US2207055A - Switching circuit - Google Patents

Description

July 9, 1940.

G. G. GOODLING, JR El- AL SWITCHING CIRCUIT Filed May 28, 1937 w ll fil BH W! kh .QQI Lw mm mam v $5 m uwe oh h ww M a mi N. V X 0. kmfikouhk a a M m a PM M H w L M N J v M 9 wk s ufi m\ r (Titorneg Patented July'9, 1940 SWITCHING CIRCUIT George G. Goodling, Jr.', Woodlynne, and Arthur C. Stocker, Haddon Heights, N. J., assignors to Radio Corporation of America, a corporation of Delaware Application May 28, 1937, Serial No. 145,394

6 Claims.

Our invention relates to switching devices, and particularly to means for actuating a plurality of switches in sequence.

The most common way of actuating several switches in a desired sequence is to employ a motor driven cam which closes or opens the switches in succession mechanically. For many applications this is undesirable because of the resulting noise, vibration, etc.

It is, accordingly, an object of our invention v to provide an improved method of and means for actuating a plurality of switches or the like in succession.

It is a iurther object of our invention to provide improved apparatus free from rotating parts for actuating a plurality of switches successively.

It is a still further object of our invention to provide improved means for connecting a plurality of circuits successively to another circuit.

In the preferred embodiment of our invention, a plurality of vacuum tubes are employed, each tube having in its plate circuit a relay winding and associated switch arms. In the input circuit of each tube there is a condenser so connected through one of the switches in the preceding plate circuit that it' may charge up to block the tube, this action taking place when the relay in the said preceding plate circuit is deenergized. If this relay is energized, the condenser is discharged whereby the said tube is unblocked as soon as the relay next becomes deenergized.

The vacuum tubes are connected in what may be referred to as back-to-back relation, the plate circuit of each tube being connected to the input circuit of another tube. Thus, once" the switching operation is initiated, it continues without interruption. I

The invention will be better understood from the following description taken in connection with the accompanying drawing in which the single figureis a circuit diagram of a preferred embodiment of the invention.

Referring to the drawing, it will first be explained just what switching operations are desired. For the purpose of illustration, it is assumed that three crystal controlled oscillators (not shown), which are identified as oscillators #1, #2 and #3, are to be connected successively to a recorder indicated at Thus the crystals of the three oscillators may be placed in an oven and their temperature-frequency characteristics recorded on a single recorder.

.Oscillator #1 is connected to a switch arm l which may be connected to the recorder I V ounded contact point through a contact point H and a conductor l2. Oscillator #2 is connected to a switch arm i3 which may be connected to the recorder through a contact point I4 and the conductor l2. Oscillator #3 is connected to a switch arm |6 which may be similarly connected to the recorder I through a contact point I! and the conductor |2.

Reference will now be made to the circuit for operating switches l0, l3 and I6 in sequence. It

includes three electric discharge tubes |8, I9 and 2|] which may be of the high vacuum type. These tubes have indirectly heated cathodes 2|, 22 and 23 which are connected t9 ground.

Considering first the connections for the tube |9, this tube has a control grid 24 and a plate 26. The grid 24 is connected through a grid leak resistor 21 to a point on a voltage divider 28 which is negative with respect to ground. The

grid 24 is also connected to a contact point 29 associated with a switch arm 3|. A condenser 32 is connected between the switch arm 3| and ground.

When the switch arm 3| is in the lower position, it connects condenser 32 between the grid 24and ground whereby the potential applied to grid 24 is the voltage across condenser 32. Also, when switch arm 3| is in this position, the condenser 32 is being charged from the voltage source across voltage divider 28. Eventually, condenser 32 will apply such a negative potential to grid 24 that the tube l9 will be blocked.

When'the switch arm 3| is in the upper position, it short-circuits condenser 32 through a I 33, thus discharging the condenser.

The switch arms in and 3| are pulled to their upper positions simultaneously by a relay wind-v ing 34 when. it is energized. When relay winding 34 is deenergized, the switch arms In and 3| drop to their lower positions.

v relay winding 36, as shown. Similarly, plate voltage is applied to the plates 38 and 39 of tubes |8 and 2|), respectively, through the relay winding 34 and a relaywinding 4|, respectively.

The control grid 42 of tube 20 is connected through a grid leak resistor 43 to a point. on the 'voltage divider 44. Grid 42 is also connected to a contact point 46 with which the switch 3'! makes contact in its lower position.

Between the switch arm 31 and ground there is connected a condenser 57 which is charged through the grid resistor 43 to block the tube 212. When switch arm 31 is pulled to the upper position, it strikes-a grounded contact point 48 and the condenser 47 is discharged. The relay winding 38 and its associated switch arms l3-and 34 function the same as the previously described relay 35, H3, in.

A starting key 39 is connected to the input circuit of one of the vacuum tubes, tube in the circuit illustrated, for unblocklng a tube to initiate the circuit operation as will lee described hereinafter.

The control grid 5! of tube it is connected through a grid leak resistor 52 to a point on a voltage divider 53. The grid id is also connected through a conductor 5 to a contact'point 56 associatedwith a switch arm 5']. A condenser 53 is connected between the switch arm 57 and ground.

The switch arm 5? makes contact with the grounded contact point '59 in its upper position.

The switch arms it and 5'! are pulled upward simultaneously by the relay coil dl when it is energized.

From the foregoing description it will be seen that the switch in each input circuit which controls the charge of the input circuit condenser is actuated by the current flow in the preceding tube. Thus, the condition of one tube determines the operating condition of the next following tube.

The operation of the circuit will be better understood by following through one complete cycle of operation. When the circuit is in its normal inactive state, as illustrated in the drawing, each vacuum tube is blocked, that is, the condensers l2, l1 and 58 are fully chargedv and apply suiliciently negative potentials to the control grids for biasing the tubes substantially to plate current cut-off. Therefore, all the relay switch arms are in their lower position.

To start the switching operation, the starting key 49 is closed momentarily, thus connecting the control grid .42 to ground and at the same time discharging the condenser 41. As a result, the tube 20 is unblocked and the relay coil ll pulls up the switch arms l6 and 51 to connect oscillator #3 to the recorder l and to discharge condenser 5:. These switch arms are held in their upper position until tube 20 is again blocked, this blocking action taking place aiter a certain period, since condenser 41 is being charged through the grid leak resistor 43. from the voltage source 44. The time required for charging condenser, to a voltage which blocks the tube 2! is determined by the time constant of the charging circuit for this condenser. Because of this, it is a simple matter to control the length of time that oscillator #3 is connected to the recorder.

As soon as tube 20 blocks, the switch arms I and 51 drop to their lower position whereby the control grid of tube I I is connected substantial- 1y to ground through the conductor 54 and the discharged condenser 58. .This unblocks the tube II and the relay coil 34, pulls up the switch arms II and 3|, thereby connecting oscillator #1 to the recorder and discharging condenser 32. Thwe switch arms are held in their upper position until tube It is again blocked, the time required for this depending upon the time constant of the circuit through which condenser 50 is being charged,

As soon as the tube 18 again blocks, the switch arms I. and II fall to their lower position, thereby connecting the discharged condenser 32 to the control grid oi tube I9 to unblock this tube and energize the relay coil 36. The switch arms l3 and..31 are then pulled to their upper position ,sition whereby the control grid of tube 20 is'conr'iected to ground through the discharged eondenser M to unblock the tube 20. The cycle or" operation is now repeated audit continues until the action is stopped by breaking a circuit, removing voltage from a tube, or the like.

It may be noted that any suitable voltage sources such as batteries or socket power units may be employed for supplying the'plate and biasing Voltages. If socket power units are employed, voltage should not be applied to the plates of the tubes until the voltage supplied by these units has reached a stable value because abnormally'high voltages will start the circuit in operation before the starting key is closed.

It will be apparent that our invention may be employed for switching any number of circuits in sequence by employing any number of tubes.

so long as at least two tubes are employed.

We claim as our invention: I 1. In combination, a plurality of vacuum tubes each having at least three electrodes including a control electrode, a plurality of relays, each relay comprlsing a relay coil and a switch, each of said tubes having-an input circuit including a control electrode and a plate circuit, said tubes being connected in cascade relation through said relays, each relay having its coil in the plate circuit of one tube and its switch in the input potential to its control electrode and for causing it normallyto be blocked, and means for causing said tubes to unblock in succession in response to the unblocklng of a certain one of said tubes,

said tubes in cascade being connected in a closed control electrode, and each tube having a plate circuit including a relay winding, each tube having means including a switch in its input circuit for blocking the tube in response tothe'switch being moved to one position, said tubes being connected in cascade relation with the relay winding of one tube positioned to actuate the switch in the input circuit of a succeedingtube. the relay winding of the last tube being positioned to actuate the switch of the first tube, and means including said relaywindings and switches for unblocking a tube in response to the blocking of a preceding tube, said tubes in cascade being connected in a closed circuit or back-'to-back relation with a relay having its coil in the plate circuit of the last tube and having its switch in the input circuit of the first tube.

3. Switching apparatus comprising a plurality of electric discharge tubes each having an input circuit and an output circuit and each having a cathode and a grid, a relay winding donnected in each of said plate circuits, each of said input circultsincluding a condenser and means for charg--' circuit of a succeeding tube, and means in'the input circuit of each tube for applying a negative,

is applied between the cathode and the grid of the associated tube the said associated tube is blocked, switching means in each of said input circuits for discharging the condenser therein in response to energization of the relay winding in the next preceding plate circuit, and means in each of said input circuits for connecting the condenser therein between the cathode and the grid of the associated tube and in series with said charging means in response to the energization of the relay winding in the next preceding plate circuit.

4. A plurality of vacuum tubes each having a cathode,-a control grid and a plate circuit each of said tubes having a source of voltage and a. grid resistor connected between the cathode and the grid with the polarity of said source such as to make the grid negative, each of said tubes having a condenser and a switch connected in series between the cathode and the grid whereby the voltage across the condenser is applied to the grid when the switch is closed, a relay winding in each of said plate circuits, each relay winding being so associated with the switch in the next succeeding input circuit that said switch is closed in response to the deenergization of the associated relay winding, and means for discharging each of said condensers in response to the energization of the relay winding in the next preceding plate circuit.

5. A switching circuit comprising a plurality of vacuum tubes each having a plate circuit and a grid circuit, each of said grid circuits including a cathode and a grid, a relay winding in each of said plate circuits, a switch in each of said grid circuits, the relay winding in the plate circuit of each tube being positioned to actuate the switch in the grid circuit of a difierent-tube, means in each of said grid circuits including a condenser for blocking the tube in response to the switch in the grid circuit of that tube resting in one position for a predetermined time, the condenser in each of said grid circuits having one terminal connected to the cathode of its grid circuit and having the other terminal connected to the grid of the grid circuit through the switch in its grid circuit, and means for discharging the condenser in the grid circuit of that tube in response to said switch moving to a different position.

6. Switching apparatus comprising a plurality of vacuum tubes each having an input and an output circuit, a relay winding in each output circuit, contacts operated thereby to perform useful switching of external circuits, and other contacts operated thereby to perform switching in the input circuit of the succeeding tube, said input circuit comprising a grid connected through a resistor to a source of bias voltage sufiicient to succeeding tube, and connected block said through said input circuit switching contacts to a condenser, said input circuit switching being so arranged that upon energization of the relay coil said condenser is disconnected from said succeeding grid and connected to a potential nearer that of the cathode of said succeeding tube, said con; denser being thereby somewhat discharged Without altering the operating condition of said succeeding tube, and further, said input switching being so arranged that, upon deenergization of u the relay coil, said condenser is disconnected from said potential and reconnected to the grid of said succeeding tube, said grid being thereby transferred to said potential permitting unblocking of said succeeding tube and consequent energization of the relay winding in its output circuit, said unblocking remaining in eifect during the time required to recharge said condenser through said grid resistor. I

GEORGE G. GOODLING, JR.

ARTHUR C. STOCKER.

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