US2570448A

US2570448A - Electronic sequence space discharge tube network

Info

Publication number: US2570448A
Application number: US124153A
Authority: US
Inventors: Burton F Holmes; Heindel Herbert Harry
Original assignee: SCHULTZ DIE CASTING Co
Current assignee: SCHULTZ DIE CASTING Co
Priority date: 1947-12-10
Filing date: 1949-10-28
Publication date: 1951-10-09
Anticipated expiration: 1968-10-09

Description

OC- 9, 1951 B. F. HOLMS ErAL 2,570,448

ELECTRONIC SEQUENCE SPACE DISCHARGE TUBE NETWORK Original Filed Deo. lO, 1947 6 Sheets-Sheet l Odi' 9, 1951 B. F. HOLMES ET Ax. 2,570,448

ELECTRONIC SEQUENCE SPACE DISCHARGE TUBE NETWORK Original Filed Dec. l0, 1947 6 Sheets-Sheet 2 Oct 9, 1951 B. F. HOLMES ETAL 2,570,448

ELECTRONIC SEQUENCE SPACE DISCHARGE TUBE NETWORK Original Filed Deo. lO, 1947 6 Sheets-Sheet 3 wwff--f- @WM/Em A TTORNE Y Oct. 9, 1951 B. F. HOLMES ET A1. 2,570,448

ELECTRONIC SEQUENCE SPACE DISCHARGE TUBE NETWORK Original Filed Dec. lO, 1947 6 Sheets-Sheet 4 Oct' 9, 1951 B. F. HOLMES ET AL 2,570,448

ELECTRONIC SEQUENCE SPACE DISCHARGE TUBE NETWORK Original Filed DGO. l0, 1947 6 Sheets-Sheet 5 @ww/@mw A TI'ORNEY Oct. 9, 1951 B. F. HOLMES ET Al. 2,570,448

ELECTRONIC SEQUENCE SPACE DISCHARGE TUBE NETWORK 6 Sheets-Sheet 6 Original Filed De ,and m success/bn ATTOPNE Y Patented ct. 9, 1951 ELECTRONIC SEQUENCE SPACE DISCHARGE TUBE NETWORK Burton F. Holmes and Herbert Harry Heindel, Toledo, Ohio, sssigrrors to SohrrltrDio Casting' Company, Toledo, Ohio, aicorporaton'of Ohio Original application December 1Q, 19,47, SerialiNo 790,838. Dividedk and this* application Qctvober 28, 1949, Serial No."1'24,153

s Claims.v (C1. 17e- 320) This invention relates to an electronic se quence operating network involving. space dis,-v

charge tubes for controlling circuits and is 'a division of our copending application, Serial No. 790,838, led December l0, 1947, now Patent No. 2,532,256, issued November 28, 1950.y

The object of the present invention is to provide a novel network arrangement in the' s equence operation of discharge tubes which has been found very' enicient in operation and par,- ticularlyuseful in connection with the operation of solenoids for controlling die casting machine operations' as set forth in our copending application.

An object of the present invention is to provide a network of the character described in which the sequence discharge of the tubes is controlled by a special arrangement and interconnection of circuits` for the maintenance vand removal of grid biasl supply including the re,-Y setting of the cycle of operations after one complete cycle has been accomplished.

More specifically, an object of the invention isk to provide an especially satisfactory operating bias control and removal thereof for the Space discharge tubes of the series in an arrangement we have found substantially fool-proof in action, our bias supply circuits involving in the main three bias circuits for certain of the tubes, namely, a main bias supply7 circuit for normally supplying a negative bias/t all of the tubes of the series to prevent firing of any of the tubes in normal inoperative position; an auxiliary bias supply circuit for certain of said tubes adapted to temporarily supply bias to such tubes during a portion of the cycle of operation and a third additional bias supply circuit for certain of said tubes during another period of the cycle of op# eration, it being an object of our invention to provide a single source of bias supply for each of said alternative circuits.

Further objects and advantages are within the scope of this invention, such as relate to the arrangement, operation and function of the re'- lated elements and circuits of the system, to various details of construction and to combina,- tions of parts, elements per se, and to economies of manufacture and numerous other features, as Will be apparent from a consideration of the specification and drawings of a form of the invention, which may be preferred, in which:

Figure I is an electrical diagram illustrating the circuits embodying our invention;

Figure II is a schematic diagram of` the bias supply circuits and controls to tubes I, 2l, 3 and 4 ausielso tho outuut oorrtrollssi relays iu soriwith russo tubos tris, Circuits bsi'us in. the sauro oondiii'ori as 'suor/ii iu Figure 'reifer tuerrrsohirrc boing rsoriy' for' orisrstiorr; "Figure VIrrr isv agissons .showing tris

truss olf

11,11, @i3d symwls, We@ ,1.1.1, Figui@ 1I 31S, Wen

su'oo'osdirrs figures:

rieure r11 is a sohsrriatis diarrrriri` similar to Figure 11 but withths. tirouits' and Controls in tos souri.' ,io'rr thor' essuirisfst thstirus of tirs firing of'tubs, l; .Fisuro IV is o schematic diagram similarto Fisurs' 1,1 butwiti' tirs" sirsuitsfsr'id soutruls iu" tho' Condition. trios! assume et trio time' oir tris'ririrrs'or tubs .Zr l

'Figure V is Aa schematic diagram similar to Figure Il but with the-'circuits and controls in 11? condition they assume Las thetime'ofthel gringo-f tuners.; l

Figure V1 isv s sohsrristis diusrsrri similar to Figure II butwith the circuitsand controls in tho Condition they assumo et tirs' time" of th firing of ytube 4, and" immediately thereafter.

lIrl tho` orubosiirrierit of our irirsrition illustrated in the accompanying drawings, we yhave sriowu su slootrissi srstfsrrr ssrt'isuirrlr adapted `for uso .ilu operating s uis oastiris maohius irlu'strated in 4our" copending applicationy and in? cluding a" source of electrical current supply and the electronic sequence' ,timing networkadapted to be operated fromwvsaidcurrent"supply which includes a plurality of space discharge tubes l?, ,2; 3 sus 4;, 'tho bissirisf disojurss: rrid' rsbiss* infr of which ers Prourrlrsorrtrollsd'in"a ut;- sirsu msuusr .toi oserais srrrrssst 'relaysy soisnoids, and interconnected electrical v'circuits and ,apparatus ror ooritrolliug tris uotiou of crtin machine `moving elements, the Yelectrical network iritoroorrusstsd with 'tuddsprids'ut iu sort upon a movement of a part ofthe machineit'- sem Referring toA Figure 1I of tris drawings., it will ro understood' that 'tirs ris-uri, ooo'rstld switch G40 is connected tov theA power'lin'e through a temporarily locking 'inil Switch mechanism through los@ .490: tol .soil A0? whioh orisrsizss coil 4.02 sus' 'oorrssuusrruymsos cantas-ts' softhst the die casting 'machine clos s. Eollloiwing this operation, `our ,ristrrork Psrrtioui'arly adapted upon the, rngy ,Qf the'. thyir'ifrcii 13111095 zl ansi 4: to* oporstsf tris rritulfirriootiorr" irl tir-o stages', rossi' tlisbias ou ,sortais of tbs tubos. sus open the ies and y,complete the resetting oflthe `mi@ toY mina; position; 'In oouusotiorr wir@ r,slrstrissu .Circuits uisclosed, we have a 220 volt input circuit supplied through leads 90, 9| and 92 and a main transformer 465. From this main transformer 465 we provide a 110 volt circuit to the primary winding of a second transformer 415, the secondaries of which supply current to the filaments of tubes I, 2, 3 and 4 at 6.3 volts and another circuit for a heat control including a 6 volt circuit for a rectier tube and a high voltage for the plate of the same to supply a negative direct current for the grid bias circuits for the thyratron

space discharge tubes

2, 3 and 4. Another transformer 482 has a primary winding which is also energized from transformer 465 and has a 24 volt secondary winding adapted to supply current to a 24 volt circuit arrangement of leads and relays for ef fecting supply of current for electrical means for actuating the apparatus with which this invention is concerned.

The plate circuits for the tubes include the terminal 468 as a common grounded cathode circuit rrom transformer 465. `On the other side from said transformer, the plate circuit includes the fuse 480, lead 500, to normally open point 50| on relay 406 when point is closed in the automatic position of the apparatus. From point 50| We provide lead 502 to normally open point 503 on relay 430 also closed in the automatic position after time delay for the tube warm up has taken place (hereinafter described). Lead 505 from point 503 connects With terminal 506, all tube plate circuits connect from terminal wire 506. Thus, for tube we have a lead 501 connected to lead 506', resistor 508 to limit the current ow, lead 509, t coil 5|0, lead 5|| to the plate of tube I. The cathode circuit of tube I is grounded as indicated by a circuit |3. We also have a condenser 5|2 connected across coil 5| 0 to supply current to coil on the negative onehalf cycle and prevent chattering.

The

other tubes

2, 3 and 4 are similarly connected.

Thus for tube 2 lead 5I4 is connected to the lead 506 common to all of tubes I, 2, 3 and 4 as indicated supra. Lead 5|4 connects through resistor 5I5, lead 5|6, to coil 596, hence by lead 5|1 to the plate of tube 2. A condenser 5| 9 is connected across leads 5I5 and 5I1, as shown.

For connecting tube 3, we provide a, lead 520 passing through the resistor 52| to lead 522, which connects with coil 600 having lead 524 connected to the plate of tube 3. A condenser 525 is connected across

leads

522 and 524. The cathode circuit of tube 3 is grounded as indicated by circuit 526.

For tube 4 we also provide a lead 530 connected with a common connecting lead 506', limiting resistor 53|, lead 532, coil 4|2, lead |3I, to the plate of tube 4. We also provide a condenser 535 across leads 532 and |3| as in the case of the other three tubes. The cathode of tube 4 is also grounded by circuit 531 as indicated.

Bias circuits `550 for the 6.3 volts for the filaments of the thyratron tubes l, 2, 3 and 4. Another secondary output circuit of 5 volts is indicated 55| for the rectifier tube 553.

The third center tapped winding 554 of the transformer 415 is for supplying voltage to two circuits, one the plates of a rectier tube 553 and the other for the main thyratron tube bias circuit. We have grounded the filament (cathode) of rectifier tube 553 as shown. At the center tap of the secondary 554 we have a lead 555 to resistor 556, lead 551 combined choke and relay coil 499. From lead 551 we also have a lead 558 to condenser 559, the other side of which is grounded as shown.

From coil 499 we have lead 560 to the cathode of voltage regulator tube 56|, the plate of which is grounded as indicated. Across tube 56| is a resistor 562 connected by lead 563 to lead 560 to said tube 56|, the other side of resistor 562 being grounded.

Our connections for these tubes also forms a time delay for the warming up of tubes I, 2, 3 and 4, since relay 499, when energized, closes points 499', there being a time delay on the make of said points 499 with a, well-known type of switch which has a quick break.

Moreover, this relay 499 provides a safety arrangement since failure of any part of the bias supply will cause 499' to open, dropping out relay 430 which disconnects the plate circuits of the

tubes

2, 3 and 4. This also drops out the 24 volt control circuit to the automatic operation.

Connections for vthe bias supply voltage for

tubes

1, 2, 3 and 4 The above circuits and the tubes 553 and 56| provide means to produce the bias voltage for the

main thyratron tubes

2, 3 and 4. We will now describe its connections to these tubes. Thus we have a lead 565 joined to lead 563 as shown. Lead 565 is the main bias supply line for all four tubes. This main lead 565 connects with three points (normally closed) on relay 566; namely, points 561, 568 and 569, lead 565 also being connected with

points

510, 51|, 512 and 513 of relay 600 controlled by tube 3.

For tube bias is normally supplied from lead 565 to point 561, lead 511, resistor 518 and lead 519 to the grid of tube I.

For tube 2, the main bias is from point 568, lead 580, resistor 58|, lead `562, to the grid of tube 2. This main bias lead 565 also has a connection for an auxiliary circuit for tube 2 by lead 515 to a contact 516 of relay 5||l controlled by tube For tube 3, the main bias includes lead 588 from point 569, to resistor 584, lead 585, to the grid of tube 3. Tube 3 also has an auxiliary bias circuit, since Iwe provide, as more clearly shown in Figure II, a lead from a bias line 565 to point 512 of the relay 600 as shown. We also provide a lead 512 from point 512 to point 595 of relay 596 of tube 2. Then we also provide a lead 595 connecting with lead 583 to the grid of tube 3. Hence, the auxiliary bias for tube 3 is so connected as to have in series therewith a switch controlled by the relay for tube 2.

For tube 4, the bias includes a lead 581 from point 513 to resistor 588, lead 589, to the grid of tube 4. As the necessary part of the operation, as will hereinafter appear more fully, we also provide additional temporary bias circuits for tubes and 2. This additional bias for tubes and 2 includes a circuit from switch point 510 of relay 600 by way of lead 510 which connects with relay point 51| bylead 51|' which connects with lead 580 tothe grid of tube 2v.

Sequential firing of tubes We have provided means for causing tubes I, 2., 3 and 4 to re in a desired sequence. for

proper machine. operation one after the other,

and moreover, any.` subsequent tube in the series cannot rire until the preceding tube has tired.- The." circuits and means for. accomplishingjthis willfnow be described. Thus, when relaycoil 566.

is,.'ener'gized this openspoints 56.1, 568K-an'd 569, removing the main bias` from tubes I, 2 and 3. However bias for tubey 2 is now being supplied through the'temporary auxiliary circuit constitilting a second supply circuit for tube 2 just described and including point 516, lead 590, lead 580, resistor 56|, lead 582vv togrid of tubefZ. When tube I res (at the endof its time delay, to be described) relay 5I6, through lead 5II, isdthen energized and normally closed point 516- now opens, removing this auxiliary bias from tube 2.

Also the ring of tube I and energizing of coil 5|0 closes the normally open point 592 thereby applying 24 Volts to the power relay I2 'byleads 631 to apply a delayed shot of metal into the mold of the die casting machine.

Firing of. tube 2 Firing of tubev 3 Removing bias from -tube 3 allowstube, 3 to fire at the end of its time delay energizing the coil of relay 666, closing normally open points 51,0 and 51I, thereby reapplying the third or temporary additional bias to tubes I and 2, thus resetting these tubes and their associated plate circuit relays.

Moreover, normally closed

points

51,2 and 513 are opened and since 512 is opened, thisprevents reapplying bias to tube 3 by tube 2 at this point of the` cycle.

Firing of tube 4 The opening of 513yremoves bias frommtube 4. When tube 4 fires at the end of its time delay, the relay 4I2 is energized, openingmnormally closed point H3 which breaks the holding ,circuit furthe die operating mechanism.

Interconnected. circuits from tube controls to machine part operated microswitch. to-tube3 The. bias control of the tube 3 is interlccked with a microswitch 602 which switch in` turn. is actuated by the. rack on the machine, which .rack is operated by a hydraulic system.y Closing, of point 602 closes relay 605 byleadsffrom contact 49,6,ofrelay 436A and leads 408, -'Illlland 606. An-l otherlead ,661 connects. from. lead 60.6I to va .point 60,8,"(normally open) of relay 4 I 2.r

011th@ other Side 0f, 10.11,I 60.5. e lead, 5l". We:

for operating the. check valve nects with normally.A open'. side.-` ofi mcrosvvitx'shr 602, referred to supra and lead. 6.II.; leadsgn. andi425, normally. open pointi.42,6r, on relay 430.

Whencoil 6;5-;is. energized, coilof relay. 566; isv4 also energized. Relay.y 605 has. three normally'. open points 612; points. 6I3fI and 6I4.. Theconnection from relay,l S05/.to yrelay 56.6;.includes point; 6 =I2,= lead. 615, relay... coil 566. From the other. side of relay. 565, lead 616 connectsto lead.,` 4.19,; point 4 I Bofrelay 4.02, theother side ofthe switch. 4I8 nasa-lead 4.I.1 extending. to terminal M6; henceibylead IiIIL to` safetyl point 6.I9r.of push; button switch 646. which also. connects. to-leada 6-20iandconnection 62I, lead 623, which conf nectsto `lead 6Il6acompletingthe circuit for enf ergizing coil SI15-and hencecoil 566; Thus, when;` point 6ll2opens,` due to the action of thev machine. part-with theedies starting. to open, from'fthef` foregoing circuitsritwill be `seen that coil 6.05v and hence coil. 566;:are. de.energized, all three, points 561, 5,68 .and -569 of relay. 566 areclosed,v thus reapp-lying the main original bias to tube 3 as well as to tubes` I and 2.

After relay 566 vh-asbeen deenerg-ized and the mai-nv bias, restored,V to tubes I ancl- 2 the additional bias'ior-LtubesfI and-2 above described. hasfbeen broken by the biasing of tube 3. This occurs sinceI the main bi-as'is restored-immediatelytc tubes I andf-2 whereas the additional bias circuitis not broken-until tube 3 becomes biased and relay 600- subsequently operates to break points 516 andv 51|Y ofgsaid additional bias circuit.

Time delay circuits ,for tubes 1, Z, 3 and 4 For eachof tubes I, 2, 3 and 4 we have a time delay network for the bias circuits thereof which includes lead 511 (bias supply lead for tube rek--r sister 518) lead A519 for example, to grid of tube` I.l Before normallyl closed point 561 opens, there isla circuit` through" resistor 518, lead 519, which alsoueharges condenser 660 which until the bias is', removed, supplies a voltage to grid I. Howf evenwhen VSwitchpoint 561 is opened, condenser 666 is. discharged through adjustable potentiometer 66I (which, may be variablyset by the opcrater) andk current limitingY resistor 662 to ground 5I3 asV shown. The other side of the bias circuit is grounded as shown in the drawing and described supra. Thus, the setting of the ad-,f justrnent aon potentiometer 66| determines the time for discharge ofmcondenser 668 which when it reaches critical grid Vvoltage of tube I allows thetube to re. Resistor 662 limits the current for a very low setting of the potentiometer 56|. Resistor 518 has two purposes, one to prevent the main bias supply from being shorted in case condenser 660 fails. Also it provides a buiter action toprevent burning of point 561, due to sudden inrush of current to condenser 660. A similar time delay network consisting of a similar condenser 660 and potentiometer 66| for the dise charge of the bias isprovided for each of the

other tubes

2, 3 and 4 as shown in the drawing.

Operation-.Une `complete cycle The .system is started in operation by theoperator closing the. quick returnclose button 64,0 throughrelay 402, relay .406 and correlated cir-v cuits, andcontrols from the relay 430 connected atrofisaA and conditions at this point are shown in diagram Figure II.

The microswitch at point 602 is operated by a machine part to thereby move the microswitch to final closed position and effect an energization of relay 605. This closes switch point 6I2 and relay 566 is energized, opening point 561 which is in the main bias circuit for tube I-this being the main bias circuit for tube I as well as for the other tubes as described above. Opening the tube I bias, permits tube I to fire through its plate circuit at the end of its time delay, thereby energizing relay I0, closing switch point 592 as stated supra. The circuits at this point are illustrated in Figure III. This, through the various circuits shown, energizes relay I2 which in turn supplies power to the pilot valve for the main air cylinder 5I, permitting a delayed shot of metal to be injected into the die as the first part of the two-stage metal injection.

Temporary auxiliary circuit for biasing

tubes

2 and 3 It will be noted that while the main bias supply circuit to the tubes controlled by relay 566 and points 561, 568 `and 569 has been broken,

tubes

2 and 3 are temporarily biased by the auxiliary circuits described above. These auxiliary circuits for

tubes

2 and 3 have been temporarily energized simultaneously with the main bias described above and the auxiliary bias circuits for these two tubes are illustrated in the diagram of Figure II.

Firing of tube 2 By the firing of tube I, just described, the auxiliary bias for tube 2 is opened because switch point 516 which is in the bias circuit for tube 2, has now been opened by relay 5I0. Removing this auxiliary tube 2 bias causes the discharge of its circuit at the end of its time delay since the main bias supply was previously removed, energizes relay 596. The circuits as now operating are illustrated in Figure IV. Thus, when point 591 is closed, current is supplied from the transformer 482 to relay I I circuits and switches for rapid metal injection. However, since the time delay in the f1ring of tube 2 after both bias circuits have been removed depends on setting of the variable potentiometer 66| for tube 2, by adjustment thereof to its low position, tube 2 may fire substantially immediately after tube I fires so that in the overall operation of the network sequential firing system disclosed, tubes I and 2 in such case lire without any appreciable difference in time but act as one tube.

Firing of tube 3 The firing of tube 2 energizes coil 596 which breaks the auxiliary bias supply for the grid circuit of tube 3. Since the main bias supply was previously removed this now removes all bias from tube 3 and causes it to fire after its time delay-illustrated in Figure V.

Firing of tube 3 acts to reset bias of

tubes

1 and 2 Next in the cycle of operations, we provide means through the firing of tube 3 to reset the bias by the additional or a third temporary circuit for tubes I and 2, described supra. However, ring of tube 3 energizes relay 600 which is lin the plate circuit of tube 3 as shown, so that energization thereof closes

switch point

510 and 51| which are in the additional bias circuits for tubes I and 2, as described above and shown in Figures I and V. By closing these switch points 510 and 51|, tubes I and 2 are rebiased. It is understood that when the proper bias is applied to tubes I and 2, discharge thereof through the plate circuit ceases.

Precention of rebiasing of tube 3 To prevent improper rebiasing of tube 3, we have also provided another switch point 512 for relay 600 so that when relay 600 is energized, as just stated, this switch point 512 opens with the result that re-establishing bias of tubes I and 2 will not also re-establish bias of tube 3.

From the foregoing it will be understood that when bais is re-established to tubes I and 2 these tubes cease firing and coils II and I2 are deenergized, permitting solenoid operated pilot valves 5I and 6I to be returned to normal position.

Firing of tube 4 and resetting circuits to initial position Firing of tube 4 is for the purpose of accomplishing the last step in the machine operation in our system; namely, re-opening the dies which in turn, by the machine controlled switch 602, causes return of circuits to initial position with the main bias on tubes I, 2, 3 and 4. This is illustrated in Figure VI. Referring back to tube 3 it will be noted that when it fires, it has Opened switch point 513 on relay 600 which in turn removes the bias from tube 4 after its time delay through its potentiometer circuit 6I I-4. VWhen the bias on tube 4 is removed, then the tube discharges, energizing coil 4I2, opening point 4|3 on relay 4I2, thereby breaking the holding circuit for relay 402 which drops out relay 402. This effects an opening of the dies and consequently opens microswitch 602 which deenergizes relay coil 605 and consequently coil 566. This allows points 561, 568 and 569 in the main bias circuit for the tubes I, 2 and 3 to be re-established, thereby resetting these in initial position. Rebiasing tube 3 in this manner thereupon permits its relay coil 600 to operate, breaking points 51I and 510 thereby disconnecting the additional bias circuits which were temporarily established for tubes I and 2. It will be also noted that this operation of relay coil 600 also closes point 513 which establishes the main bias supply to tube 4. The entire electrical apparatus is now in initial position. The system will not recycle until the operator restarts the action by pressing the manual close button 640 as heretofore described.

In referring to the bias supply circuits for the several tubes, we have referred in Figure IIa and in the description thereof to the main bias, an auxiliary bias and an additional bias. However, it is to be understood that the various circuits-some leads of which are common to the different circuits--for supplying bias at the proper time t0 the different tubes, according to the drawings and description may be properly termed additional or supplemental with respect one to other of the bias circuits.

It is apparent that, within the scope of the invention, modifications and different arrangements may be made other than is herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

What we claim is:

l. In an electrical system for causing mechanical operations, said system adapted to be connected to a source of electric current, an electronic sequence timing network adapted to be energized vfrom said `source of current; said network including a plurality of space discharge tubes connected in said network; each -of said tubes having cathode, plate and control 4grid elements; a iplateecathode 'circuit for each of said tubes; and fa variable Itime constant network for controlling 'the vsequential discharge `oi said tubes, -said networkincluding a capacitance and resistance connected to the grid 4element of 4each of said tubes; a source of bias supply; la main normally closed bias circuit; switching means therefor for connecting said main bias supply to the control Vgrid Velements of each yof said tubes to prevent firing thereof; auxiliary bias Vcircuits for the control grid elements of certain'of Vsaid tubes upon opening of the main bias circuit to said tubes; means operable to open the switch of the main bias supfply circuit to aplur'a'lity of :said tubes, said means "causing ldissipation of the 'capacitance from the `g-rid `'circuit 'of vone of lsaid `tubes through its re- Tsistance causing delayed `discharge of said one tube only through its plate-cathode circuit; 'switching means connecting said auxiliary bias to certain of the other of 'said tubes when said main bias switch is opened; means operated by the discharge of said first-mentioned tube to'open fsaid auxiliary bias suppl'y circuit to lthe control grid 'of a second tube to permit 'delayed discharge "thereof; means controlled by the discharge of I'said lsecond tube for *opening the auxiliary bias 'circuit vfor a third tube to *cause discharge there- Cof; additional bias circuits for 'the iirst two mentioned tubes; Yswi'tcl'ii'n'g means controlled by said -third tube discharge circuit for connecting said additional bias Ycircuits for the rst two tubes to the bias supply to rebias 'said tubes; switching fineans for breaking 'thebias supply to a fourth tube; and means under the control "of 'said-last'- mentioned tube 'to Yclose 'the 'first-'mentioned main bias supply circuit to each of said lplurality of tubesin said system.

2. In an electrical systernior causing mechanical operations, said system adapted to be connected to a source of electric current, an electronic sequence timing network adapted to be "ener- 'gized from said source of current; said network 'including a plurality of space discharge tubes 'connected in said network; each of said tubes having cathod-e, plate and 'control grid elements; a plate-cathode Vcircuit for leach of said tubes; and a variable time constant network for controlling the sequential 'discharge of said tubes, said network including a capacitance and resistance connected to the grid element of each of -4said tubes; a source of bias supply; a main normally closed bias circuit; switching means therefor for connecting said main bias supply to the control grid elements of each of said tubes to prevent firing thereof; auxiliary bias circuits for the 'control grid elements of certain of said tubes `upon opening nf the main bias 'circuit to said tubes; mea-ns operable to open the switch of the main bias supply circuit 'to a'plurality of said tubes, said means causing .dissipation of the capacitance from the grid circuit of one of `said -tubes through its resistance causing delayed discharge of said one tube only through its plate- 'cathodecircu-it; switching means connecting 'said auxiliary bias to certain other of 'said Vtubes when said main bias switch is opened; means operated by the discharge of said first-mentioned tube to open said auxiliary bias supply circuit to the control grid of a tube to permit delayed discharge thereof; additional bias connections for certain of said tubes; switching means controlled by a previously mentioned tube discharge circuit for connecting said additional bias circuits to the bias supply to rebias certain of said tubes; switching means for breaking the bias supply to another tube; and means under the control of said last- `mentioned tube to close the inst-mentioned main bias supply circuit to each of said plurality of tubes in said system.

3. yIn -an electrical system for causing mechanical operations, said system adapted to be connected to a source of electric current, an elec-.- tronic sequence timingl network adapted to be energized from said source of current; said network including a plurality of space discharge tubes; each of said tubes having cathode, plate and control lgrid elements; a plate-cathode circuit for each of said tubes; rand a Variable time constant network for controlling the sequential discharge of said tubes, said network including a capacitance and resistancefconnected to the grid element of each of -said tubes; a source of .bias supply; a main normal-ly closed bias circuit; `switching means therefor for connecting said main bias supply to the control grid elements of each of said tubes to prevent firing thereof; auxiliary bias connections for the control grid-of certain of said tubes upon opening of the main bias circuit to said tubes; means 4operable to open the switch of the main bias supply circuit -to a plurality of said tubes, said means Vcausing dissipation of the capacitance from the grid circuit of one of said tubes through its resistance causing delayed discharge of said one tube only through its plate-cathode circuit; switching means connecting said auxiliary bias to certain of the other of :said `tubes when said main bias -switch is opened; `rmeans operated by the discharge of -said first-mentioned tube to open said auxiliary bias supply circuit to the control grid of a second tube-to permit delayed discharge thereof; vmeans controlled `by the discharge of 'said Vsecond `tube for opening the auxiliary bias circuit for a third tube to cause delayed discharge thereof; the auxiliary bias circuit for said third tube being in series with the vswitch points of the `switch means operated 'by the discharge of each of said 'second and `said third tubes to prevent reapplication vof bias to said lthird tube through said auxiliary circuit; ,additional -bias circuits for the first two Vmentioned tubes; switching means controlled -by said third tube d-ischarge'circuit for connecting said xadditional bias circuits for the first two tubes to the bias supply to rebias said tubes; switching means 'for breaking the ybias supply to a yfourth tube; `and means under the lcontrol of said last-mentioned tube to yclose ythe -rst-inentioned main bias supply vcircuit tofeach of said plurality of tubes in said system.

` 4. In an Aelectrical system `for causing v'mechanical 'o'perations said system adapted to be connected to a source Lof electr-ic current, an velectronic sequence timing network adapted to be y'energized from said source of current; a tying-'in relay; `circuits and switches from said source of current supply to said relay; lcircuits controlled by 'said relay to connect said source of supply to 'said network; `said network including a plurality of 'space discharge tubes connected in said network; each o'f Isaid tubes "having cathode, plate and control grid elements; a plate-cathode circuit for each of said tubes; and a variable time constant network for controlling the sequential discharge of said tubes, said network including a capacitance and resistance connected to the grid element of each of said tubes; a source of bias supply; a main normally closed bias circuit; switching means therefor for connecting said main bias supply to the control grid elements of each of said tubes to prevent ring thereof; auxiliary bias circuits for the control grid elements of certain of said tubes upon opening of the main bias circuit to said tubes; means operable to open the switch of the main bias supply circuit to a plurality of said tubes, said means causing dissipation of the capacitance from the grid circuit of one of said tubes through its resistance causing delayed discharge of said one tube only through its plate-cathode circuit; switching means connecting said auxiliary bias to certain other of said tubes when said main bias switch is opened; means operated by the discharge of said first-mentioned tube to open said auxiliary bias supply circuit to the control grid of a tube to permit delayed discharge thereof; means controlled by the discharge of said tube for opening the auxiliary bias circuit for another tube to cause delayed discharge thereof; additional bias connections for certain of said tubes; switching means controlled by a previously mentioned tube discharge circuit for connecting said additional bias circuits to the bias supply to rebias certain of said tubes; switching means for breaking the bias supply to another tube; and means under the control of said lastmentioned tube to close the first-mentioned main bias supply circuit to each of said plurality of tubes in said system.

5. In an electrical system for causing mechanical operations, said system adapted to be connected to a source of electric current, an electronic sequence timing network adapted to be energized from said source of current; a tying-in relay; circuits and switches from said source of current supply to said relay; circuits controlled by said relay to connect said source of supply to said network; said network including a plurality of space discharge tubes connected in said network; each of said tubes having cathode, plate and control grid elements; a plate-cathode circuit for each of said tubes; and a variable time constant network for controlling the sequential discharge of said tubes, said network including a capacitance and resistance connected to the grid element of each of said tubes; a source of bias supply; a main normally closed bias circuit; switching means therefor for connecting said main bias supply to the control grid elements of each of said tubes to prevent firing thereof; auxiliary bias circuits for the control grid elements of certain of said tubes upon opening of the main bias circuit to said tubes; means operable to open the switch of the main bias supply circuit to a plurality of said tubes, said means causing dissipation of the capacitance from the grid circuit of one of said tubes through its resistance causing delayed discharge of said one tube only through its plate-cathode circuit; switching means connecting said auxiliary bias to certain of the other of said tubes when said main bias switch is opened; means operated by the discharge of said rst-mentioned tube to open said auxiliary bias supply circuit to the control grid of a second tube to permit delayed discharge thereof; means controlled by the discharge of said second tube for opening the auxiliary bias circuit for a third tube to cause delayed discharge thereof; additional bias circuits for the rst two mentioned tubes; switching means controlled by said third tube discharge circuit for connecting said additional bias circuits for the first two tubes to the bias supply to rebias said tubes; switching means for breaking the bias supply to a fourth tube; and means under the control of said lastmentioned tube for simultaneously directly connecting the main bias supply to the iirst three tubes; means controlled by said last-mentioned biasing of the third tube for thereafter simultaneously disconnecting said additional bias supply to the rst and second tubes.

6. In an electrical system for causing mechanical operations, said system adapted to be connected to a source of electric current, an electronic sequence timing network adapted to be energized from said source of current; said network including a plurality of space discharge tubes connected for sequential operation in said network; each of said tubes having cathode, plate and control grid elements; a plate-cathode circuit for each of said tubes; and a variable time constant network for controlling the sequential discharge of said tubes, said network including a capacitance and resistance connected to the grid element oi each of said tubes; a source of bias supply; a main normally closed bias circuit; switching means for connecting said main bias supply to the control grid elements of each of said tubes to prevent firing thereof; means operable to open the switch of the main bias supply circuit to a plurality of said tubes, said means causing dissipation of the capacitance from the grid circuit thereof through its resistance causing delayed discharge through the plate cathode circuit of one tube only; additional bias circuit means adapted to be connected to a sequential tube; switching means controlled by said first-mentioned discharge circuit for opening said last-mentioned additional bias circuit to permit delayed discharge thereof; switching means controlled by said sequential tube discharge circuit for rebiasing said rst-mentioned tube and for breaking the bias supply of another tube; and means under the control of said last-mentioned tube to close the first-mentioned main bias supply circuit to each of said plurality of tubes in said system.

BURTON F. HOLMES. HERBERT HARRY HEINDEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,422,020 Kingsmill June 10, 1947 2,483,620 Burlingame Oct. 4, 1949 2,503,127 Mumma Apr. 4, 1950 FOREIGN PATENTS Number Country Date 504,680 Great Britain Apr. 28, 1939 OTHER REFERENCES Review of Scientific Instruments, Nov. 1939, pages 323 and 324.