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Aug, 6, E946» M_. w @msm , ADJUSTMENT SYSTEM „ Filed May 5, 1942v 2,4959@ Q . 5 Shee'ts-Sheet l Rumà N_ Au@ 653946 I M. w. @All_lsîER ' _ 23405439 ADJUSTMENT áYsTEM Filed May 5, 1942 3 Sheets-Sheet 2 :Snventor mi@ @9 m@ M. W. GAESER ADJUSTMENT SYSTEM I ` Filed May 5, 1942 3 sheetsèsneei 3 ßmaentor www www@ \_` A > I, megs Patented Aug. 6, 1946 UNITED STATES PATENT OFFICE 2,405,419 ADJUSTMENT SYSTEM Martin W. Gaiser, Kokomo, Ind., assígnor to Gen eral Motors Corporation, Detroit, Mich., a cor poration of Delaware Application May 5, 1942, Serial No. 441,825 13 Claims. (Cl. Z50-40) 2 l This invention relates to means for measuring given electrical values and utilizing said meas urements for predetermined adjustments. More It is a further object of my invention to pro vide means for automatically peaking or adjust ing a circuit to its resonant condition. versal in rate of change in voltage or in the directional flow of current in a circuit to enable adjustment at a given optimum value. There It is a still further objectl of my invention to provide means for automatically adjusting an intermediate frequency transformer to ‘a pre determined resonant frequency before insertion are a number of instances where it has been lnto a radio receiver. into a radio receiver. taken on line 2'-2 of Figure 3 through the screw specifically it relates to means indicating a re T ‘ It is a still further object 'of my invention to found desirable to ascertain the exact point at which voltage flowing in a circuit ceases to in 10 provide such automatic means for adjusting a resonant circuit which 'will be simple in operation crease and begins to decrease as the values or and will not easily get out of adjustment. quantities of the various elements composing With these and other objects in view, which the circuit are varied. This may be termed find will become apparent as the specification pro ing the “peak” or resonance point of a circuit. ceeds, my invention will be best understood by There are many instances in which Such means reference to the following specification and might be advantageously employed and as one claims, and the illustrations in the accompany example there is shown in the following specifi ing drawings, in which: ' ` cation the use of such a peak relay or indicator Figure 1 is a side elevation showing the ad used in adjusting an intermediate frequency transformer assembly toa set predetermined 20 justing means of my invention; > Figure 2 is an enlarged detailed sectional View frequency automatically which is then assembled It is to be understood that this is merely for illustrative purposes and should not be considered as limiting the broader aspects of my invention. These intermediate transformer assemblies driving means for adjustment; Figure 3 is a top plan View partly in section taken online 3-3 of Figure 1; Figure 4 is an enlarged sectional view through mentioned above are factory-adjusted or tuned ‘ the gear driving means; and ’ Figure 5 is a schematic wiring diagram of the system of my invention. quency is usually below the frequency normally Referring now more `specifically to the draw employed in a broadcast band, and as one ex 30 ings, in Figure l there is provided a suitable base ample, may be 252 kilocycles. They are formed 2 which supports thereon a test block 4 which'is of two coils inductively coupled and each coil adapted to support devices to be adjusted such has a condenser connected thereacross to form as intermediate frequency transformers men a resonant circuit therewith. This therefore pro vides two capacity-inductance circuits magnet 35 tioned above. These transformers are usually obtained in the shape of a small rectangular ically coupled together and these are intended to be tuned to the same resonant frequency to pass ' metallic container of substantially square cross section having somewhat the appearance of a a maximum amount of power from the output small tube. Extending from one end of this of the ñrst detector or mixer tube to the second detector in a conventional receiver. Physically 40 container there are usually a series of connect ing wires, such as shown in dotted lines in Figure these coils are wound on a common form and 3 at 6, 8, lil and I2, which extend from the coils ì mounted on -a base with two trimmer condensers and condensers within the metallic container and which are small spaced plates separated by a are clipped under suitable connecting clips I4, dielectric, one plate being adjustable with re spect to the other by movement of a small screw. 45 lâ, i8 and 20, the metallic container itself lying between‘suitable projections `on the upper sur These trimmer condensers are so mounted on the face of the testing block 4. base that these adjustable screws are accessible As will be seen in Figure 3, this test block 4 may for adjustment, the whole assembly forming a be pivoted around its center and in this manner unitary part for insertion into the receiver chassis after the two circuits have been accur 50 one transformer assembly may be in the process of being adjusted While another is being placed ately tuned to the intermediate frequency of in the opposite end to be ready for adjustment the set for which it was designed. when the first has been completed. After the It is therefore an object of my invention to provide means for ascertaining or determining new transformer has been inserted in its test posi tion, the test block is rotated about its pivot and the resonant condition of an electrical circuit. to a given frequency which is ñxed. This fre 3 2,405,419 the transformer then assumes a position as shown in dotted lines in Figure 3 in front of the two motor-driven screw drivers whose purpose it is to engage the adjusting screws and to bring them to the proper position of resonance at a predeter 4 a shoulder on the inner surface of the supporting member 24 and against the inner end of the mem ber 26 to normally keep the latter spring biased outwardly or toward the end of the transformer. Both of the screw driving assemblies are identical. mined frequency. The driving means for the flexible driving mem Each of the adjusting screws in the transformer ber 64 and the like member 66 is provided by a is adapted to be engaged by a separate and inde gear box 68 which has two forwardly extending pendently driven screw driver which is adapted portions ‘I8 and 'l2 which contain cylindrical to fit into the slotted end of the screw. The pro 10 openings T4 and have in the outer end thereof, a jecting portions of each of these screw drivers are _ cylindrical bearing plug 16. The end of the driv supported in a suitable bracket 22 which carries ing cable terminates in a connecting tongue 'I8 a plurality of horizontal sleeves 24 in spaced rela adapted to fit within a slot 80 in the end of a tion, said sleeves telescopically carrying therein a drive shaft 82. A long sleeved member 84 is second hollow sleeve 26 which carries on its for 15 mounted upon the shaft 82 at its opposite end and ward end a hollow metallic cup-shaped member extends for substantially one-half of the total 28. This cup-shaped member has an opening 38 length of the shaft. This sleeved member carries through its base through which projects a stud a suitable ball bearing support 86 which is 32 threaded into the end of the member 26 for mounted within the opposite end of the cylin supporting the cup member 28 on said end. 20 drical opening 14. This sleeve member 84 may Within the cup 28 is a sleeve 314 of resilient insu~ rotate with respect to the shaft 82, the shaft 82 lating material within which is carried the screw projecting from the end of the sleeve and having driver 38 per se, which it will-be seen is fully insu therethrough a C-washer 85 to prevent the ex lated from its supporting screw by the insulating pulsion of various parts carried by said shaft. sleeve 34 and a small insulating pad 36 between . Intermediate the two ends of the shaft there the base of the screw driver 38 and the _head of is secured thereto a collar 88 adjacent the cylin the stud 32. The screw driver 38 is maintained drical bearing plug 16, and also a movable clutch within the end of the insulating end 34 with sum collar 90 which has diametrically opposed slots cient rigidity so that it cannot turn with respect $2 therein which are adapted to provide an open thereto, but rotates with the cup member 28 when- ' ing for a pin 94 which extends through the shaft, ever the same is driven by suitable means to be thus providing means whereby the clutch mem described. The inner end of the screw driving ber 98 may slide longitudinally of the shaft, but member 38 is hollow, as shown at 40, and also always turn with the same. The face of the clutch has a small bore 42 extending out to its front por collar S8 is provided with diametrically opposed tion. Within this bore and carried back into the grooves 92 therein which are adapted to be en hollow section 48 is a protruding pin member 4Q gaged by extending tips 95 carried by the adjacent which has a disc-like portion 46, the latter acting face of the sleeve member 84, thus providing a as one end stop for and compressing a resilient clutch drive. . spring member 48 between itself and the base of Adjacent the inner end of the clutch member the opening 40. This tends to expel the pin 44 40 90 is a washer 96 and between this washer and from the forward face of the screw driving mem the member 88 and concentric with the shaft is ber 38 which is brought to a driving tip 50. It a helical spring 88 which bears against the two therefore serves the function of a locating pin, members and tends to keep the clutch collar 88 and when the tip 50 proceeds into the groove in a in its left-hand or clutch engaging position as screw head, will of course be pushed back so that it will be> flush with the tip of the screw driver. The function of the projecting pin 44 or locating pin is that when the -screw driving assembly is 1 shown in Figure 4. Mounted on the end of the shaft 82 which projects into the main chamber < of the gear box isa bevel gear |08 which is rigidly secured to the sleeve member 84. Any driving moved up to contact the adjusting screw on the force thus applied to the bevel gear |58 is trans base of the transformer, it will tend to locate or 50 mitted through the sleeve 84, clutch members find this groove, and when it does fall into the 93 and 95, pin 94 to the drive shaft 82. The same, will bring in or guide the screw driving tip purpose of this clutch arrangement will be de 58 _into the proper groove. scribed more in detail at a later point. This The member 28 is secured, as before stated, by same construction of course applies to the op the stud 32 to the forward end of the member 26, posite drive for the second screw driver which but this construction is resilient to the extent is housed within the housing portion 'l2 which that there is provided a coiled spring 52 located in turn terminates in a bevel drive gear |82 on between the head of the stud 32 and the base of the inner end of that assembly. the member 28 which tends to maintain the cup Extending directly across the main portion of 2B forced against the end of the member 28 under 60 the gear box E8 is a main shaft |04 which i's trun normal conditions, but allowing it a certain nioned at one end in a ball bearing assembly amount of eccentricity. §06 and vin the opposite end in a second ball bear The hollow portion of the member 25 carries ing assembly |88, the outer projecting end. of therein a cylindrical member 54 which is directly which has thereon a pulley ||0 adapted to be connected to the end of a flexible drive member 65 driven by a V belt H2 from some suitable source 64 which is driven from a prime source of power. This member 54 has a slot 58 therein in which rides a pin 50 carried by the member 2G from one of power such as the motor |14. Mounted upon this shaft |84 at one side is a sleeve member || 6 which is keyed to the shaft side to the other. This pin and slot connection .by slots ||8 and |28 having therein small balls enables considerable longitudinal movement be 70 |22. Thus this sleeve may be slid axially of the tween the twomembers 54 and 26, but assures shaft, >but caused to rotate therewith at all times. that rotary or driving connection between the At its center this sleeve Yhas an indented groove two is provided at any of the longitudinally ad |2¢fi in which there rides a pin |26 mounted upon justed positions. There is also provided in this one end of a pivoted lever |28 which is pivoted instance a helical spring 62 which presses against „ at |30 and carries at its outer end an operating 2,405,419 5 spring |32 which is formed in the general shape of a hairpin, between the two portions of which projects a pin |34 mounted upon a slidable bar |36 whose position is determined by the energiza tion of certain operating coils |38 and |40. Mounted upon this sleeve ||6 and on opposite sides of the groove |24 are two bevel gears |42 and |44 which are rigidly secured thereto by of which rotates one contact position upon an actuation of the ratcheting or driving means. An electromagnet |68 is »provided for actually ratch eting the means and driving the rotating switch arms. There is also provided a second electro magnetic means |10 which releases the switch arms when they have completed their movement over a certain number of the switch points land allows them to return'by'spring pressure to their suitable set screws. These gears are spaced at such an interval that the bevel gear |00 extends 10 initial position which is that shown, namely, with ` down between them but does not contact either, it being necessary to move either upwardly or downwardly as shown in Figure 4 to form a driv switch arm |60 contacting switch point |, switch arm |62 contacting switch point -|, and switch arm |64 contacting vswitch point I3. In this Dar ing connection between |00 and |42 or |44. Thus ticular instance switch arm |66 merely acts as 15 an auxiliary spare and is not utilized. it will be seen that in the position shown no driv ing exists between the shaft |04 and the shaft 82. However, if either of the electromagnets |38 In the upper right-hand portion of the dia gram is more or lessschematically shown the screw driving means which has previously been and |40 is energized to cause the sliding mem discussed in detail and in this instance the two ber |36 to move, the spring |32 will cause the lever |28 to pivot and to move one or the other 20 screw drivers are referred to asv S and P, screw driver P being driven by gear |02 which may of the gears |42 or |44 into engagement, and if mesh with drive gears |48 or |46 and screw the shaft | 04 is rotating, such rotation will 'be driver S being driven'by gear |00 which may transmitted to the shaft 82. The same construc mesh with drive gears |42 or |44, these meshings tion prevails for driving the opposite gear |02 which in this instance may mesh with bevel gears 25 being controlled by the electromagnets |54, |56, |38 and |40 as previously described. The motor |46 or |48 which are mounted upon a sliding | |4 is shown at M. There is also provided means sleeve |50 controlled by the position of a pivoted for retracting the two screw driver tips and this lever |52 which in turn maybe moved byv electro is shown diagrammatically as a cross bar |12 magnets |54 and |56. Thus when the motor ||4 is energized, the 30 which is secured to the movable sections of ,both S and P and whose position is regulated by an shaft |04 is rotated, and by controlling the en electromagnet |14 whose armature is connected to the cross bar. ` . |38 and |40, either of the screw driving members n There is also provided a switching means, such may be rotated in either direction. From thé above description it.will be obvious that there 35 as diagrammatically shown at |16 and |18, asso ciated with the clutch members 90 `ofveach assem is herein provided a pair of motor-driven screw bly whereby whenthe clutch slips at one eX driving means which are capable of rotating in tremity of travel of the adjusting screw, a circuit either direction to turn the adjusting screws of will be made to actéuate certain necessary appa the trimmer condensers in a transformer assem bly. -In order to start at a given index, it has 40 ratus to be described. There are also shown on this diagram a series of operating relays, |80 been found desir-able to turn the screw varying ergization of the four electromagnets |54, |56, the condenser to one limit so that the condenser Whose armature |82 operates switches |84. and |66, relay |88 whose armature |00 gaps a switch ing means |62, a relayV |94 whose armature |66 tus the driving means is brought into engage 45 controls one switch |08 in its lower position, and a second switch 200v in its upper or actuated po ment with the slotted screw head and driven sition. The power supply is connected to the until the screw reaches one limit of travel. Y two incoming lines 202 and 204 in the latter of At Ythis point the force being applied by the which is a main switch 206. . gear |00 or |02, and which is transmitted to the Tapped from the incoming line is a trans screw driving head, must find some means of 50 former primary 208, the secondary of which is release due to the fact that the screw stops turn formed >of a pluralityof coils 2| 0, 2|2, 2|4 and ing. This isvprovided by the clutch arrangement `2|6 which supply vdifferent voltages for the am S3 and 05 which are the projecting and grooved plifying means and the remainder of the sys portions ofr the adjacent associated membersl 90 and 84, VThus as driving force is applied to gear 55 tem. A second transformer primary 2 I8 also has |00, the sleeve member 84 will continue to rotate, Y a plural coil secondary 220 for supplying addi tional voltages as desired. Any desired source `of but the grooved and tongue members -83-> and^05 modulated radio frequency ‘is applied across the will slip over each other and the shaft 82 will not terminals 222 and 224 for test purposes. This rotate, Thus when the screw driver itself stops, the clutch member will slip and while the main 60 input is applied to the vacuum tube VV1„ the out put of which is applied to the intermediate fre drive shaft |04 continues to rotate, no parts will quency transformer being tested which is shown be broken and this will cause a longitudinal move within the dotted line square immediately to the ment of the clutch member 90 lengthwise of the right of V1 and indicated as 226. . shaft 82. This lengthwise movement will cause The output of the intermediate frequency the closure of a switch later to be described. transformer is connected to a pair of amplifiers Referring now more specifically to Figure 5 V2 and V3 and the output of these two amplifiers which is a circuit diagram of the various con is 'connected to a transformer 228 across the pri nections of my invention, there is therein shown mary of which is connected anY indicating meter a stepped switching arrangement designated gen erally at A. This switching means is a ratchetV 70 230. The output „of the transformer 228 is con.-v nected to a Thyratron ‘tube V5 which is in this step-by-step switch having a plurality of con instance the actual detector ofthe peak or reso tact arms which are moved around circumferen nant point to be determined and the control tially upon a stepping by the control relay. It voltage in this instance is developed across the has a number of different contact'points‘and four switch arms, namely, |60, |62, |64 and |66, each 75 resistors 232 and`234 and the capacitor236. The will be at one definite limit of its capacity value, and therefore in actually operating .the appara 2,405,419, input circuit to the grid of the tube V5 is con trolled by a relay 238 whose armature controls two movable switch points: 240 oscillating be tween ñxed switch points 242 and 244 and 24S cooperating with a switch point 248. From an intermediate point between the two resistors 232 and 234 there is tapped a line 250 which extends to a resistor 252 and thence to a capacity 254 which acts as a time delay in a given 8 through switch 218 to ground. This causes relay |88 to raise its armature |90 and complete the circuit through switch |90 and |92. This switch closure completes a circuit for the stepping relay |68 of the ratchet switchwhích is then energized through the following circuit: incoming line 204, switch 206, switch |92-I90, line 288, line 290, relay coil |68, line 292 to incoming line 202. This ratchets the solenoid switch around until control circuit through line 256 back to control 10 the three switch arms |60, | 62 and |64 contact resistors 258 and 260 in the input to tube V1. the next adjacent points, namely, stationary There is also provided a differentiating circuit switch points 2, 9 and I4. At this point it is> de which consists of a condenser 262, resistor 264, sired to point out that while in its initial condi and a small resistor 266 across the bias grid sup tion switch arm |64 while resting on stationary ply of the tube V5. The tubes Va and V7 are 15 contact I3 applied a ground to the common con merely rectifier tubes which are fed by the trans nection of resistors 260 and 258, and in moving to formers 208 and 2|8 and adapted to provide the its new position removes such ground and causes necessary D. C. voltages at predetermined points a delayed automatic gain control voltage to be applied to the grid of tube V1, which will be more - There are provided at certain predetermined 20 fully described at a later point inthe specifica points in the system a plurality of condensers 268, tion. As the switch arm |60 rests on point 2 of 210, 212, 214 and 216 which are placed in the the switch. it connects relay |88 now to switch in the system. i circuit to limit current or voltage surges which |18. At the same time the switch arm |62 in might affect the operation of the Thyratron V5 moving from point 1 to point 8 on the ratchet when various solenoids are operated, but these 25 switch broke the 115 volt supply circuit through are not large enough to bypass a sufficient amount of current so that any solenoid will be energized unless direct connection is made to it. If the point 1 to the retracting solenoid |14 which was initially energized to keep the screw drivers S and P out of engagement with the screws to be ad power supply is closely regulated and certain justed. This initial energizing circuit may be shielding is employed, these condensers may be 30 traced as follows: incoming line 204, switch 206, omitted. Not all of the lines are shown connected line 294, switch arm |62, switch point 1, line 296, to the various sources of power in order to sim relay coil |14, line 298 to incoming line 202. Thus plify the drawings. For example, the ñlament this retracting coil for the screw drivers has been circuits of the various vacuum tubes are not energized, but when the switch arm |62 moves to shown connectedto a source of power and are 35 the new point 8, this coil is deenergized and the merely terminated in an arrow. This is also true screw drivers are allowed to contact the heads of the screws which it is desired to adjust. of certain of the relay circuits and wherever in the ldrawings an arrow is applied, it merely means Let us assume that screw driver S engages the that a suitable source of voltage is connected adjustable screw of the trimmer condenser in the thereto. Y secondary circuit and this now is in a position There are also provided a series of small neon to be able to turn that screw as desired.A How tubes 280, 282 and 284 which serve as short cir ever, even though the shaft |04 is rotating, no cuit indicators. 280 and 282 are normallyillumi nated' and are extinguished when a short circuit driving connection has been made through either of the bevel gears |42 or |42 to the driving gear occurs, while 285 is-normally deenergized and 45 |00. The circuit through switch arm |62 which now contacts point 8 is now completed to one of lights up when a short circuit occurs -in that the solenoid actuating coils for the driving means portion oi' the circuit to which it is connected. and in this instance is relay coil |38 which is en In the upper center part of the diagram is shown ergizedthrough the following circuit: line 204, a contact block for the various lines to make the necessary connections. switch 206, line 294, switch arm |62, switch point 50 8, line 300, line 302, relay coil |38, line 304, line We will now describe the operation of the sys 306 to incoming line 202. This causes the coil tem as units to be tested are applied to the test ' |36 to be energized, pulling the armature thereof block 4. The initial position of the ratchet or upward as shown in Figure V5, and therefore caus rotating switch A is as shown and the screw ing engagement of the gear |44 with the gear |00 driving means S and P are placed in juxtaposi tion to the screws to be adjusted so that the 55 andcausing the screw driver S to be driven. As previously mentioned, it is desired to run trimmer condensers will be of proper capacities. the adjusting'screw to one limit vof its travel The switch 206 is closed to apply the line volt before starting the adjustment so that it is as age to start the motor | I4 in operation and sup sured that the voltage iiow through the control ply power to the various portions ofthe circuit. The input terminals 222 and 224 are at this time 60 circuit for adjusting the circuit formed of the inductance and capacity in the intermediate fre connected to a modulated radio frequency voltage quency transformer will continue to flow in one of a certainpredetermined frequencyl and having direction'until a peak has been reached. Thus a value of approximately one volt. Thus the mo the screw driver S will cause the screw to be driven tor is in condition for driving the driving means which as yet have not turned the adjusting 65 to one limit position, and as the resisting torque applied by the screw becomes large, the clutch . screws, and power is applied to all of the neces mechanism before referred to will allow slippage sary parts of the circuit. . between the driving sleeve 34 and the clutch collar Switch 218 is manually depressed'mo‘mentarily and it will be obvious from the circuit that when 70 92 to allow the screw driver to stop but still per mit the gears to rotate. ' this occurs point | on the ratchet switch is con When this occurs the clutch collar is forced nected to ground. >This completes a circuit axially of its shaft which movement closes in this through relay |83 as follows: from the source instance a switch identified as |18. This com of power indicated by the arrow, through relay pletes the circuit to the solenoid |88 as follows: |88, line 286, switch arm |60, switch contact |, 75 from >ground* through switch |18, through line 2,405,419 9 10 and condenserA254~approximately .5 microfarad. 388, line 3|8, switch point 2, arm |68, line 286, The voltage thereacross will therefore take an appreciable amount of time to increase or de crease after the voltage has changed across resistor 2‘34. This negative automatic gain con relay |68, which is the stepping relay for the trol voltage which appears across condenser 254 ratchet switch A, and cause the various switch is applied through resistors 258 and 268 to the arms to be lmoved to their next adjacent switch grid of the tube V1 and decreases the gain of V1 point which is in this instance 3, 8 and I5. kin accordance with a slightly previous voltage Contact arm |64 which has now moved to point I5 connects relay 238 to ground and therefore en 10 across resistor 234. The resistor 268 is made variable so that it may be adjusted to give a ergizes the same. This energizing circuit is from convenient reading on the meter 238 with a the source of power to the arrow on relay 238, standard coil in position and peaked. All other then through 3I2, switch point I5, arm |64 to readings will be less than that. In the step re ground. This causes the armature members to be attracted toward the coil as shown in Figure 5, 15 lay position during which the switch arms occupy the positions 2, 8 and I4, it will be remembered the results being to disconnect resistor 232 from that the trimmer condenser C's also is being resistor 3I4 and connect the same to resistor 3I6, changed by the screw driver S1. This causes the and it also connects approximately 280 volts D. C. voltage across the terminals G and minus to to inductance 3 I8 through switch |88 operated by relay |94 through the following circuit: induc 20 change and subsequently the voltage across re sistor 234 and eventually the automatic gain con tance 3I8, line 328, switch 246-248, line 322, a relay |88 to the power indicating arrow. This causes relay |88 to again be energized, and, as be fore, such energization will complete a circuit to trol voltage applied through the circuit just de~ switch I 88, line 324, relay |88, line 323, resistor 328, line 338 to the plate 332 of the tube V5. This scribed to the tube V1. When the contactors ar rive at switch points 3, 9 and I5 by the last ratchet step described and while the transition is made from points 2, 8 and I4 to 3, 9 and I5, the automatic gain control voltage has had sumcient time to substantially catch up with the voltage furnishes the Thyratron with a continuous plate current and is in series with the relay |88 which will be energized at such times as the Thyratron V5 draws current. . The connection of capacitor 26 to resistor 3I6 across resistor 234. It is desired to point out by the operation of switch 248-244 connects the grid circuit of the Thyratron V5 to a differen 30 that the automatic gain control is operative at all points except the iirst switch point where it is tiating circuit comprising resistor 3I6, capacity grounded through point I to maintain the input 262 and resistor 264, which provides the neces of the transformer fairly constant. sary transient voltage to the grid circuit of the Now when the switch arms are on the positions triode when the l. F. trimmer has been peaked. 3, 8 and I5, the regulating circuit composed of In moving the contact arm |62 from point 8 to point 9 on the stepping relay switch, the 115 volt resistor 232, 2‘34 and capacitor'236 is connected circuit is disconnected from solenoid |38 and across resistor 3I6 instead of resistor 3I4. A differentiating circuit or filter now consists of connected to solenoid |48 through the following capacitor 262, resistor 264 and a comparatively circuit: line 284, switch 286, line 294, switch arm |62, switch point 9, line 334, line 336, re 40 small variable resistor 266. A change in the lay coil |48, line 384, line 386 to incoming line D. C. voltage across resistor 3I6 will cause a cur rent through this resistor or filter combination to charge capacitor 262 to a new value. The direction of this current depends on whether the voltage across resistance 3I6 increases or de driven in the opposite direction to that formerly creases, and the magnitude of the current de pends on the time rate and amount of change of applied. This then causes the screw to be that voltage across resistor 3I6. backed off from one of its limit positions, de The polarity is such that a decreasing voltage creasing the capacity of the condenser Cs. As this condenser is brought nearer or ad 50 gives rise to a decreasing negative voltage across justed more nearly to a condition of resonance _ resistor 3I6 and a transient current through re 2‘82. This causes the armature to be drawn downwardly as shown in Figure 5 and makes a driving connection between the gear |42 and the gear |88 which causes the screw driver S to be 45 sistor 264 such that the Thyratron V5 grid be in the secondary circuit of the transformer, the energy transferred therethrough will become comes more positive with relation to the ground greater and this voltage appears across the output causing tube V5 to ionize when the addition of terminals G and minus. This voltage which is 55 this positive voltage to the negative bias makes its grid sufûciently positive. It is also necessary due to an audible modulation of the radio fre quency being applied across the terminals 222 to mention that the relation between screw driver speed, rate of change of capacity Cs to the time and 224 is demodulated by one section of the 6F8G double triode tube V2 and further ampli of action of the automatic gain control circuit-l is fied by the 6V6GT tube V3. It is then fed into 60 suñîcient so that the automatic- gain con the transformer 338 which is connected to a trol circuit does not catch up while the screw second transformer 228 and mounted between driver is running out the screw on Cs to reach the two is a small meter 238. The two trans one of the extremes. However, in adjusting back formers may be replaced by a single one if the to the peak adjustment and when the peak is meter is not used at this point in the circuit. closely approached, the automatic gain control .6.5 The output of the signal >appearing across circuit can catch up because the voltage change these terminals is fed into the half wave rectifier in the region of the peak of the frequency is not V4 and the rectified voltage is converted into a as rapid as that Voltage change in approaching nearly D. C. wave by the filter system compris the peak. It should also be pointed out that as ing condenser 236, and resistors 3I4, 232 and v2‘34, 70 the rectified voltage approaching D. C. which is and having conductive polarity toward resistor 232. A portion of this negative voltage which supplied to the capacity 236 becomes larger, more current is drawn by the resistors 232, 2‘34 and 3| 6 and the filtering action thereof is not as good as previously. The grid of tube V5 will appears across resistor 234 is applied across re sistor 252 and capacity 254. As an illustration in this case, resistor 252 is about two megohms 75, have impressed upon it a more or less pulsating 1l 2405,41@ voltage. As long however as C’s is being adjusted toward peak, there will be a considerable direct current component of transient current through resistor 264 in such a direction as to add to the negative bias on the grid» to prevent V5 from ionizing. Í When, however, the rate of change of voltage through the ampliiier circuits becomes less as C5 is reaching a value to correspond to the top of the resonance peak, less additional bias is applied to the grid by the transient current through re sistor 264 and a great proportion of this pulsating component will pass through condenser 262 which will also tend to cause tube ionization. it will thus be apparent that a rather compli 12 causes the circuit to energize relay |10 which is the lock-in relay for the ratchet switch l»and upon this energization the wholeY ratchet switch mech anism is allowed to lreturn to the position ini tially described where it is ready for another operation of the mechanism. The operation of the system may be summar ized as follows with respect to the various switch positions of the automatic stepping relay A: First position (d) Screw drivers S and P retracted by coil |14. (b) Automatic gain Acontrol circuit grounded through switch point |3. f 15 (c) All of the relays deenergized. cated relation is obtained from screw driver Second position (a) Screw drivers S and P contact adjusting screws (relay |14 deenergized). tolerances in variation with the inductance as 20 (b) Automatic gain control circuit energized. (c) Driving relay |38 energized to drive adjust sociated with the two condensers in the I. F. ing screw to one extremity. transformer, the amount of filtering of the recti (d) Clutch switch |18 operated to stop drive at fled audio voltage and the automatic gain con speed, mechanical and electrical relay delay, and limits of rate of change of voltage which is caused by variation in CS and Cp with manufacturing trol constant in the feedback circuit. limit of screw driver. ' Thus with the screw driver S backing oil the Third position adjusting screw and approaching the peak of the resonant circuit, we reach a point at which the rate of change of voltage ceases and at that point the tube V5 is allowed to ñre or ionize which (a) Screw drivers still Contact the screws. (b) Automatic gain control circuit still ener gized. action causes a flow in the plate circuit thereof 30 (c) Driving relay |40 now energized to reverse screw drive by screw driver S toward peak which has been previously traced and includes the relay |30. The energization of this relay point. (d) Relay |80 energized at peak by ionization of tube V5. plete the 115 volt A. C. circuit to relay |68 and relay |14, the first through the following circuit: 35 (c) Screw drivers withdrawn at once by energi closes a pair of switches |84 and |86 which com incoming line 204, switch 20S, switch IÜS, line 288,V relay coil |68, line 292 back to incoming line 202. This circuit energizes the stepping relay zation of relay |14. Fourth position (a) Screw drivers again contact screws. |58.- The circuit for relay |144is as follows: in coming line '204, switch 20B, line 294, line 340, 40 (b) Automatic gain control circuit energized. (c) Driving relay |54 for screw driver P ener switch |84, line 29E, relay coil |14, line 298, to gized to bring the screw to one extremity. incoming line 202. (d) Clutch switch |16 operated at extremity to The energizatlon of relay |68'0f course causes limit drive. the relay to be stepped along one further step to change the switch arms |60, |62 and |64 to sta 45 Fifth. position tionary switch points 4, l0 and I6 respectively. (a) Screw drivers still contact screws. Also, the energization of relay V|14 causes the (b) Automatic gain control circuit energized. screw drivers to be immediately retracted from (c) Driving relay |56 now energized to back oli engagement with either of the adjusting screws screw by driver P toward peak point. to give an accurate peak setting. When switch 50 (d) Relay |80 energized at peak by ionization of arm |62 moved from switch point 9 to |0, it _ tube V5. , broke the circuit to the relay coil |40, but com (e) Withdrawal of screw drivers at peak point. pleted a circuit to relay coil |54 to operate the second screw driver P, which, as previously de sixth position scribed, is substantially the same operation as 55 traced through with regard to the condenser (a) Energization of unlocking relay to return known as Cs, and this screw driver tends to run down the adjusting screw in capacitor Cp until . whole system to its initial condition. It will thus :be evident that the full cycle of it is entirely at one Vencl of its travel as in the the apparatus provides'for the adjusting of two former case. This again causes the Voverload 60 screws to vary capacity to resonant circuit po clutch mechanism to slip and switch |16 to close, sition, separately and independently, and an au which again causes the energization of relay |88 tomatic return to the initial position when that to energize the stepping relay |68 and advance has been accomplished. Immediately upon the various switch points one more notch, name reaching the resonant condition of either cir ly, to 5, || and |1. 65 cuit the adjusting means is withdrawn so that At this time the system is ready to adjust the the setting is very accurate. All that it is neces screw in capacitor Cp back to its peak value as sary fcr an operator to dois to apply these trans in the prior instance and this will cause the former units to the testing block and put them screw to be backed off until such time as the in juxtaposition to the adjusting screw drivers, tube V5 is allowed to ionize and cause energiza 70 close the two main switches and the machine tion of the relay |80 which immediately with then takes care of the rest. As previously men draws the screwv drivers from contact with the tioned, this is only one of a number of instances adjusting screws and also causes the step relay wherein means for measuring the peak of reso to actuate once more. This carries the switch nant value of a circuit can be used and the ap contact |02 to position I2 and in this position 75 plicant’s invention should not be limited to theA `:2,405,419 413 disclosure of the specific means shown here to illustrate its utility.V 1. In-‘an adjusting system for a coupling unit formed of capacity and inductance and having screwable means for adjusting the capacity to tune the unit to a predetermined resonant fre quency, a driven screw driver normally held out of engagement with the screwable means, a step by-step relay switch, means for driving the screw driver in either direction, magnetic means for controlling said screw driver drive connected to said relay switch, and a switch controlled by lon gitudinal movement of the driving means where t121: formed of inductance and capacity, one of which is adjustable to tune said circuit »to a predeter mined resonant frequencyfa source of power of vthe desired frequency connected to the input of the tunable circuit, amplifying means connected tov the output of the tunable circuit, control means for adjusting the adjustable element in the tuned circuit, means connecting the amplifier output tothe >control means and also feed back 10 to the input of the tunable means for volume regulation, and delay means in the feed back means to prevent too rapid correction for volume regulation. » 6. In an adjusting system for a tunable circuit formed of inductance and capacity, one of which 15 by the movement of the relay switch to different is adjustable to tune said circuit to a predeter positions causes energization of the screw driver mined resonant frequency, driving means for ad first to engage the screwable means and then justing said adjustable portion in either direction, rotate the same to a limit in one direction and switching means to control said driving means then to a predetermined position in the opposite 20 vautomatically to ñrst drive said adjustment in direction. one direction and then the other, means con 2. In an adjusting system for a coupling unit trolled by the output of the tunable system to ~ formed of capacity and inductance and having screw means for adjusting the value of the capac ity to tune the unit to a predetermined fre quency, screw driving means, a source of power therefor capable of driving the screw driving means in either direction, magnetic means to control the direction of rotation of the screw driving means, a slip friction clutch in the driv ing means whereby when the torque exceeds a certain amount it will slip and cause longitudi nal movement of one of the parts of the clutch, switch means operable by such movement, a step ‘by-step ratchet switch controlling the magnetic means for the driving means and actuating means for said step-by-step switch controlled by the clutch switch whereby the screw driving deenergize the driving means and a second switching means between the output of the tun 25 -able means and the controlled means to apply said output’to the controlled means only when the tunable means is being adjusted in the second direction. '7. In an adjusting system for a tunable circuit 30 formed of inductance and capacity, one of which is adjustable to tune said circuit to a predeter mined resonant frequency, reversible driving means'for driving the adjustable means in either direction, step-by-step switching means to con 35 trol said driving means to automatically drive said adjustable means iirst in one direction and then in the reverse direction, control means to deenergize the driving means at the desired point, an electronic tube controlling the energization of means will be driven in one direction, stop, and rotate in a reverse direction automatically. 3. In an adjusting system for a coupling unit 40 the control means and a second switching means controlledby the step-by-step switching means connected to the electronic means whereby the latter is in circuit only on the reverse driving of> formed of capacity and inductance and having screw means for adjusting the value of the ca pacity to tune the unit to a predetermined fre quency, screw driving means, a source of power therefor capable of driving the screw driving means in either direction, magnetic means to control the direction of rotation of the screw driving means, a slip friction clutch in the driv ing means whereby when the torque exceeds a certain amount it will slip and cause longitudi nal movement of one of the parts of the clutch, switch means operable by such movement, a stap the driving means. 45 by-step ratchet switch controlling the magnetic _8. In an adjusting system, a thermionic tube in which current flows through an ionized path between an anode and a cathode, operating appa ratus connected to said anode, a control electrode in said tube to control the flow between the cath ode and anode, a source of fluctuating voltage, means interconnecting said source and said con trol eleotrode whose output voltage at the control electrode varies in proportion to the rate of change of voltage at the source so that the biasing for said step-by-step switch controlled by the 55 voltage at the control electrode is a function of the speed of variation of source voltage to control clutch switch whereby the screw driving means the conductive periods of the tube and the appa will be driven in one direction, stop, and rotate means for the driving means, actuating means ratus controlled thereby in proportion tothe rate in a reverse direction automatically, and ther of voltage change. ` mionic means connected to the output of the unit 9. In an adjusting system, a thermionic tube controlling the driving means to cause the same 60 to stop further adjustment upon a peak of energy passing through the unit. 4. In an adjusting system for a tunable circuit formed of inductance and capacity, one of which is adjustable to tune said circuit to a predeter mined resonant frequency, a source of power of the desired frequency connected to the input of the tunable circuit, amplifying means con nected to the output ofthe tunable circuit, con trol means for adjusting the adjustable element in the tuned circuit and means connectiing the amplifier output to the control means and also feed back to the input of the tunable means for volume regulation. in which current flows through an ionized path between an anode and cathode, operating appa ratus connected to said anode, a control electrode 5 in said tube to control the flow between cathode and anode, a circuit containing capacity and re sistance in series connected between the control electrode and the cathode, a source of varying voltage and conductive means connecting said source to the circuit at a point between the re sistance and capacity so that as the rate at which the voltage changes varies, the current through the resistance will change and charge the capacity to a different value to alter the biasing potential 5. In an adjusting system for a tunable circuit 75 on the control electrode and thus control the 2,405,419 I16 .conductive periods of the tube and the operation of the apparatus. purposes, driving means 'to change the value 'of , the variable means, a power input to vthe tunable , 10. In an adjusting system, a thermionic tube in which current flows through an ionized path between an anode and cathode, operating appara tus connected to said anode, a control electrode .in said tube to control the flow between cathode and anode, a circuit containing capacity and re sistance in series connected between the control electrode and the cathode, a source of varying voltage and conductive means connecting said source to the circuit at a point between the re sistance and capacity, an adjustable negative biasing circuit also connected to the control elec trode both circuits controlling the bias potential and the conductive periods of the tube in propor tion to the rate of voltage change at said source. 11. In an adjusting system for a tunable circuit circuit, an amplifying output circuit connected to the'tunable circuit, means for controlling the op D eration of the driving means including a normally non-conductive thermionic tube having an anode and cathode, a control element in said tube to determine the conductive periods thereof, a re sistance and capacity connected in series between the cathode and control element and conductive means interconnecting a point between the re sistance and capacity to the ampliñer output and an adjustable biasing means connected to the con trol element so that as the rate of change of volt age in the ampliñer output changes, the current through the resistance will change to vary the charge on the condenser and the bias on the element and theV driving means will be controlled having inductance and capacity, the value of at by the rate of voltage change. least one of which may be varied for tuning pur 20 13. In an adjusting system for a tunable cir poses, driving means to change the value of the cuit formed of capacity and inductance, the ca variable means, a power input to the tunable cir pacity being adjustable, means for continuously cuit, an amplifying output circuit connected to varying the value of the capacity, an input cir the tunable circuit, means for controlling the operation of the driving means including a nor 25 cuit connected to the tunable circuit having a predetermined frequency, a normally non-con mallynon-conductive thermionic tube having an ductive thermionic tube having a grid, cathode anode and cathode, a control element in said tube and plate, ñlter means interconnecting said grid, to determine the conductive periods thereof and cathode and tunable circuit whose output voltage iilter means interconnecting the ampliûer output and said control element Whose output voltage is 30 as applied to the grid is proportional to the rate of change of voltage in the tunable circuit and proportional to the rate of change of input volt control means for the continuously varying means age so that the rate of change of voltage in the connected to the plate of the tube so that as the tunable circuit controls the driving means for varying means adjusts the tunable circuit to res stopping the same'as the tuned circuit reaches onance the rate of voltage variation in the output peak resonance. 35 of _the tuned circuit will vary, the tube will con l2. In an adjusting system‘for a tunable cir duct through control grid variation and the con cuit having inductance and capacity, the value of trol means will be deenergized. atleast onev of which may be varied for tuning MARTIN W. GAISER.