessitates the anticipation of any temperature changes to be encountered under operating conditions.

In the conventional locking circuit both anodes L wherein a pentode tube and a triode tube are used,

in combination with suitable circuit components for carrying out theinvention.

Referring to the drawing, I show therein a pentode discharge tube l and a triode discharge. In the pentode tube I show a cathode 3 connected to ground, a control grid G to which.

tube 2.

signal input voltages may be applied, a screen grid 5 and a suppressor grid 6, the latter being.

connected directly to the cathode 3.

The anode l of the tube I is connected through an anode resistor 8 to the positive terminal of a In order to overcome the difiiculties heretofore encountered as indicated in the foregoing paragraphs, I have found it possible to design a looking circuit having only one voltage divider, the respective values of its sections being less critical for proper operation of the circuit than was heretofore considered necessary.

I also have found it possible to obtain two sets of outputs from the anodes, one set of which varies between potentials which are above below the common ground potential. I

It is, therefore, an objectof my invention to provide a simply designed locking circuit having features which relieve it from the necessity for critical adjustment of its components.

It is also an object to obtain an output which varies from a point above to a point below the common ground potential.

It is another object of my invention to provide a dependable polar locking circuit for use in signaling and in other applications.

My invention will now be described in more detail, reference being made to the accompanying drawing the sole figure of which represents illustratively a preferred circuit arrangement and tentials, one of which direct current source, one section of which is indicated atS. Another section of this source I0 is in series with section 9 and has its negative ter minal connected to ground.

In the tube 2, I show a cathode H, a control grid l2 and an anode 13. The cathode l l is maintained at a negative potential with respect to ground, the bias voltage being suppiiedby a direct current source 14. Another biasing source I5 is connected between the cathode Ii and the control grid [2, a resistor l6 being interposed between the negative terminal of the source l5 and the grid l2. The grid i2 is also connected to the anode l in tube I through. a resistor ll. The two resistors 16 and I1 constitute a voltage divider which provides interaction between the pentode tube and the triode tube.

The anode I3 is connected through a resistor It to the junction between the two direct current source sections 9 and Ill. The anode I3 is also directly connected to the screen grid 5 in tube l.

Shown also are output terminals i9 and 20. Terminal i9 varies between two potentials above ground while terminal 20 varies between two pois above and the other below ground.

Before proceeding with an explanation of how the circuit operates, it should be pointed out that one of the well known characteristics of pentode tubes is that even with a negative screen voltage the tube may still be rendered conductive, provided the control grid is driven sufiiciently positive with respect to the cathode. The anode of course, must be maintained at a positive potential in order to produce a conductive state.

I will now show why it is unnecessary to fix the values of the respective elements 16 and ll with great exactitude in order to maintain suitable operating conditions for the circuit. The diiferent kinds of outputs from the two anodes will also be explained.

Assume first that tube l is normally conductive in the absence of a signal potential. The voltage drop through the voltage divider #1, i6 is such as to maintain a negative voltage on grid [2 inthe trio-de tube 2 so that this tube is biased to cutoff, especially since a negativegrid bias. is afforded by the C-battery [5. The anode l3 and the screen grid 5, being interconnected, are both maintained at a relatively high positive potential. The conductive state in tube I and the non-conductive state in tube 2 may, therefore, be said to be relatively stable.

This condition makes available two different anode voltages. One from anode l is the direct current source lD-l-S minus the IpRfl drop in 9 where I1) is the pentode tube current. subtracted from 3+9 is also IdRi where Id is the current flowing through the divider i0, H. The other output from anode I3 is the direct current source 10 minus IsRlS where Is is the pentode screen current. Both of these outputs are at a potential above ground.

Now assume that a signal potential is applied in suificient magnitude and negatively to the control grid 4 with respect to the grounded cathode 3. The pulse so applied need be of only momentary duration in order to reverse the conductive states in the two tubes. Tube 1 being now blocked, its anode voltage rises substantially to the voltage at the posit ve terminal of the source 9. A positive increment of voltage is, therefore, applied to the control grid I2 in the triode tu e 2 which is sufiicient to render the grid i2 more positive than the cathode N. This drives the tube 2 conductive and at the same time lowers the screen grid voltage 5 in tube i. In this state the potential of the anode i3 and of the screen grid 5 is so far reduced that it is negative with respect to ground. This negative screen potential prevents tube from conducting.

In this condition the out uts are as fol ows: Terminal i9 is at a potential eoual to the direct current sources 9+"! minus the IdRS drop in resistor 8, and the terminal 20 is at a potential equal to the direct current source E minus the l'zPuia drop, where I2 is the triode plate current. This output potential is actua ly more negat ve than ground while the output at terminal 19 is above ground.

The locking circuit as herein shown and described the efore fulfills the following conditions: The potential of the anode 7 in tube is shifted between two posit ve va ues with respect to a certain reference potential, while the anode H3 in tube 2 is shited from positive to negati e values with respect to such a reference potential.

It should be understood that the input control signal could be applied to the grid :12 in the triode tube 2 if so desired. In fact, controll ng signals of the same polarity could be applied alternately to grids 4 and 12 in the pentode and triode tubes res ectively.

Mv invention is capable of modification in various ways, as will be well understood by those skill d in the art.

I claim:

1. In a locking circuit, two electron discharge tubes at least one being of the multi-grid tyne with a screen grid and both having a. control grid, a cathode and an anode, a first direct current potential source connected between the anode and cathode of said multi-grid tube, an impeder in said connection between the anode of the multi-' grid tube and said source, a second direct current potential source of less positive value connected between the anode and cathode of the other tube, an impeder in said connection between the anode of the other tube and said second source, a connection between the cathode of said multi-grid tube and a point on said second source which is positive with respect to the cathode of said other tube, whereby the anode and cathode of said multi-grid tube are normally more positive respectively than the anode and cathode of said. other tube, a direct current potential divider including at least two impeders in shunt to said first direct current source, a connection between a point on said potential divider between said two lastnamed impeders and the control grid of said other tube, a direct connection between the anode of the other tube and the screen grid of the multigrid tube, means for applying signals to the control grid of one tube, and means for deriving output from the anode of one or the other tube.

2. In a locking circuit, two electron discharge tubes each having a cathode, an anode and a control grid, one of said tubes also having a screen grid, means for causing said one tube to be conductive while causing the other tube to be cut-oil, said means including a source of direct current potential connected between the anode and cathode of said one tube with its positive terminal toward the anode of said one tube, a resistor in the connection between said source and the anode of said one tube, a resistor connecting a positive point on said source to the anode of the other tube, connections to said source for maintaining the cathode of the other tube negative relative to the cathode of the fi st tube, a direct current potential divider includin series resistances connected indirectly across said source, a connection between a point on said divider between said series resistances and the control grid of the other tube such that a reduction of direct current potential on the anode of said one tube applies a more negative bias to the control grid of the other tube, means including a direct current connection between the screen grid of the said one tube and the anode of the other tube for holding said screen grid at a relatively high positive direct current potential when said one tube is conductive and said other tube is non-conductive and for materially reducing the potential on said screen grid when said other tube is conductive and said one tube is non-conductive, and means for applying signal pulses to the control grid of said one tube, the arrangem nt being such that the potential on the anode of said screen grid tube varies with respect to a positive value and the potential on the anode of said other tube varies plus and minus with respect to a base value as said locking circuit is tripped.

ARTHUR E. CANFORA.

REFERENCES CITED The following references are of record in the file of this patent:

.UNITED STATES PATENTS Number Name Date 1,978,461 Hoover et al Oct. 30, 1934 2,050,059 Koch Aug. 4, 1936 2,071,759 Minorsky Feb. 23, 1937 2,250,202 Matusita July 22, 1941 2,354,930 Stratton Aug. 1, 1944 2,431,591 Snyder, Jr., et al. Nov. 25, 1947 2,434,916 Everett Jan. 27, 194.8

OTHER REFERENCES Electrical Counting (1943) by Lewis, The Mac- Millan Co., New York.

Time Bases, by O. S. Puckle, October 1943, John Wiley & Sons.

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