US 2472604 A
Description (OCR text may contain errors)
June 7, 1949. E: F, MCDONALD, JR 2,472,604
RHEOSTAT WITH SWITCH Filed Jan. 20, 1945 2 Shee'ts-Sheet 1 0 FIG. 4
' Enu enef M D M/J INVENTOR nEsw ATTOR NEY$ June 7, 1949. Mc JR 2,472,604
RHEOSTAT WITH SWITCH Filed Jan. 20, 1945 2 Sheets-Sheet 2 l4 I23 H8 l2l I09 I38, :8; P 3 52 n9 I08 1 I I04 89 lv 1 9 s5 86 I33 I34 I37 FIG. 6
INVENJ'OR ATTORNEY 5 Patented June 7, 1949 UNITED STATES PATENT OFFICE 1 Claim.
The present invention relates to a control system for a radio set, and more particularly to an improved system by which certain functions of a radio receiving set, such as muting, tuning and control of the volume of sound emitted from the loud speaker of the set, may be controlled in a simpler and more expeditious manner.
The present invention is particularly useful in connection with radio receivers mounted in motor vehicles, although it has general application wherever it is desired to control a plurality of functions of a radio receiver. The conventional hand tuning or actuation by hand of station selectors with conventional automobile radio receiver installation constitutes a serious hazard, as the drivers attention is distracted and serious accidents have frequently resulted. Furthermore, it is many times important to mute the radio receiver for short periods of time in order to be able to listen for warning bells at railroad crossings or for the sounds of approaching vehicles or trains. In addition, it is many times desired to change the volume of sound emitted from the loud speaker of the radio receiver, and in accordance with the present invention this function may be controlled by means in combination with the muting and tuning means without distracting the drivers attention,
In accordance with the present invention, muting of the radio receiver, the selection of the desired signal to be received, and control of sound volume from the receiver can be accomplished through a single member actuated, for example, by foot control with a special type of switch mounted on the floor board of an automobile. This enables the control operations of the radio receiver, which ordinarily require close attention by the driver, to be carried out without requiring the driver to look at the radio set or remove either hand from the steering wheel.
Another aspect of the invention also provides a multiple circuit switch for controlling a plurality of circuits which embodies novel features of construction which permit manufacture of its parts from low cost readily formed materials, and which also facilitate assembly of the parts.
The embodiment of the switch selected for illustrating this aspect of the invention is designed so it may control two electrical circuits by interrupting both circuits in its normal position and sequentially closing these circuits in a predetermined order as the switch operator is moved from its normal to its fully operated position. The point at which the first circuit has been closed and the second circuit is about to be closed is indicated to the sense of touch of a person operating the switch. As the switch operator returns from its fully operated position to its normal position, the circuit last to be closed is opened first, the point where the second circuit has opened and the first circuit is about to be opened again being indicated to the sense of touch. Upon completion of movement of the switch operator to the normal position, both circuits are opened. This design also makes it possible for the first circuit to be closed and thereafter opened without disturbing the second circuit which remains open under such circumstances. This design also embodies a contact spring of great durability and a contact arrangement which is not affected by excessive operating pressures. And, moreover, this design readily lends itself to use in combination with a volume control or other type of rheotate operable by the operating member of the switch. It will be understood that a switch having the novel structural features to be disclosed herein may be designed to occommodate a variety of circuit controlling contact arrangements.
The primary object of the present invention is to provide a novel control system for a radio receiving set.
Another object of the present invention is to provide a novel safety control system for an automobile radio receiving set.
Another object of the invention is to provide a novel device for muting a radio receiver or selecting a desired signal, or performing both of these functions simultaneously.
Another object of the invention is to provide a novel device for muting a radio receiver, selecting a desired signal, or changing the volume of sound emitted by the loud speaker.
A still further object of the present invention is to provide a novel switch having a plurality of operating functions which are indicated to the sense of touch of the person operating the switch.
Another object of the invention is to provide a novel switch for closing a plurality of circuits in sequence and maintaining each circuit change and restoring the circuits to their original condition in reverse order.
A further object of the invention is to provide a muting or tuning switch for radio apparatus controllable by the foot of a vehicle operator.
A still further object of the present invention is to obtain substantially complete shielding of the circuits of a remote tuning control device connected to a radio receiver to prevent connectedto a ratchet gear l8.
carriesor is otherwise connectedto a plurality of' A still further object of the present. invention is to provide a novel switch'of the type subjected to heavy operatingpressures .in which a relatively light contact spring of great durability is employed and in .which adjustment of the contact arrangement is not disturbed by employment -of excessive operating pressures.
\ Other and morespecific objects of the inven- --tion will become apparent as the following de- ---taileddescription of a specific embodiment of-the -invention'proceeds with reference to the-accompanying drawings in'which:
Figure 1 is an elevational view partly in section of a switch embodyingtheinvention; the section being takenon line E-I ofFigure 2.
' Figure 2 is a view in plan of the switch of Figure 1.
Figure 3' is a viewin plan of a portionof the switch of Figure 1.
- Figure tie a diagrammatic"representation of a-system'in which aswitch of the invention may H be used.
Figure 5 is an' exploded view showing-the parts partially sectioned on line Il"of-Figure 2.
Figure 6 is an elevational view, partlyin sec- 'tion, of modification of the switch of-Figure 1, "the sectionbeing taken on line 5-6-of Figure 7.
Figure 7 is a'view inplan of a portion of-the switchof Figure 6.
Figure 8 is a diagrammatic representation of a system'in'which the switch'of Figure 6'may be used.
Figure 9 is a diagrammatic representation similar to Figure 8-=of a modified system.
The operation of the switch of -this invention,
shown in Figures 1 to 3- and 5 of-the drawings; will -be, described in" connection: withthe'rcontrol icircuits-of a muting and tuningdevice for a radio receiver. It will be understood, however, that the switch of this invention may be used for general :1 circuit control purposes.
Referring'to the drawings indetail and for the present to Figures 3 and 4 thereof; reference numeral Ii]. indicatesptunable. radio apparatus such as a radioreceiver having. asolenoid oper- ::;ated station selecting. device indicated generally .by reference character I l. This device is shown diagrammatically ,as; being located exteriorly 10f the'receiver *1 E), for the? sake of convenience of illustration. The switch of this invention to be described in detail hereinafter, isindicated by" reference character ll-and is operatively connected to the device by. ashieldedmcable l l. The device comprises a shaft 17 .operatively The shaft l7 switches (not shown) which connect previously tuned sets of cooperating circuit elements in the "tunable circuits of the receiver so as to obtain automatic tuning-of a pluralityof preset stations. The operative connection to the tuning switches" '4 within the receiver it is indicated by the shaft H and may be obtained by mounting the switches on this shaft as suggested above, or in any other suitable manner, such as by means of gears, belt drives, etc. It will be understood that any type of electrically operated tuning device may be operated by the switch [2. One type of such device is shown in Patent 2,216,671 granted to Eugene F. McDonald, Jr., and dated October 1, 1940. This patent mayb referred to for further details of a system of radio control in which a \SWitCh of this invention may be used to obtain the advantages pointed out herein.
The electrical connections of the tuning and muting system will now be described briefly before proceeding to a detailed description of the switch hi2. The power supply may comprise a vehicle battery 19 which is connected to the receiver by way of a receiver power switch 2 l. The receiver is provided with a speaker 23 operated by a voice "coil- 24supplied by the output of the receiver and 1 having one-terminal connected to ground atZli. Conductor 2i of the cable I l-connects the other terminal of'the voice coilt i to a contact 28 -'of the switchl2. The switch 12 is preferably -mountedonthe floor boards of the vehicle in which the'system isinstalledor upon some part of the" vehicle easily reached by the' occupant "thereof. The movable contact 29 oftheswitch iselectrically connected'to the grounded base plate '45 through members-59, 65, till, ill and' lfl. The base plate iiiiand hence the switch casing is "connected to ground-at "3% by way of the metallic "sheath 3! of the cable It.
The point of connecti'onto ground 36 is preferably some metallic part of 'the device the circuits'of which are operated "'bythe switchlzand to which the cable l iis connected. In Figure 4, theground. may be made i" directly'to the external casing of the receiver ii The switch l2 has another contact'fit connected to a solenoidtt byway of a'conductor 35. This solenoid is connectedto' one terminal of the battery Iii-through the receiver power 'switch"2l.
'Zifheoperatingbutton 3! serves as a switchoperatortomove' the'movable contact 29. Depressing "the operating ,button 3? of the switch l2 causes contact 29 to engage contact'28 grounding'con- .ductor 21 to short circuit the voice coil ofthe speaker; through ground. This serves to mute thespeaker. Afurtherdepression of the operat- "ing button 3? of the switch completes the circuit "throughthe-solenoid from ground at1'3tl byway of the tcable'sheath' 3!, the contacts29, 28, and
"Ed the-conductor 36 and the batteryli].
ally'connected, asat 39, a pawl ll "The-solenoid 34 has a core 38' to which is pivot- A pawl spring 52" biases the pawl into engagement with1the ,teethon theiratchet wheel Hi.
'When' the circuit ',"through" the solenoid is completed, the .core" is retractedto rotate the ratchetlt in the direction indicated. After the solenoid has rotated the ratchet to tune in a transmitting station, which occurs almost immediately, the switch button ,may: be released and the solenoid core will be returned jto'its original position by means'of a spring 46.
' The--switch12 the parts ofwhich are shown in section by "Figure 1 of the drawings, and-disassembled imFigure 5, includes a base 'plate"'@'51to which is secured by tubular rivets 5i awafer-like contact assembly 36 "comprising-sheets ofxinsulating'material-"liland 48 secured together 'also -"by-rivets- 5 I. "The previously described-contact memb'er fiit is secured on a protuberant portion 52 of a-metallicstrip "53- whichis retained between the sheets 41 and 48. Ear 54 on the strip 53 provides a terminal to which the conductor 36 may be integrally secured in a permanently conductive manner by soldering or welding. The contact 28 is secured on a resilient member such as a spiral spring 56 which is secured to the insulating sheet 41 by eyelets 51. The contact spring 56 of spiral form has an inherently long life in use. Since the spring 56 is free of abrupt bends, and since its resilience does not depend on its being bent at any one point between its ends, it is not subject to crystallization and breakage. An upturned portion 58 provides a terminal connection for integrally receiving the conductor 21 in gOOd electrical contact.
The cup-shaped contact enclosing member 59 is apertlned for connection to the base plate 45 by eyelet connections 8! or other suitable means. The eyelet connections shown possess the advantage of receiving bolts, screws or other connecting means for securing the switch l2 to the floor board or other part of the vehicle, and also, the switch may lie closely in contact with the vehicle floor board or other part. Notches 62 (Figure 2) are formed in the contact enclosing member 59 to accommodate the insulated conductors 2'! and 36. A guide bushin $3 of insulating material is crimped to an aperture 54 located substantially concentrically with respect to the contacts 28 and 33. The guide bushing 63 serves a three-fold purpose in that it provides an insulating abutment for the contact spring 56, serves as a guide for the contact 29 and positions a comparatively powerful contact biasing spring 66. The spring 65 presents two substantially flat ends, one of which rests on top of the member 59 and the other of which reacts against a disk or washer 8'5 which surrounds the reduced portion 88 of the circular body of the contact 29. The washer 57 is seated in the shoulder 69 of the contact 29. The disk 61 preferably has an outside diameter such that it fits slidably in the cylindrical housing It which has an inwardly turned flange H providing a restricted portion indicated by the reference character '52 which serves to limit outward movement of the washer ti and thereby holds the spring 56 partly compressed. It will be seen from this that the movable contact 29 is guided for longitudinal movement without assistance from the aperture 13 in the housing IQ. At the end of the housing opposite the flange 7! is an outwardly turned flange it by means of which the housing is fastened by welding or other suitable means to the top of the contact enclosure member 59. Above the washer t? is a cylindrical sleeve 16. This sleeve is surrounded by another spring H, which is lighter than the spring 66, and the whole is enclosed by the operating button 3'! which is riveted onto the top of the contact 28 at 18. The operating button 3! overlaps the housing Hi to prevent dirt and foreign matter from entering the switch body. In this manner the sprin '3'! is somewhat compressed under ordinary conditions. The aperture '53 in the housing .53 is large enough to accommodate the spring 11. Upon eX- ertion of pressure on the operating button 31 to move the contact 29 toward circuit closing engagement with the contact 28, the spring TI is compressed until the inner surface of the button 3! engages the top of the sleeve 15. At this time, the contact 29 is in full circuit closing engagement with the contact 28. This completes a circuit. In Figure 3, the circuit is completed from the speaker voice coil to ground in the manner explained above by grounding the conductor 21,
thereby muting the speaker. At this point, the contact has not yet engaged the contact 33. Further movement of the operating button 3'! must necessarily cause compression of the spring 66 since there is now a direct connection between the button 3?, the sleeve 13 and the washer 61. The added resistance of the heavier spring 6% enables the operator to sense the point at which the circuit of conductor 2'5 has been closed and the closing of the circuit of conductor 38 is about to occur. Upon additional movement of the contact 29, the contact 28, which is now grounded by the contact 2c, engages the contact 33 to complete the circuit to be controlled which includes conductor 36. In Figure 3, this circuit is completed through the solenoid 3 and serves to change stations.
In operation of the switch, it will be noted that the alignment of the contacts 29, 28 and 33 by reason of their concentric arrangement, prevents damage or misalignment thereof by excessively heavy pressures exerted on the operating button 3?. With the button tl' fully depressed, the thrust of contact 2.9 is talzen by the contact 28 which is solidly in contact with the fixed contact 33. The spiral spring 56, therefore, is not called upon to resist any of the excess pressure which may be exerted on the operating button, but it is fully effective to maintain the concentric location of the contact at. Any force tending to displace the contact 28 laterally is prevented by the resistance to bending of the spring in the direction of its greatest dimension in cross section. In this respect, the spring may be regarded as a beam curved to spiral shape.
Figure 5 of the drawings serves to show the simple nature of the switch parts and the ease with which they may be assembled. While the manner of assembling the parts of the switch [2 is believed to be apparent from the foregoing, a suggested mode of assembly will be briefly described. The contact spring 56 is secured to insulating sheet Al, and this and insulating sheet 48 are assembled as a unit 46 together with the contact suppor 53 to which contact 33 has already been secured. This unit is fastened together and secured to the base 35 by means of the rivets 5|.
The insulating guide bushing 53 may be formed into position over the aperture 64 in the contact enclosing member 59, following which the parts carried by the member 59 may be assembled to it by slipping the washer 6! over the reduced part 833 of the contact member 29 until it rests against the shoulder 59. The contact 29 with the washer 6'! in place is inserted upwardly through the aperture 13 in the housing 15. The sleeve l6 and the spring '5'! may then be slipped into place to surround the reduced contact portion tB. The operating button 3'! is then riveted in place as indicated by the reference character it. The spring 66 may now be placed on the member 59 in a position determined by the bushing 63. The housing It may now be secured to the contact enclosing member as by welding the flange M thereto. Assembly of the switch is completed by crimping the fastening means 6! on the base 45 to the contact enclosure 59 as shown in Figure 1.
Assembly of the switch l2 may be carried out in other ways to suit particular manufacturing methods and assembling machinery if used. The foregoing description of a suggested mode of assembly is illustrative only of the ease with which the switch of this invention may be assembled.
Figures 6 and '7 of the drawings disclose a modified and multiple circuit controlling switch in accordance with the present invention. In this case,
"7 a combined circuit controlling switch -BI', which a'modification of theswitch'lz of Figures 1 to 3 and 5, provides for reducing the volume of sound as well as for muting and tuning the receiver.
Figure 8 of'the drawings discloses the modified system, and similar reference characters are used todesignate the same elements as in Figures 3 and 4. The receiver II], the station selecting device II and the accessory equipment for the receiver are substantially like those illustrated in Figure 40f the drawings. The combined multiple circuit controlling switch BI, the parts of which are shown in section by Figure 6 of the drawings, is similar in structure to the switch I2 of Figures '1 to 3 and 5 of the drawings, and is preferably I mounted on the floor board of the vehicle in which the system is installed so as to be in a position for convenient operation by the foot of the driver of the vehicle, or it may be installed upon some part of the vehicle easily reached by another occupant thereof. The switch 8I is operatively connected to the device I I by a shielded cable 82 which encloses the conductors 83 and '84. The conductors 83 and 84 correspond to the conductors 21 and 36 of Figures 3 and 4 of 5;
the drawings. The conductor 83 of the cable '82 connects'the undergrounded terminal of the speaker voice coil 24 to the contact 85 of the switch I2. The conductor 84 is connected to one terminal of the solenoid 34 and to the contact '86 of the switch 8I. The other terminal of the solenoid, which is the same as the solenoid 34 of Figure 4, is connected to one terminal of the battery I9 through the receiver power switch 2!. The conductor 83 also provides a connection to the volume control section 81 of the circuit controlling switch BI from the voice coil 24 of the speaker. The operating connection between the solenoid core 38 and the ratchet wheel I8, constituting parts of the device II, is the same as that shown in Figure 4 of the drawings.
The switch contact 85 is carried by a spiral spring member 88 and the contact 86 is secured 'upon a contact supporting strip 89. A wafer-like "contact assembly 9|, comprising sheets of insulating material 92 and 93, is secured to the base plate 94"ofth'e switch'by'tubular rivets or other suitable fastening means 96. The rivets 96 also serve to secure the sheets 92 and 93 together so as to retain the contact strip 89 in position between sheet92 by suitable fastening means such as the eyelets I02. An upturned portion I03 of the spring 88 provides a terminal connection; for.
integrally receiving the conductor 83 in good electrical contact.
'The'cup-sh'aped contact enclosing member IE4 is adapted for connection to the base plate 94 by eyelet connections I86 or other suitable securing means. A series of notches located in, the same position as the notches 62 in Figure 2 of thedrawings may be provided in the annular wall of'the contact enclosing member I 04 to accomodate the insulated conductors 83 and 84. The
re'ciprocable and rotatable contact 'III'I is guided annular member for longitudinal movement by a guide bushing I08of insulating material which is'crimped to'an aperture located substantially concentrically with the apertures in the contact supporting members 88 and 89. The guide bushing IDBperforr-ns substantially the same functions as the bushing =63 shown in Figures 1 and 5 of the drawings. A disk or washer'lflt surrounds the reduced portion III of the circular body of the contact I89 and is seated on theshoul-der I I2. A spring II4 presents two substantially flat ends, one of which rests on the member I04, and the other rests against the washer I09. The-washer I09 fits slidably in a cylindrical housing IIG which has-an inwardly turned flange I I1 providing-a restricted portion indicated at H8. Outward movement of the washer Ill-9 is limited by the restricted portion II8 to thereby hold the spring II4 partly compressed. The housing IIB may be secured to the top of the contact enclosure member I04 by welding its outwardly turned flange II9 to the enclosure member. A cylindrical sleeve I2=I surrounds the reduced portion III of the contact Ill! and rests on the washer I89. This sleeve is surrounded by another spring I23 which is lighter than the spring I I4. The aperture provided at the top of the housing H6 is large enough to accommodate the spring I23. The combined operating knob and button I24, comprising the cup-shaped member I25 and'the annular member I21, is riveted onto the top of the contact member I07 as indicated by reference character I28. The I21 is knurled or otherwise formed to provide a roughened surface as indicated by reference-character I 29, so that it may be rotated by the foot of the person desiring to control the volumeof sound emitted by theloud speaker of'the radio receiver Ill. The cap-shaped member I25overlaps the housing II6 to prevent dirt and foreign matter from entering the switch. After the connection I28 is-made the spring I23 is held incompression between the combined knob and button I24 and the washer I09. The portion of the contact II]? which provides the permanent connection I28 is preferably square in cross section to fit a square aperture in'the cap member I25, thereby to insure rotation of the contact I81 when the combined operating knob and button is rotated. It will be understood that any irregular shape-in cross-section may be given to the portion of the contact IIZ which provides for the riveted connection for the purposeof insuring rotation of the contact IU'I with "the combined knob and button I24. The switch casing is connected to ground at I36 (Figures 7 and 8) by way of the metallic sheath I3I of the cable 82. The point of connection to ground I30 is, like the point 39 of Figure 4, preferably some metallic portion of the device to which the cable 82 is connected. In Figure 8 the ground connection may be made directly to the external casing of the receiver I8. The movable contact I81 of the switch M is electrically connected to the grounded base plate 94 througlrthe members I84, H4, I89, I23 and I25.
The combined operating knob and button I24 is operated in the same manner as the operating button 31 of the switch I2 of Figure 1 to mute and tune the receiver. Upon exertion of pressure on the combined operating knob and button I 24 to reciprocate the contact Iill towardcircuit closing engagement with the contact 85, the top ofthe sleeve I2'I is engaged by the inner'surfaoe of the combined knob and button following initial compression of the spring 123.
At this time the contact I'OI'is in full circuit closing engagement with the contact 85, completing a circuit from the speaker voice coil to ground by grounding the conductor 33 and thereby muting the speaker. At this point in its movement, the contact IU'I has not brought the contact 85 into circuit closing engagement with the contact 86. Further movement of the combined knob and operating button I24 causes the spring II4 to be compressed since there is now a direct connection between the knob and operating button I24, the sleeve I2I and the washer I09. Because of the added resistance of the spring II4, the operator can sense the point at which the circuit of conductor 83 has been closed and the closing of the circuit of conductor 84 is about to occur. Additional movement of the contact I II! will cause the contact 85, which is now grounded by the contact IN, to engage the contact 86 to complete the circuit including the conductor 84.
The volume control section 81 of the combined switch 8! includes a volume control rheostat I32 which may be of any well known type, adjustable by rotating its operation shaft I33. The rheostat I32 is shown as being secured to a bracket 534 by means of a nut I36. The supporting means for the rheostat just described is con venient since volume control rheostats are readily available which are of the panel mounted type shown, employing the nut I36. However, it will be understood that any type of rheostat may be mounted in any desired manner on the switch 8| with its operating shaft projecting upwardly into the body of the switch as shown in Figure 6 of the drawings, or the combination of a switch and volume control may be effected in other ways. To prevent ingress of foreign matter into the volume control section 81 and the contacts of the switch SI, a cover member I31 is provided which encloses the rheostat I32 and the lower end of the switch.
The operating shaft I33 of the rheostat is slotted or bifurcated as shown at I38 so as to provide an extensible driving connection with a pin at I39 projecting from side to side through a bore MI in the end of the contact I01. The extensible connection provided between the bifurcated end of the shaft I33 and the pin I39 permits the contact III! to be moved longitudinally in the mamier explained above to control the circuits of the conductors 83 and 84. Rotating the combined knob and button I24 will adjust the amount of resistance included in the muting circuit, and hence will regulate the volume of sound emitted by the loud speaker. This is preferably to be accomplished by foot operation as explained above. The set may be muted at any time in the manner pointed out above irrespective of the angular position of the rheotat shaft I33.
The operation of the multiple circuit control system of Figure 8 will now be explained briefly. Muting and tuning is accomplished in the manner already pointed out in connection with the de scription of the structure of the combined switch BI. The volume of sound emitted by the loud speaker 23 is controlled by varying the amount of resistance placed in shunt with the loud speaker voice coil 24. The usual volume control ar rangement, indicated by reference character I453, ordinarily forming a part of the receiver, is operated in the normal manner to select a desired volume level, and the volume control rheostat I32 serves to reduce the volume below this level when desired. The volume control arrangement of Figure 8 of the drawings does not interfere 10 with the use of the ordinary volume control, nor does it interfere with the automatic'volume control usually supplied with present day receivers. Special shielding or insulation need not be provided for the conductor 83. The arrangement illustrated by Figure 8 of the drawings has the advantage that it does not require any conductors between the combined switch 8! and the receiver II] in addition to those shown in Figure 4 of the drawings. It will be understood that the volume control section 81 of the switch BI may be used to replace the regular volume control of the receiver if suitable precautions are taken to shield the leads between the receiver and the volume control so as to substantially eliminate the posstray signals.
Figure 9 of the drawings is a diagrammatic showing of a modified radio control system in accordance with this invention in which volume control as well as muting and tuning may be accomplished by the combined switch SI of Figures 6 and '7 of the drawings. In this figure similar reference characters are used to designate the same elements as are illustrated by Figure 4. The receiver I0, the station selecting device I I and the accessory equipment for the receiver may be of any conventional type such as is illustrated in Figure 4 of the drawings. Suitable output terminals on the receiver IIi serve to energize the voice coil 24 of the loud speaker 23. The combined switch 8Ia, which is similar to the switch 8| of Figures 6 and 8, is provided with a volume control potentiometer I44 which has one terminal of its resistor I46 connected to ground at any suitable point in or on the switch casing, or on the sheath I4! of the shielded cable I48. The remaining terminal of the resistor I46 is connected to the muting contact 86 of the switch 8 la preferably by way of a conductor I 49 connected to the conductor I5 I. The conductor [5| corresponds in function to the conductor 83 of Figure 8 and is connected to one terminal of the voice coil 24 of the loud speaker, the other voice coil terminal being grounded. The conductor I52 connects to the solenoid 34 which performs the same function as the solenoid 34 of Figure 4 of the drawings. A contact I54, slidable on the resistor I43, is connected to the cathode I55 of an amplifier tube I51 in the radio receiver II) by way of a conductor I58. This tube I51 is preferably one of the audio amplifier tubes and may be the combined detector and amplifier tube used in most present day radio receivers. The volume control arrangement just described does not interfere with the use of the regular volume control I 59, nor does it interfere with the automatic volume control arrangement if one is provided in the receiver. The volume control arrangement just described operates by including some of the voltage appearing across the voice coil 24 in series with the cathode circuit of an audio amplifier tube. The phase relationship of the voltage applied to the amplifier tube cathode is such that a reduction in gain results. Since the signal voltage fed into the audio amplifier depends on the setting of the regular volume control I59 of the receiver, the auxiliary inverse feed back volume control of Figure 9 gives a variation in audio output about a reference level established by the main volume control. The value of the resistor I46 is not critical and may, for standard receivers of present day design, be in the neighborhood of 500 ohms. The system of Figure 9 has the advantage of not requiring high impedance circuits externally of the receiver which tendency to pickup extraneous signals or noisesgenerated by: the vehicle engine.
A- plurality of switches, such as those shown. in
Figures 1 and 6, may be'employedsothat the re-- ceiver may lee-controlled from more than one, point, The system of the present invention enables station changing, control of sound volume and muting of the radio set by a. single foot-op eratcd. control device without the: operator having -to look at the set, ordial, or remove his hands from. the automobilecontrols. The system of the v presentinvention is-particularly applicable to the control of automobile radio sets and has been described in detail with respect to operation. from lowvoltage batteries. However, other types of radio sets, such as sets operated from alternating. current or higher voltage direct current, may bejoperated from aremote point in accordance withv the principles of the present invention. The invention has been illustrated in connection with an electrical type of automatic tuning wherein individual presettable condensers or inductances are employed, but is also applicable to other types ofautomatic tuning arrangement.
Fromtthe foregoing detailed description of the switch of thisiinventionv it will be seen that a low cost multiple circuit switch is provided, the parts of which may be readily manufactured from cheap materials and assembled by a few relatively simple. operations.
It will also be seen that the switch of this invention may readily be adapted for controlling the volume of sound emitted by the loud speaker associated with a radio receiver.
This application shows certain devices claimed in my co-pending application Serial. No. 406,677, filed August 13, 1941 now Patent No. 2,374,873 issued May 1,. 19.4.5.
While. there is shown and described here an illustrative. embodiment of the invention, the invention may be embodied in other forms, and
1:2 therefore thel inventionv isnot limited except as indicated by the terms and. scope of the appended claim.
. I claim:
.Incombination, ahousing, a rheostat and a pairof switches mounted in said housing, a. common operati-ng-- member having a shaft journaled inawall-otsaid housing and an enlargedv member on the! end of said shaft outside of said housing arrangedfor convenient rotation or linear movem'ent of-"said-shaft; said. shaft having alongitudinal' slot therein, a pin connected with said rheostat; said pin being arranged so that rotation-ot-said enlarged member adjusts said rheostat by rotation of said shaft and pin in any position of linear movement of said shaft, a spring having a portion fixed: in said housing and a free part spaced therein, in the path of linear movementof said: shaft, one of said switches having a contact on the end. of said shaft within said hous ing and: having a second contact on the free part of said spring and the other-switch having a first contact .fixed on said free part of said spring and a second contact fixed in said housing in the path of travel of said free'part of saidspring whereby linear movement of said shaft into said housing first'closes'the contacts of said one switch and; later closes the contacts of said other switch and adjustment of said rheostat by rotation of said shaft then wipes the contacts of said one switch.
EUGENE F; MCDONALD", JR.
REFERENCES CITED The following references are of record in the idle of this patent:
UNITED STATES PATENTS Number Name Date 1,063,541 Honold June 3, 1913 2,015,425 Gaubert Sept. 24, 1935 2,039,117 Schellenger Apr. 28, 1936 2,086,752 Thornburg July 13, 1937 2,166,803 De Reamer July 18, 1939 Certificate of Correction Patent No. 2,472,604. June 7, 1949.
EUGENE F. MCDONALD, JR.
It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:
Column 2, line 19, for rheotate reed rheostat; line 23, for occommodate read accommodate; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Oflice.
Signed and sealed this 8th day of November, A. D. 1949.
THOMAS F. MURPHY,
Assistant Commissioner 0 f Patents.
Certificate of Correction Patent No. 2,472,604. June 7, 1949. EUGENE F. MCDONALD, JR.
It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:
Column 2, line 19, for rheotate read rheostat; line 23, for occommodate read accommodate; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.
Signed and sealed this 8th day of November, A. D. 1949.
THOMAS F. MURPHY,
Assistant Commissioner of Patents.