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Nov. 26, 1946. M. E. BIVEINS 2,411,703 ELECTRIC CONTROL CIRCUIT Filed April 8, 1944 5 Sheets-Sheet 1 F5 .ia. inventor‘ 3 Maurice E. Bivens, by ?anyffjwjm Hi5 Attorney . Nov. 26, 1946. 4 M E. BIVENS 2,411,708 ELECTRIC CONTROL CIRCUIT Filed April 8, 1944 5 Sheets-Sheet 2 Fig. Eb. /25 ms ‘I /75 74 '174 / W79 /797 @nventor : Maurice E. Bivens, gHis Attorney . Nov._26, 1946. ~ M. E. BIVENS 2,411,708 ELECTRIC CONTROL CIRCUIT Filed April 8, 1944 5.Sheets-Sheet 3 Fig. lc. Invent or- I Maurice E. Bivens, His Attorney . NW, 226, 1946., 2,41 1,79% MI E. BIVENS ELECTRIC CONTROL CIRCUIT Filed April 8, 1944 5 Sheets-Sheet 4 PRESS URE PA 7' TERM Figza, Pl mi P’i F] CURRENT PATTEFTN Fig. 2b“ 13 rzlm com’? ___[T1___ 15 I7 M rslm ‘T7 ! ‘EL? T9 17/0 lTl/i I9 HOLD 1 255 I251 : l l VALVE I55 VALVE I54 RELA Y5 I58 I39 I28 20 7 I 76 I ‘7/ l8 5 I99 FY2205 7/ 72 75 74 75 I26 TIM/N9 RHEOSTAT HEAT CONT/70L \RHEOSTAT FOOT SWITCH I67 VALVE 2/8 VALVE 2/7 RELAY we’ — RELAY 139’ TIMING nwzosmr TIM/N6 CAPACITOR 286 23! ‘23s 251 2:15 ‘251 ' 221/ RELAY ms’ ?mve‘m?or" 3 Maurice? E3. Bivens; MALL“ H565 At?orne 9 ., Nov. 259 1945., M, E BWENs 2,411,79 ELECTRIC CONTROL C IRCUIT Filed April 8, 1944 5 Sheets-Sheet 5 Emvam‘bnri Mauwiae E, Bivens, ttor‘neg. _ Patented Nov. 26, 1946 2,411,708 UNITED ~STATES PATENT OFFICE.‘ 2,411,708 ELECTRIC CONTROL CIRCUIT Maurice E. Bivens, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application April 8, 1944, Serial N0. 530,136 1 19 Claims. My invention relates to electric control cir cuits and more particularly to improved electric control circuits for effecting a plurality of cir cuit controlling operations in timed sequence. While not limited thereto, my invention is particularly adapted for eiiecting the transmis sion of a predetermined current pattern to a re (Cl. 171-97) 2 a pressure pattern for resistance welding sys tems, which are readily coordinated but which afford a maximum of ?exibility with respect to independent adjustment. . In accordance with one of the illustrated em bodiments of my invention, current is supplied to a resistance welding load by means of a pair sistance Welding load in which a plurality of of reversely connected electric valves preferably timed applications of current of di?erent magni of the gaseous discharge type employing a liquid tudes are supplied to the load and are separated 10 cathode. The ' periods of energization of the by periods of deenergization during which the welding transformer are controlled by control work is allowed to cool. The current pattern ling the periods during which the electric valve may also be coordinated with a pattern of pres means are conducting, and the level of current sure according to which the work is subjected to supplied to the load circuit is controlled by de diiierent pressure levels during diiferent timed 15 termining the instant in the anode-cathode volt’ intervals which may be adjusted in length inde age waves of the electric valve means that con pendently of the intervals during which different duction is initiated. In accordance with this em levels of load current occur. Control circuits of bodiment of my invention, the periods of ener this general type have been provided for effect gization of the load circuit are controlled by a ing the transmission of a predetermined current 20 group of control relays which selectively com pattern to a welding load circuit in which the plete and interrupt the supply of a turn-on volt» periods of energization may be separated by an age component in the excitation circuit of the “oil” or cool period, and one of these systems is reversely connected electric valve means. _This described and claimed in my copending applica group of control relays also includes contacts for tion Serial No, 460,240, ?led September 30, 1942, controlling the magnitude of the resistance in and now Patent 2,390,982 granted December 18, one arm of a bridge-type phase shifting network 1945, and assigned to the assignee of the present which controls the instant of initiation of com invention. These prior systems have worked sat duction of the electric valve means. The opera isfactorily but as the number of di?erent periods tion of these relays is controlled by a novel timing of the pattern have increased, the amount of circuit including a timer oi the single-tube in equipment required has rendered the extension verter type in which the magnitude of the re of these systems somewhat impracticable. In sistance in circuit with a capacitor, which to accordance with the teachings of my present in gether determine the interval between succes» vention, I provide an improved control circuit sive operations of the electric valve of the in which is readily extended to provide any desired verter, is altered by operation of the same group number ‘of independently adjustable intervals of relays which controls the periods of conduc with a minimum amount of equipment, and in tion and instants of initiation of conduction of which the ?exibility of adjustment of the timed the reversely connected 1 electric valve means. intervals and current levels is increased. The successive operations of the single-tube in It is an object of my invention to provide a verter circuit effect the successive operation of new and improved electric control circuit. these various control relays by means of a con- I It is another object of my invention to provide trol circuit which is essentially a parallel-type a new and improved electric control system for inverter, the valves of which are normally biased effecting a predetermined pattern of circuit con negatively and which conduct alternately at in trolling operations at accurately timed intervals. 45 stants determined by the conduction of the valve It is still another, object of my invention to of the single-tube inverter. The alternate con provide an improved control circuit for e?ecting duction of the valves of the parallel-type inverter a plurality of timed operations of independently eiiects alternate operation of a pair of control re adjustable duration which is characterized by lays which control the energizing circuit of the ' the ?exibility of control and the small amount of 50 group of relays which control the periods of ener equipment required. gization and instants of initiation of conduction It is a still further object of my invention to of the main electric valve means so that these lat provide a new and improved control system for ter relays are energized in succession, one for providing a plurality of independently adjustable each conduction of the valve of the single-tube patterns of control, such as a ‘current pattern and 55 inverter timer. The pressure pattern is con 2,411,708 trolled by a pair of 'solenoid'valves which are in i turn controlled by a‘pair of independent elec tronic timers and which may, if desired, be in terlocked with the relays controlling the current pattern to be supplied to the'load ‘circuit. My invention will b'e-better understood by ref erence to the following description taken in con nection with the accompanying drawings, and its I 4 conductor 30, the anode-cathode circuit of valve 26. conductor 3 l , unilaterally conducting device 32 to the cathode l2 of electric valve ill. The cir cuit of ?ring electric valve 21 may be traced in ‘ a similar manner and found to be connected be ' tween the anode and cathode of valve l0’, through a circuit including unilaterally conducting de vices 33 and 34. With this circuit it is apparent that the electric valves I0 and ill’ will be ren scope will be pointed out in the appended claims. dered conducting during cycles of the supply cir 10 In the drawings, Figs. la, lb and 10, considered cuit voltage and at instants during the cycles of together, are a schematic representation of one the supply circuit voltage which coincide With the ‘ embodiment of my invention. Figs. 2a and 2b initiation of conduction of electric valves 26 and represent, respectively, pressure and current pat» 21, respectively. Since the excitation circuits for ' terns that may be provided by the embodiment of my invention illustrated in Figs. 10-10 and 3, and 15 electric valves 26 and 21 are identical, only one will be described and the same reference numerals Figs. 2c and 2d indicate the operative condition will be applied to corresponding elements in the of various elements of the circuit illustrated in excitation‘ circuit of the other valve. Consider. Figs. la-lc and Fig. 3 during diiferent portions’ ing valve 26, the cathode thereof is connected to of the current and pressure patterns illustrated the control member or grid through a circuit 20 in Figs. 2a and‘2b. Fig. 3 is a schematic repre including four components of voltage. The ?rst sentation of a modi?cation of a portion of they is an alternating current hold-off voltage supplied I system illustrated in Figs. la-lc. Referring vnow to Fig. 10; I have shown my in vention incorporated in a control system for con trolling the conduction ,of a pair of electric valve means i0 and 10' which are preferably of the type employing a gaseous discharge and each includes by the secondary winding 35 of a transformer 36 having a primary winding 31 energized from an alternating current supply which is synchronous with respect to the supply circuit l4 and prefer ably is energized from the supply circuit l4 through connections not shown. This compo nent of ‘voltage is impressed in the cathode to ing electrode l3; The electric valve means it! and I0’ are reversely connected in parallel between an 30 control member circuit of valve 26 across a ca pacitor 38. The second component of voltage is alternating current supply circuit l4 and the pri an alternating current turn-on voltage impressed mary winding of a resistance welding transformer . an anode II, a pool-type cathode i2 and a start . I5 having the secondary winding thereof con nected to the electrodes l6 of a resistance weld ing machine. A transient voltage limiting im pedance I1 is connected across the primary wind ing of the welding transformer and may to ad on the grid circuit of valve 26 across the termi nals of a parallel resistor 39 and capacitor 40 by the secondary winding 4i of' a transformer 42 having the primary winding 43 thereof energized from the primary side of transformer 36 through vantage be a resistance having a- nonlinear cur a resistor 44, and through one or more of a plu an operating coil 22 and to the lower side of the piston by a second solenoid valve 23 having an static phase shifting circuit through a ?lter in rality of relay contacts connected with conductors rent resistance characteristic. As illustrated 45 and 46. The third component of voltage is 40 schematically, the pressure exerted on the work impressed on the control member of valve 26 l8 by the electrodes is may be controlled by con across the terminals of a resistor 47 by the sec trolling the pressure exerted on a piston I9 work ondary' winding 48 of a saturable peaking trans ing in a cylinder 20. As illustrated, the applica former 49 having the primary winding 50 there tion of ?uid pressure to the upper side of the of energized from the terminals 5i and 52 of a piston is controlled by a solenoid valve 2| having cluding a reactor 53 and a capacitor 54. A re sistor 55 is also connected in series with the pri mary winding 50 of peaking transformer 49 to levels of pressure may be exerted on the work by control the instant at which the transformer 49 50 selective energization of the coils 22 and 24. With saturates and the width of the secondary'volt coil 22 energized alone, pressure is transmitted age peak vproduced by the transformer. A fourth ‘only to the upper side of piston I9‘and a high component of voltage is impressed on the control level of pressure is exerted on the work. -When member of valve 26 by a self-biasing circuit in coils 22 and 24 are energized simultaneously, the cluding a parallel resistor 56 and capacitor 5i. net pressure on piston i9 is reduced and a, lower Additional ?lter or transient suppressing ca level of pressure on the work is established. pacitors 58 and 59 are also connected with the Control of the energization of coils 22 and 24 from control member circuit of valve 26. The compo a suitable source of alternating current 25 will nents of voltage impressed on the control mem be considered in detail at a later point in the 60 bers of valves 26 and 2? have such relative mag speci?cation. nitudes that both the alternating current turn-on The control circuit for supplying discharge voltage supplied by transformer secondary wind initiating impulses to the control electrodes is ings 4i and the peaked voltage wave supplied by of electric valves to and I0’ will now be de the transformer winding 48 are required to ini scribed. These impulses are transmitted to the tiate conduction of the ?ring valves and as a result control members i3 of valves i8. and ill’ by a to initiate conduction of main electric valves i6 pair of excitation or ?ring valves 26 and 27, re and it’. Thus the periods during which the load spectively. These valves are preferably of the hot circuit is energized are determined by controlling cathode gaseous discharge type and are reversely the intervals during which the transformer sec connected in parallel in a manner similar .to the . ondary windings 41 are energized and the instant main electric valves Ill and I0’ and are energized _ during the cycles of supply circuit voltage at respectively in accordance with the anode-cath which valve means it) and 10' are rendered con ode voltages of valves Ill and I0’. For example, ductive are determined by controlling the phase the anode-cathode circuit of electric valve 26 position of the peaked voltages of secondary may be traced from the anode of valve it through windings 48. As indicated previously, the inter 75 conductor28, a unilaterally conducting device 29, operating coil 24. With this arrangement, two 2,411,708 5 .. 6 vals during which transformer 42 is energized are determined by controlling the connection of con doctor 45 with conductor 46. The phase position 01' the peaked voltages provided by transformer secondary windings 48 is determined by control Cl ling the phase position of the‘ voltage impressed on the terminals 5| and 52' by the phase shifting network including the arms of the midta-pped transformer winding 31 of transformer“, a ca ‘ pacitor 60, an adjustable resistor 6|, and the mag nitude of resistance included between conductors 82 and 83 which completes the fourth arm of the phase shifting network. controlling the sequential connection of the tim ing rheostats 83-I02, inclusive, in circuit with a capacitance I03 01 a single-tube type inverter or timing circuit designated generally by the nu meral I04. Across the operating coil of each of the relays ‘II-80, inclusive, is connected an indi cating lamp I05'and a series resistor I06 to pro vide a visual indication as the relays ‘II-430, in elusive, become energized to indicate the interval 10 of the current pattern which is being supplied -tb_y the equipment at any time during its opera ion. The manner in which the relays ‘II-80, inclu In accordance with important features of the sive, are energized in sequence at the beginning present invention, improved control circuits are 15 of the time intervals from T2 to ‘II I, inclusive, provided for controlling the connection of con will now be described. Referring now to the up ductor 45 with conductor 46 to determine the pe per portion of Fig. 1a, a source of direct current riods of energization of the load circuit and for control voltage is impressed across a pair of con controlling the selective insertioncf heat control ductors I01 and I08 by the output of a biphase rheostats 64-10, inclusive, between conductors 62 20 recti?er. including a supply transformer I09 and and 63 to complete the fourth arm of the static an electric discharge device IIO having a pair of phase shifting circuit through diiierent magni discharge paths. The direct current output of tudes of resistance. v A group of electromagnetic the recti?er is ?ltered by a series smoothing re relays ‘I I-80, inclusive, are provided for selectively actor III and a shunt ?lter capacitor I I2. Volt controlling the heat control rheostat which is ef age dividing resistors II3_I I'I, inclusive, are con iectively connected ‘between conductors 62 and 63 nected in series across the conductors I01 and I08 and for controlling the connection of conductors to impress different levels of direct current volt 45 and 46 to determine the periods of energiza age on conductors H8, H9, I20 and I2I. Con tion of the load circuit to establish the current ductors I20 and I2I are connected by adjustable pattern indicated in Fig. 2b and including in 30 taps with the voltage dividing resistor I I5 to pro tervals designated T2-TI I, inclusive. These re vide adjustable levels of voltage. lays are provided with operating coils 8I-90, re~ The single tube inverter I 04 includes an elec spectively, each having one terminal connected tric discharge valve I22, preferably of the gaseous with an alternating current supply line 9| and discharge type, having a control member or grid ,another terminal arranged to be connected to a 35 I23 connected to conductor I2I through a current second alternating current supply line 92 through limiting resistor I 24. The anode of the dis a sealing-in contact. These sealing-in contacts charge device I22 is connected with the direct have been designated ‘Ila to 80a, inclusive. Re current supply conductor through a normally lays ‘I2, 13, ‘I5, ‘I6, 11 and ‘I9 are each provided closed contact E25 of a resetting relay I26, a with a pair of contacts designated 12b and 120, 40 normally open contact I27 oi- an initiating relay etc., for controlling the heat control rheostats I28 and a commutating reactor I129. The ca 64-'I0,-inclusive. The “1)” contacts of these lat— pacitor Hit of the single tube inverter circuit is ter relays are normally open and the “c” con connected between the direct current supply con tacts are normally closed and are connected to ductor Ill'i and conductor 836i which is connected control circuits in shunt with the respective heat with the cathode of the single tube inverter‘ valve control rheostats so that all but one of the rheo ‘I22. Conductor 530 is arranged to be connected stats is shunted from the circuit between con to the direct current supply conductor H08 by ductors 62 and 63 at any one time. For example, means of ‘a normally open contact 13d of the before relay 12 picks up heat control rheostat 64 initiatingrelay lit through a circuit including a is connected between conductors 62 and 63. ‘When 50 timing rheostat I32 and the normally closed con relay 12 picks up, contact 72b closes and estab tact ‘I Ie of relay ‘ll. Rheostat i32 determines the lishes a short circuit around heat control rheo timing of the interval TI of the current pattern stat 64 and contact 120 opens to effectively con illustrated in Fig. 2b. Timing rheostats 93-402, nect rheostat 65 between conductors 62 and 63. inclusive, are arranged to be sequentially inserted As relays ‘I3, ‘I5, ‘I6, ‘I1 and ‘I9 pick up in sequence, 55 in a'circuit between the conductor I30 and the heat control rheostats 66, 61, 68, 69 and 10 are direct current conductors E08 as the relays ‘II-80, eiTectively connected in succession between con inclusive, are picked up in sequence. The circuit ductors 82 and 63. Relays ‘II, ‘I3, 14, 11, ‘I8 and ‘ ofthe timing rheostats 93-! 02 also includes a ?xed 80 are each provided with a “d” contact which is resistor I34. connected to control the circuit between con 60 In order to provide for the energization of only ductors 45 and 46 to establish the periods of en one additional relay of the group of relays ‘I I—80, ergization and deenergization of the load circuit inclusive, for each conduction of the valve I 22 of as indicated in Fig. 22) for the periods from T2 the timer circuit I04 I provide a control circuit to TI I, inclusive. For example, closure of con I35 which is in general a parallel-type electric tacts 'IId connects conductors 45 and 46 together 65 valve inverter whichoperates to energize alter to establishv a period or energization. Contact nately the operating coils I36 and I 31 of relays 13d opens the circuit between conductors 45 and I38 and ‘I39 having contacts I40-I45 and '46 when the relay ‘I3 is energized. Similarly, con inclusive. These contacts are con tacts 14d and 18d are effective when relays ‘I4 rected to control the energization of the oper and ‘I8 operate to connect conductors 45 and 48, 70 ating coil-s 8I-60 of the relays ‘II-80 from the and contacts 11d and 80d are e?'ective to dis alternating current supply conductors SI and 92 connect conductors 45 and 46 when relays TI and to effect the energization of only one additional 80, respectively, are energized. Each of the re relay for each conduction of the valve I22 of lays ‘II-80 is also provided with a‘ normally closed the timer I04. Referring now to the circuit I35, “e" contact and a normally open “l’i'contact for it comprises a pair of electric discharge devices ' 2,411,708 control relay I1I having one pair of normally open contacts I12 connected to energize the oper I53 and I54, each preferably of the type employ ing an ionizable medium such as a gas or a vapor, ating coil 22 of the high pressure solenoid 2I ‘ and including a control member or grid I55. The cathodes of electric valves I53 and I54 are con through conductors I13 and I14. Since theoper ‘ating coil of initiating relay I28 is connected between conductors 9I and 92, it is energized immediately upon closure of the initiating switch nected together and to the direct current supply conductor I I9 and the anodes of these valves are connected to the direct current supply conductor II8 through the operating ‘coils of relays I36 and I31, respectively, so that relay I38 is energized when valve I53 conducts and relay I39 is ener I61 and closes its contact I65 to seal itself in and closes an additional normally open contact 10 I15 to maintain-the pressure control relay I1I energized. As pointed out earlier in the speci? gized when valve I54 conducts. A commutating capacitor I56 is connected between the anodes cation, the higher pressure is maintained on the welding electrodes at all times that the high pres sure solenoid 2I alone is energized. When it of electric valves I53 and I54 to effect commu tation of current between the valves as the vcon trol member of a nonconducting one of the valves 15 is desired to reduce the pressure supplied to the ‘ electrodes, the operating coil 24 of solenoid valve is rendered positive. The control members I55 of electric valves I53 and I54 are normally main tained at a negative voltage with respect to the cathodes thereof by an amount equal to the volt 23 is energized to introduce a back pressure on the lower side of the operating piston I9. A second pressure control relay I16 having an oper age drop across voltage dividing resistor II‘! by 20 ating coilv I11 is provided with a normally open contact I18 which is connected to control the virtue of the connection of the control members energization of the operating coil 24 from the with conductor I08 through a resistor I51 and the alternating current source 25 through conduc-' respective current limiting resistors I58 and I59. tor I13, contact I12 of relay HI and a conduc The vcontrol members I55 of electric valves I53 and I54 are rendered positive with respect to the 25 tor I19. For controlling the operation of the relay I16 to e?ect the application of lower pres cathodes thereof momentarily each time electric sure to the electrodes I6 during predetermined valve I22 is rendered conductive as a result of timed intervals, ‘a pair of electronic timers illus the connection between the cathode of electric trated generally by the numerals I80 and I8I are valve I22 and the control members I55 through provided. These timers are of the general type 30 a circuit including a capacitor I60. Since the capacitor I60 cannot charge immediately when valve I22 conducts, the voltage of the control members I55 is rapidly raised to the voltage of conductor I01 when valve I22 conducts. The time constant of the circuit including capacitor I60 35 described and claimed in Schneider Patent No. 2,171,347 dated August 29, 1939, and assigned to the assignee of the present invention. Referring particularly to the timer I80, it comprises an electric discharge valve I82 preferably of the gas ?lled type and having the anode thereof con and resistor I51 is very small so that the voltage nected with the alternating current supply con of capacitor I60 rapidly returns to the voltage of ductor 92 through a resistor I83 and the operating the conductor I08 and the positive impulse sup coil I84 of a'relay I85. The cathode of the elec plied to control members I55 is, therefore, of very tric valve I82 is connected to the same alter 40 brief duration. In order to establish an initial nating current supply conductor as the anode charge. on the timing capacitor I03 of the single ' through a resistor I88. The cathode is also con tube inverter a connection with the direct cur- . nected to the alternating current supply conduc tor I64 through an initiating circuit including rent supply conductor I20 is provided by a nor— mally closed contact I6I of initiating relay I28. A normally closed contact I62 of the initiating relay I28 is provided to complete a connection. between the control member I55 of electric valve I53 and the direct current conductor I I9 to insure that electric valve I53 will be rendered conduc tive upon energization of the conductors I01 and I08 prior to operation of the initiating re lay I28. As previously mentioned, the control relays 1 I-80 are energized from alternating current sup; ply conductors 9| and 92. Conductor 92 is ener gized directly from one terminal of the second ary winding of an alternating control voltage supply transformer I63, while the conductor 9| is energized from the other terminal of the sec ondary winding of transformer I53 through con ductor I64, a normally open contact I65 on the initiating relay I28 and a normaly closed con tact I68 on the resetting relay I26. The appli cation of control power to conductor 9I is e?ected by closure of an initiating switch I61 which may be the foot switch of the welder and which, as , a normally open contact 1 I g of relay 1 I, conductor I81, a normally closed contact 14g of relay 14, conductor I88 and contact I15 of the initiating relay I28. The control member of valve I82 is connected to a point of adjustable alternating current voltage on a resistor I89 which is con nected in series with voltage dividing resistors I90, I9I'and I92 which are connected across the alternating current supply conductors 92 and I64. Resistor I9I is a range resistor for the control and is provided with a shunting switch I 93. The circuit between control member of valve I82 and resistor I89 includes a current lim iting resistor I99 and a timing resistor I95 which is shunted by timing capacitor I96 through a 60 normally closed contact I91 of the relay I85. The timer I8I is in general the same as timer I80 and includes an electric discharge valve I98 and a relay I99 having the operating coil 200 connected in the anode-cathode circuit of the 5 valve I98. The remainder of the elements of the control 58I correspond exactly to the ele ments of control I80 and have been designated _ illustrated, has two sets of normally open con .by the same reference numerals. The initiating tacts I68 and I69. Contacts I68 close ?rst and circuit for timer 181 connects the cathode of are used for applying pressure only and contacts I68 and I69 are both closed to- place the system 70 valve I98 with conductor I64 and includes a normally open contact 20I on relay I85, con; in operation for supplying both pressure and cur ductor I81, normally closed contact 14g of relay rent to the electrodes. Contact I69 of initiating ' 14, conductor I88 and contact I15 ‘of initiating switch I61, when closed, connects conductor I69 with conductor 9I, and contact‘ I68 completes a ~ relay I28. The relay I85 of timer I80 is pro- ' circuit for the operating coil I10 of a- pressure 75 vided with a second normally open contact 202 2,411,708 which establishes an energizing circuit for the operating coil I11 of relay I16 by completing a circuit‘from the lower terminal of the operat ing coil through a normally closed contact 203 on the relay I99 of timer I8I, conductor 204 and ‘ a contact I15 of initiating relay I28. Thus relay ' I85 of timer I80 picks up to establish a circuit 10 chart of Fig. 20 indicating the operative condi tion of the various relays, valves, timing resistors and heat control resistors of the system during the various time intervals of the current and pressure patterns. Let it be assumed that all of the supply circuits indicated on the drawing are for pressure relay I16 and establish the ?rst period of low pressure indicated in the pressure energized and that the electric valves are in tact 14h, conductor I88 and contact I15/of ini ciently so to prevent conduction of valve I22 al most immediately upon completion of its anode proper operating condition. Under these condi pattern of Fig. 2a. When relay I99 of timer |8I 10 tions, electric valve I53 is conducting and relay I38 is energized. The capacitor I03 of the time " picks up, this circuit is interrupted by contact ing circuit I04 is charged with the lower plate 203 to re-establish the period of high pressure. When relay 14 picks up, it closes its normally " thereof at the voltage of the conductor I20. The control member of electric valve I 22 is slightly open contact 14h to establish an-energizing cir cuit for relay I16 through a conductor 205, con 15 negative with respect to the cathode but not su?i tiating relay I28 to establish a second period of low pressure indicated in the pressure pattern of Fig. 2a. Indicating lamps 206 may be connected cathode circuit by the initiating relay I28. Under these initial conditions, the conductors 45 and 45 are open circuited by virtue of the open across the operating coils of relays HI and I16 to indicate the level of pressure being applied to 20 contact 1| d of relay 1| to prevent conduction of current by the main electric valves I0 and I0’. the work. When it is desired to initiate a welding operation, , In order to provide an indication of the begin the switch I61 is closed. Closure of contacts I68 ning of the timing interval of application of pressure to the electrodes, a relay 201 having an 25 of switch I61 completes an energizing circuit for the operating coil I10 of relay I1I which through operating coil 208 is provided. The operating its contact I 12 e?ects energization of the sole coil 208 has one terminal connected to the alter noid valve 2| from the alternating current sup nating current supply conductor 9| and the other ply 25 to establish pressure PI on the electrodes terminal connected to the supply conductor 92 through a normally closed contact I40 of relay 30 as indicated in Fig. 2a. Also, upon operation of initiating switch I61, contact IE9 is closed to I38 so that relay 201 is energized as a result complete an energizing circuit for the operating of deenergization of relay I38 upon the ?rst con coil of initiating relay, I28. Contacts I65 and duction of timing valve I22. The relay 201 is I15 of relay I28 shunt the contacts of initiating provided with a sealing-in contact 201a. An indicating lamp 209 connected in series with re 35 switch I 81 so that the foot switch may be re leased without interrupting the welding opera sistor 2I0 across the operating coil indicates that tion. Closure of initiating relay I28 also estab the ?rst interval of the pattern or TI is in lishes the anode-cathode circuit of timing valve progress. I 22 through contact I21, disconnects the timing As indicated previously, the successive ener capacitor I03 from the direct current conductor gization of relays 1| to 80 is accomplished !by 40 I20, and connects the lower terminal of capac the alternate energization of relays | 38 and I39 itor I03 with direct current conductor I08 to produce the current pattern illustrated in Fig. through timing resistor I32. Contact I62 of relay 2b. In many applications it may be desirable I28 is opened to remove the bias voltage from to eliminate one or more of the intervals of the the control member of valve I53 which rendered complete pattern and for this reason single pole, 45 it initially conducting. Almost immediately upon double throw switches 2| I, 2| 2 and 2 I 3 and double operation of relay I28, tube I22 conducts to dis pole, double throw switch 2|4 are provided. With charge the capacitor I03 to a voltage which is all of these switches in the right-hand position somewhat positive with respect to the direct cur as indicated, the complete pattern of Figs. 2a rent line I01 due to the oscillatory char and 2b will be provided. By moving two or more 50 actersupply of the circuit including capacitor I03 and of the switches to the left-hand position, one reactor I29. As the voltage across the anode or more of the intervals may be eliminated as cathode circuit of tube I22 reverses, conduction will be described in more detail in connection by tube I22 is terminated and the lower plate with the operation of the system. of capacitor I03 starts to charge to the voltage ‘In the interest of simpli?cation, the supply of 55 of the direct current supply lines I01 and I08 heating current for the ?laments of the various through the timing resistor I32 to establish the electric discharge devices as well as the time duration of the interval TI of the current pro delay relay circuit for preventing the applica gram. tion of anode-cathode voltage to these discharge devices before the cathode has reached proper operating temperature have been omitted from the drawings. It will be understood that these so At the instant that electric valve I22 became conductive the control members I55 of valves I53 and I54 were momentarily raised to a pos itive voltage by the coupling capacitor I60 con means would be provided in a physical embodi nected between the cathodes of valve I22 and ment of the circuit illustrated, and that the vari ous alternating current supplies as indicated on 65 control members I55. The application of positive voltage to the control member of valve I54 in the drawings would preferably be derived from cooperation with the voltage of commutating ca the main alternating current supply circuit I4. Although the operation of thesystem has been :onsidered with'the various components of equip pacitor I56, ‘which has previously charged through the anode~cathode circuit of valve I53, ment as they were described, it is believed desir 70 e?’ects the commutation of current from valve I53 to valve I54 to deenergize relay I38 and en able to consider brie?y the operation of the ergize relay I39. The duration of the commuta iystem as a whole when functioning to supply tion and the operating characteristics of the re 2he current and pressure patterns indicated in lays I38 and. I39 are such that both relays are F'igs. 2a and 2b. In following this description >f the operation it will be helpful to follow the 75 maintained in the energized position for a short interval during commutation so that at no time 2,411,708 11, are the contacts of both of these relays closed. This is~indicated in Fig. 2c and is essential to in sure that only one additional relay will be ener gized for each conduction of tube E22. As a result 12 out and pick up relay 985 is greater than the timed interval of the single tube inverter timer we so that a new current period T3 is initiated by the next conduction of valve 922 prior to the oi‘ the deenergization of relay 138, the operating 5 decrease in pressure to the level P2. > The level of current It for the interval T3 is established by coil are of relay 201 is energized through contactv the. magnitude of the'vheat control rheostat 85 on and relay 2M is maintained closed by a hold» which is e?ectiv'ely connected between conduc= ing circuit including the sealing-in contact 267a tors $2 and 63 upon energization of relay 712, it oi the relay 2W. This sealing-in contact also conditions the energizing circuit for the next 10 being noted that operation of the relay ‘it’ to closed position shorts out rheostat do and opens relay to be operated, namely, relay ‘ll, upon the the short circuit around rheostat 65. Contacts next conduction of the timing valve W2. Thus ‘52a and ‘Hi also adjust the timing rheostat cir the ?rst conduction of valve H22 will take place cuit of timer M6 by removing the control rheoe substantially immediately upon closure of initiat stat 93 and inserting the timing rheostat $35 ing relay lit and eifects energization of relay which determines the duration of the interval T3. it‘?! which by indicating lamp 209 indicates that The operation of the single tube inverter circuit the squeeze period or interval Ti is in progress. to‘cause alternate conduction'by valves 553 and Returning now to a consideration of the opera its continues at intervals determined by the tim tion oi the timing circuit 504, the lower plate of the capacitor m3, as previously indicated, 20 ing rheostats 96-502, inclusive, and to e?ect the transmission of current to the load as indicated charges through timing resistor E32 toward the in Fig. 2b in accordance with which one of the voltage of conductor m8 and at a predetermined‘ mint in this charging operation, dependent upon 7 rheostats eo-‘ld is connected between conductors 52 and $3. The “off” periods ‘I'd, T83 and TM are the voltage of conductor iZ? connected with con trol member 823, tube I22 is again rendered con 25 introduced by the contacts ltd, lid and 80d of relays l3, Ti and 313 since these contacts open the ductive with the interval between these ?rst two circuit between conductors t5 and $6 in response conductions of valve 822 corresponding to Ti and to energization of the respective relays. being determined by the rheostat W2. ‘When Returning now to a consideration of the pres valve £22 conducts, the control members of valves tied and 515% are again rendered momentarily pos 30 sure timers 58d and itl, it will be noted that itive and they current is commutated- from tube let to tube i553 with the aid of commutating ca-' pacitor 55d, and as a result relay I39 is deener gized and relay i38 is energized. Deenergiza when relay 985 of timer 88B is energized it closes a contact 2M which establishes an initiating cir cuit of timer Eel. This circuit may be traced from cathode of valve .598 or timer it! through tion of relay" itit'establishes an energizing cir 35 contact 2M, conductor 53?, contact idg of'relay ‘it, conductor 868, and contact 6'65 of relay E28 to cuit for operating coil iii of relay ‘El through conductor i613. This initiation of operation of its contact M5 and the sealing-in contact 20M‘ timer i8! is indicated by the dotted line forrelay of relay toll. Energization of relay B38 opens use in Fig. 20. When relay- W9 is energized, its contacts lat-E85 to prevent the energization opening of itscontact 2% is e?ective to deenere of more than one relay of the group ‘ii-8d for gize pressure control relay Hi6 and as a result to this conduction of valve l22. Operation of relay ll initiates a period of energization of the load ‘ deenergize solenoid valve 23 and restore the high pressure. level‘ Pi to the electrodes. When relay circuit by closing contact 1 id to connect conduc ‘it operates, opening of the normally closed con- ' tors at‘) and £36. The level of current 12 of Fig. 2b for this interval T2 of the pattern‘ is deter- 45 tact 'idg thereof resets both of the timers E80 and , it! and establishes the low value of pressure P2 mined by the magnitude of the resistance of the by completing the energizing circuit for the pres heat control rheostat 64 which is at this point in sure 'controlrelay 576 through contact “it. As the program e?ectively connected between con the current and pressure pattern proceeds from doctors 62 and 53. Operation of relay“ also. ‘opens contact lie and closes contact ii} to re 50 T2 to Ti i, relays ‘ii to there picked up in se nuance and remain energized. At the expiration move timing rheostat Hi’ from the‘circuit with of the next timing interval after energization of ‘timing capacitor 563 and to insert in place there relay 8E9, as determined by the timing circuit 804 of timing resistor 93 which determines the rate at which capacitor Hi3 charges toward the volt-= I and timing resistance M2, the resetting relay 6% age of'conductor W8 and, therefore, determines 55 is energized to open its contacts 625 and M56 and thereby open the anode-cathode circuit of con the duration of interval T2 by determining the trol valve H2 and to deenergize the operating interval before the next conduction of valve l22. ‘ coils. of relays E28, 26? and‘ ll-til; inclusive. Operation of relay ll to’the closed position also Dropping out of relay I28 deenergizes the relay closes a contact ‘llg which initiates operation of the timei° circuit 53$ by COImec?ng the cathode 60 52b and restores the system to its initial condi tion in which valve 553 is conducting and relay of valve 882 to the alternating current supply - H8 is energized. conductor ltd. Relay N5 of timer 980 is ener In order to render it possible to omit certain gized an interval of time after this completion of of the ‘timing intervals from the complete pat the initiating circuit determined by the voltage to which capacitor m6 has previously been 65 tern, I provide manual switches 2i i, 292,2!3 of the single pole type and double pole switch 2". charged and the magnitude of discharge resistor ‘With these switches all in the right-hand posi 6%. The capacitor i96 charges by grid recti? cation through a circuit including the slider on tion as indicated in the drawing, complete cur rent and‘ pressure patterns are supplied to the resistor E89, the grid-cathodecircuit of valve 682 and resistor 886. As indicated in Fig. 2c, energi- 7 0 work. If any one of the switches 21 i-2l3 is moved to the left, the hold period is initiated nation of the relay I85 of timer I80 e?ects ener immediately upon completion of the interval of gization of the pressure control relay I16 to ener the pattern controlled by the relay immediately gize the solenoid valve 23 and‘ reduce the pressure to the left of the manual switch; For example, applied to the work. For the particular pattern indicated, the time required for relay I80 to time 75 ii switch 2!! is moved to the leftI the hold period 13 2,411,708 14 follows immediately after the interval T3. If the double pole switch 2I4 is moved to the left, the hold period is omitted. It will be apparent that of synchronizing transformer 228 to a conductor 235. This conductor is connected to the anode of electric valve 2I8 through a capacitor 236 and switches connected in accordance with the teach through a parallel circuit to an adjustable point ings of this disclosure may be arranged to omit in on resistor 22I determined by the position of the any desired intervals from the complete pattern. slider 237/. This parallel circuit includes one of In Fig. 3 I have shown a modi?cation of the the resistors 93’, 95’, 91’, 99’ or IOI’, dependent upon the operative position of the sequencing re lays l2’-'I8’. Suitable transient suppressing ca those parts of the system which (infer from Fig. 1 10 pacitors '238 are preferably connected between timing and sequencing arrangement of Figs. la-lc. In order to simplify the drawings, only have been illustrated and it will be understood the control members and cathodes of the respec that the remainder of the system of Fig. 1 would tive discharge devices H6 and 2". Before de be employed in a complete embodiment. In the scribing the operation of the timing circuit 2I5 arrangement shown in Fig. 3, the functions of to effect alternate energization of the operating the timing circuit I04 and the control circuit I35 15 coils I36’ and I31’ of relays I38’ and I39’, the of Figs. la-lc have been incorporated in a single control circuits of the sequencing relays will be control circuit 2I5 which is ‘energized from the described. Relays ‘IV-80’, inclusive, I26’, I28’ direct current control voltage supply conductors and 20'I_’ correspond generally to the relays desig I01 and I08. While this circuit 2I5 may be em nated by the same unprimed numbers in the ar ployed to control the same sequencing relay sys 20 rangement described in Figs. la-lc and control tem shown in Figs. la-lc, I have illustrated a the same periods of the pattern in the same man modi?cation of this sequencing arrangement in ner. The energizing circuits for these relays are Fig. 3 which requires less contacts on the relays slightly different in the arrangement shown in which are alternately operated but which requires Fig. 3. In Fig. 3, one terminal of the operating additional contacts on the relays which are en 25 coil of each of these relays is energized from the ergized in sequence. Referring now to Fig. 3, the alternating current supply conductor I64, through circuit 2I5 includes a pair of electric discharge a normally closed contact I66’ of relay I26’ and valves 2I6 and 2I‘I having their anode-cathode conductor 9i. The other terminal of each of the circuits connected in parallel circuit relation for operating coils is maintained energized through energization from the supply of direct current 30 its sealing-in contact or‘ “a” contact which com voltage provided by conductors I07 and I08. Re pletes a circuit from the other terminal of the ferring to discharge device 2 I 6, the cathode there operating coil to'the conductor 92. The relays are of is connected to a conductor 2 I8 which is main picked up in sequence through a circuit including tained at a voltage intermediate the conductors one of a pair of conductors 239 and 240 which I01 and I08 by voltage dividing resistors 2I9 and 35 are arranged to be energized alternately from the 220. The anode of valve 2I6 is connected with the supply conductor 92 through the contacts of re conductor I01 through a circuit including the lays I38’ and I39’. As indicated, conductor 239 operating coil I36’ of relay I38’ and a resistor is connected with conductor 92 through normally 22I. In a similar manner, the cathode of dis open contact “I of relay I39’ and a normally charge device 2!? is connected with conductor 2I8 40 closed contact 242 of relay I38’, and conductor. and the anode is connected with conductor I III '240 is connected with supply conductor 92 through through a circuit including a normally open con a normally closed contact 243 on relay I39’ and tact 222 of relay I28’, the operating coil I31’ of a normally open contact 244 on relay I38’. With relay I39’ and a resistor 223. A commutating'ca this arrangement only one of the conductors 239 pacitor 224 is connected. between the anodes of »' or 240 is energized at one time dependent upon the discharge devices 2I6 and 2Il' and cooperates which of the relays vI38’ or. I39’ is deenergized. with the control members thereof to eifect com Each of the sequencing relays ‘I I '—80’ includes in mutation of current from one of the discharge devices to the other, and thereby to effect alter addition to its seal-in or “a” contact a normally open 2' contact and relays 'I2’-80’, inclusive, a nate energization of the operating coils I36’ and 50 normally closed 7' contact. The 2‘ contact condi ‘I31’ of the relays I38’ and I39’. In order to tions the initiating circuit for the next relay in control the interval between successive transfers the sequence and the 11' contact interrupts the cir of current from one of the discharge devices to cuits of the energizing coils with conductors 239 the other, the control members of devices 2I6 and 240 to prevent these latter conductors from and 2 I 'I are provided with energizing circuits hav 55 being connected directly with the supply conduc ing timing functions. The control member of tor 92 through the seal-in contacts of the relay, valve 2I6 is connected ‘with a conductor 225 through a current limiting resistor 226 and a Secondary Winding 227 of a transformer 228 which which have been picked up, since such a connec age through a resistor 230. which conditions the initiating circuit of relay tion between supply conductor 92 and either of conductors 239 and 240 would-render relays I38’ is preferably of the saturable inductive type for 60 and I39’ ineffective. Relay I38’ is provided with producing voltages of peaked wave form. The an additional normally closed contact 245 for in primary “winding 229 of transformer 228 is ener itiating energization of relay 201’, and relay 201’ gized from a source of alternating current volt is provided with a normally open contact 20'I’z' The conductor 225 _ is connected with the circuit controlled by the 65 ‘II’ in the same manner that the 1' contacts of the anode-cathode of electric discharge device 2I'I remainder of the sequencing relays condition the by a capacitor 23I and through a parallel circuit energizing circuit for the next succeeding relay to to an adjustable‘ point on the resistor 223 deter be operated. Relay 20'!’ is also provided with a mined by the movable tap 232. This parallel normally closed contact 246 which initially im circuit includes one of the resistors I32’, 94’, 96’, 70 presses a negative bias of voltage dividing resistor 98’, I00’ or I02’ dependent upon the operative po- ' 220 on the control'member of electric valve 2I'I. sition of the sequencing relays ‘II’ to ‘I9’, inclu , This bias maintains electric valve 2I‘I noncon sive. In a similar manner, the control member of ductive until the ?rst synchronizing voltage peak electric valve 2I'I is connected through a current -of winding 234 occurring after closure of con limiting resistor 233, a secondary winding 234 75 tact 222. ~ 2,411,708 15 . The manner in which the arrangement of Fig. 3 functions and the features which distinguish it 16 has been made to the control of the heat control rheostats or the timing circuit including con ductors 45 and 46. It will be understood that from the arrangement of Figs. la-lc will be bet the relays are provided with b, c and d contacts ter understood by a brief consideration of the sequence of operationswhich take place in sup 5 for controlling these circuits in the same manner as described in connection with Figs. 10-10. It plying a pattern of weld current to the load cir will also be apparent that the pressure program cuit. With conductors I01 and I08 energized and may be coordinated by the g and 71. contacts on before closure of initiating switch I61, electric relays ‘Ii’ and 14’ in the same manner as it is'in.v discharge valve 2I6 is conducting thus maintain ing relay I38’ energized. During conduction of 10 the system of Figs. la-lc. From the description of the operation of the electric valve 2I6 capacitor 23I charges through illustrated embodiments of my invention, it will the grid-cathode circuit thereof until the voltage be apparent that a large number of intervals are of the right-hand plate of the capacitor is essen established during which currents and pressures tially at the voltage of conductor 2I8. When it is desired to initiate a period of energization of the is of diiferent levels areapplied to the work circuit, and that the duration of the intervals as well as load circuit, manual switch “51' is closed and. the levels of current may be‘ adjusted with the closure of contact I68 initiates a supply of pres sure to the electrodes in the manner described in greatest ?exibility and at the‘ same time the equipment required is very simple considering I69 operates initiating relay I28’ which closes 20 the variety of current and pressurepatterns made available by the control. _ ‘ contacts I65 and I15 to establish sealing-in cir While I have shown and described particular cuits around contacts I68 and I69. Closing of connection with Figs. la-lc. Closure of contact embodiments of my invention, it will be obvious relay I28’ also closes contact 222 to establish the to those skilled in the art that changes and modi anode-cathode circuit of electric valve 2 I ‘I. Elec tric valve 2|‘! conducts upon the occurrence of 25 ?cations may be made without departing from my. invention in its broader aspects, and I, there the next positive peaklof voltage supplied by fore, aim in the appended claims to ‘cover all such synchronizing transformer winding 234;.which is changes and modi?cations as fall within the true synchronous with the alternating current supply spirit and scope of my invention. voltage of the welding system. Conduction by What I claim as new and desire to secure by discharge device 2I'I energizes the operating coil 30 Letters Patent of the United States is: of relay I39’ and e?ects the transfer of current 1. In combination, a pair of, electric discharge to discharge device 2 I ‘I with the aid of commutat " devices each including an anode, a cathode and a ing capacitor ‘224, interrupting the ?ow of cur control member, a pair of electromagnetic circuit rent in discharge device 2I6 to deenergize relay I 38’. Dropping out of relay I38’ closes contact 35 controlling devices each including an operating 245 to energize relay. 201’ which seals itself in ' through its contacts ‘20‘I'a and conditions an coil, a supply of direct current voltage, said oper ating coils and said discharge devices being con nected to provide‘ two circuits energized in parallel from said direct current supply with each circuit H" by closure of its contacts 201%. At the end of a timing period determined by the interval 40 including one of said operating coils and the anode-cathode circuit of one of said discharge ‘ required for the capacitor .23I to charge through devices in series, timing means connected with resistor I32’ to such a voltage that the next posi the control members of said discharge devices for tive peak of the synchronizing transformer wind modifying the voltage thereof to effect transfer of ing 22'! renders electric valve 2 I6 conductive, cur rent is transferred from valve 2H to valve 2IS 45 current from one of said discharge devices to the other at intervals and thereby effect alter to energize relay I38’ and deenergize relay I39’, nate energization of said operating coils, said thereby closing contacts 243 and 244, respectively, timing means including capacitance and resist - to energize conductor 24!] from supply conductor ance, and means responsive to the alternate oper 92. This completes an energizing circuit for the operating coil 8| ' of relay ‘H’ from conductor 50 ation of said circuit controlling devices for changing the effective magnitude of the resistance 240'through the a‘ contact of relay 72’, the 2' con of said timing means to establish the duration of tact of relay 201' to the conductor 9I. During said intervals at di?erent values in accordance conduction-by valve 2I'I capacitor 236 charges with a predetermined time pattern. through the grid-cathode circuit thereof so that the right-hand plate thereof is substantially 55 2. In combination, a pair of electric discharge devices each including an anode, a cathode and at the voltage of conductor 2I8. The duration acontrol member, a pair of electromagnetic cir of the second interval T2 is determined by the cuit controlling devices each including an oper time required for capacitor 236 to charge through ating coil, a supply of direct current voltage, said ‘resistor 93' and conductor 23'! to such a voltage that the next positive peaked voltage of winding 60 operating coils and said discharge devices being connected to provide two circuits energized in 234 ‘renders electric discharge device 2I'I con parallel from said direct current supply with each ductive. The successive energization of‘ relays circuit including one of said operating coils and ‘EV-80’ proceeds at intervals determined by the the anode-cathode circuit of one of said discharge charging time of capacitors 23I and 235 as con trolled by resistors I32’ and 93'-Ill2’ until reset 65 devices in series, timing means connected with the control members of said discharge devices for ting relay I26’ is energized to reset the relays and modifying the voltage thereof at intervals to ef restore the system to its initial condition with fect transfer of current from one of said dis valve 216 and relay I38’ energized. The opera charge devices to the other at the end of each tive conditions of valves 2I6 and 2I'i and relays I38’ and I39’ as well as the effective timing re 70 of said intervals and thereby-effect alternate‘ en ergization of said operating coils, said timing sistor and timing capacitor are indicated in Fig. 2d means including a capacitance and a plurality of for each interval of the current pattern of Fig. 2b. resistances of different pre-established magni The remaining relay operations are indicated in tudes, and means responsive to the alternate op Fig. 20 for the corresponding relays in Figs. 10-10. In this description of Fig. 3 no reference 75 eration of. said circuit controlling devices for energizinglcircuit for the operating coil of relay 2,411,708 18 connecting different ones of said resistances in circuit with said capacitance to establish the dura 6. In combination, a pair of electric discharge devices each including an anode, a cathode and a control member, a supply of voltage, the anode cathode circuits of said discharge devices being connected in parallel circuit for energization from said‘ supply of voltage, timing means connected , tion of said intervals at different values. _ 3. In combination, a pair of electric discharge devices each including an anode, a cathode and , a control member, a supply of direct current volt age, the anode~cathode circuits of said discharge with the control members of said electric dis devices being connected in parallel circuits for charge devices for modifying the voltage thereof energization from said supply of direct current voltage, timing means connected with the control 10 at intervals to effect transfer of current from .one of said discharge devices to the other at the members of said discharge devices for modify end of each of said intervals, said timing means ing the voltage thereof at intervals to effect trans including capacitance and resistance, a pair of fer of current from one of said discharge devices electromagnetic circuit controlling devices each to the other at the end of each of said inter ,including an operating coil, means for effecting vals, said timing means including capacitance and 15 alternate energization of said operating coils in resistance, a pair of electromagnetic circuit con response to the alternate conduction of current in said parallel paths, a plurality of relays each trolling devices each including an operating coil, , means for effecting alternate energization of said including an operating coil, means for energizing operating coils in response to the alternate con an one of said relays for each trans duction of current in said parallel paths, and 20 fer additional of current between said discharge devices means controlled by the alternate operation of including contacts of said circuit controlling de said circuit controlling devices for establishing different preset values of resistance in said tim ing means to establish the duration of the suc cessive intervals in accordance with a pre-estab 25 lished pattern. 4. In combination, a pair of electric discharge devices each including an anode, a cathode and a control member, a supply of voltage, the anode vices and contacts on said relays, and means re sponsive to the successive operation of said re lays for establishing different preset values of resistance in said timing means and thereby es tablish the duration of the successive intervals in accordance with a pre-established time pat tern, ~ 7. In combination, a supply circuit, a load cir cathode circuits of said discharge devices being 30 cuit, electric translating apparatus interconnect connected in parallel circuit relation for energi ing said circuits and a control means for con zation from said supply of voltage, timing means trolling said translating apparatus to effect the connected with the control members of said dis transmission of a pattern of current to said load charge devices for modifying the voltage thereof circuit having a plurality of intervals of differ at intervals to effect transfer of current from 35 ent durations during which currents of different one of said discharge devices to the other at the - end of each of said intervals, said timing means including a capacitor and a plurality of resistors each having a pie-established value and circuit controlling, means controlled in response to, the transfer of current from one of said discharge devices to the other for effecting the sequential connection of said resistors in circuit with said levels are supplied to said load circuit, said con trol means including a first control circuit for determining the intervals during which said load is energized, a second control circuit including a plurality of impedances of different predetermined magnitudes for establishing different levels of current to be supplied to said load circuit during different ones oi.‘ said intervals, a timing circuit for establishing the duration of said intervals in~ for said capacitance to charge from one predeter ' eluding a plurality of resistances of different premined value of voltage to another and thereby 4 determined magnitudes, and a plurality of cire determine the duration of the intervals between cuit controlling means connected to be controlled successive transfers of current from one of said in response to the operation of said timing-means discharge devices to the other. and to operate in succession one for each suce 5. In combination, a pair of electric discharge 50 cessive operation of said timing means to con devices each including an anode, a cathode and nect different ones of said resistances in said tim a control member, a supply of direct current volt ing circuit in succession to determine the dura~= age, the anode-cathode circuits of said discharge tion of the successive intervals of the pattern, devices being connected in parallel circuit rela said circuit controlling means being provided with tion for energization from said supply of direct 55 circuit controlling elements connected in either current voltage, timing means connected with the said ?rst or second control circuits to establish control members of said discharge'devices for which ones of said intervals that said load is ener== modifying the voltage thereof at intervals to ef gized and to establish the level of current sup~ fect transfer of current from one of said discharge plied to the load during each interval of ener devices to the other at the end of each of said 60 gization by controlling the effective impedances intervals, said timing means including a capacitor in said second control circuit. and a plurality of resistors each having a pre 8. In combination. a supply circuit, a load cir— established value, a plurality of circuit control cuit, electric translating apparatus interconnect ling means controlled in response to the trans ing said circuits and a control means for con fer of current from one of said discharge devices 65 trolling said translating apparatus to effect the to the other and operated in sequence, one for transmission of a pattern of current to said load each transfer of current between said discharge circuit having a plurality of intervals of different devices, for effecting the sequential‘ connection durations during which currents of different levels of said resistors in circuit with said capacitance are supplied to said load circuit, said control to determine the interval required for said capaci means including a ?rst control circuit for deter tance to charge from one predetermined value of mining the intervals during which said load is capacitance to determine the interval required voltage to another and thereby determine the duration of the intervals between successive transfers of current from one of said discharge devicestothe other. ' ' i energized, a second control circuit for establish ing different levels of current to be supplied to said load circuit during different ones of said in tervals, a timing circuit for establishing the dura 2,411,708 19 tion of said intervals including a plurality of re Lsistances of different predetermined magnitudes and a plurality of circuit controlling means con nected to be controlled in response to the opera tion of said timing means to operate in succes— sion, one for each successive operation of said timing means, to connect different ones of said resistances in said timing circuit in succession to 20 energization thereof, and additional timing means controlled in response to operation of the timing means for controlling the current pattern for effecting selective control of the electrically controlled means associated with said electrodes to establish periods during which pressures of di?erent magnitudes are impressed on said elec trodes, said last mentioned timing means being independently adjustable with respect to the tim- . determine the duration of the successive intervals of the pattern, said circuit controlling means 10 ing means for controlling the current pattern so that the changes inpressure are accomplished at being provided with circuit controlling elements instants which are independent of the instants connected in either said ?rst or second control that changes in load current are effected but in ‘ circuits to establish which of said intervals that de?nite timed relation with respect thereto. said load is energized_and to establish the level 11. In combination, a pair of electric discharge of current supplied to the load during each inter 15 devices each including an anode, a cathode and a val of energization. control member, a supply of direct-current volt 9. In combination. an alternating current sup age, the anode-cathode circuits of said discharge ply circuit, a load circuit, electric translating ap devices being connected in parallel circuits for , electric valve means having a control member, a 20 energization from said supply of direct current voltage, a timing circuit connected with the con ?rst circuit for controlling the energization of trol member of each of said discharge devices and said control member to control the cycles of said paratus interconnecting said circuits including each including a capacitor connected between the supply circuit during which said valve means is control member of one of said discharge devices conducting to determine the periods of energiza tion of said load circuit, a second control circuit 25 and a point the potential of which is controlled by conduction of the other of said discharge de for controlling the energization of said control vices, so that the time required for the capacitor member to determine the instant in the voltage associated with the control member of one of said wave of said supply circuit that said valve means discharge devices to charge to a voltage which is rendered conducting to determine the level of current supplied to said load circuit during each 30 will render said one of said discharge devices con ductive is determined by the magnitude of the re period of energization, said second control circuit sistance connected therewith and the level of including a plurality of impedance elements and voltage of the point to which it is connected, circuit controlling means for selectively connect— means controlled by the transfer of current from ing said impedance elements in said second con , said‘ one of said discharge devices to the other trol circuit, a timing circuit for e?ecting opera to eifect a change in the magnitude of the resist tion of said circuit controlling means in sequence ance connected in circuit with the control mem and for eifecting the selective establishment of ber of the other of said discharge devices to con said ?rst control circuit to effect the transfer of trol the time required for a subsequent transfer a predetermined pattern of current to said load circuit including a plurality of periods of ener 40 of current between said discharge devices, and circuit controlling means energized in response to gization and at least one intermediate period of the alternate conduction of current by said dis deenergization, said timing means including an charge devices for effecting-a sequence of circuit electric discharge device and a plurality of re controlling operations at intervals the duration of sistance-capacitance combinations for control -_which are determined by the magnitudes of re ling the duration of the intervals between suc sistance in the timing circuits connected with cessive conductions of said device, and means re said control members. sponsive to the successive conductions of said dis 12. A circuit for e?ecting a plurality of circuit charge device for controlling the establishment of controlling operations in sequence at different said ?rst control circuit, for controlling the cir cuit controlling means of said second control 50 predetermined intervals comprising a supply of direct current voltage, a pair of electric discharge circuit and for eifecting successive alterations of devices each including an anode, a cathode and a said resistance-capacitance combinations to es control member, means connecting the anode tablish the duration of the successive intervals of cathode circuits of said devices in parallel circuit said pattern. 10. In combination, an alternating current sup 55 relation for energization from said supply circuit, commutating means interconnecting said anode ply circuit, a resistance welding load circuit in cathode circuits, a capacitor for controlling con cluding a pair of electrodes, electric translat ing apparatus interconnecting said supply circuit duction of one of said devices having one terminal connected with thecontrol member thereof and a predetermined pattern/of current to said elec 60 the other terminal connected with the anode cir cuit of the other of said devices, a second capaci trodes including electric valve means having a tor for controlling conduction of the other of said control member, electrically vcontrolled means devices having one terminal connected with the associated with said electrodes for controlling control member of said other device and a second the application of pressure to said electrodes, an excitation circuit for controlling the energiza 65 terminal connected with the anode circuit of said one device, said capacitors cooperating with said tion of said control member to determine the. commutating means to effect the transfer of cur periods of energization of said load circuit and rent from one of said devices to the other, a plu the levels of current supplied to said load circuit rality of circuits connected with the terminal of during each period of energization thereof, tim ing means for effecting a plurality of switching 70 each of said capacitors connected to said control members and points of potential which are sub operations in de?nite timed sequence to control stantially more positive than the cathodes of said excitation circuit to establish the periods said devices, said circuits including circuit con of deenergization of said load circuit and to trolling means operable to change an electrical establish the different levels of current to be sup plied to said load circuit during each interval of 75 characteristic of said circuits to adjust the inter and said electrodes to effect the transmission of 2,411,708 val required for said capacitors to charge from of said electric’ valve, and commutating means one predetermined voltage to another and there for e?ecting transfer of current from one of said discharge devices to the other for each of said - by determine the interval of time between suc voltage impulses. cessive transfers of current between said devices, and means responsive to the successive transfers of current between said devices for operating said 15. In combination, means for establishing a supply of direct current voltage including a plu rality of points of diiferent voltage, a timing circuit controlling means in sequence to establish the duration of a subsequent timing interval for circuit 6f the single tube inverter'type including each transfer of current between said devices. an electric valve having an anode, a cathode 13. A circuit for e?ecting a plurality of circuit and a control member, means connecting said controlling operations in sequence at different anode to a point of relatively positive voltage, predetermined intervals comprising a supply of means for connecting said cathode to a point of direct current voltage, a pair of electric discharge relatively negative voltage through a circuit in devices each including an anode, a cathode and a cluding a timing resistance, means for estab control member, means connecting the anode 15 lishing said control member at a voltage inter cathode circuits of said devices in parallel circuit. mediate said points, a capacitor connected in relation for energization from said supply circuit, parallel circuitv relation with respect to the commutating means interconnecting said anode anode-cathode circuit of said valve so that‘said cathode circuits, a capacitor for controlling con capacitor discharges rapidly through the anode duction of one of saiddevices having one terminal 20 cathode circuit of said valve when said valve connected with the control member thereof and conducts and so that the charging of said capac the other terminal connected with the anode cir itor through said resistance determines the inter cuit of the other of said devices, a second capaci val between successive conductions by said valve, tor for controlling conduction of the other of said a pair of electric discharge devices connected devices having one terminal connected with the across a portion of said supply of direct current control member of said other device and a second voltage in parallel circuit relation, each of said terminal connected with the anode circuit of said devices including a control member, means for one device, said capacitors cooperating with said impressing a voltage on the control members commutating means to eifect the transfer of cur of said discharge devices to maintain said de— rent from one of said devices to the other, circuits 30 vices nonconducting, a capacitor connecting said , connected with the terminals of said capacitors control members with the cathode circuit of said connected to said control members for establish electric valveto impress a positive voltage on ing charging circuits for said capacitors to a point the control members of said discharge devices of potential which is substantially more positive in response to each conduction of said electric than the cathodes of said devices, said circuits valve, and means controlled by the transfer of including circuit controlling means operable to current from one or" said discharge devices to change an electrical characteristic of said circuits the other for changing the effective value of said to adJ'ust the interval required for said capacitors timing resistance to establish different intervals to charge from one predetermined voltage to an of time between successive conductions of said other and thereby determine the intervals of time 40 electric valve. between successive transfers of current between 16. In combination, means for establishing a said devices, and means responsive to the transfer supply of direct current voltage including a of current between said devices for operating said plurality of points of different voltage, a timing circuit controlling means to condition said cir circuit of the single tube inverter type including cuits for a subsequent timing interval. an electric valve having an anode, a cathode and >14. In combination, means for establishing a a control member, means connecting said anode supply of direct current voltage including a to a point of relatively positive voltage, means for plurality of points of different voltage, a timing connecting said cathode to a point or" relatively circuit of the single tube inverter type includ negative voltage through a circuit including a ing an electric valve having an anode, a cathode timing resistance, means for establishing said and a control'member, means connecting said control member at a voltage intermediate said anode to a point of relatively positive voltage, points, a capacitor connected in parallel circuit means for connecting said cathode to a point relation with respect to the anode-cathode cir of relatively negative voltage through a circuit cuit of said valve so that said capacitor dis including a timing resistance, means for estab charges rapidly through the anode-cathode airlishing said control member at a voltage inter cult of said valve when said valve conducts and mediate said points, a capacitor connected in so that the charging of said capacitor through parallel circuit relation with respect to the said resistance determines the interval between anode-cathode circuit of said valve so that said successive conductions by said valve, a pair or“ capacitor discharges rapidly through the anode cathode circuit of said valve when said valve conducts and so that the charging of said capac 00 electric discharge devices connected across a itor through said resistance determines the in terval between successive conductions by said valve, a pair of electric discharge devices con nected across a portion of said supply of direct current voltage in parallel circuit relation, each of said devices including a control member, means for impressing a voltage on the control members of said discharge devices to maintain - said devices nonconducting, a capacitor connect ing said control member withthe cathode cir cuit of said electric valve to impress a positive voltage impulse on the control members of said portion of said supply of direct current voltage in parallel circuit relation, each of said devices including a control member, means for impress» ing a voltage on the control members of said discharge devices to maintain said devices non conducting, means connecting said control mem bers with the circuit of said electric valve to impress a positive voltage on the control mem bers 01' said discharge devices in response to each conduction of said electric valve, commutating means for e?'ecting transfer of current from one of said discharge devices to the other for each conduction of said electric valve, a pair of re lays each having an operating coilameans con‘ discharge devices in response to each conduction 75 necting said operating coils to be energized alter 2,411,703 23 nately in response to the alternate conduction by said discharge devices, a plurality of circuit con trollers to be operated in sequence, energizing circuits for said circuit controllers, and means including contacts on said relays and means con trolled by one of said circuit controllers for ef fecting operation of an additional one of said circuit controllers for each transfer of current between said discharge devices. 1'7. In combination, a supply of direct current voltage including means for establishing a plu rality of points of di?erent voltage levels, a tim ing circuit of the single tube inverter type in 24 which the voltage of said capacitance changes from one voltage to another to determine the du- - rations of the intervals between successive con ductions of said electric discharge device, said cir cuit including means for effecting the connection therein of different magnitudes of resistance in , succession to establish different predetermined , intervals between successive conductions of said electric discharge device, a plurality of relays connected to be energized in succession in re sponse to the successive conductions of said elec tric discharge device with one additional relay being energized for each conduction of said elec tric discharge device, and means responsive to cluding an electric valve having an anode, a cathode and a control member, means connecting 15 operation of said relays for controlling the suc said. anode with a point of relatively positive cessive changes in resistance of said timing cir cuit and for effecting a, succession of switching voltage and means for connecting said cathode to a point of relatively negative voltage through a operations in accordance with the time pattem established by the successive operations of said circuit including a timing resistance, means for connecting said control member to a point having 20 electric discharge device. a voltage intermediate the voltages of said points, 19. In combination, a pair of electric discharge a capacitor connected in parallel circuit relation devices each including an anode, a cathode and with respect to the anode-cathode circuit of said a control member, a supply of direct current valve so that said capacitor discharges rapidly voltage, the anode-cathode circuits of said dis through the anode-cathode circuit of said valve 25 charge devices being connected in parallel cir-. cuits for energization from said supply of direct when said valve conducts and so that the charg ing of said capacitor through said timing resist current voltage, a timing circuit connected with the control member of each of said discharge ance from one predetermined voltage to the other » devices and each including a capacitor connected determines the interval between successive con ductions of said valve, and circuit controlling 30 between the control member of one of said dis- ' charge devices and a point the potential of which means operated in response to the successive con ductions of said valve for e?ecting switching op is controlled by conduction of the other of said erations in timed sequence in accordance with a discharge devices, so that the time required for predetermined timing pattern, said circuit con the capacitor associated with the control mem trolling means also including means for altering 35 ber of one of said discharge devices to charge to a voltage which will render said one of said dis said timing‘ resistance for each conduction of charge devices conductive is determined by the said valve to establish the duration of the succes sive intervals of said pattern. magnitude of the resistance connected therewith and the level of voltage of the point to which it 18. In combination, a supply circuit, an elec tronic timer connected for energization from 40 is connected, and means controlled by the trans fer of current from said one of said discharge de said supply circuit and including an electric dis charge device having a pair of principal elec vices to the other to eil’ect a change in the mag nitude of the resistance connected in circuit with trodes and a control member, a capacitor con the control member of the other of said discharge nected in circuit with said supply circuit and said electric discharge device to control the volt 45 devices to control the time required for a sub age between the control member and' one of the sequent transfer of current between said dis charge devices. . principal electrodes of said electric discharge de vice, a timing circuit for controlling the rate at MAURICE E. BIVENS.