US2401747A - Timing device - Google Patents

Description

June 11, 1946.

H. J. DlBBLEE TIMING DEVICE Filed April 21, 1944 INVENTOR.

HAROLD J. DIBBLEE I BY %@M.

ATTORNEY Patented June 11, 1946 UNITED STATES PATENT OFFICE 2,401,747 TIMING DEVICE Harold J. Dibblee, Newtown, Pa. Application April 21, 1944, Serial No. 532,200

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 13 Claims.

The invention described herein may be manufactured and used by or for the- Government for governmental purposes, without the payment to me of any royalty thereon.

My present invention relates to timing devices, and more particularly, to devices of the general character indicated for determining the time elapsing between the occurrence of two successive events, especially, but not necessarily, two events so related to each other that the happening of the second is dependent upon and initiated by the happening of the first.

While not limited thereto, my present invention is eminently suitable for measuring the time intervening the energization of the operating coil of an electro-magnetic relay and the opening or closing of the contacts thereof; or, the de-energization of the coil of said relay and the opening or closing of the contact thereof.

Devices in the prior art, designed for similar purposes, have certain disadvantages attendant thereto. For example, the limit of accuracy of some of such devices is of the order of plus or minus 0.01 second, and the design of some of such devices is such that their use i limited to relays in which the functioning of the contacts is brought about only by the energization of the coil, and not by the de-energization thereof. Other prior art devices require high-speed clock mechanisms actuated by quick-acting clutches which introduce errors preventing accurate measurements. Still other devices utilize sensitive electric oscillographs, which are delicate and not particularly suitable for routine laboratory technique. All of these devices are elaborate, cumbersome, and costly.

It is, therefore, the main object of my present invention to eliminate the foregoing disadvantages by providing a relatively simple and inexpensive time-measuringdevice which is extremely accurate, down to a microsecond.

It is a further object of my present invention to provide a time-measuring device which is completely electronic in operation, and therefore includes no elements which, because of inertia, ordinarily tend to introduceerrors.

It is a still further object of my present invention generally to improve the art of measuring short time intervals, and provide a method and means therefor which is capable of a wide variety of applications. I

These, and other objects and advantages, which will become apparent as the detailed description progresses, are attained in the present invention in the following manner:

'2 It is known that the voltage on acapacitor, which is being discharged through a resistor, may be determined from the equation:

where E1=the voltage to which the capacitori initially charged,

Ez=the voltage remaining across the capacitor at the end of the discharge period,

t =the discharge time in seconds,

R=the value in ohms of the resistor through which the capacitor is being discharged,

and

C =the'capacitance in farads of the capacitor being discharged.

Therefore, if a capacitor is charged to a known voltage, then discharged for an unknown period of time, and the residual voltage across said calog, El -log, E

pacitor is determined, the length of time during which current flowed through said capacitor may readily be calculated. I

The present'invention makes use of this fact by causing a capacitor, which has been charged to a known voltage, to commence discharging, through a resistor and a vacuum tuba-upon the happening of the first of the above mentioned successive events, the vacuum tube functioning as a control valve which becomes instantaneously cut off upon the happening of the second of said events. By measuring the potential across said capacitor at said cutofi, and utilizing the principles involved in the above equation, the drop in the potential across said capacitor, occasioned by said discharge, maybe translated intothe time elapsing between the happening of said two events. The initial and final measurements of the voltage across the capacitor are preferably made with a modified. vacuum-tube voltmeter so as not to draw any current from the circuit. The initial measurement of the voltage across thecapacitor in the exercise of the'present invention is indicated herein by the voltmeter needle. at its. maximum reading. The final measurement of the voltage acrossthe capacitor is indicated herein by a redline or a red mark at 37% of the full scale on the voltmeter, as determined mathematically by the above equation and as referred to with more particularity hereinafter. The red line is of use during the calibration Of the device.

In the accompanying specification shall describe, and in the annexed drawing show, what is at present considered a preferred embodiment As mentioned previously, the acid to olefin monomer ratio is an important factor in securing the desired polymerization reaction. Since an important object o! my invention is to secure not only a polymerization reaction, but to also recover the two types of product, i. e., the saturated hydrocarbons and the highly unsaturated, terpenelike products soluble in the catalyst, the relative proportions of acid to total hydrocarbons in the reaction zone is important. In the absence oi inert solvents an amount of acid of from about 20% up to about 400% by weight or the olefinic hydrocarbons may be utilized, or expressed in another way from 25% to 500% by weight of olefins may be added to the hydrofluoric acid with separation possible into readily separable layers. Preferably the amount of olefins added is from 33%% to 200% by weight. Where inert solvents are utilized, the amount of olefin which may be added to the acid-hydrocarbon mixture will largely depend upon the relative proportion of acid and inert hydrocarbon solvent, and is normally within the range of from 16%% up to about 200% by weight of the amount of acid, with amounts from 25% to 150% by weight preferred. The diilerence in preferred ranges is due to the fact that the inert solvent does not react to produce larger molecules (which as a result of hydrogen exchange distribute themselves between the acid and hydrocarbon phases) but remains as a distinct hydrocarbon phase. Hence, assuming that the amount of solvent is at least as great as the amount of acid, the minimum amount of olefins necessarily added, where solvents are employed, is generally reduced by about one-half to obtain satisiactory conditions of layer separation. similarly, especially where it is desirable to use relatively large amounts oi inert solvent, the maximum amount oi olefin which may be added to the catalyst with satisfactory separation after the reaction has been completed, is reduced.

The process may be carried out, in either the presence or absence of solvents. under conditions similar to those utilized in carrying out. alkylation reactions, or the conditions used are what might be termed "alkylation conditions" with respect to pressure, temperature (within the ranges indicated), reaction system, mode of introduction of reactants and the like.

Since the reaction gives oi! a substantial amount heat, it is usually desirable to provide suitable cooling means in order to maintain the temperature within the preferred limits. Usually the reaction will be carried out so that the hydrogen fluoride catalyst is in liquid phase, and, therefore, in such cases sumcient pressure should be provided to maintain the catalyst in liquid phase. However, such procedure requires only sufilcient ressure to maintain the inert solvent, it any, and the hydrogen fluoride in the liquid state. The olefin is then passed through the well-agitated liquid at such a rate that it all reacts to higherbolling hydrocarbons, wherefore no rise in pressure results. Accordingly, relatively low pressures can be used.

Since, in addition to the initial olefin polymerization, I desire to allow hydrogen exchange reactions to occur within the original polymer products, further contacting or the reaction mixture with the acid catalyst is desirable. The amount of residence time, o! the hydrocarbon products in contact with the catalyst, required to achieve substantial or nearly complete saturation of the acid immiscible hydrocarbons varies with the reaction conditions and the particular olefin monomer being processed. At normal room temperature levels, total residence times of from 30 minutes to three hours are generally satisfactory, although these residence time are not intended as limiting on the operation of my process. The residence time is correlatable with the reaction temperature and the degree of saturation of the hydrocarbon layer products desired.

Referring to the drawing one possible form of carrying out the process of my invention is diagrammatically illustrated, which enables the continuous production of the conjunct polymer products. According to the form illustrated, the reaction is carried out in the presence of a normal paraihn hydrocarbon solvent.

To an emulsion of hydrofluoric acid and an inert solvent such as normal butane, obtained in the manner hereinafter described, in a coil I in temperature control zone 2, an olefin is introduced through line 3 provided with a suitable pump I. The contact time of the olefin charge with the acid catalyst should be sufficiently long within the temperature control zone 2 so that a substantial portion of the olefin reacts therein to form the olefin dimers, trimers, etc. From coil I, the olefin polymer, solvent-catalyst mixture is led through lines 5 and I to reactor 8 provided with a suitable agitator 5, wherein the emulsion is maintained for the desired residence time to permit the polymerization reactions to become completed and allow hydrogen exchange to occur between the olefin polymers as previously described. Product mixture is continuously withdrawn from the reactor 8, and sent through line ID to settling tank I5 wherein the emulsion is allowed to stratify into an upper hydrocarbon phase and a lower acid catalyst phase. From the lower portion of the settling tank, catalyst phase is continuously withdrawn through line I6, and sent to fractionator I'l, wherein the major portion of the hydrofluoric acid is distilled off from the highly unsaturated terpene-like polymers contained therein. The hydrofluoric acid vapors overhead from fractionator II are then sent through line I8 to condenser I9, collected in receiver 20, and returned through lines 2|, 22 and 23 to reaction coil I. Line 23 is provided with a suitable pump 24 to provide the necessary acid circulation. Make-up hydrofluoric acid is admitted, as necessary, to line 22 through line 25, provided with a. control valve 26. The highly unsaturated polymer is removed from the bottom of the fractionator I7, and sent through line 30, provided with a suitable pump 3I, to acid stripper 32. In acid stripper 32, the final traces of hydrofiuoric acid are removed from the unsaturated polymer product by scrubbing the polymer with a hot inert gas such as nitrogen or methane introduced through line 33. This includes not only hydrofluoric acid present as such, but also hydrogen fluoride which may have added to double bonds in the unsaturated polymer and is driven off by moderate heating. The overhead from the stripper 32 is sent to condenser 34 through line 35, and any condensable material, principally hydrofluoric acid, collected in receiver 38, provided with a suitable vent 31, and recovered from line 38. Any hydrogen fluoride escaping with the vent gases may be recovered by any suitable means. The unsaturated polymer product is recovered from the bottom of the acid stripper through line 39.

The hydrocarbon phase is withdrawn from the top of settling tank I5, and sent through line 45 to solvent stripper 46. Solvent vapors are taken contacts 38-3l or 32-33. The switch 21 is then closed to engage the contact 28. This places the selected capacitor across the potential existing between ground and some point tn the potentiometer l8, which is negative with respect to ground, to charge said capacitor to said potential.

The switch 21 is then thrown upwardly to engage the contact 28, thereby connecting the previously grounded side of the selected capacitor to the gride of tube 2 Up to this time the tube 2| will have been blocked since its grid, being isolated, will have collected a negative charge due to electrons emitted from its cathode.

The left hand plate of the selected capacitor is below ground potential since the tap l8 of the potentiometer I8 is below the ground potential of the tap IT on the potentiometer IS. The cathode of the tube 2| is grounded thru the small impedance of the milliarnmeter 22. The connection of the grid of the tube to the previously grounded side of the selected capacitor by the changing of the switch arm 28 from the contact 28 to the contact 28 causes the tube 2| to begin to conduct since its grid and cathode are initially at ground potential and the plate thereof has a positive potential. The tube 2| will continue to conduct at a constant rate which causes meter 22 to read a constant value which preferably is adjusted to the maximum full-scale mark on the meter. This condition pertains until the beginning of the interval to be timed at which instant the selected capacitor begins to discharge thru its R.-C. network thereby reducing the potential on the grid of tube 2|. The tube 2| will continue to conduct at a decreasing rate as indicated by the movement of the needle downwardly on the scale of the meter 22 as the selected capacitor continues to discharge. At the termination of the interval to be timed the selected capacitor ceases to discharge thereby holding the grid of tube 2| at the residual potential of the capacitor and causing the meter 22 to indicate a constant reading. The scale being calibrated in time units, this final meter reading indicates the elapsed time.

The tube 2|, when so conducting is operating preferably on the straight portion of its characteristic curve and hence for a given plate voltage, the plate current will vary linearly with variations in grid potential. With a given grid potential the plate current of the tube 2| will vary in an approximately linear relation with variations in plate potential. The plate potential of the tube 2| is determined by the setting of the tap on the variable resistor 28.

With the grid of the tube 2| connected to the previously grounded-side oi the selected capacitor, the resistor 28 is adjusted so that the tube draws suflicient plateicurrent to give a full scale needle deflection on the meter 22. During the time of the making of this adjustment, the tube 2| is drawing current from thebleeder or potentiometer l6 because of the bias on the tube 2| as controlled by the charged selected capacitor. The vacuum tube voltmeter 22 is thereby adjusted to its initial position with the needle reading thereof at a maximum value.

The selected capacitor is discharged thru the tube 88 beginning with the throwing of the switch 36 upwardly. The tube 88 controls the time of discharge of the selected condenser. The grid bias on the tube 88 is controlled by the opening or the closing of the relay contacts 14 and '15.

The interval of time between the upwardly closing of the switch 38 and the opening or closing of the relay contacts 14 and 15 determines the change in position of the needle of the meter 22. The change in position of the needle of the meter 22 is determined by the R.-C. time of the selected capacitor 34 or 35 and a selected resistor 1'|--85, inclusive, from the switch 18. The meter 22 may, if preferred, be disposed in series between the potentiometer tap I6 and the late of the tube 2|. When the meter 22 is so positioned in the circuit the cathode terminals of the tube 2| are connected to ground.

The procedure to be followed from this point on depends upon the type of relay being tested;

that is, whether the relay is one in which the ergization of the relay coil, or one in which the contacts are normally closed, and open upon deenergization of the relay coil, or, finally, one in which the contacts are normally open, and close upon de-energization of the relay coil.

The four procedures will be described in the order mentioned.

In the first case, the switch 31 is closed in its lower position, and the'switch 38 is closed in its upper position. The switches 36 and 38 remain open.

The relay to be tested has its coil conniected, in series with an appropriate source of D. C., such as a battery 86 or the like, to the binding posts H and 12, and the normally closed con cts of said relay are connected across the bin ing posts 14 and I5. It will be noted that the grid of the tube 88 is connected directly to the oathode of said tube through the resistor 88, contacts 62, 58,6l, and 66 of the switch 38, the relay contacts connected to the-binding posts 14 and I5, and the contacts 65 and 68 of said switch 38.

Upon the application of plate voltage to the tube 88, upon closing the switch 38 upwardly the tube 88 will become conducting so as to permit the selected capacitor to discharge therethrough. For this purpose, the adjustable arm 81 of the selector switch 16 is engaged with an appropriate one of the resistors ll-85, inclusive, the switch 36 being closed. The latter operation initiates two simultaneous events. Closing of the circuit between the contacts 4| and 43, the switch 31 being closed downwardly energizes the relay coil connected to-the binding posts "II and 12 by way of the contacts 52-5|l and 535| of the switch 81. At the same time, engagement of the contacts 48 and 42 connects the plate of the tube 88 to the positive side of the selected capacitor through the chosen resistor of the selector switch 16, thereby permitting said selected capacitor to commence to discharge. Energization of the relay coil, after the passage of a certain time, causes the relay contacts to open, and break the circuit at the binding posts 14 and 15. This removes the direct connection between the grid and cathode of the tube 88, and causes said grid immediately to assume a potential which is negative with respect to said cathode, thereby blocking the tube 88, this condition being brought about through the bias battery 88, contacts 58 and 64 of the switch 38, resistor 13, contacts 58 and 62 of said switch 38, and resistor 88. This negative potential blocks the tube 88 simultaneously with the opening of the relay contacts, and the charge remaining on the selected capacitor is therefore indicative of the time during which the R. C. circuit was in operation since the motion of the pointer on the meter 22 is stopped at the blocking of the tube It. The read ing on the meter 22 is an indication of the p tential remaining across the -capacitor, which reading will. of course. be lower than the full scale reading to which the meter was set at the start of the test. Interpretation of this reading in terms of time will be better understood after consideration below of the method of calibrating the device.

Assume now that the relay to be tested is one whose contacts are normally closed, and open when the relay coil is energized. To carry out this test. switches 31 and 33 are both closed in their down positions, and switches 38 and 30 are open. The operating coil and relay contacts are respectively connected, as before, to the binding posts Ii-l2 and ll-Iii.

The selected capacitor 34 or 35 is charged by throwing the switch 21 into engagement with the contact 23. said switch then being thrown upwardly into engagement with the contact 23, and

the resistor 20 being adjusted so that the tube- 2| of the vacuum tube voltmeter draws sumcient current to obtain full scale deflection on the meter 22.

It will be noted that the grid of the tube 33 is connected through resistor 30, contacts 62 and 31 of the switch 39, resistor 13, and contacts 83 and 33 of said switch 33 to the cathode of said tube, and, upon the application of plate voltage to said tube. through one of the resistors of the selector switch ll, said tube will conduct. The switch 33 is now closed. As in the preceding case, the relay coil is energized and plate voltage is applied to the tube It so as to conduct the charge from the selected capacitor. when th relay contacts close, the grid of the tube 33 is immediately connected to the negative side of the bias battery 33 through resistor 30, contacts 62, i1, 83, and 38 of the switch 39, the relay contacts across the binding posts H and I3, and the contacts 66 and ll of said switch 39. The tube 30 is therefore immediately biased below cutoff, and, as in the preceding test, a reading of the meter 22 gives an indication of the elapsed time.

Assume now that the relay to be tested is one whose contacts are normally closed, and open when the coil thereof is de-energized. The

. switches 31 and 39 are both thrown into their up positions, and the switches 36 and 33 are both closed. It will be noted that the grid 01 the tube 33 will then be biased to cutoff through the contacts 53 and N of the switch 33. The tube 33, therefore, will not conduct even though the plate thereof is connected to the charged capacitor through the switch 36. The switch 33 is now opened, and this causes two simultaneous actions. The bias is removed from the tube Is, the grid of said tube becoming connected to the cathode thereof through resistor 30, contacts 32, 33, II, and 63 of the switch 33, the relay contacts connected across the binding posts I4 and 15, and the contacts 83 and 80 of said switch 33. This permits the tube 33 to conduct as long as the relay contacts remain closed. At the same time, the relay coil connected across the bindin posts II and 12 becomes de-energlzed by the opening of the contacts 53 and 51 of the switch 33. Upon the opening of the relay contacts, after the passage of time, the grid of the tube 33 again becomes connected to the negative terminal of the bias battery 33, and said tube, as in the previous case, becomes cut off.

Finally, it is to be assumed that the relay to be tested is one whose contacts are normally open,

and close when the coil thereof is de-energized. For this test the switch 31 is closed in its up position, the switch 39 is closed in its down position, and th switches 38 and 33 are both closed. As in the immediately preceding case, th tube II is biased below cutofl throush the contacts I and 56 of the switch 33. When said switch 33 is opened, the relay coil is de-energized and, at the same time, the blocking bias on the tube 33 is removed. The grid of said tube is therefore connected to the cathode thereof, and said tube will conduct until the relay contacts close, at which time, negative bias is again applied to the grid of the tube and the latter becomes non-conducting.

It will be noted that the only difference between the various procedures outlined for the four types of tests is the switching sequence. The object in each case isto have the discharge tube 88 in a conducting state only during the time interval to be measured. This is accomplished by having th grid of said tube connected to the cathode at the beginning of this time interval, and biasing the tube below cutoil at the end of this time interval.

This completes the description of the operation and mode of use of the present invention and there remains, merely, a description of the manner in which the devic is calibrated, this being as follows:

The calibration of this device depends upon the fact that th voltage across a capacitor which is bein discharged through a resistor drops to a value in other words, 37% of its initial charge, when the discharge period is equal to the time constant of the resistance-capacitance combination. For calibration purposes, a resistor of megohms is used in combination with a 2 mid. capacitor, this combination having a time constant of one minute. Therefore, if the circuit is permitted to discharge for one minute, the voltage across the capacitor will drop to a value of 37% of its initial charge, and, due to the linear characteristic of the vacuum tube voltmeter being used, this will correspond to a scale reading approximately 37% of full scale. .As described, the device incorporates a timer 9i which, when the push-button s2 is operated, automatically closes the circuit across the binding posts I4 and 15 for a period of one minute.

In order, therefore, to calibrate the device, the switch 25 is closed in its down position to insert the 2 mid. capacitor into the circuit. The switch 21 is then engaged with the contact 23 to charge the capacitor to the potential determined by the position of the adjustable arm 19 of the potentiometer Ill. The selector switch 13 is then manipulated to bring into the circuit the resistor having a value of 30 megohms. The switches 31 and 39 are then thrown up, and the switches 36 and 33 remain open. The switch 21 is then thrown up to engage the contact 29, and the variable resistor 20 is adjusted so as to obtain a full scale deflection on the meter 22. The push button 82 is now depressed, causing the timer 3| to short circuit the binding posts H and 15 for a period of one minute by operation of an electrical clock or the like, that closes the cam switch 9! at the end of one minute from the start of the electric capacitor 35 will have dropped to approximately 37% of its initial value. The scale of the meter 22 is marked, for example, with a red line at the point indicated by the meter needle at this time. Now, knowing the position on the scale of the meter 22 which corresponds to 37% of the initial voltage, said scale may be calibrated in terms of time intermediate the 37% red mark and full scale deflection.

For subsequent use of the device, the needle of the meter 22 may be readjusted to the red line on the scale thereof if necessary b the readjustment of the potentiometer l8 and the rheostat 20 to assure accuracy in the results thereof.

The meter 22 may be provided with additional conveniently calibrated scales by utilizing different time constants available by use of the different resistors ll-85, inclusive, in the switch 16 and well known resistance-capacitance mathematical computations.

This completes the description of the present invention.

It will be noted from all of the foregoing that I have provided a relatively simple and inexpensive time m asuring device which is extremely accurate since the full range of the meter 22 scale can be used with the smaller condenser and the smallest resistor, the meter, condenser, and resistors being of high degrees of accuracy, even down to a microsecond, by means of which the time elapsing between two successive events, for example, the energization or de-energization of the operating coil of an electro-magnetic relay, and the functioning of the contacts of said relay, may be precisely determined.

It will further be noted that my present invention is substantially electronic in operation and avoids the use of elements which, because of inertia, ordinarily tend to introduce errors.

And it will further be noted that while I have described the present invention as particularly useful in testing the lags inherent in electromagnetic relays, it is not necessarily limited to such application, but may find a wide variety of other uses.

Other objects and advantages of my present invention will readily occur to those skilled in the art, to which the same relates.

I claim:

1. The method of utilizing an R.-C. network containing a capacitor and an electron discharge device for determining the time elapsing between the occurrence of two successive events which includes the steps of: initially charging the capacitor of said network to a predetermined reference value as indicated by a direct current vacuum voltmeter calibrated to read directly in units of time to provide a timemeter while maintaining said discharge device inoperative; rendering said discharge device operative upon the happening of the first of said two successive events whereby said capacitor commences to discharge therethrough of which events either event may be an opening of a contact; interrupting the operation of said discharge device, and consequently the discharge of said capacitor, upon the happening of the second of said two successive events; determining the residual charge remaining upon said capacitor; and reading the desired elapsed time between the occurrence of the events from the timemeter.

2. i'he method of utilizing an R.-C. network containing a capacitor and an electron discharge tube for determining the time elapsing between the occurrence of two successive events which includes the steps of initially charging the capacitor of said network to a predetermined reference value as indicated by a vacuum voltmeter reading directly in time units while maintaining said discharge tube nonconducting; rendering said discharge tube conducting upon the happening of the first of said two successive events whereby said capacitor commences to discharge therethrough; rendering said discharge tube nonconducting upon the happening of the second of said two successive events whereby the discharge of said capacitor is interrupted by the closing of a contact; determining the residual charge remaining upon said capacitor; and taking the reading of the elapsed time between the events directly from the voltmeter.

3. The method of utilizing an R.-C. network containing a capacitor and an electron discharge tube for determining the time elapsing between the occurrence of two successive events which includes the steps of initially charging the capacitor of said network to a predetermined reference value while maintaining said discharge tube without any plate voltage applied thereto; applying plate vol a e to said discharge tube upon the happening of the first of said two successive events whereby said capacitor commences to discharge therethrough; biasing said discharge tube below cutoff upon the happening of the second of said two successive events whereby the discharge of said capacitor is interrupted; opposing the discharging of the capacitor by placing its charge in opposition to the original voltage thereon; determining the residual charge remaining upon saidcapacitor; and translating the difference between said initial and residual charges includes the steps of initially charging the capacitor of said network to a predetermined reference value while maintaining said discharge tube biased below cutofl; lifting the bias on said discharge tube so as to render the same conducting upon the happening of the first of said two successive events whereby said capacitor commences to discharge therethrcugh at substantially an exponential rate and opposed by its original voltage change; applying bias to said discharge tube sufficient to render the same-nonconducting upon the happening of the second of said two successive events whereby the discharge of said capacitor is interrupted; determining the residual charge remaining upon said capacitor; and translating the difference between said initial and residual charges into terms of time.

5; Means for determining the time elapsing between the occurrence of two successive eventscomprising: an R.-C. network containing 9. capacitor; means for initially charging the capacitor of said network to a predetermined reference value; an electron discharge device; means for so connecting said network and said. discharge device as to permit said capacitor tc commence discharging against the voltage of its original charge upon the happening of the first Jf said two suc cessive events; means for controlling the operation of said discharge device whereby the discharge of said capacitor is interrupted upon the happening of the second of said two successive events; and means for measuring the residual charge remaining upon said capacitor, and translating the difference between said initial and residual charges into terms 01' time.

6. Means for determining the time elapsing between the occurrence of two successive events comprising: an R.-C. network containing a capacitor as a part thereoi; means for initially charging the capacitor of said network to a predetermined rei'erence value; an electron discharge tube; means for so connecting said network and said discharge tube as to permit said capacitor to commence discharging against the voltage of its original charge through said tube upon the happening oi the first said two successive events; means for biasing said discharge tube beyond cutoi! upon the happening 0! the second of said two successive events whereby the discharge of said capacitor is interrupted; and means for measuring the residual charge remainl upon said capacitor, and translating the dii'- ierence between said initial and residual charges into terms of time.

7. Means for determining the time elapsing between the occurrence of two successive events comprising: an R.-C. network containing a capacitor; means for initially charging the capacitor 0! said network to a predetermined relerence value; an electron discharge tube; means for so connecting said network and said discharge tube as to apply the charge acquired by said capacitor as plate voltage to said discharge tube whereby said capacitor commences to discharge therethrough against the voltage at its original charge upon the happening 0! the first of said two successive events; means for biasing said discharge tube beyond cutofl upon the happening of the second of said two successive events whereby the discharge or said capacitor is interrupted; and means for measuring the residual charge remaining upon said capacitor, and translating the dill'erence between said initial and residual charges into terms of time.

8. Means for determining the time elapsing between the occurrence of two successive events comprising: an R.-C. network containing a capacitor; means'ior initially charging the capacitor of said network to a predetermined reference value; an electron discharge tube; means for maintaining said discharge tube normally biased beyond cutoii; means for so connecting said network and said discharge tube as to lift said bias and render said tube conducting upon the happening oi the first 01' said two successive events whereby said capacitor is permitted to discharge therethrough against the voltage of its original charge; means for restoring said cutoi! bias to said discharge tube upon the happening 0! the second of said two successive events whereby the discharge of said capacitor is interrupted; and means tor measuring the residual charge remaining upon said capacitor, and translating the diflerence between said initial and residual charges into terms of time.

9. A timer, comprising in combination a capacitor, a direct current vacuum tube voltmeter for measuring a charge on said capacitor, a voltmeter needle sweeping across a scale part oi! the voltmeter, means ior adjusting a desired scale reading range oi the voltmeter needle indicating the magnitude of charge on said capacitor, a resistance in series with said capacitor, a tube for controlling the time interval of the discharge 0! said capacitor, and means for controlling the grid bias on said tube so that the tube will conduct or block as desired.

10. A timer, comprising in combination a chargeable capacitor, means for charging said capacitor, an R.-C. circuit controlling the discharge rate of said capacitor, means ior initiating the discharge interval immediately upon the opening oi a contact apart from said R.-C. circuit, and means for terminating the interval immediately upon the opening of a second contact apart from the R.-C. circuit.

11. A timer, comprising in combination a chargeable capacitor, means for charging said capacitor, an R.-C. circuit controlling the discharge rate of said capacitor, means for initiating the discharge interval immediately upon the opening of a contact apart from R.-C. circuit, and means for terminating the interval immediately upon the closing of a second contact apart from the R.-C. circuit.

12. A timer, comprising in combination a chargeable capacitor, means for charging said capacitor, an R.-C. circuit controlling the discharge rate of said capacitor, means for initiating the discharge interval immediately upon the closing oi'a contact in said R.-C. circuit, and means for terminating the interval immediately upon the opening of a second contact apart from the R.-C. circuit.

13. A timer, comprising in combination a capacitor, a resistor connected to said capacitor in a circuit having a time constant, a voltmeter measuring the potential across said capacitor and calibrated in time, a first electronic tube having a control grid for initiating a discharge oi said capacitor, a second electronic tube having a control grid for stopping a discharge of said capacitor, multiple ganged switching means connecting the circuit of said timer to the control circuit of a relay through the grid of said first electronic tube and adaptive to initiate discharge 0! said capacitor immediately upon either make or break of the control circuit, multiple ganged switching means connecting the circuit of said timer to a controlled circuit of the relay through the grid of said second electronic tube and adaptive to stop discharge of said capacitor immediately upon either make or break of the controlled circuit.

HAROLD J. DIBBLEE.

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