US2307329A

US2307329A - Radio control system

Info

Publication number: US2307329A
Application number: US359137A
Authority: US
Inventors: Jr Eugene F Mcdonald
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-09-30
Filing date: 1940-09-30
Publication date: 1943-01-05
Anticipated expiration: 1960-01-05

Description

Jan. 5, 1943. E. F. M DONALD, JR

RADIO CONTROL SYSTEM Filed Sept. 30, 1940 3 Sheets-Sheet 1 Jan. 5, 1943.

E. F. MCDONALD, JR

RADIO CONTROL SYSTEM Filed Sept. 30, 1940 3 Sheets-Sheet 2 g w E g \l II. .1 l rty 50. -NJEUQIFQ M f y x .2 m: ii Q Zliwmwkw -0361216- FM Donald, Jr.

Jan. 5, 1943. E. F. MCDONALD, JR 2,307,329

RADIO CONTROL SYSTEM Filed Sept. 30, 1940 I5 Sheets-Sheet 3 Patented Jan. 5, 1943 UNITED STATES PATENT OFFICE RADIO CONTROL SYSTEM Eugene F. McDonald, Jr. Chicago, Ill. Application September 30, 1940, Serial No. 359,137

Claims.

This 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 may be controlled in a simpler and more expeditious manner.

The present invention is particularly useful in connection with radio receivers mounted in automobiles although it has general application wherever it is desired to control a radio receiver. The conventional hand tuning o1 actuation by hand of station selectors with conventional automobile radio receiver installations 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 accordance with the present invention, muting of the radio receiver for controlled periods of time as well as the selection of the desired signal to be received can be accomplished through a single member actuated, for example, by foot control with a special type of switch mounted on the fioorboard 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.

In addition to the safety features above discussed the driver can easily mute the radio receiving set in order to engage in conversation with passengers and furthermore, a plurality of control devices can be employed so that control of the radio set may be accomplished from the rear seat or the passengers side of the front seat, if desired.

It is, therefore, an object of the present invention to provide an improved control system for a radio receiving set.

Another object of the invention is to provide an improved safety control system for an automobile radio receiving set.

Another object of the invention is to provide an improved device for muting a radio receiver or selecting a desired signal or performing both of these functions simultaneously.

A further object of the invention is to provide a system for controlling the changing of the transmitting station being received and muting of the radio set from a remote point by single actuating member.

A further object of the invention is to provide a. mechanically actuated switch for controlling a radio set from a remote point by means of a single actuated member.

A still further object of the invention is to provide an electrically actuated switch for controlling a radio set from a, remote point by means of a single actuated member.

Other objects and advantages of the invention will appear in the followin description of preferred embodiments thereof disclosed in the attached drawings, of which:

Fig. l is a schematic diagram of a radio set and control mechanism embodying the present invention.

Fig. 2 is a view similar to Fig. 1 of a modification of the control circuit of Fig. 1.

Fig. 3 is a view partly in section of a mechanically operating mechanism showing the station selecting switch rotating mechanism and muting contacts.

Fig. 4 is an elevation of the station selecting switch rotating mechanism and muting contacts of Fig. 3.

Fig. 5 is a view similar to Fig. 4 showing the mechanism of Fig. 4 in a partially operated position.

Fig. 6 is a fragmentary perspective view of the mechanism illustrated in Figs. 3 to 5, showing the details of the muting contacts.

Fig. 7 is a section through an electrical switch, adapted to control the o eration of a solenoid operated switch, and including a muting switch.

Fig. 8 is a plan view of the contacts of the switch in Fig. 7.

Fig. 9 is a plan view of the contacts fication of the switch of Fig. 8.

Fig. 10 is an elevation partly in section of a solenoid operated switch.

Fig. 11 is a plan view of the switch portion of Fig. 10.

Fig. 12 is a fragmentary elevation of a modification of the switch of Figs. 10 and 11, in which the solenoid is adapted to control both the muting of the set and the changing of the stations.

In general Fig. 1 illustrates a radio circuit, various portions of which are controlled by a plurality of switches. These switches are actuated by a solenoid, the power to which may be controlled by a foot operate-cl switch mounted on the floor-board. With reference to Fig. 1, 15 indicates in general the radio frequency amplifying circuit of the set; 16 indicates the oscillator and mixer circuit; I'. the intermediate frequency circuit; IS the detector circuit and IQ of a modithe audio frequency circuit of the set. Most of these circuits are more or less conventional and require no detailed description. Only the portion of the radio set which controls the operation of the various circuits and the various circuits affected thereby will be described in detail.

A plurality of

rotary switches

29, 2|, 22 and 23 are operatively connected to the ratchet gear 24. This operative connection is indicated by the dotted line through the centers and may be obtained by mounting the switches upon the same shaft as the ratchet or in any other suitable manner, such as by means of gears, belt drives, etc. Switch 2|! selectively connects any one of a plurality of adjustable or variable condensers efiectively across the coil 24 of the antenna coupling circuit and may comprise an annular rotatable member 25 having diametrically opposed tabs 25 and 27. Stationary contact 28 connected to one terminal of the coil 24' slides upon the annular member 25 and is continuously in contact therewith.

Stationary contacts

29, 30, 3|, 32, 33 and 34 are spaced from the body of the annular member and are adapted to bev contacted only by the tabs 26 and 21. Contact 29 is connected to variable condenser 35a of the three gang condenser generally indicated as 35. The position of the switch shown in the drawing is the manual tuning position and it will be apparent that variable condenser 35a is effectively connected across coil 24 in the antenna coupling circuit of the radio frequency circuit. Rotation of the switch through 180 will connect in sequence adjustable condensers 36, 31, 38, 39 and 40 and then 35a into the antenna coupling circuit and further rotation will repeat the cycle. Condensers 35 to 40, inclusive. may be each preset to tune the antenna coupling circuit to any desired station.

Switch 2| is used to introduce a tuned coupling 4 circuit between the radio frequency amplifying circuit and the oscillator and mixer circuit when the set is used for manual tuning. It introduces an untuned coupling circuit when the preset stations are tuned. It is composed of an annular rotatable ring split in two halves 4| and 42. The hall 4| has a tab 43 and the half 42 has a tab 44 diametrically opposed to the tab 43. The body of each half of the annular ring is adapted to engage stationary contacts 45 and 46 and the tab portions engage stationary contact 41. In the position shown in the drawing one terminal of a tuned coupling circuit including a coupling coil 41 across a variable condenser. 35b of the gang condenser 35 is connected to the oscillator and mixer circuit through contact 41, half annular member 4| and contact 45. This is the position of the switch when the receiver is set for manual tuning. (It will be noted that there is no connection through the switch between contacts 45 and 4'5 because of the gaps between the half members 4| and 42). Rotation of the switch 2| in the direction indicated will disconnect the condenser 351) and coil 41 from the oscillator and mixer circuit since contact 41 does not engage the body ofthe half members 4| and 42. However, an untuned coupling circuit including the inductance 46 will be introduced between the radio frequency amplifying circuit and the oscillator and mixer circuit since both contacts 45 and 46 will then engage a half member 4| or 42. Thus, the tuned coupling circuit is disconnected and an untuned circuit substituted when the receiver is tuned to one of the preset circuits. It will be observed that rotation of the switch 2| through denser 350.

180" will complete the cycle to disconnect the untuned coupling circuit and reconnect the tuned coupling circuit.

Switch 22 is composed of an annular rotatable member 43 having diametrically

opposed tabs

49 and 58. Contact 5| engages the body of the annular member while contacts 52, 53, 54, 55, 56 and 5'! are adapted to engage the tabs 49 and till only. In the position shown in the drawing the switch is set for manual tuning. In this position variable condenser 350 of the gang is included in the oscillator grid circuit, and serves to tune that circuit in conjunction with the oscillator grid coil 58.

Rotation of the switch 22 disconnects the con- At the same time contact 53 is engaged by tab 5% and introduces the adjustable inductance 59 into the oscillator circuit. Further rotation introduces in sequence adjustable inductances 6K3, 6i, 52 and 63. Each of the inductances 59 to- 63 is connected to ground at 54, and is part of a preset oscillator circuit.

Switch. 23 has a split annular ring composed of the half members it and having tabs 12 and 73, respectively. Contacts 14 and i5 engage the body of each half member Whereas contact '36 is adapted to engage only the tab portions 12 and 13. The position shown in the drawing is for manual operation and connects the oscillator grid coil 58 into the oscillator circuit by means of contact 16, tab '52, half member H3 and contact 55. A tracker condenser H is included between ground and one end of the oscillator grid coil 58. Rotation of the switch in the direction of the arrow disconnects the coil 58 from the oscillator circuit since contact 16 does not engage the body of a half member ill or H. However, a second oscillator grid coil i8 is substituted. This is accomplished through contact it, half member 1H and contact 14. It will be observed that a condenser '59 is connected in parallel with oscillator grid coil '58 and that rotation of the

switches

22 and 23 from the position shown, selectively connects inductances 59 to 63 in parallel with the coil '18 to form the tuned oscillator grid circuits for the preset stations. Coil i8 is magnetically coupled to an oscillator plate coil as is the coil 58. Thus for all positions of the switch 23 other than that illustrated, coil l8 and condenser 1'9 form part of the tuned oscillator grid circuit.

The power supply is generally indicated as 85. It may be of conventional design and requires no specific description. It is connected to any suitable source of power, such as battery 86. The set may be provided with a speaker 87 operated by a voice coil 88 supplied by the output of the receiver and having one terminal connected to ground at 88. Conductor 89 connects the other terminal of the voice coil 88 to the contact 9|! of a switch 8| mounted on fioorboard 92 and having an operable member 92' connected to ground at 93.

, Switch 9| has a second contact 4 connected to a solenoid 95 through conductor 96. This solenoid is connected to one terminal of th battery 36 through the main power switch 33 of the set and a choke 94, the other terminal of the battery being connected to ground. Depressing the switch 9| in. the direction by the arrow short circuits the voice coil 88 through ground. This serves to mute the speaker. A further depression of the switch 9| completes the circuit through the solenoid from conductor 91 and conductor 96 to contact $4 and ground at 93. The solenoid has a core 98 with a pawl adapted to engage the teeth of ratchet 24. When the circuit through the solenoid is completed this core is retracted to rotate the'ratchet 24 in the direction indicated: The ratchet illustrated has twelve teeth so that a single actuation of the solenoid will rotate the shaft on which the ratch- 'et is mounted through 30%. 'Since -the switches 20 to 23 are mounted on this same shaft or operatively connected thereto in some manner it is apparent that these-switches will also be rotated through an angle of 30%. a

After the solenoid has rotated the ratchet,- the switch may be released 'and'it will be returned to its original position by means of spring I00. The pawl will be returned to its original positionby means of spring 99. The switch 9| is preferably "designed so that contact 90 will be-maintained in engagement with the movable member 92' upon further depression thereof after it has first =engaged contact 90. This insures the continued muting of the set while the station is'being changed.

f It will be seen from the above that intheposition of the switches shown in Fig.1 the antenna coupling'circuit will be manually tuned-by means of condenser 35a, the radio frequency coupling circuit by means of condenser 35b,and the oscillator grid circuit by means 'of condenser 350.

2 The inductance of the oscillator grid circuit-under these conditions will be furnished by coil-58.

Rotation of the'switches through 30, that is, by

means of a single actuation-of the solenoid will remove the variable condensers of the gang .35

from the various circuits. The tuned antenna coupling circuit will then contain adjustable-con- The coupling between the radio fre-- quency amplifying circuit and the oscillator and denser 36.

mixer-circuit will then be by means of'an-un- F tuned circuit in place of the tuned circuit. The oscillator grid circuit will be tuned by means of circuit. When the switches have been rotated through 180 it will be apparent that a cycle has been completed and further rotation will merely serve to repeat the cycle.

In Fig. 2, I have illustrated a modified circuit for actuating the solenoid and for muting the speaker. In this case the solenoid is used to perform the function of both muting and of changing stations and only one conductor other than a ground connection is necessary between the set I and the solenoid controlling switch. In this figure similar numbers are used to designate the same elements as in Fig. 1. Conductor 89 from the voice coil is connected to a fixed contact IOI This contact is positioned to be engaged by a second contact I02 mounted upon a spring I03 carried by support I04. The pawl 98 on the solenoid is adapted to engage the end of the spring I 03 to hold the contact I02 spaced from contact MI in the normal position of the solenoid core. Switch 9I when depressed in the direction indicated makes contact with contact I06 which completes a circuit through line 91, solenoid 95, line 96. resistance I07, contact I06 to ground at 93. A shielding sheath I06 may be employed as a ground connection if the switch 9| is mounted upon an insulated member. The resistance I! is of suitable value so that the solenoid will receive sufficient power to cause the pawl 98 to muting the speaker.

move and contacts I02 and IOI to engage, thereby connecting the voice coil to ground and thus This is accomplished by allowing a slight amount of play at I08 between the pawl 98 and the adjacent tooth on the ratch et 24. Thus the pawl 98 is permitted to move a slight distance sufficient to complete the circuit through contacts IUI and I02 before it picks up the teeth on the ratchet. The resistance is of sufliciently low value to permit this movement of the pawl 98 but is sufiiciently high in value to prevent enough power being developed by the solenoid to rotate the ratchet 24. In this manner it is possible to use the solenoid to mute the speaker without changing stations. Further depression of the switch 9I engages contact I09, thus short circuiting the resistance I01. In this position the solenoid 95 receives sufficient power to rotate the ratchet 24, thereby changing stations.

Figs. 3 to 6 illustrate a mechanically operated switch operating mechanism adapted to carry outthe function shown in Fig. l. The switch rotating mechanism is composed of a base member IIO having an upturned flange III and Y a downturned flange I I2 disposed at opposite ends thereof. The upturned flange III has a hole through which a tubular connector I I3 is adapted to be placed. This connector has a threaded portion H4 which passes through the hole in the flange III. A cap nut IIS screwed on the threads I it serves to hold the connector locked in position. The connector has a hole through whichthe Bowden wire I 26 is adapted to pass. This Bowden wire is enclosed Within a flexible housing I I! provided with a flange II'I' adapted to be engaged by the cap nut II5 threaded upon the connector I33 to secure the housing II! to the switch rotating mechanism. Bowden wire a hole in a vertical wall of the base member.

. passes into a switch operator generally indicated at H8.

. tubular member I22 having an outturned flange I I23 which may be spot welded to the base member. Intermediate, its height the tube I22 has a washer I24 fastened to its inner -sides. Disposed within the hole in this washer is a curved tube I25 which is suitably fastened to the Washer as by brazing. This tube has a portion I26 which extends above the hole in the washer and also has a portion l2! adapted to pass through A tubular connector I28 having a shoulder I29 and a threaded portion I surrounds the tube at the point I21. This tubular member I28 is held I position by means of the cap nut I3I which also holds the flexible housing II? by means of the connector I32, having a flange adapted to be engaged by the cap nut. The Bowden wire H6 engages at its upper end a cylindrical plunger I33 which passes through a hole in the cap I34 and is riveted over at I35. A spring I35 is disposed between the inner side of the cap and the upper face of the washer I24 and serves to hold the cap I34 in its uppermost position. The

a plurger I39 slidable in the tubular connector I I4 and secured to the flange I40 of the movable member M! of the switch. This movable member has another upturned flange I42 disposed t its other end. The shaft of the switch which is adapted to be rotated is shown at I43. Fixed one end of the shaft is the ratchet 24. The end of the shaft extends through a slot I44 in the movable member and through a hole in the base member IIO. The base member of the switch is held in spaced relation from the stationary contact supporting portion of the switch shown in outline at I44 by means of bolts I45 and nuts I46. On its far side the movable member has a spring pawl I41 with a slot 143 therein adapted to surround the ratchet 24. The spring pawl is bent at right angles and fastened to the flange I42 by means of a rivet I49.

' Movement of the Bowden wire causes the movported from members II and I52 carried by the base member and the movable member, respectively. The other end of the shaft I43 may extend through the switch and be provided with a knob I53 to enable the shaft to be also turned by hand so that station selection may be performed optionally either by hand or foot operation. By making the slot I48 in the spring pawl 3.41 of sufiicient length so that the pawl clears the ratchet 24 when in normal position the switch may be turned by hand in either direction.

With particular reference to Fig. 4, which is an elevation of the switch in Fig. 3, the base member has a downwardly extending bracket I55. The contact support I56 is supported by the bracket I55 through the means of rivet I51. The layers of insulation I58 serve to insulate the contact support I56 from the bracket I55. The contact support I56 carries contact I59 of the muting switch. The other contact of the muting switch I60 is carried by a spring member I6I supported by the downturned flange I I2 of the base member. A finger I62 carried by the movable member engages the spring I6I to normally hold the contacts I59 and I60 separated. Movement of the movable member to the left allows contact I60 to approach the contact I59 and to finally complete the circuit. In Fig. 5 the switch is indicated in solid lines in the position in which contact is made. The dotted lines indicate the ultimate position of the movable mem- I her after it has rotated the ratchet 24. The ultimate position of the spring member I41 is also shown in dotted lines in Fig. 5. In Fig. 6

shown a perspective View of the switch in inverted position to illustrate the relative positions of the various elements. It will be seen that the flange I42 carries the finger I62 which is adapted to engage the spring I6I to separate contacts I60 and I59. The spring I BI is shown as being carried by the flange II2 of the base member H6. Likewise the contact support I56 is shown carried by the base member. The connection I63 on the contact support is used for connecting line 89 from the voice coil.

The slot I48 in the spring pawl I41 is preferably long enough to permit sufiicient movement of the movable member to complete the circuit through contacts I59 and I60 before the end of the slot engages the tooth of the ratchet 24 to rotate shaft I43. In this manner depressing the cap I34 of the foot switch must be made against springs I36 and I50. These require a constant exertion of effort up to the point at which contacts I59 and I60 meet to mute the speaker. At this point, or shortly thereafter, the end of the slot I48 engages the tooth I24 and puts an additional load on the Bowden wire. Further movement of the Bowden wire requires a greater exertion on the cap I34 and thus it is possible for the operator to sense the point at which muting occurs and before which station changing occurs. In this way one is able to mute the set and hold it in a muted position without the station being changed. The added load required to rotate shaft I43 is generally provided by means of a spring detent (not shown) since the switch connected to shaft I43 is preferably of the snap action type.

Fig. 7 is a section through an electrical switch adapted to mute the speaker and to complete the solenoid circuit so as to change stations, the muting being performed before the station changing. The switch is composed of the base member 200 having cylindrical portions ml. The body member 202 is cylindrical in shape and has a flange 203, which is superimposed on the base member 200. The cylindrical portions 20I pass through holes in the flange 203 and are riveted over as shown at 204. The base plate carries insulating blocks 205 upon which contact supports 206 are mounted. These contacts supports carry

contacts

201 and 208. The opposite contacts 209 and 2I6, respectively, are carried by spring members 2I I supported on the member 2I2 by means of rivets 2I3. Near the middle of the spring members 2II are cam members 2I4 and 2I5. Cam member 2 I4 is longer and extends higher than cam member 2I5. These cam members are adapted to be actuated by cam 2I6 on one end of a plunger 2 I 1 which passes up through a cylindrical flange 2I8 in the top of the body member 202. This plunger H1 is surrounded by a cylindrical body 2I9 which has an outwardly turned flange 220 by means of which it is fastened to the top of the body member 202, for example, by spot welding. At the opposite end of the body 2| 9 is an inwardly turned flange 22I which serves to retain a washer 222 which in turn holds spring 223 partly compressed. Above the washer 222 is a cylindrical sleeve 224. This sleeve is surrounded by another spring 225 and the whole enclosed by a cap 226 which is riveted onto plunger 2I1 at 221. In this manner spring 225 is somewhat compressed under ordinary conditions. Upon the exertion of pressure on the cap 226 the spring 225 is compressed until the inner surface of cap 226 engages the top surface of the sleeve 224. This movement of the shaft 2I1 causes cam 2I6 to engage the member 2I4 and thus forces the spring member 2II to the side making contact between contacts 208 and 2I0. This completes a circuit from. the voice coil to ground, thereby muting the speaker. At this point the cam 2I6 has not yet engaged the cam member 2I5. Further movement of the cap 226 must necessarily cause compression of. the spring 223 since there is now a direct connection between the cap 22 6, the sleeve 224 and the washer 222. This additional resistance enables the operator to sense the point at which station changing is about to occur. Upon the additional movement of the shaft 2I1 cam 256 engages cam member 2I5 and causes the spring member 2II to move to the side, thereby engaging

contacts

201 and 209. This completes a circuit through the solenoid and serves to change stations.

In Fig. 8 is illustrated a top view of the contacts of the switch of Fig. 7. The manner of operation will be apparent from the previous description.

Wires

89 and 96 which connect the voice coil and the solenoid, respectively, are shown in this figure. The

contacts

209 and 2! are electrically connected to the base plate 200 by means of the springs 2H and the support member H2. The metallic sheath 230 surrounding the insulated wires is electrically connected to the base plate by means of wire 23!. This metallic sheath is connected to ground at 232.

Fig. 9 illustrates a modification of the switch shown in Fig, 8. In this figure the base plate, the insulation, the contact supports, the contacts, the spring members and the support for the spring members and the

cam members

214 and 215 are the same as in Fig. 8. The modification in this instance consists of a lever 233 which is pivotally mounted on the shaft 234 supported by ears 235. This lever extends between the two spring members 2H and is adapted to engage the cams 2M and 215. This lever is actuated by means of the plunger 2!! and does not require a cam at the end of the plunger. This modification is of advantage in that the lever 233 may be aligned with respect to the cam members 214 and H before the switch is completely assembled. It is not necessary that the plunger 2" approach the lever 233 at exactly a right angle since any reasonable angle of approach will cause the lever 233 to properly engage the cams and actuate them and also exact centering of the plunger with respect to the movable contacts is unnecessary. Upon release of pressure on the foot button, the lever 233 may be returned to its normal position by a suitably disposed spring.

In Fig. 10 is illustrated the means whereby the solenoid rotates the ratchet 24. The solenoid is composed of a sleeve 240 preferably of brass and preferably slit to reduce time delay action. Winding MI is wound upon this core and is retained thereon by means of insulating washers 242. The sleeve forms a guide for the solenoid core 243 of magnetic material and extends through a hole 244 in the front of a bracket of magnetic material forming a return path for the flux so as to separate the relatively movable magnetic elements. The core 203 is adapted to slide in the sleeve 240 and is normally held in the indicated position by means of spring 248. The movable member of the switch 249 has a flange 250 to which is rigidly secured end of the core 243. The spring pawl i4: is fastened between the flange 250 and the end of the core 243. This spring member has a slot I46 adapted to receive the ratchet 24. It

will be observed that the lot I48 is of sufficient length to permit partial movement of the movable member before the pawl engages a tooth of the ratchet 24. The station changing switch may be secured in spaced relation to the fixed member of the switch rotating mechanism by bolts 252 and nuts 253 and the switch shaft I43 may likewise have a knob on its other end for manual operation. A slot 254 in the movable member permits the shaft 143 to pass through the movable member and be journaled in the fixed member. A stop 255 on the movable member limits the motion of the movable member by engaging in a notch on the ratchet 24 when moved to the right in Figs. 10 and 11. This switch is and with the foot button shown in Figs. 7 and8.

to mute the speaker before the change of station Muting is accomplished by means of the muting contact in the foot button and the change of station is accomplished by means of the solenoid, the circuit of which is completed by means of the contact in the foot button.

Fig. 12 is a modification of the switch rotating mechanism shown in Figs. 10 and 11. The movable member, the pawl, the ratchet, the spring, the solenoid and the supports may be the same as in Figs. 10 and 11. The fixed member 25! may have a bracket 260 adapted to carry the muting contacts. One contact 263 is electrically connected to the bracket 260 by means of support 26! and spring 262. The other contact 264 is supported by bracket 265 which is insulated from the bracket 260 by means of the insulator 266. The end of the spring 262 abuts the stop 255. In the normal position of the movable member 249 the stop 255 contacts the spring 262 and holds contact 263 separated from contact 264. The first movement of the solenoid moves the movable member 249 sufficiently to permit the spring 262 to force contact 263 against contact 264, completing the circuit from the voice coil to ground. This serves occurs. f

This switch rotating mechanism is partic larly adapted for operation with the circuit illustrated in Fig. 2. When the switch 9| makes contact at I06 a circuit is completed through the solenoid and through the resistance I01. The resistance l0! limits the amount of power applied to the solenoid and, therefore, permits its movement only under the limited load required to operate the muting switch. When the pawl engages the gear 24 an additional load is applied to the solenoid. This will stop the solenoid since insufiicient power is supplied through the resistance I0! for further movement under the addi- :tional load. Further movement of the switch 9| closes a circuit through contact I09, thereby eliminating the resistance I07 from the circuit. In this position full voltage is applied to the solenoid and it is able to move against the additional .load to change the station.

It will be seen that in each of the switching arrangements shown, muting will occur upon partial actuation of an actuatable member. Release of the actuatable member will remove the muting.

- Complete actuation of the actuatable member of any of the modifications described will change stations. Partial release of the actuatable member after complete actuation maintains the muting. The pawl can be released sumciently to engage the next succeeding tooth on ratchet 24 without removing the muting action. If the actuatable member is then depressed from its partially actuated position, another change of station will occur. It is apparent, therefore, that the devices herein disclosed can be used to mute a radio set and maintain the same muted during any desired number of station changes. In this way the operator may skip as many tations in the sequence as he desires without having the speaker connected.

A plurality of actuatable devices may be employed in parallel so that the receiver may be controlled from more than one point. Likewise, such devices may be located in other places than on the floorboard.

The system of the present invention enables station changing and muting of an automobile radio set by a single foot operated control device without the operator having to look at the set or dial or remove his hand from the automobile controls. The system of the present invention is particularly applicable to the control of automobile radio sets and has been described in detail with respect to operation from low voltage batteries. However, other types of radio sets, such as sets operated from alternating current or higher voltage direct current, may be operated from a remote point in accordance with 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 of automatic tuning arrangements.

This application is a continuation in part of my copending application Serial No. 347,516, filed July 25, 1940, now Patent 2,216,671 granted July 25, 1940.

While I have disclosed the preferred embodiments of my invention, it is understood that the same is not limited to the details disclosed but may be varied within the scope of the following claims.

I claim:

1. A radio receiving system comprising a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, muting means for muting said set, a stepby-step selecting means for selecting a desired one of said presettable means, said selecting means including a movable member, remote control means for operating said movable member from a remote point, said muting means being actuated by partial movement of said movable member, said selecting means being actuated by further movement of said movable member, and means to permit the operator to sense a point at which the set is mute before said movable memer actuates said selecting means.

2. A radio receiving system comprising a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, muting means for muting said set, a stepby-step selecting means for selecting a desired one of said presettable means, ratchet means for operating said selecting means, a pawl for actuating said ratchet, means operatively associated with said pawl for operating said muting means, and means for actuating said pawl.

3. A radio receiving system comprising a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, a step-by-step selecting means for selecting a desired one of said presettable means, ratchet means for operating said selecting means, a pawl for actuating said ratchet, said pawl having a normal and an actuated position, means for moving said pawl from normal position to actuated position for actuating said ratchet, additional means for operating said selecting means, said pawl in its normal position being spaced from said ratchet sufficiently to permit said additional means to operate said selecting means in either direction.

4. A radio receiving system comprising a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, muting means for muting said set, a stepby-step selecting means for selecting a desired one of said presettable means, ratchet means for operating said selecting means, a pawlfor actuating said ratchet upon complete movement of said pawl, said pawl having a limited movement before engagement with said ratchet, said muting means being actuated by said limited movement of said pawl, and means for selectively actuating said pawl through either said limited movement or through said complete movement, said limited movement of the pawl permitting the set to be muted before operation of said selecting means occurs.

5. A radio receiving system comprising a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, muting means for muting said set, a stepby-step selecting means for selecting a desired one of said presettable means, ratchet means for operating said selecting means, a pawl for actuating said ratchet, said pawl having a limited movement before engagement with said ratchet, said muting means being operatively associated with said pawl and actuated by said limited movement of said pawl, means including a solenoid for actuating said pawl, and means for supplying a limited amount of power to said solenoid to actuate said pawl to its limited movement and for supplying a larger amount of power to fully actuate said pawl, thereby actuating said selecting means.

6. A radio receiving system comprising a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, muting means for muting said set, a step-by-step selecting means for selecting a desired one of said presettable means, ratchet means for operating said selecting means, a pawl for actuating said ratchet, said pawl having a limited movement before engagement with said ratchet, said muting means being actuated by said limited movement of said pawl, and actuating means for said pawl including a flexible member for actuating said pawl from a remote point, said limited movement of the pawl permitting the set to be muted before operation of said selecting means occurs.

'7. A radio receiving system comprising a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, muting means for muting said set, a step-by-step selecting means for selecting a desired one of said presettable means, ratchet means for operating said selecting means, a pawl for actuating said ratchet, said pawl having a limited movement before engagement with said ratchet, said muting means being actuated by said limited movement of said pawl, means including a solenoid for actuating said pawl, a power circuit for said solenoid, a switch in said circuit, said switch having at least two contacts, the first engaged of said contacts completing said circuit to supply limited power in said circuit so as to move said pawl through said limited movement but insufiicient to fully actuate said pawl, the second engaged completing said circuit to supply sufficient power to fully actuate said pawl.

8. A radio receiving system comprising a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, selecting means for selecting a desired one of said presettable means, ratchet means for operating said selecting means, a pawl for actuating said ratchet, said pawl having a normal and an actuated position, means for moving said pawl from normal position to actuated position for actuating said ratchet, and manual means independent of said ratchet and pawl for operating said selecting means, said pawl being constructed and arranged to permit said manual means to operate said selecting means when said pawl is in its normal position.

9. An automobile radio receiving system comprising a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, selecting means for selecting a desired one of said presettable means, and means for operating said selecting means to select any one of said presettable means including a foot pedal positioned on the floor board of said automobile to be actuated by the driver of said automobile and a mechanical connection between said foot pedal and said selecting means for mechanically operating said selecting means from said foot pedal.

10. In an automobile receiving system, a receiving set having a plurality of presettable means for presetting said set to receive a signal from any one of a plurality of transmitting stations, a step by step rotary selecting device for selecting a desired one of said presettable means, and means for rotating said device in steps to select any one of said presettable means including a foot pedal positioned on the floor board of said automobile to be actuated by the driver of said automobile and a mechanical connection between said foot pedal and said rotary selecting means for mechanically rotating said selecting means in steps from said foot pedal.

EUGENE F. MCDONALD, JR.