US2445031A - Remote radio tuning control system - Google Patents

Description

July 13, 1948. E. F. McDoNALD, JR 2,445,031

Y REMOTE RADIO TUNING CONTROL SYSTEM Y Filed Dec. 1o, 1942 4 sheets-sheet 1 E. Hh

Illy

July 13, 1948. E. F. McDoNALD, JR

. REMOTE RADIO TUNING CONTROL SYSTEM 4 Sheets-Sheet 2 Filed Dec. 10, 1942 Medan Mmm d@ July 13, 1948. E, F, MCDONALQJR 2,445,031

REMOTE RADIO TUNING CONTROL SYSTEM Filed Dec. 10, 1942 4 Shee'tS-Sheet 3 TUNER; AMPL/F/ERS l Jaz/ejor:

`July 13, 1948- I E. F. MCDQNLD, JR f 2,445,031

REMOTE RADIO TUNING CONTROL SYSTEM Filed Dec. 10,*1942 4 Sheets-Sheet 4 Q7' M @www 7%' yand changethe tuning, adjustment by a footl operation without diverting;ghis.l atten.

. operation'V by-suchv person or Y u,appended claims. I -to its organization.and-manner ofjv'operation, to-

gether; withgurther -;objectsand, advantages tl 1ereof.,- mayV bestgbe understood by referenceto A .the following description ,takengi in; connecti on rvention;

A Patented July 13, 1948 UNITED STATES PATENT OFFICE y. 2,445,031 VREIVIOTE vRADIO TUNING CONTROL SYSTEM EugeneTrMcDonald, Jr., Winnetka, Ill. Application December 10, 1942,. Serial No. V468,478

` reclaim. (crest- 20) -v'rlhis invention relates to control-systemseand whose Vattention must befocusedflse- 11n/Patent No. l2,216,671, 4for Radiocon trol system, issued to me on October 1, 1954i),- I Vhave disclosed and .claimeda controlsystem for @a radio receiverinounted in a vehicle whereby c thedriver-of the vehicle can silence the receiver ofthe receiver tion from driving the. vehicle. Irrmyy United States Letters Patent No.. 2,307,329 issued `to me c January,5,v1943, for

Radio control system, 'l .have .v disclosed and claimed an improved controlsystem of ,the same type in which such foot ,opera-.Ur

tion ,mechanically` silencesfthe radio receiver, and then, if desired, changes the tuning .adjustment land. in which the foot operation does notinterfere with. the manual operation whenit is, desired instead of foot operation. 11n mycopendingapplication'V Serial'No. 390,406, filed' April 25, 1941, now Patent No.`2,346,1'77 .granted April '11, l1944, forRadio controlwsystem and multiplemcircuit switch, I have disclosed and claimed aL iurther improvement in such a ,controlsysteim in which vfoot operation is effective, inaddition to produc ing the'eifects set'forth above, to adjust the output volume ofthe radio receiver at the will ofthe driverwithout diverting his attention-from operation of thevehicle.

An object -of this invention is' t0 -provide a new and improved control-system for useby aper-son Whose attentionA must be Y focused l elsewhere, vwhich systeml includesv means whereby the conytrol system-may `be arranged at will. either for some other. person in a different position.

"-lf More specifically, it is an object. of `my invention Vto yprovide'an improved control system,y for a radioreceiverin a vehicle, the receiver having fmeans-Wherebythe driver can control the .re-

--aceiver by a foot operation Without removing, his attentionl from. operation ofthe vehicle,,or;altern nately control may be diverted for operation `by otherimeans.

r .Withthe accclflflpanying drawings in which:

:Figure: ,1; illustrates;f one yernbodirnent of ,my infor operation by' ceived by lthe antennav yoperation of the radio Figures 2 to 8 illustrate various yoperating elements useful in the modication illustrated in Figure 1; and

Figures 9 and 10 illustrate `other embodiments of my invention.

In Figure 1, a` radio receiverarranged tobe installed .in a vehicle includes an antenna I0,`a tuner, amplier, and power supply represented by a rectangle II, an electron discharge Adevice I2 arranged to detect and lamplify signals re- I0 and tuned and ampliiledby the tunerand amplifier I I, apower vamplier dischargeA device I3, and a speaker 14.1; T he receiver is normal insofar as it successively receives amodulated carrier Wave from the antenna I0, tunes ,and ampiiiies such wave through the tuner and ampliiier II, detects the signal in accordance withrvihichthe carrier` wave. is modulated, `such detectionmbeing ycarried .out in the circuits associatedwith .the

l ,discharge device I2, amplifies such signal through gized by .devices "and |3andreproduces the siggglin rvspeaker I4. y

, The signal detectioncircuit associatedwithfthe discharge `device .I2 .includes a high :ireguency vtransformer 20 Whose primary winding nerthe amplified carrier wave ufromj'rthe ftuner, and amplifier I I, the secondary` of `trans- .'.former `.20 being tuned ggquencyof such. carrierwave ,by a condenser 2l.

to resonance atgthewfre- One terminal of the/secondary of thetrans- .for-.mer 20 is connected to theanode22 lof as diode sec'tion of, the electron ydischarge device IZWand @the `other yterminal is connected ior Vhighwfreassociated with the ldiode section includinga ode l22and with a triode section including acontrol '40.- .'22 .the cathode condenser 23, to, the

quency currents through, a 4

I2, whichcathode is the device nalof the secondaryof the `transformer-2 Ill lwhich visfconnected to the condenser 23 is,-g r,ound'ed Y .through two. seriallyconnected resistances ,2J and 45 he .features of my invention-which I. ...believe to be novel are set forth with particularityinthe `r`lconnected toground4 and to .through a high frequency ,28. QA pointbetweenresistances 21 and- 28, is

l n the cathodee ,-24 by-passing .condenser r0 whereby signalsdetected .in vthe detectionhcirc, i cuit; appear across- -50 ierred through the. resistance i. 2 8. Y

the .resistance 23.. is...) trans- `de- The vsignal across either of two circuits-,tog

l. scribed hereinafter and through a .couplin Tcondenser 3| to the control electrodeof discharge g; idevice j I 2'; 'This control electrodev 2i is connected cathode 24. The anode 26 is connected through a suitable load resistance 33 to a source of posi-l One circuit for transferring signals from the" resistance 28 to the control electrode25 includes a Volume control resistance 31, which is embodied in a unit 46, to be described hereinafter, suitable for mounting near the feet of an operator of a vehicle in which the receiver is mounted. The ungrounded terminal of the resistance 28 is connected through a switch 38, conductor 3'9, terminals 40 of a plug .4I and socket 42, and a conductor 43 to one terminal of resistance 31. The other terminal of resistance V31 is connected through a conductor 44 and terminals 45 of the plug 4I and socket 42 to ground. This ground is preferably the chassis of the receiver at a connectedV listen `for train whistles at railroad crossings.

Further depression of the switch contact 54, sol

that it carries the movable contact 55 with it to A complete a circuit between the contacts 54 and l 56, energizes the operating coil 62 from battery l35, so long as switch 34 is closed, to change the poin't near the points where cathode 24 and one terminal of resistance 23 are grounded. To ground a terminal of the resistance 31 in any other place would make it possible for extraneous voltage between such ground point and the chassis of the receiver to produce undesirable current flow through-resistance 31, which would result in undesirable noise being produced in speaker I4.

The movable contact 55 of the volume control resistance 31 is connected through a conductor 5I, terminals 52 of the 'plug 4I and socket 42, a switch 53, and the condenser 3l to the control electrode 25. By such connections, signal voltage appearing across the resistance 28 appears also across the volume control resistance 31, so that any desired portion of this signal voltage across resistance 31 may be impressed through movable contact l5I) upon control electrode 25, thereby controlling the output of speaker I4. Suitable means are provided, as describedhereinafter, to control the position of the movable contact 50 by a foot operation of the` vehicle driver.

In the unit including the foot operated volume control resistance 31, there is also provided means operable by the foot of the vehicle driver for silencing the speaker I4 and for changing the tuning adjustment of the tuner represented by rectangle II. This means includes a switch contact 54, movable by the foot of the vehicle driver, a second switch contact 55, movable when engaged with Icontact 54, and a third, xed, switch contact 56. The contact 54 is connected through a conductor 51 and terminals 58 of the plug 4I and socket 42 to ground. The contact y5 6 is connected to switch 34 through a conductor 59, terminals 60 of the plug 4I and socket 42, a conductor 6I, yand the operating coil 62 of an` electromagnet suitably arranged for changing the tuning adjustmentof tuner-I I. The Contact 55 is connected through a" conductor 63 and terminals 64 of the plug 4I and socket 42, to one terminal of the secondary of output transformer 36. The other terminal'of the secondary oftransformer 36 `is grounded.

In operati-on the driver of a vehicle inr which this receiver is installed-may at will control the tuningY adjustment of the tuner represented by the rect-angle VII so as to receive a different station. Y

Switches 34, 33 and 53, as well as the movable contact 10 of a volume control resistance 1I are mechanically arranged to be controlled by operaation of a single operating element, preferably so positioned that it may be operated by an occupant of a vehicle other than the driver, and preferably so located that it also may be operated by the driver.

Upon initial 4movement of this operating element, to be more fullyrdescribed hereinafter, from one extreme position, the switch 34 is first closed without affecting switches 38 and 53 so as to energize the receiver power supply represented by the rectangle II, and so `as `to connect the operating coil 52 of the station selecting electromagnet in readiness for energizaticn by the movable contact 54 in unit'46., jA' vslight additional movement of this operating 'element is effective then to change the positions of Vswitches 38 andV 53, so as toY disconnect the upper terminal of resistance 31 inunit 46 from resistance 28, and to disconnect the movable contact from condenser 3|. The movement of switch 38 simultaneously connects volume control resistanc'e 1I in parallel with resistance`28, and the movement of switch 53 simultaneously* connects the movable contact 16 of volume control resistance 1Ik through condenser 3l to the control electrode 25. Still further movement of this operating element leaves switches 34, 38 and 53 in the positions, to -which they have beenmoved, and thereafter moves contact 10 along. resistance 1I to increase that portion of the signal potential acrossiresistance 28 which is applied through resistance 1I to -control electrode 25.

In Figure 2 there is shown a side View of such an operating velement 80, illustrated asa knob which may suitably be turned by hand.` This knob 80 is arranged to turn a shaft8I Yon which iszmounted the volume control resistance `1I and switches 34, 38 and 53. This unit mayconveniently beso mounted that knob 881s on'the dash panel ofthe vehicle in which the receiver is mounted, so that it may convenientlyfbe operated by the driver of the vehicle or by a passenger.-

In Figure 3 there is shown an end View of this assemblyin which an arrow 82 on' thefface of the knob 8! may be seen.l When-theknob80is turned in a clockwise direction, as indicated by the arrow 82, its initial movement mentioned heretofore, which is Aeffective -only to close'the ser-l 3| 'fro'mV urlit` 46 to the volume control resistancefl. -frAd- Vthean'gle 85 is effective to movable contact 54 the volume control .'resistanceffSl--rin ditionalv rotation of knob ..80 thereafter: through change the setting. of the variable conta-ct -on sistance 1|, so as to apply any desired-'portion of the signal potential across resistance-@Nibetween .the .control electrode' 25 and 1cathodef'24.

` The volume'control resistance 1| may be yoffa usualtype inwhich rotation :through a-'small angle at one end of the total angle through-which itzmay be operated is veffective tochange-the .resistance to a yvery slightdeg-ree, ifat-'alL Angles 83'and v84 should be fat'suchend' ofvthe -total .angle lof movement 'of' knob. .80. `c'illL-l or -by -far the Amajor part, ofthe resistance "change'in resistance 1| occurs during rotation ofthenknjob -80 'through the angle 85.

The switches 34, 38-and 53. mayconveni'ently be of the type termed in the art ,switch"covers,,

which are soarranged that they may be fitted on theback of volume control resistance 1 |,-of.usual form, and are -actuated'during rotation Aofxthe shaft 8| of the volume control resistanceA through a desired part of its angular-movement.

In Figure 4, there is illustrated onetmodiflcationof the unit 46 shown schematically-in Figure 1. This modification of unit 461is fullydescribed and claimed in my co-pending application-Serial No. 406,677, filed August 13, 1941, now Patent No.

2,374,873, granted February.21, 1945, for-Radio control. system and multiple circuit switch.

`Brieflyuthe `casingln of .this unitzis so arranged f. that it may beconveniently 'placed yon the-floor boardof avehicle suchas an automobile:v and a foot but-ton 9| on the top of casing y9|) isfarranged so thatit-'may be either depressed or rotated with respect to the casing 90. Rotation fof the button 9| by the foot of the Vehicleoperator is effective torotate the f shaft 102 of 'the volume control resistance 31, which is schematical-ly shown in unit 46 ofFigure l.- Depression ofi-fthe button- 9| by the foot of the vehicleoperator` -is effective first to compress a relativelyfweak Spring 93 and .complete4 a connection between Athe grounded V contact 1,54 ofthe foot button -9| and the movablecontact 55, both vof which areillus- .Hated-schematically in..11igure 1. Furthendepression of the foot buttonl is effective to compress the relatively stronger spring 94 and, while maintaining a connectiontbetween the grounded and movable'contact 55, moves both of .these contacts down.,so that connectionis made between the mov-ablecontact `55 y and the fixed ,contact56, which are all schemati- .callyillustrated in Figure 1.

I'n Figure `5 only the central supporting plate 95 of the-switchbody is illustrated together with the fixed`r contact 56 ,and the movable contact- 55- and-associated wiring. Theconductor 5L-shown in Figure. las being connected-between movable switch ,contact-54 and ground through the plug 4| and-socket 42, is shown in Figure 5 to be;.a -shie1ding braid ylilsethat around the two n conductors-43 and 5|,.which,V as shownin Figure 1, -are passed throughthe` shielding braid Awhich constitutes the conductor V44 `of Figurel. -Ityis desirable that the two `sets of conductors 1 be l thus shielded, not -only `from eachother, 1 but @from external4 electrostatic and electromagnetic fields, 4so as toreduce the possibilityy ofintroducing yundesirable voltages 4vinto conductors attached to vthe Vvolume `controlresistance :131.` Introduction of such undesirable voltage into ,resistance31 results fin the` production fen-noise` in; the, speaker f.

the volumecontrolire- I 4twhi'ch -interferes -w th: proper reproduction fof' signals.

A `form fof foot switch for. r function as the unit illustrated inx-Figures 4 and 5. iiriefly,` 1 this junit comprises a fhousingl-fIrrp-.ligure 6v ith-ere 5 is :illustrated Vein-alternative :performing rthe *same --cd1-tobep-placed on 'the4 footboard` of a vehicle near the operator. A wheel |0| is mounted-within I .Vehicleioperatoramay `:depress the--wheel 1|0|- withinathe fhousin'g |00- =by.his1 foot, or-A alternatively wheel-10| byhis foot. Turning-of theI --w-heel ;-|0| is effective tof adjust the volume control resistance |02- and depression of the wheel zoldownward-lyfthe -freeend- |05-of the spring 03 on |00 is,-effective-to` bend which two movable contacts |06 and fm1-'fare carried. Two cooperating fixed contacts` |08 'and -|09-are1-.mountedf--upon insulation -flxedto a part Iof-t-hefhouslng |-00 `and are iso :arranged that as v` 25.the movable contact l--lrsttouches the, contact :xedjand'mova-ble contactsin -a manner.- like that described forv the unit- 4B illustrated Ain Figures- 4 -and- 5. Conductor 51--is-connected to: the housing electromagnet.

The vehicle operator, upon depressing the wheel .10 -within the housing |00, sensesfbyrpressure Vthe point aty which contacts |06 and-|08 touch, and

can,v if so desired, stop depression ofthe-wheel |0| at thatpoint TheA increased pressure required to depress wheel I 0| further is quite sensible since further'.depression'of the wheel -|0 must vnot only cause the bending `of spring |03 at its upper portion, Y.but also-must cause bending 4j of lthe lower end of spring |05 adjacent -contacts Hit` y and.|01',.so-asf,to allowl contact |01to touch vvconftact |09. 'By vthis constructionftherefore,` the same-resultsare attained-"as with the unit 46 --illustrated in-'Figure/l, in which theA relatively arrangement of volume control resistance '1|' arid knob 3 80with s'wi'tchelements which idiffer to some'v extentv 'from those illustrated in Figures 2 and 3. .A lsinglegsi'ivi'tch coverv 34 is attached' to the back of the volume control 1,' resistance 1.|, l

asisrquite-common` 1n radio receivers. yA double pole,v 'double throw, vtoggle switch ||0 isarranged "sdas' tobe operated by rotation 'of .the-shaft'l soas to perform the functions performed inthe .embodiment .or Fig-urea -byv-,switches 53 81, and .53.

its operating handle III facing toward theirshaft 8| `and arranged c for movement. in a` plane .perpendicularto that shaft. A resilient operating member I|2is attached to the' shaft 8| and. is w sullciently` long to` engageI `the operating handle III during a certain portion of the angularrotation of knob 80. l f' The. resinentmember mais aixed to theshaft 8| at a certain angle, asmay be seen in Figure:

8', and is just long-enoughand possesses just sufi cient resilience that,A during rotation-ofthe knob 80, the member II2 engages the operating-handle IIIandmoves it to its opposite position.and

thereafter bends .suiliciently so that the yendof member f||2 passes-over the end of handle III. Opposite rotation of 'theknob 80 thereafter causes member I2 to engage the opposite side of handle III and thereupon move handle III to its initial position, lthen bending suiiiciently ,to` epass by handleIII. i a .Y

`The resilient member I |2-is"aflixed`to the shaft 8| at such an angle with respect to theang-ular position of knob `80 Yat? the vtime 'whenswitch 34 operates, that switch AI I is operated imrnediatelypI thereafter That is, when knob80 isfin =one extreme positionfmember ||2 isi spacedl from the handle III by such a distance that,4 upon'initial rotation of knob 80, switch'34 is operated by the timethe resilient member I I2 touches handle L11 Further rotation of :the knob 80 operates switch |I0 through the resilient member I|2 and handle III as described, and-thereafterfurther rotation of the knob 80 causes adjustmentof the volume controlresist-,ance1I.Y i l In Figure 9 many elements are identical with those illustrated in Figure'k L-fand are Vgiven-"like reference characters. In Vthe modification illuse tratedin Figure 9,switch 38 is omitte d,*conduc tor 39 beingconnected directly to a` point between.

resistances 21 and 28 and also to the ungrounded terminal of volume control resistance 1|. By this connection the volume control resistances 31and |I are always connected `in parallel Vwhen the plug 4I is in the socket 42, and operation ofthe switch 53 is eiective'to takesignalvoltage-from either of these volume control resistances 31 and 1I and apply it to the control electrodeV y 25 throughthe couplingcondenser3l, i

In order that selection may Vbemade of the volumecontrol which it is desired to `use,'switch 53 isarranged to be controlled in-unison with the movable contact 'I0 of resistance 1 I in al manner similar to that described in connection with Figure 7for the volume control resistance '1I and switch 34. That is, in-one extreme position of the 4control member'which` operates both-switch53 and movable contact v10, the parts are as` illustrated in Figure 9. Initiall movement of theioperating member from this extremeposition first-A operates the switch 53 to disconnectyolume control resistance 31 from condenser 3| andtoA con- Y nect volume control resistance 1I thereto, ZFurther movement of the operating member for switch 53 and.k

lsistance f1|, thereby tol increase @the volumefof `with a tone control-resistance |20: Thej'movable contact 12| of thelresistance I 20 i is connected* W movable contact I0is,eiectiveitof-y move the contact 10 along the volume controlire- T.the;inperatixigr` member: isfeiective' to adjust the l movablefcontactf I2I. along the tonepcontrolresistanee-Izae f l f, :,Inuorder that adjustment of. the :resistance I 20 be :effective :to .produce tone; control, resistance |20 connected in series 'with aszcondenser j I 22 1, betweenrground and'iconductor 39. z Consequently,

whenthe" valuef-of: resistance I 20 is low; aconsiderable; proportionlof :high frequency V components of4 the'rsignalacross-resistance 28ris:;short circuited to4 ground through` condenser I 22, which is suitably made: withvaflowireactance; :When'resistance I 20 .issadjustedlto havea high value, substantially .nov signal.` current isJdiverted fromconductor 30 to ground, the'r maximum valuezof resistance::| 2llffbein'g`i s'uiilciently. high i to'A prevent such-:diversion: i 1115..: I y j i It :may be noted that the terminal of resistance 28, which was illustrated in Figure.' 1 :l 'as being g'rounded,-is :Illustrated in Figure 9 as being connectedfto: ground through ahy-'passing condenser |30. In this` circuit arrangement a path for continuous `current fromtthe anode 22 exists through the `secondary 'ofitransformer 20 resistance 21, and through ,-volume" control .rsistances 1 I andi 3 1 in paralleli back to .the cathode24 ofi the device I2."' 1.

Aicontinuous voltage is" developed across' the condenserI1I30, Which voltagev is 'proportional to the average intensityf the carrier `wave at transformer 20, and whichvolta'ge issuitable for automatic. volume control-'purposes f yTo this end this voltage lis l`appliedati-suitable points in the tuner and amplier' representedv by rectangle I I-through conductor 'I3I'2 i" "i `o 'I A In'Figurefilmanyelements are identical with those illustratedinlligures 1 and 9,3 and aregiven like reference" characters. In this" arrangement the volume "'control resistance 1| iisomitted entirely, and '-a' resistance'f'l 40 having" two taps 'I4 I and |Il2 isf'con'nected between groundand a point between-Tesistances 2-'I-f'and28 'A multiple pushbutton switch AI 43 is arrangedin some position where it may beconyeniently operated either by thevehicle drlver-orbyanother loccupant of the vehicle; f Thisf'switch-'l lis sofarranged that its ve" buttons Arespectively` "furicztiori (O) to Vdisconnect all operatingpower'from the receiver; (F) to transfer control of speakerf'volume toy unit 46; (1) -tofoperate lthe'receiver with loud output yvolume independently -ofl'unit 46 except forsits `muting and station changing control; (2)'to 'operate the receiverfasin-caseV (l) with" medium output'v'olumej and A(3)-to operate the receiver as incase v('lirwith'l'ow output volume.

To this' 'end the switch |43 includes lve buttons marked l'respectively A 0, Y F,"1, 2I and -3, which-buttons,respectively correspond to the abovel enumerated operations. `'lhese 4buttons have'respective contact bridges |44, |45,-I46,"|41 and 'Milf-'The buttons ofthe switch? |43'are arranged 'withlshouldersysuch as the shoulderr|50 of the-button marked 3`," to cooperate with a laterally slidable latch bar` 5 so that depression of any button'automatically yreleasesall other buttons andv locks--the depressed button in the downwardv position'. The button* marked 2 is illustrated inV thepositlon in which-the latch bar I5Iho1ds'it down." Aspring |52 tends to move the latchn bar I5| *to the rig-ht," thereby `locking dowri anyJ buttn'i when its -shoulder- |50 is beneath the latch barV I5 I ,tand releasing 'that `butarenal.

ton whenever another button is depressed softhat The button marked of iserreetive-tedeenergize the entire receiver by reason ofthe fact connects the source v35 of potential from the.

receiver.`

The contact bridge I45foi" thebutton marked F. of .switch |43 cooperates with contacts |66,

IBI, |62 andA |63 sothat when the button marked F is inits upward position, connection is made between .the -contacts |60 and v| 62, and. whenbutton. ymarked ,.F- is-in. its downward. position connection is made between the contacts |61 and |63... Contact .|66 is` grounded, preferably at the chassis of the.receiver.- `Contact ||i| is connected to apoint. betweenv resistances 21,` 28v and |40. Contact- |62. is connected'to the-cathode 24 of the discharge dev-ice. |.2..and alsoto terminalsv |64 'of Plug the movablecontact 56.01E- the volume control resistance @31 in .unit 46... Contact. |63of switch |43.is connectedthrough..condenser 3| to the control electrode .25 ofdevice -|2.

When the button marked F of switch .|43 is in itsfupward position, thecathode 24er-the discharge device. AI2 .is grounded through a circuit which may. be .tracedfrom the .cathode 24, contact |62,.contact.bridge .I 45.and contact |66 to ground. No connection. is made between contactv |6I .and |63 so that. no signalvoltage from resistance is applied` through. circuits connected. with the Abutton .markedF to the control. electrode. of .device I2...v Y l. When the button marked VF of switch |43 .is inits downward positionpthe cathode24 oi device I2 is connectedto ground only through the movthe |65 .and socket :|E6,.which are connected. to

fao,

able contact 560i. volume. control resistance31 in .unit ,46 to. which. it .is connected .through f the terminals. .|64 ofA .plug..|65 .and socket |65. In that position of the button marked EL thecontact bridge |45 completes a connection between contacts |6|.and |53, so that thecontrol electrode 25 of theY discharge I2 is connected through condenser. 3| toafpoint between vresistances 21 and 28wh'ereby the entire signal potential across resistance. |40 is. impressed betweencontrol elec trodej 25 and ground... When the button. E is thus connected, circuit's are completed with the.

volume control'resistance 31Lof unit .46 sothat signal potentialsirom Athe secondary of` trans-4 former 36 are impressed in degenerative phase between cathode 24 and ground, wherebyadjustment of, the adjustable contact. 5|) .of volurneconY trollresistance31 is effective to adjust the amount of such degenerative feedback, and thereby adjust` the overall'amplication. of signal potential across-theresistance vlllthrough devices |2 and |3 sothattheyare reproducedby the speaker I4 in volume determined by contacts 50. 4of resistance .31..

Togthis.` endA the vconductor 51', which is v the shield braidof athreeconductor. cable including conductors 59 and|3iand the conductor between.

the setting of adjustablel ,and socket v15 Yving. operatiom the conductor secondary of transformer station changing operations of unit 46 are identi-4 of unit46 is also connected to .one terminal of..

resistance 31., .conductor 51 b-eing connected to the Vother terminal.. Conductor 63 extends from. movable .Contact .of unit 46 to the p1ug |65 andisconnectedto terminals. |1I ofthe plug |65 |66 and to ,conductor |12, whichin. turn is connected to oneterminal of thesecondarv of output transformer 35, the other terminal of that secondary beingv grounded.

In orderthat. unit 46 may vcause station changf. 59 viscOnnected be, tween. the .stationary contact 56 j and coil.62.. throughterminals |13 of. plugls and socket |66; Themovable contacts54 and 55 of.. the unit 46 are thusconnectedeach to one terminal of the.

36, and the mutin'gand cal. with those described in connection ure .1.A

In Aorder that. the degenerative. vfeedbackdrom.. the output -of the ,amplifier includingdischarge with Fig'.

devices I2 .-and..|3 ,toftheinputthereof .may be better understood, the .circuits involving...thi`s..de. generative.. feedback.. aredescribed, when the. buttonmarked FV of. switchv |43.is in itsfdown.-Y

ward position.: The...input .-circuit 4of. the.. device l2 for. currents of signalffrequency.extends from: the control electrode- 25 rthrough` condenser 3 contact |63, contact -bridgelll;fcontact |6|,-re sistance- |46, ground, terminals |16 of socket l66r and Yplug-I 65; conductor 51,y that portion ot, re-'- sistance r`31V between conductor-511 and :movable contact 56, contact 56; terminals 16A-"of plug |155 f andi socket |56, and-thus'to the-cathode 2li-'of'v the device |2. Alnplied signal 'potentials-from' `1 the lanode 26appear across th'esecondary of but: put-'transformer 35, which is included in -atfci'n` cuit as follow'sr One :terminal 'of'the secondary i' of 'output transformerv 3 6"'is connected tlirough'v conductor' |12, terminals |1| vvof socket |66`and' plug' |65,e condctor 53, resistance 31, conductor I* 51f,`terminals' |1|)"`of plug |B`5"and 'socketv |'66,and' ground yback to the other terminal of "the 'se'cJ ondaryof output transformer 36. Y

It is notable'that both of these circuits include that portionoffthe resistance 31 between the movable vcontact 56 and the conductor 51. Cul",- rent flowing through such portion of the 'resist` ance-31f which current is proportional to the`v amplie'd signal potential energizing speaker |4`, l

produces Aa voltage across such portion ofl resistance 31,'whicli voltage is in the inputcircuit` of the discharge device I2, and"is`inpha"s'eop position to the signalpotential developed'across Athe resistance |4|l `*to "be amplified through" de# Vice .12."

Adjustmenty Vofthe adjustable vcontact 50 "along" resistance 31v is' therefore effective to reduce the amount ofl degenerative feedback'as contact"50"` is movedv toward-that end`of"resstance 31 'con` v nected to conductor 51'-, "whereby theY overall am'- plication of dischargedevicesff I2 andl3 f is increased so as to increase tlief'sound'output of*r speaker- I 4.- Conversely; as f the vmovable'- corr-A tact 50 is adjusted downward so-astobe nearer' conductor. 63, the` degenerative feed back -from-V output transformer? -36' to -the1input of discharge device .-I2-is increased, wherebyj the .'-overall degenerativer feedback `is .increased 4and the -netgain through discharge devices I2 and |3'is re-' diodeanode 22 and cathode 24 with such po-v larityfas to make diode anode 22 negative with respect to cathode 24. It is usually undesirable that' such a bias potential should exist between the anode vand cathode of a diode detector `arrangement, but so long as the continuous potential developed across resistance 31 be not more than about one volt, such bias potential is tolerable. It is notable that, when the button marked F isin its upward position, thecathode 24 is grounded so that no continuous potential exists across the resistance 31 and no bias potential exists '.between the diode anode' 22 and cathode 24 of device l2.

When" the button marked 1 of switch |43 is in its downward position, the contact bridge |46 completes a connection between contacts |80 and |8I'." Contact |80 is'connected to contact Mil and to apointbetween resistances 21, 28, and |40."

and contactY I 8| is connected to contact |53, and to contact I83'and |85, associated respectively with buttons marked 2 and "3 of switch I 43.

Depression of the button marked 1 therefore completes a circuit between control electrode through condenser 3| to the ungrounded terminal of resistance |40, whereby the entire signal potential across resistance is impressed between the control electrode 25 and cathode 24, so that the 'sound output'of the speaker I4 is maximum.

When button 2? of switch |43 is depressed, the

contact bridge |41 completes the connection betweenthe contacts |82 and |83, and since contact |82 is connected to the tap I 4I of resistance |40, onlylthat portion of the signal potential across resistance I 40 which exists between tap I 4I and ground is applied between the control electrode 25 and cathode 24 of the'discharge device I2. Accordingly, the sound output of the speaker I4 is reduced in proportion as the resistance between tap I 4I and ground is less than the total amount of resistance |40.

Depression of the button ,3 of switch |43 completes aconnection between-contacts |84 and |85,

and since contact |84 is connected to tap I 420i' resistance |40, the still smaller signal potential between tap |42 and ground across resistance |40 is the only part of the entire signal potential across resistance |40 which is applied. between control electrode 25 and cathode 24 of device I2. Accordingly, the sound output of speaker I4 is still `further reduced.

Control of the sound output of speaker |4 from the foot control unit 46 of Figure 10 by means of degenerative feedback, as illustrated. has an important advantage in that signal potentials necessarily present in the unit 46 between the movable contacts 54 and 55 for muting purposes, need not be carefully shielded from volume control resistance 31, as would be necessary if the only potentials across the resistance 31 were the small signal potentials developed by the Asignal detection produced in the detecting circuit including diode anode 22 and anode 24. Furthermore, extraneous currents induced in the various conductors involved in the degenerative feedback circuits have little effect upon the output of speaker I4 because of low impedance characteristics of such degenerative feedback circuits.

While Inhave` shownanddescribed the particu! lar'embodiments of my invention, it will VYbe obvious to those skilled infthe'@ art'that changes and modifications may be' made without departing l' from my invention in its broader aspects, and I,

therefore, aim in the appended claims'to cover all such changes and modifications as fall within thetrue spirit and scope of my invention.

Iclaim: v f

1. A control system for controlling a radio re-f ceiverforan automobile, `comprising means op' er-"able` by the foot ofthe automobile driver for" controlling the-volume of output of said radiov receiver, meansY operable on-the vda'slipanel` of said automobile for controlling the volume'ofoutput of said radio receiver, and means responsive to an adjustment of said means on saiddash panel for transferring control between said means on said dash panel "and `saidfoot operable means. ,2, In asystem for controlling the output volume of a -r-ad-ioA receiver in-a moving vehicle, said receiver having `a first portion including a signal detector, and a secondportion including a signal amplifier and reproducer, meansfor controlling `the output volume 4off said radio receiver by 'adjusting the amount of signal transferred from said detector to said amplifier, said'means being operable by theoperator-ofsaid vehicle whose attention must-beefocused upon the operation of 'said vehicle, me'ansplaced `at a position different from said first `means for adjusting the amount of Vsignal transferred from said detector to said amplier, and means responsive to an adjustment of said last means fortransferred `control over said output volumefrorn'said rst means to said last means. 3. In a control system for controlling theouty put volume and tuning of a radio receiver in a moving vehicle, means for controlling such output volume operable by the operator of said vehicle whose attention must be focused upon the operation of saidvehicle, said means being also arranged upon operation by said operator to reduce the output volume of said receiver substantially to zero instantaneously and thereafter at thevv will of said operator to adjust the tuning of said receiver, means for controllingsaid output volume located at aposition different vfrom`said' jiirst means, vand means responsive toV an adjustment of said Alast means for 4transferring control over said outputvolume from said rst means to said last means. Y

4. In a system for controlling the output volurne of a radio receiver on a moving vehicle, means for controlling such 'output volume oper- -able by the operator of said vehicle whose attention must be focused upon the operation of said vehicle, means positioned differently from said iirst means for controlling said output volume, means for controlling the' supply of power to said receiver, and means for controlling said differently positioned volum-e control means, said power control means, and the transfer of control between said first volume control means and saidV differently positioned volume control means by a manual operation performable by said operator.

5.` In a system for controlling the output volurne of a radio receiver on a movlngvehicle, means'for -controlling said output volume operable by lthe operator of said vehicle whose attention must be focused upon the operation of said vehicle, diiierently positioned means manually accessible by said operator for controlling said output volume and for transferringcontrol of casomai saidfoutput volume betweensaid two means,f-an d separate manually operable means for controlling the supply 4of power to sai-d receiver and :the joutputtOneofsaidreceiVer.

6. Ina system'forcontrollingtheoutputvlume of a radio receiver ihavingav rst portion including -a signal Adetector and a second portion including a signal amplifier and "reproducen means for controlling ysaid output volume at one position effective 'to adjustthe 'amount of signal transferred from said vsignal Avdetector vto saidiamplifier, means for feeding signal from the output of said amplifier to the input thereof in degenerative sense and in adjustable amounts to adjust said output volume, said signal feeding means being located 'at a position different from said one position, and means for transferring independent control between said first two means.

7. In a system for controlling the outpu-t volume of a radio receiver including a rst portion having a signal detector and a second portion having a signal amplifier and reproducer, means at one position for feeding signal from the output of said amplifier 'to the input thereof in degenerative sense, and in adjustable amounts to adjust said output volume, and means for adjusting the output volume of said receiver at another position by disabling -said rst means and adjusting the amount of signal transferred from said signal detector to said amplifier.

8. In a system for controlling the output volume of a radio receiver in a moving vehicle, said receiver having a first portion including a signal detector and a second portion including a signal amplifier and reproducer, means for controlling :su-ch output volume operable by the perator of said vehicle yWhose attention must be focused upon the operation of said vehicle, said means being arranged to feed signals in degenerative sense and in adjustable amount from the output to the input of said amplifier, means in a different position from said first means for controlling said output volume, and means responsive to an adjustment of said last means for transferring control over said output volume between said first means -and said last means.

9. A control system for controlling a radio receiver in a vehicle, comprising means operable by the foot of the vehicle driver for adjusting the volume of output of said receiver, means located elsewhere at a point remote from the firstmentioned means in said vehicle for adjusting the volume of output of said receiver, and means actuated simultaneously in response to actuation of said means located elsewhere for transferring permanently control over adjustment of said output volume between said foot operable adjusting means and said second adjusting means.

10. A control system for controlling a radio receiver in a vehicle, comprising means loperable by the foot of the vehicle driver for adjusting lthe volume of output of said receiver, means located elsewhere at a point remote from the first-mentioned means in said vehicle for adjusting the volume of output of said receiver, and means responsive to an adjustment of one of said adjusting means for transferring permanent control over adjustment of said output volume between said two adjusting means.

11. =A control system for controlling a radio receiver in a vehicle, comprising a first means operable by the foot of the vehicle driver for adjusting the volume of output of said receiver, and second means located at a position in said ve- 14 hicle remote from fsaidafrst means for consecutively disabling permanen'tly said foot operable adjusting'means to control adjustment 'of said output volume and thereafter adjusting-thevolyume of output of said receiver.

12.1[nk a control system lfor, a radio receiver in ka vehicle, said receiver having meansfor`se quentially vselecting 'predetermined signals and means for muting rthe output volume ofsaid :receiver.' thelcombination of ya footswitch .located for .convenient operation bythe vehicle driver While' his attention is "absorbed in Ithe operation of said vehicle, said footswitch having a member operable in one fashion to cause said muting means to mute the output volume of said receiver and operable further in the same fashion to cause said signal selecting means to select a predetermined signal, said member of said footswitch kbeing operable in a different fashion for adjusting over a range the output volume of said receiver, means located in said vehicle at a position remote from said footswitch for adjusting over a range the output volume of said receiver, and means for transferring control of the adjustment of said output volume from said foo'tswitch to said means a-t a different position.

13. In a control system for a radio receiver in a vehicle, said receiver having means for sequentially selecting predetermined signals and means for muting the output volume of said receiver, the combination of a footswitch located for convenient operation by the vehicle driver while his atten-tion is absorbed in the operation of said vehicle, said footswitch having a member operable in one fashion 'to cause said mu'ting means to mute the output volume of said receiver and operable further in the same fashion to cause said signal selecting means to select a predetermined signal, said member of said footswitch being operable `in a different fashion for adjusting lover a range the output volume of said receiver, and means loc-ated at a position in said vehicle remote from said footswitch for consecutively disabling said footswitch to control a-djustment of said output volume and thereafter adjusting the volume of output of said receiver.

14. In ia control syst-em for a radio reeciver 4in a vehicle, said receiver having means for sequentially selecting predetermined signals and means for muting the output volume of said receiver, the combination of a footswitch located for convenient operation by the vehicle driver while his attention is absorbed in the operation of said vehicle, said footswitch having a member operable in one fashion .to cause said mu'ting means to mute the output volume of said receiver and operable further in the same fashion to cause said signal selecting means to selecty a predetermined signal, said member of said footswitch being operable in a different fashion for adjusting over a range the output volume of said receiver, means located at a position in said vehicle remote from said footswitch for consecutively disabling said footswitch to control adjustment of said output volume and thereafter adjusting the volume of output of said receiver, and means for resisting movement of said member and said footswitch to cause the muting means to mute the output volume of said receiver and for resisting with sensibly greater resistance further movement of said member in the same fashion to cause said signal selecting means to select a desired signal.

EUGENE F. MCDONALD, JR.

(References on following page) REFEBENCESCHED H l f le of this jpatnt:

Number UNITED STATES`PA'1ENTS" Name. .y Date, Renwck Dem-31', 1929 Clement JuneV 27,1933 Thompson Oct. 23,` 1934 Schnell Dec. 4, 1934 Thomas Nov, 19, 1935 Number Certificate of Correction Patent N o. 2,445,031.. I

EUGENE/fr. MCDONALD, JR. y It is hereby certified that error appears in the printed specication of the above '*numbered patent requiring correction as follows: Column 12, line 34, for the Word transferred read transferring; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent OfIice.

Signed and sealed this 12th day of October, A. 1948.

[SEAL] THOMAS F. MURPHY,

Assistant Commissioner of Patents.

July 13, 1948.11? i.

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