US2021766A - Electronic timer - Google Patents

Description

Nov. 19, 1935. M'. E. BIVENS ELECTRONIC TIMER Filed June 28, 1934 5 Sheets-Sheet 1 FigJ.

Inventor: Maurice EBivens.

X7 (f-fiumiam His ttor'nezg.

Nov. 19, 1935. M, E BWEN 2,021,766

ELECTRONIC TIMER Filed June 28, 1954 5 Sheeis-Sheet 2 2 l8 oPEFAnou RESET Inventor.

Maurice E. Bivens.

HIS Abborne u Nov. 1 1935.

M. E. BIVENS ELECTRONIC TIMER Filed June 28, 1934 5 Sheets-Sheet 5 V Y e WW m mm WIS Hm WNH Nov. 19, 1935. M, E, BNEN 2,021,766

ELECTRONIC TIMER Filed June 28, 1954 5 SheetsSheet 4 57 58 Hi F210 '77 O A n 27 6%; as Y 7 J L3 L4 as 55 L La .51?

fayig -19 I2, 76

Irfiventor:

Maurice E. BiVeF-WS,

Nov. 19, 1935. M. E. BIVENS ELECTRONIC TIMER Filed June 28, 1934 5 Sheets-Sheet 5 Fig. l5.

Inventor" Maurice IiBivens,

by His Attorney,

Patented Now-19,1935

UNITED STATES ELECTRONIC rm Maurice E. Bivens, Media, Pa., assignor toGeneral Electric Company, a corporation of New York Application June as, 1934, Serial No. 732,827

16 Claims. (01. 175-183) My invention relates to timing devices and concerns particularly electronic timers for checking relay operations.

It is an object of my invention to provide an inertialess device for measuring extremely short, as well as longer, intervals of timewith accuracy.

It is a further object of my invention to provide a device which may be set.for measuring not merely the time interval between the opening and closing of an electrical contact or vice versa but also the time interval between the opening or closing of one electrical contact and the opening or closing of another electrical contact.

The objects of my invention include providing a relay timer for measuring both total time, open or closed, as well as the operating time of either normally-open or normally-closed relays either when energized or when deenergized.

Other and further objects and advantages will become apparent as the description proceeds.

In accordance with my invention in its preferred form, I determine the time required for the consummation of an operation by determine ing the amount of charge supplied to a timing condenser through a constant-current circuit during the operation. Preferably, I supply inertialess means, such as grid-controlled discharge tubes, for controlling the starting and stopping of the charging current at the beginning and the end of an operation to be measured. The

discharge tubes are connected in parallel circuits with resistors in their anode leads or source of current. Current is initiated in one tube at the beginning of a time interval to be measured and shifted to the other at the end of the interval by controlling potential of the control grids in response to operations to be timed. In consequence, a potential difference is built up and then reversed between the tube anodes. A timing condenser in series with a constant-current rectifier is connected between the anodes of the discharge tubes and receives charging current only during the time interval. The voltage acquired by the timing condenser is compared with; a measurable voltage to determine the. length' of the time interval. Changeable connections are provided to permit connecting a relay to be tested in the apparatus in difierent ways with respect to the control grids of the tubes for the purpose of checking different types of relay operations.

The features of my invention which I believe to be novel and patentable will be pointed out in the claims appended hereto. A better understanding of myinvention, itself, however, may be obtained by referring to the following description taken in connection with the accompanying drawings- I Fig. 1 of the drawings is a circuit diagram of an embodiment of my invention; Fig. 2 is a simplified diagram of a portion of the apparatus of 5 Fig. 1 showing the circuit made when the apparatus is set for adjusting the charging current of the timing condenser; Fig. 3 is a symbolic op:- eration diagram showing the manner in which the apparatus is manipulated to obtain the cirl0 cuit of Fig. 2 and to adjust the condenser-charging current; Fig. 4 is a simplified circuit diagram of the apparatus set for testing theclosing of the contacts of a relay when the relay is energized; Fig. 5 is the circuit diagram of the setting 15 for measuring the charge collected by the timing condenser to determinethe operating time of the relay; Fig. 6 is a symbolic operating diagram of the manipulation of the apparatus for timing the operation of a relay when energized. Simplified 20 circuit diagrams of the apparatus set for timing some other types of relay operations are shown in the following figures: Fig. 7, relay with circuit- I opening contacts when energized; Fig. 8, relay with circuit-closing contacts when deenergized; 25 Fig. 9, relay with circuit-opening contacts when deenergized; Fig. 10, operating time of relay with circuit-closing contacts when energized including summation of opening time intervals of bouncing contacts, or duration of one or more intervals 3 with contacts open; and Fig. 11, duration of one or more intervals with contacts closed. Figs. 12,

13 and 14 are symbolic operating diagrams representing themanipulation of the apparatus respectively for testing the operation of a relay 35.

when deenergized, for measuring the duration of one or more intervals with contacts open, and for measuring the duration of one or more intervals with contacts closed. Fig. 15 is a simplified circuit diagram of the apparatus set for tim- 40 ing the first only of a series of contact closures. Referring now more in detail to the drawings in which like reference characters are used to designate like parts throughout, in Fig. 1, a relay tobe tested is shown at H with a movable con- 45 tact I2 and stationary contacts 13. The timing apparatus includes a timing condenser H, a constant-current tube l5 connectible in series with condenser i4, and a pair of grid-controlled discharge tubes IB and H for controlling the charg- 50 ing of condenser I4. Switches l8 and it! are provided for operating the apparatus to test a relay, and a switch 20 is provided for changing the circuits of the apparatus for adjusting, relay testing, or reading in a manner which will be explained hereinafter. A plurality of connection posts or terminals 2| to 33, 91 and 98, adapted to be joined by connecting links or leads are provided for reconnecting the apparatus to make different types of time measurements or for test-' ing different types of relay operations also in a manner to be explained. Current is supplied to the apparatus from a suitable source through terminals 34 and 35.

If desired, the range of the apparatus may be extended by connecting a second condenser 36, preferably of different capacity, in series with condenser I4 and either connecting a jumper from terminal 33 to one of the terminals 3I or 32 to short out one of the condensers or leaving the condensers in series to obtain different values of capacity.

The constant-current tube I5 may be of any desired type, such'as a three-element vacuum tube having an anode 31, a filamentary cathode 38, and a grid 39 which may be tied to the oathode 38 or to a point 48 slightly more positive.

The cathode 38 is heated by a current source 4I,.

and its emission is controlled by a rheostat 42. The tube I5 is operated in the saturated portion of its characteristic curve so that the entire filament emission is attracted by the anode and the current remains substantially constant regardless of variations in anode voltage within the operating range.

The discharge tubes I6 and Il may, if desired,

be of the gas or vapor-filled discharge type and are provided with anodes 43 and 44, cathodes 45 and 46, and control grids 41 and 48. The anodes 43 and 44 are connected through resistors 48 and 58 to terminal 34 of source 34--35, and the oathodes 45 and 46 are joined and connected through a resistor 5| to one terminal of switch I8, which is interposed between resistor 5| and terminal 35 of source 34-35. The grid 41 is connected to the common terminal of resistor 5I and switch I8, and the grid 48 is connected through a resistor 52 to the live terminal of switch I8 or terminal 35 of source 34-35. Preferably, a condenser 53 is connected between cathode 46 and grid 48 to hold grid 48 negative for an instant and prevent tube I! from firing when switch I8 or I8 is closed. A condenser 54 is connected across the ends of resistors 49 and 58 to depress the anode potential of either tube I6 or I! when the other is made conducting and to facilitate shifting current from tube I6 to tube I1 and vice versa, as will be explained.

A thermionic voltmeter for measuring the charges accumulated by condenser I4 is also provided, including a three-element discharge tube 55, a plate milliammeter 56, potentiometers 51 and 58, and a comparison voltmeter 59, which may, of course, be calibrated directly in milliseconds.

The switch 28 has three positions indicated by the positions I, 2 and 3 of the handle 58 by means of which the movable contacts may be moved upward for position I or downward for position 3, as is apparent from the drawings. In order to adjust the charging current of condenser I4, the switch 28 is moved to position I or the adjusting position; before timing a relay, switch 28 is-moved to position 2 or the testing position; and for reading the length of the time interval measured in the testing position, the switch 28 is moved to position 3 or the checking position.

When switch 28 is moved to the adjusting position I, its movable contact 6| is lifted, breaking the charging circuitfrom terminal 34 and resistor 58 to timing condenser I4, and contacts 82, 63 and 64 are lifted against corresponding stationary contacts to' form-a circuit from terminal 34 of current source 34-35 through conductor 65, resistor 58, conductor 66, contact 63, milliammeter 56, contact 62, conductor 61, contact 64, conductor 68, constant-current tube I5 (through electrodes 31 and 38), discharge tube I6 (through electrodes 43 and 45), resistor 5|, switch I8, conductor 69, to terminal 35 of source 34-35. For 10 convenience this circuit has been redrawn as Fig.2, showing only the portion of the apparatus included in the circuit. It will be observed that the lifting of contact 64 also shorts out the timing condenser I4 (or 36) by closing a connection 15 across the condensers through a conductor I8,

contacts II, 64, I2 and conductor I3. The desired charging-current adjustment is obtained by adjusting the emission of tube I5 by means of rheostat 42 until thetube passes the desired cur- 2" rent as indicated by the milliammeter 56.

The manner of manipulating the apparatus to adjust the value of charging current is shown symbolically in Fig. 3, in which the switches I8,

I9 and 28, the rheostat 42, and potentiometer 51 15.", are represented schematically by means of theirv operating handles or control dials. The switches I8 and I9 are open when the handles of switches I8 and I9 are down, and closed when their handles are up. Likewise, the positions marked I, 2,

and 3 are the positions of handle 68 of switch 28 for the current-adjusting, testing and reading positions, respectively. As indicated in Fig. 3, before the charging current adjustment is made, switches I8 and I9 are in their open positions, :1 and switch 28 is in position I. The letters a, b, 0 along the bent arrow I4 which rises along the slot for the handle of switch I8 and then points toward the control dial of rheostat 42, indicate that in adjusting charging current, first switch 40 I8 is moved from the open to the closed position (operation a), then the rheostat 42 is adjusted (operation 1)), and finally the switch I8 is returned to the open position (operation 0) Since change of position or adjustment of switches I8 45 and I9 and potentiometer 51 is not required during the adjustment of charging current, no arrows are shown in Fig. 3 along the symbols for these elements of the apparatus.

To time a relay with circuit-closing contacts, 50 when energized, the relay II is connected as shown in Figs. 1 and 4 with the lower blade and stationary contact I5 0f double-pole switch I9 interposed in the circuit to the exciting winding of relay I I from a source of current IS. The 5 switch 28 is moved to position 2 and the circuit of Fig. 4 results, as will now be explained.

Referring to Fig. 1, condenser I4 and constantcurrent tube I5 are connected in series across the ends of resistors 49 and 58 in a circuit compris- 60 ing conductor 66, contacts 6|, conductor 61, contacts l2, conductor 13, timing condenser I4 (assuming that the alternative timing condenser 36 is shorted out by means of a jumper across its terminals 32 and 33), conductor I8, contacts 1|. 5 conductor 68, anode 31 of tube I5, its cathode 38, and conductor 11. A plate circuit for thermionic voltmeter tube 55 is formed from terminal 34 of source 34-35, through conductor I8, contacts 63, milliammeter 56, contacts 62 and I9, anode 88 of tube 55, cathode 8I to tap 82 of potentiometer 58. A grid circuit is also formed from grid 83 of tube 55, through contacts 84 and 85, and conductors 86 and 68 to terminal 35 of source In timing the relay, after switch 28 has been moved to position 2 to give the circuit of Fig. 4,

switch I! is closed. This simultaneously energizes relay II by closing contacts 13, and energlzes discharge tube It by closing contacts 81 oi switch l8. In the specific embodiment of my invention illustrated in the drawings, the arrangement is such that I prefer to employ at both l8 and il tubes having negative grid-control characteristics, i. e., they are conductive when the grid voltage is less negative than a given value. When switch I8 is closed, the negative charge on condenser 53 holds the potential of grid 48 below the critical value for a sumcient length of time to prevent tube ll from becoming conducting and permitting tube 16 to become conducting.

Accordingly, current flows from terminal 34,-

through conductor 85, resistor 48, conductor 1-1, link L9, anode 43 oftube It, cathode 45, resistor 5!, link L1, contact, 81 of switch i8, link La, and conductor 69 to terminal 35 oi source 34-35. Both grids 4'! and 48 are driven negative by the drop in resistor 5| so that current cannot start in tube ll. However, current having started in time it continues regardless of the grid voltage in accordance with the known characteristic of gas or vapor-filled discharg tubes.

The tube It has a high conductivity compared with tube i5 and when tube 3 becomes conducting there is a relatively large voltage drop in re-- sistor 48.. This voltage drop is impressed on timing condenser l4 through resistor 58 and tube 15, and condenser I4 is charged at a substantially constant rate controlled by constant-current tube l5 from the instant when switch I8 is closed.

When the relay I l operates to close-its contacts l3, however, the grid 48 of tube I! is driven positive being connected to the positive side of the line through lead La, contacts I3, lead L4, and a resistor 88. In consequence, tube i'l becomes conducting, current flows from terminal 34 through conductor 65, resistor 58, tube l1, resistor 5i, switch l9, and conductor 89 to terminal 35 of source 34-35. A voltage drop takes place in re-- sistor 58 and the anode potential of tube i6 is momentarily depressed so far as to extinguish the current in tube It by reason of the voltage drop in resistor 591 and the negative charge which had been built up in condenser 54. Although the charge then quickly leaks off condenser 54, tube i6 cannot regain conductivity since its grid 41 is held negative, by the voltage drop in -resistor 5i, now maintained by the plate current of tube ll.

As a result of the shift of currentfrom tube IE to tube I1, and from resistor 49 to'resistor5ll, reversing the polarity of the IR drop in circuit 49, 58. l4, l5, H, the cathode of tube i5 becomes positive with respect to its anode 31 and current cannot flow therein, thereby stopping the charg= ing of timing condenser i4 and isolating it from the circuit. The reading of milliammeter 56, indicating the plate current of voltmeter tube 55, is observed. The plate current may be set at a suitable value if desired by adjusting the ratio between plate voltage and grid bias of tube 55 by means of sliding tap 82 of potentiometer 58.

The magnitude of the charge collected by condenser i4 is now measured to determine the operating time of the relay ii, the time during which condenser l4 was being charged. For this purpose, switch 28 (Fig. 1) is moved to its read ing position 3. I

In order to prevent shorting the timing condenser the arrangement is such that the contact 84 opens before the movable contacts Ii and I2 close on the corresponding lower stationary contacts. 7

It will be observed thatdu'ring the opening of contact 85, the grid 830i the tube 55 is momentarily free. During this transition period, the negative grid bias (from 82 to 35) is removed and the plate current of tube i5 would, increase appreciably, possibly causing the milliammeter 58 to swing on scale materially if it were not for the simultaneous operation of contacts 18 and 85.

A resistor provided in series with anode 80 of tube 55 and the-movable contact 13 is of such magnitude that when the resistor 88 is inserted in the anode circuit by the momentary opening of contact 19, the plate current is limited to approximately normal value, that is, the value of plate current with no plate resistance and with the grid bias opposed by the drop from 82 to 35.

When the switch 20 (Fig. 1) is moved to position 3, the reading position, the circuit shown in the simplified diagram of Fig. 5 results as will now be explained.

In Fig. 1 lowering movable contacts 19, ll, 12

and of switch 20 against the corresponding lower stationary contacts closes a circuit from terminal 34 of source 34--35 through conductors 18, contacts 63, milliammeter 56, contacts 82, contacts 13, anode 88 of tube 55, its cathode 8i, to

tap 82 of potentiometer 58-just as in the testing position 2 of switch 20, represented by Fig. 4. The grid circuit, however, is changed. 1.. may

. be traced from grid 83 through contact Ii, conductor I0, condenser l4 (assuming again that condenser 38 has been shorted out by a jumper between posts 32 and 33), conductor 13, lower contacts 12, conductor 89, lower contacts 85, conductor 38 to tap 9| of potentiometer 51. The voltmeter 59 is permanently connected between tap 9i and the lower ends 35 of potentiometers 51 and 58.

'It will be observed that instead of being connected directly to terminal 35, grid 83 is now connected to tap ill of potentiometer 51 through the timing condenser 14 (Figs. 4 and 5). The condenser I4 is so connected that the voltage of the condenser l4 opposes the positive bias provided by tap 9]. If necessary, the tap 9| is adjusted along potentiometer 5'! until milliammeter 56 gives the same reading of plate current as before,

indicating that the voltage of condenser l4 equals that between tap 9| and terminal 35. This voltage may be read by voltmeter 59.. Since condenser I4 is in'the grid circuit, no current is drawn from it and its voltage is accurately determined.

- The time interval to be measured or the operating time of the relay i l is readily deduced from the voltage just measured of condenser i4. If E represents the voltage developed in condenser l4 during a time interval to be measured, I represents the charging current in milliamperes, C the capacity in microfarads, and T the time in milliseconds, then C V T-E If the charging current in milliamperes I is adjusted to be numerically equal to the microfarads C of the timing condenser, the voltage reading of voltmeter 59 will represent the time in milliseconds. For other adjustments of the charging current or capacity to extend the operating range of the timer, a multiplication factor (C/I) is used. For example, if condenser 36 is made to have ten times the capacity of condenser i4, the

range of the time may be increased ten times by short-circuiting condenser I4 by a jumper between posts 3I and 33 and allowing condenser 36 to be charged instead.

' The operations to be performed in timing a relay when energized and'reading the length of the time interval are represented symbolically in Fig. 6, in which the parts of the apparatus to be operated are illustrated schematically as explained in connection with Fig. 3. Part 6a of the figure represents the operation and part 6b the resetting of the apparatus. Referring to the Figure 6a, and following the broken line 92 towards its arrow head, switch 29 is moved from position I to testing position 2 (operation a), switch I9 is moved from open position to closed position (operation 2;), switch 20 is moved to its reading position 3 (operation 0), and the potentiometer 5'! is adjusted to restore the plate current reading of milliammeter 56 to its original value (operation d). Alternatively, if desired, after operation 0, following the dotted line, switch I9 may first be opened, and then potentiometer 51 may be adjusted.

Referring to Figure 6b, following broken line 93, the apparatus is reset by opening switch I9 again (operation e) and moving switch 20 back to its current-adjusting position I (operation The charging-current must be adjusted when the timer is first placed in service, but thereafter needs only to be checked occasionally except for readjustment to provide a diiferent time range. However, the switch 20 must be momentarily placed in position I before making a time measurement in order to dissipate the charge existing from the preceding measurement, which would otherwise add directly to the measurement to be made.

Other types of time interval measurement are made and the timing of other types of relay operations is performed in an analogous manner, having modified the connections of the apparatus with removable links or leads and in some cases rearranging the order of the operations performed.

To measure the time required for a normallyclosed relay to open its contacts instead of for a normally-open relay to close its contacts, a connecting link L5 is placed between connection posts 24 and 25, and leads L3 and L4 are attached to posts 25 and 26 as in Fig. 7 instead of between posts 24 and 25 as in Figs. 1 and 4. The charging current of condenser I4 may be adjusted in the manner already explained. The sequence of operation in actually timing the relay and obtaining the reading is also the same as that described in connection with Figs. 4, 5 and 6, since this case also involves measuring the time required for a relay to operate after it has been energized. When switch I9 is closed, the relay II becomes energized as before and tube I6 becomes conducting as before, causing 2. voltage drop in resistor 49 which is impressed on condenser I4 which commences being charged. Tube II now has its grid 48 continually connected to the positive side of the line through the resistor 88, but it is now initially connected directly to the negative side of the line through leads L3 and L4 and relay contacts I2 and I3, which short out resistor 52.

,When'the relay II opens its contacts, however, and removes the short across resistor 52, the potential of grid 49 rises to a value at which the tube II becomes conducting, the ratio of resistances of resistors 88 and 52 being such that the required division of voltage is obtained. As before, when tube I1 becomes conducting, tube I B is extinguished, the voltage applied to the constant-current tube reverses and condenser I4 ceases being charged. The voltage of condenser I4, due to its accumulated charge, is measured in the same manner as already explained in connection with Fig. 5.

' In measuring the time required for a normallyopen relay to close its contacts when deenergized, a different sequence of operations is employed while actually testing the relay but the methods of adjusting charging current and of reading the voltage of the timing condenser I4, in this case as in all the subsequent cases to be described, may be the same as has already been described. Before making the test, links L1 and L2 are removed from between connection posts 21 and 29 and between 28 and 39 and placed between posts 29 and 3 I and between 30 and 32. Leads La and L4 are connected to posts 24 and 25, respectively, and link L5 is removed from between posts 24 and 25.

The test is begun with switch 29 in position 2 and switch I9 closed (Figs. 8 and 12a). First, switch I8 is closed (operation a, Fig. 12a), and then switch I9 is opened (operation b). Referring to Fig. 8, when switch I8 is closed, tube I6 becomes conducting and charging current commences to flow through tube I5. Condenser I4 cannot begin charging, however, until the short across it through switch blade 81 is removed by opening switch I9, at which time relay II is deenergized by the separation of contacts I5 and commences to operate. the relay operation and the closing of its contacts I3, grid 48 is driven positive, causing current to be shifted from tube IE to tube I1 and stopping the charging of condenser I4. The reading is then taken (operations 0 and d, Fig. 12a) and the apparatus is reset for another test (operations e and ,f, Fig. 12b) For observing the time required for a normallyopen relay to open its contacts when deenergized.

the removable links and leads are placed as shown in Fig. 9; L1 between connection posts 29 and 3|; L2 between 30 and 32; L5 between 24 and 25; leads L3 and L4 connected to 25 and 26. The sequence of operations is as described just above and shown in Fig. 12. The operation of the circuit will be apparent from the, explanation of partially analogous circuits, Figs. 7 and 8. When switch I8 is closed, tube I6 starts conducting; when switch I9 is opened, relay II is deenergized and condenser I4 starts-charging; and when contacts I3 open, grid 48 is driven positive, communicatingthe tubes I6 and I1 and condenser I4 stops charging.

It is apparent, that in the cases previously described bouncing of the-contacts after the original closing or opening is without efiect on the operation of the apparatus. Once the contacts I3 have operated to make grid 48 positive and tube I'I conducting, grid control of tube I I is lost and it continues to conduct in the known manner of grid-controlled gas or vapor discharge tubes. Resumption of charging of condenser I4 is prevented and the relay operating time for only theoriginal closing or opening operation is measured. However, if it is desired to take into ac- Upon the completion of tying the circuit shown in Fig. 4 to produce that shown in Fig. 10; that is, link L0 is removed from between posts 22 and 29 and leads L: andLi' are connected to posts 2| and 22. The sequence of operations in manipulating the apparatus is as shown in Fig. 6. Comparing Fig. 10 with Fig. 4. it will be apparent that the distinction in opera tion of the apparatus is that in Fig. 10 whenever contacts I! reopen, the circuit through resistor 58 to conductor 69 is broken and current is reestablished in tube l6 instead of continuing to flow through tube I! as in Fig. 4. Consequently, charging current flows in condenser ll during the time that contacts it are open and the measurement obtained is the summation of closing time and open time intervals. Obviously, the circult of Fig. 10 may be used generally for measuring the duration of one or more intervals that a pair of contacts l3 are open. The initial positions of the switches and the sequence of operations would-be as indicated in Fig. 13.

For measuring the operating time of a relay closing when deenergized including the summation of opening time intervals for bouncing contacts, the connection of Fig. 8 is modified as indicated in connection with Fig. 10, that is, link L6 is removed from between posts 22 and 23 and leads Lo and L4 are connected to posts 21 and 22. The sequence of operations in manipulating the apparatus is as shown in Fig. 12 and as explained in connection with that figure. For the reasons stated in the previous paragraph, the measurement includes the summation of open time intervals.

Fig. ll'represents the arrangement of the apparatus used when it is desired to-measure the duration of one or more intervals that a pair of contacts, such as l3, remains closed. Links L1,

1a and L6 have been removed from between connection posts 29 and 3|, 38 and 32, 22 and 23, respectively, and leads L3 and L4 have been connected to posts 21 and 28, respectively. Manifestly, condenser I4 is charged only during the periods that a circuit is closed through contacts I3 and tube l6 conducts current. Fig. 14 represents the sequence of operating during the ma- 'nipulation of the apparatus.

Another type of measurement which the extreme flexibility of my apparatus permits is the measurement of the time duration of the first only of a series of contact closures. To make a measurement of this type, the apparatusillustrated in Fig. 1 is connected to include a transformer 94 and a voltage source 95, forming the circuit illustrated in Fig. 15. The link L9 is removed from between posts 91 and 98 and the contactsl3 of the relay II are connected in series with the primary winding 96 of the transformer 94 to the connection posts 91 and 98 by means of the leads Lo and L4. The secondary winding 99 of the transformer 94 is connected in series with the voltage source to connection posts Hand 28 by means of leads L! and La. The connections are such that the negative side of the voltage source 95 is connected to the grid 48 of tube 11, and the terminals of transformer windings 96 and 99 connected to posts 98 and- 25 have the same polarity.

In measuring the time duration of the first of the series of closures of contacts IS, the switch.

cult of tube It is open through contacts I: and the voltage source 95 maintains a negative potential on the grid 48 of discharge tube I1. Upon a closure of the contacts 12 and I3, the anode circuit of tube I8 is closed and tube I9 begins to 5 conduct. As explained in connection with the previous measurements, the charging current begins to flow into the timing condenser l4 upon the initiation of a discharge in tube Hi. The current impulse through the primary winding 99 of .transformer 94 caused by the closure of contacts l3 produces an induced voltage in secondary winding 99 but the polarity is such that the grid 48 of tube I1 is merely driven further negative by 15 this induced voltage and the induced voltage .has no effect on the discharge tube I! which is maintained non-conducting by thecurrent flowing in resistor 5| from discharge tube l6, which produces a negative bias on grid 48 oftube I1.

Upon the. opening of the contacts l2 and I3,

the current through primary winding 98 of transformer 94 is interrupted and a voltage of opposite polarity is induced in transformer secondary 99, causing the grid 48 of tube H to become positive with respect to its cathode 46 and making the tube II conducting. The circuit to tube l6 having been interrupted, the polarity of the voltage acting in the circuit of the timing condenser is reversed, as in the previous examples, and the charging of the condenser 14 ceases. should the contacts l2 and I3 be reclosed subsequently, tube IE will remain non-conducting owing to the fact that the current flowing through tube l1 and resistor 5| biases the grid 41 of 5 tube l6 negatively and prevents the reestablishment of a discharge in tube I6. The charge accumulated in timing condenser I4 is measured, as explained in connection with the previous examples, by moving switch 28 to position 3, adjusting the potentiometer 51, and taking the reading of milhammeter 58 and voltmeter I9.

It will be seen, therefore, that the connection of Fig. 15 permits measuring the duration of the first of a series of contact closures irrespective 5 of the number of reclosures which may occur.

In accordance with the provisions of the patent statutes, I have described apparatus which I now consider to represent the best embodiment ofmy invention and certain methods of operation embraced therein for the purpose of explaining its principle and showing some of its applications but it will be obvious to those skilled in the art that many modifications and variations are possible and I aim, therefore, to cover 55 all such modifications andvariations as 'fall within the scope of my invention which is defined in the appended claims.

WhatI claim as new and desire to secure by Letters Patent of the United States, is:

1. An electric device for timing relay operations comprising a condenser, means adapted to charging said condenser at a substantially uniform rate, means for starting and stopping the charging of said condenser simultaneously with 65 the beginning and end, respectively, of a relay operation to be timed, and means responsive to the charge accumulated by said condenser.

2. A device for timing relay operations comprising a condenser, means adapted to charging 70 said condenser at a substantially uniform rate, means for modifying the connections of said device to permit measurement of both closing and opening times of normally-open and normallyclosed relays, means for starting and stopping the 75 charging of said condenser simultaneously with the beginning and end, respectively, of a relay operation to be timed, and means responsive to the charge accumulated by said condenser.

3. Apparatus for timing the operation of an electrical relay having an energizing winding and a pair of relatively movable contacts adapted to open and close an .electrical circuit, which timdenser,

ing apparatus comprises a condenser, means adapted to charging said condenser at a substantially uniform rate, means for starting and stopping the charging of said condenser, adjustable means for connecting the contacts of the relay being timed to said charge-starting and stopping means, said connecting means being adapted to setting the apparatus for measuring opening and closing times of normally-open and normally-closed relays, and means for determining the charge collected by said condenser.

4. A method of timing the operation of a relay having an energizing winding in a relay-operating circuit and having a pair of relatively movable contacts, which comprises simultaneously initiating an operation of said relay through control of said operating circuit and causing a condenser to start charging through a constant-current unidirectional circuit, causing the polarity of the supply to said last mentioned circuit to be reversed simultaneously with the operation of said contacts, and determining the voltage of said condenser.

5. The method of timing the operation of an electrically operated contact controlling relay which consists in simultaneously initiating the operation of said relay and starting to charge a condenser at a constant rate, stopping the charging of said condenser simultaneously with the operation of said relay and measuring the initiation of such relay operation and the completion of the relay operating movement and then measuring the charge on said condenser.

7. A device for timing relay operations which comprises a unidirectional constant-current circuit including a condenser, a direct current source of charging current supplying said circuit, means for connecting said condenser circuit to said source in a direction normally to cause current to fiow in said circuit at the beginning of a relay operation, means for reversing the polarity of said source upon the completion of said operation, and means for determining the quantity of' charge collected by said condenser.

8. -A timer comprising in combination, a cona constant-current rectifier in series therewith, a direct current voltage source connected to said condenser and said rectifier in a direction normally to cause current to flow in said rectifier, means for energizing said voltage source at the beginning of an operation to be timed, means for reversing the polarity of said voltage at the conclusion of the operation, and means for determining the amount of electric charge accumulated by said condenser during said operation.

9. A timer comprising in combination, a condenser, a thermionic tube having an anode and a cathode and operated in the saturated portion of its characteristic curve in which the entire emisplied to the electrodes of said tube, a direct ourrent source 01 voltage to which said condenser and said tube are connected in series, the connections a being such as normally to tend to cause current to fiow in said tube, means for energizing said volt-- 5 age source at the beginning of a time interval to bemeasured, means for reversing the polarity of said voltage at the end of the time interval, and means responsive to the amount of electric charge accumulated by said condenser during said time w interval.

10. A timer comprising in combination, a source of current, a pair of discharge tubes, each having an anode, a cathode, and a control grid, and being connectible in parallel to said source of current, 1 separate resistors connected in series with the anodes of said tubes, a timing condenser and a constant-current rectifier connected in series between the anodes oi. said tubes, a second condenser connected between the anodes of said tubes, means for closing a circuit from said current source to said tubes at the beginning of a time interval to be measured, thereby initiating a discharge current in one of said tubes, giving rise to a potential difierence in one of said series resist- 25 ors and in the circuit of said constant-current rectifier and said timing condenser and giving rise to a charging current in said condenser, means for momentarily at least maintaining the control grid of the other of said tubes at too low a potential to 30 permit the tube to become conducting at the beginning of the time interval, means for raising the potential of the control grid of said latter tube at the conclusion of the time interval, thereby making the tube conducting and shifting current from 35 the former of said tubes to the latter and from one of said-series resistors to the-other, whereby the potential diflerence between. said anodes and in the circuit of said rectifier and said timing condenser is reversed, terminating the'charging of 4 said condenser.

11.- A timer comprising in combination, a source of current, a pair of discharge tubes, each having an anode, a cathode, and a control grid, a resistor connected between the anode of one of said tubes 45 and one side of said current source, a second resistor connected between the anode of the other of said tubes and the same side of said current source, a constant-current rectifier and a timing condenser connected in a cross-circuit in series 50 between the anodes of said tubes, a second condenser connected between said anodes, a switch between the other side of said current source and the cathodes of said tubes arranged to be closed at the beginning of a time interval to be measured, 55 thereby initiating a discharge in the first oi. said tubes, a second switch adapted to connect the control grid of the second 01' said discharge tubes to the anode side of said current source and arranged to be closed at the end of a time inter- 60 val to be measured, thereby making the latter discharge tube conducting, shifting current there: to from the first of said tubes and reversing the potential difi'erence in said cross-circuit, whereby said timing condenser receives charging current 65 only during a time interval to be measured.

12. A timer comprisingin combination, a pair of capacitatively-coupled parallel circuits including grid-controlled discharge tubes and having a cross-connection including a rectifier and a tim- 70 'aoamoe 7 tential of the tube in the second of said parallel circuits at the end of a time interval to be measured, thereby making said second-tube'conduct- 'ing, depressing through said capacitative coupling the voltage acting onthe tube in the first of said parallel circuits until said tube is deenerzized, shifting the current between said parallel circuits to reverse the voltage in said cross-circuit and terminate the charging of said condenser.

13. A device for timing the opening of the contacts of a relay when the relay is energized which comprises a pair of parallel circuits including grid-controlled discharge tubes and having a cross-connection including a rectifier and a timing condenser, means for simultaneously energizing said relay and one of said tube circuits, thereby giving rise to a voltage in said cross-circuit causing said condenser to start receiving a charge, a voltage divider having a tap determining the grid potential of the tube in the second tube circuit, one side of said voltage divider being initially shortcircuited by the contactsof the relay, whereby the grid potential of said second tube is initially held below the point at which said tube becomes conducting, and the opening of the contact serves to raise the grid potential of said tube, causing it to become conducting, to shift the current between said parallel tube circuits, to reverse the voltage in said cross-circuit, and to terminate the charging of said condenser.

14. A device for timing the operation of a relay when deenergized comprising a pair of parallel circuits having a cross-connection including a rectifier and a timing condenser in series, one of said parallel circuits initially carrying current and producing a potential difierence in said crosscircuit tending to cause a charging of said condenser, means initially maintaining said relay energized andshort-circuiting said condenser to prevent it from receiving charging current, said means being adapted simultaneously to deenergize said relay and to remove the short from said condenser, permitting charging thereof, means for shifting the current from the initially conducting circuit to the other parallel circuit upon the operation of said relay, thereby reversing the potential difierence in said cross-circuit and terminating the charging of said condenser.

'15. A device for measuring the summation of the original operating time'of a circuit-closing relay having bouncing contacts and the time during which the conacts may be open again, which comprises, in combination with a source of current, a tube circuit supplied thereby comprising a resistor and a discharge tube in series, a second circuit in parallel with-said tube circuit including a second resistor in series with the contacts of the relay being tested, a cross-circuit between said firstmentioned circuits including a timing condenser and a rectifier in series, capacitative coupling between said first mentioned circuits, and

means for simultaneously starting the operation of the relay and closing saidtube circuit, there- 5 by energizing said circuit and giving rise to a voltage in said cross-circuit causing .sald condenser to start receiving a charge, whereby said condenser continues receiving a charge until the relay contacts close causing currentto flow in 1 said second circuit, depressing through said onpacitative coupling the voltage applied to said tube below. that at which current can continue to flow in said tube circuit,-reversing the voltage. in said cross-circuit to stop the charging of said 15 condenser while the relay contacts are closed, but permitting current to fiow again in said tube circuit and in said condenser-charging cross-circuit during such time as the relay contacts may again be open. 1 '20 16. A device for timing the first of several repeated closures of a pair of contacts which comprises a pair of parallel circuits including gridcontrolled discharge tubes and having a crossconnection including a rectifier and a timing condenser, said discharge tubes each having an anode, a cathode, and a grid, a transformer having primary and secondary windings, a source of biasing potential, and means for reversing the polarity of voltage acting in said cross-circuit when current shifts from one parallel circuit to the other,

the primary winding of said transformer and said contacts being connected in series with one of said discharge tube circuits and the secondary winding of said transformer and said source of biasing potential being connected between the cathode and control grid of the discharge tube in the other of said parallel tube circuits whereby the initial closing of said contacts closes a circuit through the first mentioned of said discharge tubes and causes current to flow in said crosscircuit starting the charging of said timing condenser, and the initial opening of said contacts induces a voltage in the secondary winding of said transformer impressinga positive potential on the control grid of said second mentioned discharge tube causing it to become conducting and to commutate said first mentioned discharge tube, reversing the potential in said cross-circuit and terminating the charging of said timing con- 5 denser, said first mentioned discharge tube having its grid connected to be negatively biased by the resistance drop due to current flowing in the, circuit of said second mentioned discharge tube, preventing the first tube fromagain becoming conducting in response to subsequent contact closures.

MAURICE E. BIVENS.

commune oi CORRECTION.

v Patent No. 2,021,765. November 19, 1935.

MAURICE E. BIVENS.

- It is hereby certified that error appears. in the printed specification of the above numbered patent requiring correction as follows: Page 4, second column,

line 56, for the syllable "communicat-" read commutat-;page 7, first column, line 53. claim 15, for "conacts" read contacts; and that the said LettersPatent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 7th day of'January. Ar D 1936.

Leslie Frazer (Seal) Acting Commissioner of Patents.

CERTIFICATE or CORRECTION.

. Patent No. 2,021,766. November 19, 1935.

MAURICE E. BIVENS.

- ll is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 4, second column, line 56, for the syllable "communicat-" read commutatqpage 7, first column, line 53. claim 15, for "conacts" read contacts; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 7th day of January. A. D. 1936.

Leslie Frazer (Seal) v Acting Commissioner of Patents.

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