US2488207A - Radio program selector - Google Patents

Description

Nov. 15, 1949 w. A. LEA ,2

RADIO PROGRAM SELECTOR Filed Feb. 23, 1945 2 Sheets-Sheet 1 INVENTOR. er A. L811 flT'TOK/VEY- Nov. 115,- 1949 I W; A. LEA I 2,488,207

7 RADIO PROGRAM SELECTOR Filed Feb. 23, 1945 2 Sheets-Sheet. 2

To Tum/v6 v cm C T HT TOENEY,

Patented Nov. 15, 1949 UNITED STATES 2,488,207 RADIO PROGRAM SELECTOR Walter Alexander Lea, Los Angeles, Calif., assignor of one-third to George Henry Cunnington and one-third to Nils A. Thiebaud, both of Los Angeles, Calif.

Application February 23, 1945, Serial No. 579,470

'7 Claims. (Cl. 25020) The invention relates to a program selector and more particularly to tape controlled apparatus employing a tape having punch marks which form a record of desired radio programs, the tape controlling the apparatus to turn a radio receiver on or 01f and change or select a broadcast station.

Paper may be used as the tape. If the tape is employed to break a control circuit, an electric spark results which may damage or burn the tape. This is overcome according to the present invention by employing the tape only to make the control circuit, not to break it, the circuit being broken elsewhere remote from the tape. For this purpose, the invention provides a switch which may be designated a selector switch for each tuning device and for the power supply circuit, with means operative, when the tape operates a particular switch, to (1) look that switch in actuated position, (2) open the energizing circuit of that switch, and (3) restore the previously actuated switch to the control of the tape, thus saving current.

Use may be made of an endless tape or a strip of tape having ends. When using a strip of tape, it has been found that when the end of the tape arrives in the apparatus, a noise is produced in the radio receiver due to the fact that all the selector switches are energized whereby the tuning devices and power supply circuit are inces- V santly and rapidly cut in and out of circuit, as a switch when energized releases the others, and when a switch is released it is immediately energized again. This defect is overcome according to the present invention by rendering inefiective tape control of the selector switches when the end of the tape arrives. Also before the end of the tape arrives, assuming the program is over, a punch mark in the tape is operative to operate the power, supply selector switch which mechanically locks up, using no current, with the power supply cut off and with the tuning control selector switches in idle position. When the same or another tape is started through the apparatus, it is not necessary to start a program by using a punch mark for the power supply, as a punch mark for a given radio station operates the corresponding tuning control selector switch to thereby release the power supply selector switch to idle position and connect the power supply in circuit.

For further details of the invention, reference may be made to the drawings wherein- Fig. l is a plan view, partly in section, looking down at the top of what is shown in Fig. 2.

Fig. 2 is a sectional elevation looking at the timing means as connected to actuate the tape record as the same is passed under electrical contacting fingers which are a SQclated with the record tape,

Fig. 3 is an elevational view of a detail spring means for holding electrical contact fingers in place.

Fig. 4 is a plan view, with parts broken away, looking at the bottom of the spring means of Fig. 3.

Fig. 5 is an end view in elevation, with parts broken away, looking towards the right at the contact fingers in Fig. 3.

Fig. 6 is a plan detail on line 6-6 of Fig. 2, showing the mechanism for holding the tape in contact with the feed drum which is actuated by the timing means.

Fig. '7 is a plan view of a set of stripping fingers contacting the inside of the record tape for stripping the tape from the feed drum. These fingers indicated in Fig. 2.

Fig. 8 is a vertical elevation of a magnetic switching block, parts of which are omitted for clearness of illustration.

Fig. 9 is a sectional elevation of one of the magnetic switching blocks of vwhich there are a plural number shown in Fig. 8. What is shown in Fig. 9 is a transverse view as to what is shown at the left unit as shown in Fig. 8. This being a single unit of a magnetic switch connected into the system for any given single radio circuit, there being a plurality of this structure as indicated by Fig. 9 in any given unit of my invention. These units of Fig. 9 switch in and out any radio program arranged for by the holes in the record tape.

' Fig. 10 is a transverse detail looking in the opposite direction on line lfll0 of Fig. 8.

Fig. 11 is a vertical elevation'on line ll-ll of Fig. 8 of a magnetic switch unit, of which only one unit is used in the magnetic switching block and this unit is indicated by the unit at the right end of Fig. 8. The purpose of this switching unit of Fig. 11 is to switch on and off the line current of any electrical supply needed in the use of my invention.

Fig. 12 is a wiring diagram indicating the electrical circuits which are switched in and out by the magnetic construction of what are indicated. in Figs. 8, 9 and 11.

Fig. 13 is a sectional View similar in part to Fig. 11 showing some of the parts in different posi tion from what is shown in Fig. 11.

Fig. 14 is a plan View on line 14-44 of Fig. 8.

Fig. 15 is a vertical sectional elevation through a part of a solenoid as shown in Fig. 9.

Fig. 16 is a perspective view of a wiring connection to a solenoid.

Fig. 1'? is a perspective view of a switching block as relates to the electrical contact the details of which will be described later.

Fig. 18 is a perspective View of an interlocking Par Which holds a switch in a definite position.

With my invention, referring now to the drawing, tape 2 is made of any suitable material, such as paper. This strip of tape 2 is provided in the form of a definite length and width measured for the service desired and may be made as wide or as narrow as needed, and also as long as needed, to provide a sufiicient area to carry seven lines of punch holes through the tape 2.

The tape here shown as to the number of lines of punch holes in the tape 2 is marked to carry five lines of punch holes for five difierent radio stations, each line representing one station. In addition to those five station lines there is another line of punched holes in the tape 2 and this line of holes control an operating switch which shuts an the electric current supply to the radio in which my magnetic switch is installed for any given unit of radio receiving set.

In addition to the above mentioned rows of holes in the said tape '2, there is another line of holes of a continuous line equidistantly spaced by the means of which the tape is fed continuously through the timing unit as herein described.

This tape is provided in a definite length to cover the number of radio programs to be provided for as desired. The tape may be made as continuous band or belt, or may be made in a definite length and have the ends joined together as desired or may be made in certain special cases as a continuous length sufficient to run for a given length of time, and then become discharged from the timing mechanisms and then re-entered as desired for further service.

Referring now to the clock or timing means as hereinbefore mentioned, the tape after being punched in any suitable manner with holes S, T, may be placed into the timing mechanisms as a single piece of tape of any given length or for a single or for a number of programs on one piece of tape. Or a given length of tape measured for a certain period of time may be made and punched for programs as desired and the ends of that tape connected together bringing about; an endless ring of tape which is placed into the timing means to be passed through the said timing means completely around and around as. many times as desired for any given service of programs;

The timing means in which the tape is used aster: having been prepared by the punching means are indicated by Figures 1 through 7. In this timing means the; endless band of tape as mounted, therein is indicated by 2. The timing means is indicated by a clock dial: 6! in which the minute hand is indicated by 62 and the hour hand by 63. On theshaft of the hour hand there is a gear 64 see Figure 2. This gear 64 meshesinto aconnecting gear 65 which in turn meshes into a gear 66 on a shaft 61. A tape drum 68- is: frictionally mounted on the shaft 61.

The tapedrum 68 is provided at its middle portion with a sprocket wheel 69 which sprocket wheel engages the. perforations 8- of the tape 2 as and when, the tape 2. is mounted and trained around suitable guideways and idler supporting drum. as. desiredin any given case.

The rows of holes in the tape 2 indicated by S, and T being program system of holes, are synchronized. to the time periods by means of fVOlVing the drum 68 on the shaft 6'! by frictional slippages. on the shaft 6? without thereby revolving the, shaft of the hand gear of the timing mechanisms. This frictional resistance is carefully adjusted to revolve the tape drum but not the hour hand.

Mounted in a suitable frame and means for supporting the timing means, there is supported a table 10 over which the tape 2 is trained. This table HI carries on its underside an insulating block H which extends to the left and is provided at the edge with contact bars Ha, Hb, the tops of which are flush with the table 10. And to this contact bar Ha there is connected an electric conductor wire 12 connected to a springswitch blade 12a which is connected by conductor 12b to the secondary windin of the power supply transformer 13, see Fig. 2. As shown in Fig. 4, the switch blade 32a is shunted by a conductor I121) connected at one end to conductor 12b and at its other end to the contact bar 'Hb.

Mounted in any suitable manner across the top of the timing means as herein shown there is a rocking shaft 15 on which is fixed a block of insulating material 16. Connected into this block 16 there are a series of conductor fingers 11', the left ends of which are turned downward and adapted to spring into the holes S and T in the tape 2 and thereby contact the bar Ha as the tape 2 is moved toward the left in Figures 1 and 2.

At the connection of the conductor fingers 17 with the block 16 there are screws 18 which clamp the fingers 11 to the block 16. Connected to the screws 78 there are conductor wires 19 which are combined in the cable 36 which extend to a switching block previously mentioned in the early part of this specification.

In the use of thi program selector, as a general situation, the record tape will be made in a continuous band, but it may be composed of special strips not connected together as a continuous band. These strips of any desired length will be inserted into the timing mechanisms manually by inserting the end of the strip into the feeding means provided in the timing means. The tape, when in the machine, as and when it may be passed through to the end of any one strip, there would then occur a sudden contact of all the conductor fingers ll, making an electric disturbance of the program selector. To guard against such an emergency, I provide a spring switch blade 12a as previously described, which becomes a circuit-breaker. This is made of conducting material and is provided with an upward projecting portion 12d, which bears on the underside of the tape 2, see Figures 3, 4 and 5. Immediately above this projection 7212 there is mounted a couple of small rollers 72c mounted on a spring arm- 12), which spring arm is secured to the underside of the block 16.

As and when the tape 2 passes along to where the end of it clears the roller [20, the spring 12 presses down theswitch blade 12a, and thereby breaks open the electrical circuits to the timing mechanism, which circuits extend to the solenoid switching mechanisms as a safety device in using the program selector. However be it observed that there is a shunt 'Wire 1721) that bridges around the opening caused by the roller 'i2c depressing switch lever 12a, which leaves closed the circuit from the segment of contact bar 'Hb to the solenoid I96; thus when the tape runs out, the finger in position over segment lib makes contact therewith, thus energizing solenoid I which acts to discontinue the electric service to the radio in which this unit is installed.

Any suitable means may be used for revolving the shaft 15 in position to hold the contact fingers I1 in-a slight spring pressure sufiicient to cause any single finger TI to drop through a hole in the tape and contact the electric conductor in two sections straddling the sprocket wheel 59 and the roller is held in place by aspring arm 84 the ends of which are fixed to a block 85 on a shaft 86. The shaft 86 is mounted in any suitable manner in the framework of the device. 'On the end of the shaft 86 there is mounted a radial arm 81 which is hinged to a rod 88 which exifj e l f th r htan s'ib id h radial. a r82; as the shaft I5 is moved by the vertical'spring 8|, that same movement acts upon the the 88 to rock the shaft 86, and'thereby hold ythe roller 83 to hold the tape 2 onto the drum 681 tAhan'dleBB is provided for rocking the shaft the handle is lifted upwardly in a man- ]rier to lift'the'roller 83'clear of the tape 2 and the drum *68. Whenthis action takes place the connecting rod 8 8 act sto rock the shaft 15 in the same direction as the shaft 85 is rocked. And this results-in lifting the'spring contact finigers 1T, thus making a clear way to introduce a new tape or remove an old one or allowing the tapeZ' to" travel through its'course continuously without being contacted by the contact finer's 11.

As and when thecontact Tl are not contacting the tape, no current will flow to the switching mechanism to which the cable wires 80 are connected from the timing mechanism in any instance wherein a radio station is switched'in as hereinbefore described. 4 By referring to Figure 2, the tape 2 at the top of the figure and underneath the fingers TI -is drawn toward the left by the clock-or timing movement and thus the tape 2 will pass downward off from the drum 68. To insure the stripping of the tape 2 from the sprocket wheel 69,

there is provided the stripping fingers 90, s'ee Figures 2 and 7, which fingers are fastened to a a cross block 9 I fixed in the framework of the device in any suitable manner.

Referring now to Figures 8, 9, l0, 11, 12, .14land 15, they relate to the switchingmechanismshereinbefore mentioned and described as magnetically operated switches. In the aforementioned cable 80 there are six conductor wires insulated from each other in the cable. In the diagram of Figure 2 the wire connection 721) enters a transformer I3 which is in turn connected to the terminal block I4. The terminalblock T4 is a part of. the magnetic switching block as hereinbefore referred to. j

The said magnetic switching block is provided with the supporting base hereinshown as.a "fiat bed plate I00 made of any suitable material. Extending upward from the base I00,there:are the end supporting walls IOI which may-beLof metal or any suitable material. At the'top portion of these walls and on'the inside thereof, there is fixed endcross blocks I02 'of insulating material. Onthe top of these blocks. I02 there 7 is mounted a plate I03 of insulating material,

which is the top frame plate of the magnetic {switch This plate I03 isfixed on thetops of i the end cross blocks I02. The end cross blocks I92 are connected across on the back by the aforementioned terminal block I4.

Mounted to the lower side of the end cross blocks I02, there is a plate I04 of insulating material. On the underside of the plate I04 there are fixed six solenoids as indicated in'- Figures 8 and 14. These solenoids-are allsimilanin construction and five of'them,'indicated'by I05, being --all of those five at the left of Figures 8 and 14,

relate to switching in and out for different radio "stations, and the other, indicated by I90 or the {.sixthone being the solenoid at the right of Fig- :ure 8, is used in switching off the current to the radio. a v

The numbers of these solenoids may be more i or less than those five indicated as I05 for tuning in on any given program for which this.instrument maybe provided for. e

. LThese solenoids I55 and I06 are substantially alike in construction and areof a construction of more or less cornmonsypracticeas tolth'e details'of the part of the solenoids.

The magnetic coil of all of the six solenoids are indicated in Figure .16 .as I01. This .coil isienclosed by a protecting'shellt'l08'madefof iron;see 1 Figure 9. This shell adds tothemagneticpower of the solenoid.v The'plunge'rsused in thesesoles holds 105 and I06 may be. of .any. suitable construction for thepurposedesireibut I prefer to 1 provide a special plunger indicated in cross section in Figure in which the lower end I09Iof i the plunger is made of so'ft'iron and isvsuitably connected at. itstop bya non-magnetic block I I0 1 which may be made from any suitable" non-magnetic material.

011 the inside 0f the block Hi] I provide. a screwthrea'ded stem I I I of non-mag- 'netic metal 'on .the top of which 'there is provided a cone-shaped cap H2. The stem IIIpasses 1 through an insulating plate I I3, which-is a small r'ectangular. plate shown in perspective in Figure 2 17. I Above theplate 'I I3 .there is screwed onto the stem I I I ,a clamping nut I IA 'of any suitable nonmagnetic material. A plateilike II3'withits 1 three contacts is provided for the plunger for each of the five solenoids I05 andlplate, I34 with its i contact strip 131, provided for solenoid I05,:plat'es I13 and I34 are each provided witha projection II5 made of the insulating material as that of T the plate itself or other suitable form composed of insulating material. I.

.The' electrical contact fingers all trail along over the insulating tape 2which is punched with holes S, T, and thecontact fingers TI ride on the h tape 2, the unpunched..part of aitfholds the circuit open at fingers TI. .When 'aihole S, "1, passes under one ofthe-fingers.I.I,Lby spring action the points of these'contact fingers drop down through one o'f the" holes'S, T, in'the tape 2,and there- 1 by close an electrical circuit which causes oneof the fivesolenoids I05 or solenoid i 06 to act. This circuit is shown in Fig; '2'and is as follows, one terminal of all six of the solenoids I05, E06 are connected together to line I2: which is connected to one'side of transformer I3. The other 'side of while the remaining five solenoids I05 terminate in "contact" fingers 'I'Iabove contact plate Ila. When those contact fingers'l'l are lifted bythe tapethe're' is opportunity.- for a spark? or; heating contact which might damage the tape as the circuit is broken. This is overcome by the present invention as each solenoid is mechanically locked up in actuated position and its operating circuit is opened instantly through contact fingers H9, being separated by projection H on the plate H3 or I34 on the plunger of the actuated solenoid.

Mounted on the inside underneath the plate I03 there is mounted an interlocking bar I I6 having trunnion pins I I? which are hinged into the cross blocks I02. On the lower edge of the interlocking bar IIB there is a curved catch lip II8. The trunnion pins of the bar II6 are located substantially in a direct line above the cone-shaped cap I I2 in vertical center line of the solenoids I05 and I06. The lip H8 being ofiset from the body of the bar III: causes the gravity action to cause the bar to rock downwardly as the apparatus is normally mounted with the solenoids located in plumb line vertical alignment, the action of gravity on the bar H5 is to cause its hooked shaped catch to swing across the top of the cone cap I I2 as and when the cap H2 is below the bar IIG in any given instance of the six solenoids herein indicated.

As and when any solenoid is in its maximum downward position with its cap I I2 below the bar I It, gravity tends to cause the catch I I8 to swing across over the center of the said cap I I2.

On any given impulse upwardly of the solenoid plunger excited by an electrical current, the cap II2 of the plunger contacts the bottom edge of the catch H8 and thereby forces the bar IE6 aside until catch I I8 is released to swing by gravity to hook under the cap I I2 as shown in Figures 8, 9 and 10, thereby locking the solenoid plunger upwardly as shown in Figures 9, 10 and at the left of Figure 8. Thus there becomes broken the electrical circuit which was energized by a contact finger passing through a punched hole in the tape as brought about by timing mechanisms as herein before described. Thus there is prevented by this means any heating current which is brought into service by the switching means of the timing means.

As and when any solenoid is actuated by the electrical current throwing up its plunger to the limit of upward stroke, there is thereby cut off the current which energized the said solenoid. The means of cutting off this current is provided by the block I I3 which is mounted on its solenoid plunger and carries the projection H5 which is located between the spring contacts, see Figure 16, which are fastened on the insulating plate I04. These contacts II9 on one side are connected by a conductor wire I connected to the electrical coil of the solenoid and the other leg is connected to the conductor wire I2 I, which is common to all the solenoids as being the return circuit for the six different contact fingers of the timing means controlled by the moving tape herein described.

The sudden upward impulse of each solenoid plunger causes the projection I I5 of its insulating block I I3 or I32 on the complete upward stroke of the plunger to spread apart its spring contact finger H9 to break the circuit of that solenoid as will be apparent from Fgures 9, 10, 13 and 16.

Across the blocks II3 of insulating material there is mounted three strips of electrical conductor material I22 on the blocks H3 for all of the five solenoids I05. The plate like I I3 for solenoid I06 is shown at I32 in Fig. 14. Plate I34 controls the power supply circuit I30, I3I which is closed by contact strip I31 when plate I33 is in its lower position shown in Fig. 8 where solenoid E08 is deenergized. The power supply circuit I30, I3I is broken at strip I31 when solenoid I06 is energized.

Mounted on the top edges of the insulating plate I03, there are spring contact fingers I23, see Figures 8, 9, l0 and 12, in groups above each of the solenoids I05. The spring contacts II9 are present with each of the solenoids I05 and I06 in the form indicated by Figures 9, 10 and 11. These spring contact fingers as shown in Figure 12 are arranged in groups of three on each side of the plate I03. Those on the side I24 of the plate I03 are connected to conductor wire lines three in number indicated by I25, all three of which lead to one side of the tuning circuit of the radio. On the other side I26 of the plate I03 the three conductor lines I2'I in each group are connected to one side of condensers I28 which are of suitable value, and the other side of the condensers of each group are connected to wires I20 which lead to the other side of the tuning circuit of the radio. In the example shown in Fig. 12, wherein there are three condensers in each group, it is assumed that the radio has three tuning elements such as tuning coils, one condenser of a group would be connected to one tuning coil, a second condenser of one group to a second tuning coil and the third condenser of a group to a third coil, the values of the three condensers in each group being appropriate to whatever kind of radio circuit is employed, as well understood. Hence, each time one of the plungers is held up to thereby operate a selector switch having the contacts like I23, a particular group of three condensers is connected to the radio so as to tune it for a particular station, other stations being tuned when other plungers operate. If the radio circuit has only two tuned circuits, there need be only two condensers in each group I20.

The conductor wires controlled by the solenoid I06 are indicated by I30 and I3I and these conductor wires I30 and I3I constitute the electric circuit of the power supply for the radio.

In the position indicated by Figure 11, the electric current supply is at all times connected up for operating the switching mechanisms involved by the solenoids I05. As and when the timing mechanism carries the tape through the spring fingers to a punched hole arranged for making the contact to the solenoid I06, a projection H5 of a plate I I3 moves up between the spring fingers II9 as indicated in Figures 11 and 13 from the position of Figure 11 to that of Figure 13.

Referring now to Figure 14 the terminal block hereinbefore mentioned as I4 is connected at its end to the cross blocks I02. Conductor wire I33 of Figs. 2 and 14 goes to the cable to the timing mechanism and conductor wire I2 I extends therefrom to the other terminal of the solenoids I05 and I06.

What is claimed is:

1. Program selector apparatus for changing the tuning of a radio set in accordance with a tape program record, said apparatus comprising means providing a path for the tape, a plurality of tape controlled switches in said path, a plurality of solenoids and circuits therefor each controlled by one of said switches, a plurality of plungers each operated by one of said solenoids, a switch controlled by each of said plungers and controlling the circuit of its respective solenoid, means for holding said plungers in actuated position, a power supply circuit for the radio set, one of said plungers having a switch closing said 9 power supply circuit when said one plunger is not operated by its solenoid and opening said power supply circuit when said one plunger is operated by its solenoid, tuning devices and circuits therefor controlled by others of said plungers, and means operated on actuation of the plunger of a selected solenoid to release the plunger of the previously energized solenoid and operate its plunger switch to restore the control of such previously energized solenoid to its respective tape controlled switch.

2. Program selector for changing the tuning of a radio set in accordance with a tape program record, said apparatus comprising means providing a path for the tape, a plurality of tape controlled switches in said path, a plurality of solenoids and circuits therefor each controlled by one of said switches for idle or actuated condition, a plunger for each of said solenoids, a power supply circuit for the radio set, one of said plungers having a switch closing said power supply circuit when said one plunger is idle and opening said power supply circuit when said one plunger is actuated, tuning devices operated by others of said plungers, means responsive to the operation of each plunger to open the said circuit for its solenoid instantly after that solenoid is actuated and close that circuit when such solenoid is idle and its plunger is released, and a mechanical latch device constructed and arranged to hold an actuated one of said plungers in actuated position and release the previously actuated one of said plungers.

3. Program selector apparatus for changing the tuning of a radio set in accordance with a tape program record, said apparatus comprising means providing a path for the tape, a plurality of tape controlled switches in said path, a plurality of solenoids and circuits therefor each controlled by one of said switches, a plunger for each of said solenoids, a power supply circuit for the radio set, one of said plungers having a switch closing said power supply circuit when said one plunger is idle and opening said power supply circuit when said one plunger is actuated, tuning devices operated by others of said plungers, means responsive to the operation of each plunger to open the said circuit for its solenoid instantly after that solenoid is rendered active by its tape switch and close that circuit when the plunger of such solenoid is released by its tape switch, a mechanical latch device constructed and arranged to hold the actuated plunger in actuated position and release the previously actuated plunger, and means responsive to the absence of tape in said path to prevent said tape controlled switches from actuating their respective tuning control plungers.

4. Program selector apparatus comprising a series of tape controlled switches, a corresponding series of radio circuit selector switches each having and actuated by a solenoid in circuit with one of said tape switches, a plurality of switches each in series with the circuit of one of said solenoids, means responsive instantly after the actuation of each of said selector switches to open the series switch for its solenoid, and a mechanical latch device common to said selector switches trolled thereby, tuning means controlled by said selector switch, a second tape controlled switch, a selector switch controlled by said second tape switch, a power supply circuit controlled by said second selector switch, a latch for holding either of said selector switches in operated position and releasing the other, each of said selector switches having means for operating said latch also having means for removing itself from control of its tape switch when held by said latch, said first selector switch being in closed position when held by said latch, and said second selector switch being in closed position when released from said latch.

6. Program selector apparatus for changing the tuning of a radio set in accordance with a tape program record, said apparatus comprising means providing a path for the tape, a plurality of tape controlled switches in said path, a selector switch and associated solenoid for and controlled by each of said tape switches, a tuning device controlled by each of said selector switches, and tape operated means responsive to the absence of tape in said path to remove said solenoids from control of said tape switches and prevent said tape controlled switches from actuating their respective selector switches.

'7. Program selector apparatus comprising a series of station switches, timed controlled means for selectively rendering said switches operative, a corresponding series of solenoids controlled by said switches, each of said solenoids having a plunger, a series of tuning switches one for each of said plungers, each of said plungers actuating its tuning switch when that plunger is actuated, a corresponding series of breaker switches each in series with its respective solenoid, each of said plungers having means for opening its respective breaker switch when the plunger is actuated, a series of tuning elements, one for each of said tuning switches, and a latch bar common to said plungers, said latch bar having catch and release means operative to catch any one of said plungers when it is actuated and release any previously actuated one of said plungers, each of said breaker switches being closed when its respective plunger is in idle position released from said latch bar.

WALTER ALEXANDER LEA.

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

UNITED STATES PATENTS Number Name Date 1,142,604 Moore June 8, 1915 1,172,080 Voigt Feb. 15, 1916 1,983,759 Houston Dec. 11, 1934 1,989,558 Myers et al Jan. 29, 1935 2,050,719 McClure Aug. 11, 1936 2,056,282 Lanyon Oct. 6, 1936 2,084,205 Lane June 15, 1937 2,166,691 Pare July 18, 1939 2,228,969 Osborne et a1 Jan. 14, 1941 2,229,100 Lapsley Jan. 21, 1941 2,337,568 Owens Dec. 28, 1943 2,367,363 Matt Jan. 16, 1945 FOREIGN PATENTS Number Country Date 95,506 Sweden Apr. 25, 1939 110,591 Australia May 23, 1940

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