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Dec. 17, 1946. 2,412,571 w? FEW ELECTRONIC TIMING SYSTEM Filed March 11, 1944 2 Sheets?Sheet 2 _ _ INVENTOR. ,/4/////am QM BY w/ ? V Patented Dec. 17, 1946 2,412,571 UNITED STATES PATENT OFFICE 2,412,571 ELECTRONIC TIMING SYSTEM William Few, East Cleveland, Ohio, assignor to The Clark Controller Company, Cleveland, Ohio, a corporation of Ohio 1 Application March 11, 1944, Serial No. 526,046 5 Claims. (Cl. 250-27) This invention relates to electronic timing sys tems of the type in which, upon the closing of a control circuit, a circuit to be controlled is ener gized and after a timed period is automatically de-energized. The underlying principles of the invention may be variously embodied, but the particular em bodiments thereof chosen for illustrative purposes, and described hereinafter, comprise the follow ing. The winding of an electro-magnetic relay is in the controlled or timed circuit, and this circuit is connected to a ?rst set of anode and cathode electronic space-discharge electrodes, 2 is maintained operated throughout the timed pe riod referred to; Figs. 2 and 3 are views each similar to Fig. 1, illustrating different embodiments of the inven tion in the use of which a control ccntactor may be operated only momentarily to initiate the timed period referred to; Fig. 4 is a fragmentary view illustrating a modi?cation of either of the embodiments of Figs. 1, 2 or 3, and in which tWo electronic tubes are employed instead of a single tube as in Figs. 1, 2 and 3; Figs. 5 and 6 are fragmentary views illustrat under the control of a ?rst grid. A second anode ing modi?cations which may be employed in and cathode set of electrodes under the control 15 either of the embodiments of Figs. 1, 2 or 3; of a second grid is also provided. The grids are Fig. 7 is a View illustrating a different type of normally energized at the polarity to prevent current ?ow between their respective electrode sets, the second grid being energized by a con adjustment of an adjustable resistance shown in Figs. 1, 3 and 4. Referring to the drawings 1. have shown at l denser normally kept charged. Upon closing a 20 a transformer having a primary 2 connected to control circuit by a control contactor, the polar alternating current supply mains 3 and 4 and ity of the ?rst grid reverses, and discharge cur having secondaries 5, 5, ?I, and 8. The derived rent flows in the controlled circuit through the voltages of the said secondaries may be variously ?rst anode and cathode set and operates the re selected, but for illustrative purposes I have lay; and the condenser discharges at a retarded 25 found suitable voltages to be 225 volts, 95 volts, rate, thereby determining a time period during 25 volts, and 110 volts for the secondaries 5, 6, which the inhibiting potential on the second grid ?l, and 8 respectively. diminishes to a non-inhibiting value. At the end At 9 is an electronic tube comprising two sets of the time period the second anode and cathode of electrodes, one set comprising an anode, cath set pass discharge current, the flow of which cur 30 ode, and grid, at H), ll, !2, respectively; and rent causes the polarity of the ?rst grid to again the other set comprising an anode, cathode, and reverse and stop the discharge current in the grid, at l3, l4, [5, respectively. controlled circuit. This causes the relay to return I prefer to use a double tube of this type for to the restored condition. purposes of simplicity and economy. Such tubes Thus upon closing the control ccntactor the 35 are available commercially, illustrative of which relay operates, stays operated for a timed period, is the commercial tube RCA 6AD7-G. This tube and then restores. is a high vacuum tube because of which the two Contacts on the relay may be provided to con sets of electrodes can function independently. trol extraneous load circuits as will be under At It is a condenser; a suitable capacity for stood. which may be 1A micro~farad; and at l1, l8, I9, The primary object of the invention is to pro 28 are resistance units, the unit 20 being adjust vide generally an improved timing system hav able, and suitable values for these resistances be ing the end results referred to above. ing 1500 ohms, 250,000 ohms, one megohm, and Another object is to provide a timing system 600,000 ohms respectively. having the characteristics and mode of oper At 2| is an electro-magnetic relay having a ation referred to above and more fully described winding 22, bridged by a condenser 23, and hav hereinafter. ing normally open control circuit contacts 24. Other objects will be apparent to those skilled The relay may have also any desired number of in the art to which the invention appertains. normally open or normally closed contacts to The invention is fully disclosed in the follow 50 control other load circuits and illustrative of this ing description taken in connection with the I have shown at 25 normally open contacts con accompanying drawings in which, trolling the load circuit 23. Fig. 1 is a diagrammatic view of a circuit and The control switch or contactor referred to is apparatus illustrating an embodiment of the in shown at 21,. vention, in the use of which a control ccntactor 55 ?The various circuits and connections and other 2,412,571 3 rent ?ow between the anode l0 and cathode H elements of the system not thus far described starts, these electrodes being in a circuit compris will now be described in connection with a de ing the switch 21, the resistance unit I8, and the scription of its operation as a whole. secondaries ?I and 8; the derived potential in Upon energization of the transformer second aries by the primary 2, the 95 volt secondary 01 ducing this ?ow being the sum of the potentials of the secondaries 1 and 8 or 135 volts. 6 charges the condenser � The charging cir It will be observed that because of the high re cuit comprises the resistance um't l'i?, wire 28, wire sistance of the unit [8, the greater part of the 29, condenser 56, wire 39, grid 12, cathode H, potential drop in the circuit of the electrodes ill and wire 3|; the current ?owing between the grid and cathode being that sometimes referred to as 10 and H is accounted for by the drop of potential in the resistance unit 18. It follows that the the grid current. The grid and cathode act in secondary ?I is of little effect, and that the polarity this respect as a recti?er and pass only alternate of the wire 3'2 and the grid l5 will be negative half waves of the derived alternating current, (for positive values of the anode [3) as soon as and the current is in the direction to charge the the recti?ed current flow between the anode and condenser so that the plate of the condenser 15 cathode ill and H starts; and that this will cause connected to the grid l2 by wire 38 is negative. the grid IE to out off the ?ow between the anode The condenser I6 is thus fully charged in the l3 and cathode ill to de-energize the relay and normal state of the system. The resistance units allow it to restore. 19 and 20 across the condenser stabilize its charge In operation therefore, the condenser i6 is 20 in a known manner. charged by the secondary t; and maintains the The potential across the anode IE! and cathode grid l2 negative; and the grid i5 is maintained II is the algebraic sum of the potentials of the negative by the algebraic sum of the voltages of secondaries 6, 1, and 8 or 40 volts but current flow the secondaries 6 and ?1. Upon closing the control is prevented by the negatively charged grid i2. switch 21, the secondary 6 is neutralized, and The grid [5 of the tube is also energized to be the secondary l acting alone, changes the grid negative (for positive values of the anode [3), it �to positive, and the anode 13 and cathode it being in a circuit comprising the secondary 6, pass current which operates the relay 2!. The grid 15, cathode ?wire 28, secondary 1, wire 32, condenser It then discharges through the ad .l4, and wire 3|, and the potential on the grid being the algebraic sum of the voltages of the 30 justable resistance 26 and contacts 24 on the re lay, and after a time period current flows between secondaries 6 and ?i, or '70 volts, so that the grid the anode It] and cathode I l, induced by the sece I5 prevents flow of current between the anode ondaries ?I and 8 and this current, ?owing through l3 and cathode l4 notwithstanding that they have the high resistance l8 changes the polarity of the potential of the secondary 5 or 225 volts im pressed thereon. 35 the grid I5 to negative, and the relay operating current is thereby interrupted and the relay re As will be observed, the winding 22 of the mag stored. netic relay is in the circuit of the anode l3 and cathode M, the circuit comprising the secondary 5, wire 33, winding 22, wire 34, anode I3, cathode Upon opening the switch 21, the condenser again charges and renders the grid l2 negative _ l4, and wire SI, and current flow in that circuit 40 and flow between the anode It and cathode H is will operate the relay, but normally the relay re mains unoperated or restored. Upon closing the control switch 21 the sec ondary 6 is in effect cut o? from the system, the again cut oil and the system is ready for an other operation. _ , It will be observed that in the above-described operation of the system of Fig. 1, the control switch 21 is maintained closed for the duration of the timed interval, and this is desirable in cer providing a high resistance by-pass for it. The tain uses of the system. In some uses, however, grid i5 is therefore then energized by the sec it may be desirable to effect the initiation-of the ,ondary ?I alone, and the grid l5 now becomes posi timed interval by only a momentary closure of tive (for positive values of- the anode l3), and current ?ows between the anode l3 and cathode 50 the switch 21, and to render this switch incapable of interrupting the timed interval thus initiated 714 in the circuit above-described and operates even if the switch be again operated before the the relay 2!. ~ interval has been completed. This type of con This relay operating current being recti?ed by trol of various classes of electrical apparatus by the tube 9 and therefore flowing only on alternate half waves, the condenser 23 is provided to main? 55 a manual switch is sometimes called ?non-beat? control. Such a system is shown in Fig. 2.?. tain energization of the winding 22 during the i switch 21 and the resistance unit I?! and wire 3! , In this system, the relay 2|, besides having the contact 24, has another contact 37 which is closed when the relay operates; and this contact (SU is connected by wire 38 to the wire 3|. By this means, upon operation of the relay, theswitch 27 is bridged by, a circuit comprising the wire 36, lowered-resistance discharge circuit for the con contact 31, and wire 38. denser H5 at the relay contacts 24, the circuit Upon momentary closure of the switch 2?, and being, from the condenser, by wire 30, through upon the consequent operation of the relay 2!, the adjustable resistance unit 20, by wire 35, con this bridging circuit is closed and the switch 21 tacts 24, wire 36, wires 28 and 29 to the other may then be opened and the system will go on side of the condenser; the grid to cathode circuit, operating as described for the system- of Fig. 1. to maintain the grid [2 effective to prevent flow, At theend of the timed period, when the relay now'being through the switch 2?. ' The condenser now discharges through the re- 7' 2i opens again and opens the contact 31, the switch 21 being open, the condenser again charges sistance unit 20 at a rate determined by the ad other half waves in a well-known manner to hold the relay continuously in operated condition. When the secondary 6 was by-passed by the control switch 21, the condenser it stopped charging. When the relay operated, it closed a justment of that unit. At the end of a time as before preparatory for another operation. . . _ In the form of Fig. 3, a similar ?non-beat? period during which the discharge goes on, the manual operation is provided ,bya diiierent ar negative potential on the grid 12 produced by the condenser has'fallen to so low a value that our a rangement of contacts on therelay 2| which 5 2,412,571 makes possible the use of a smaller relay requiring less power to operate it. An additional resistance unit 39 is introduced bridging the wires 28 and 3|, a suitable ohmic value for which (when the ohmic values of the other resistance units are the same as those mentioned hereinbefore) is 15,000 ohms. 6 circuit including the relay winding 22 and the anode and cathode i3 and H! of the tube, is that of the sum of the secondaries 5 and 5, and that therefore a larger more powerful relay may be employed for the same size relay as before. The adjustable resistor 29 is shown, in the ?g~ ures described above, by the conventional sym On the relay 2!, besides the aforesaid contact bol. In Fig. '7 it is shown more as it would be ar 24, which is normally open and is closed when the ranged for adjustment in practice. The re relay operates, a. contact 40 is provided which is 10 sistance 29 is in the two banks 43 and 4d. The normally closed in the open position of the relay. bank 43 is divided into ten sections l?i5?/35, each The condenser 15 is normally maintained with a tapped contact 46; and a movable contact charged by the transformer secondary 5 through ii? connected by a wire 48 to one end of the bank the resistance unit ll, a wire Ill, the contact 43, is movable to any contact. The bank 33 may a wire 42, and thence by wire 28 to the condenser 15 therefore be cut in or out by tenths. . as before, the resistance unit 39 bridging this The bank 5% has two sections rid-?159 of equal charging circuit being of sui?ciently high ohmic resistance, and the resistance of each equal to the value as not to effectively by-pass the condenser entire bank and each section has a tapped charging current and interfere with its charging. contact 52. A movable contact connected by Upon closure of the control switch 27, the sec a wire 53 to� one end or" the bank as can be moved ondary 6 is by-passed through the resistance 61 to either of the contacts 52~52. as before and charging of the condenser is in By suitably positioning the movable contacts terrup'ted and the relay 21 operates as described on the tapped contacts of the two banks, the before. The circuit for the secondary 1 through value of the resistance 26 can be changed by wire 32, grid 55, wire 3|, and back by wire 28 to thirty steps; to correspondingly change the tim� the secondary l, which keeps the grid l5 positive ing eifected by the condenser H3. to maintain the relay operated, now takes place The invention is not limited to the exact de through the resistance unit 39 so that the switch tails illustrated and described. Changes and 21 may be opened after its momentary closure, or modi?cations may be made within the spirit of released and allowed to open, if, as would be 30 the invention without sacri?cing its advantages customary, it is normally held open by a spring, and within the scope of the appended claims. like a push button. The circuit from the condenser IE to the grid l2 and to the anode ll, wire 3| and by wire 28 back to the other side of the condenser also takes place through the resistance unit 39 to maintain the grid l2 effective until the time interval has passed. In other respects the operation is the same as that of the other systems. The con denser !8 of course discharges as before through the adjustable resistance 26, wire 35, contact 211, and wire 42, and wire 28 as before. As to the modi?cations of Figs. Q, 5, and 6, Fig. 4 illustrates the use of two tubes 9A and 9B in stead of a single tube 9 as in the other ?gures, the anode, cathode, and grid, [0, H, and 12 re spectively being in the tube 9A; and the anode, cathode, and grid, i3, i4, and !5 respectively be ing in the other tube 93. The operation is the same as that of the other ?gures. As described above for Figs. 1, 2, and 3, a re sistance unit i9 is used in connection with the condenser l5 and discharge of the condenser is initiated upon operation of the relay 2!, the dis charge taking place through the relay contact : 24. This is the preferred arrangement particu larly when the timed period is to be short. For longer timed periods, the arrangement of Fig. 5 may be used. As shown the adjustable resistor, This application is in part a continuation of my copending application Serial No. 432,897, February 28. 1942, for Electronic timing systems. I claim: 1. In a timing arrangement, a source of alter hating potential, a work circuit, an electronic an ode and cathode in the work circuit subjected to source derived potential, and a control grid there- for normally negatively energized by a secondary alternating potential derived from the alternating source potential; timing means; a control con tactor; a control contactor circuit; means includ ing circuit connections rendered effective upon closing of the contactor circuit to reverse the polarity of the secondary alternating grid ener gizing potential to immediately start ?ow of cur rent in the work circuit, and to initiate the run ning of a time interval by the timing means, and again to reverse the polarity of the secondary alternating grid energizing potential tostop ?ow of current in the work circuit at the end of the time interval, and maintain it stopped so long as the contactor circuit is maintained closed. 2. In a timing arrangement; a source of poten tial; a work circuit comprising an electronic space-discharge path subjected to source-derived potential; a grid normally negatively energized by source derived potential and normally pre here 28A, is simply connected across the con 60 venting current ?ow in the discharge path and denser IS, the resistance unit 19 and ?the relay work circuit; a control contactor; a normally contact 24 being dispensed with. When charg charged condenser; means rendered e?ective upon ing of the condenser is stopped, the condenser operation of the contactor to reverse the polarity begins at once to discharge through the resistor of the grid energizing potential to thereby start 20A. The successive timed periods with this ar current flow in the Work circuit, and rendered rangement may vary more than with the pre effective to start retarded discharging of the con ferred arrangement of Figs. 1, 2, and 3 but� when denser; and means subject to condenser poten the periods themselves are relatively long the tial and rendered e?ective by the reduction there variation will be negligible. of after a time interval of condenser discharging, Again, in Figs. 1, 2, and 3, the resistance unit 70 to again reverse the polarity of the grid ener l7 associated with the secondary 6 is connected in gizing potential and stop the flow of current. the line 28. Fig. 6 shows a modification in which 3. In a timing arrangement, a source of poten it is connected in the line 3 I. With this position tial; a work circuit comprising a ?rst electronic of this resistance unit, it will be observed that, for space-discharge path subjected to source-derived example in Fig. l, the voltage impressed upon the 75 potential and controlled to normally prevent cur 2,412,571 7 rent ?ow therein by a ?rst grid normally ener gized by source derived potential; a normally charged condenser; a second electronic space-dis charge path subjected to source-derived potential and controlled to normally prevent current flow therein by a second grid normally negatively en ergized by the condenser; a control contactor; circuit means rendered effective, upon operation of the control contactor, to reverse the polarity of 8 being initiated by said source derived potential upon discharging of the condenser for a prede termined time period; controlling means?, respon sive to current ?ow in the said second path, to again reverse the polarity of the energizing po tential of the ?rst grid to stop current ?ow in the work circuit. 5. In a timing arrangement, a source of po tential; a transformer energized from the source; the energizing potential of the ?rst grid whereby 10 a work circuit to be controlled subjected to source derived potential and comprising a ?rst electronic current flow starts immediately in the ?rst dis space-discharge path and a ?rst control grid charge path and work circuit, and rendered ef therefor; a second space-discharge path and-a fective to start retarded discharge of the con second control grid therefor; a ?rst, a second, denser whereby current ?ow starts in the second discharge path after a time interval of con 15 and a third transformer secondary?; connections normally energizing the ?rst grid by the di?er denser discharging; and means rendered e?ective ential potential of the ?rst and second secondar by current ?ow in the second discharge path to ies to normally prevent current flow in the ?rst again reverse the polarity of the energizing po path and work circuit; a condenser; connec tential of the ?rst grid to stop the current ?ow in 20 tions maintaining the condenser charged by po the ?rst path and work circuit. tential of the ?rst secondary and applying the 4. In a timing arrangement, a source of po condenser potential to the second grid to nor tential; a work circuit to be controlled subjected mally prevent current flow in the second path; to source-derived potential and comprising a ?rst a control contactor; circuit connections rendered electronic space-discharge path and a ?rst con trol grid therefor; a second electronic space-dis 25 effective upon operation of the contactor to neu tralize the said ?rst secondary and cause the said charge path subjected to source-derived poten second secondary to reverse the polarity of the tial and a second control grid therefor; connec energizing potential of the ?rst grid to cause cur tions normally energizing the ?rst grid from rent flow to start in the ?rst path and'work cir source derived potential to prevent current from ?owing in the ?rst discharge path and work cir 30 cult, and to stop charging of the condenser, and to start retarded discharge of the condenser; cur cuit; a condenser; connections normally main rent ?ow in the second path being initiated by taining the condenser charged from source de the sum of the potentials of the second and third rived potential and applying the condenser po secondaries after discharging of the condenser tential to the second grid to normally prevent current ?ow in the second discharge path; a con 35 for a predetermined time period; and resistance in the second discharge path producing a drop of trol contactor; circuit means rendered effective responsive to operation of the contactor to inter rupt charging of the condenser and to reverse potential which e?ects reversal of the polarity of the energizing potential of the ?rst grid and thereby stops ?ow of current in the ?rst path and the polarity of the energizing potential of the ?rst grid to start current flow in the work circuit, 40 work circuit. WILLIAM FEW. and to initiate retarded discharging of the con denser; current ?ow in the second discharge path?