US2179043A - Multiunit radio receiving system - Google Patents

Description

Nov. 7, 1939. R. KIMBALL MULTIUNIT RADIO RECEIVING SYSTEM Filed July 3, 1937 4 Sheets-Sheet 1 Nov. 7, 1939. R. KIMBALL MULTIUNIT RADIO RECEIVING SYSTEM Filed July 3, 1957 4 Sheets-Sheet 2 w haw Nov. 7, 1939. R. KIMBALL MULTIUNI'I RADIO RECEIVING SYSTEM Filed July 3, 1937 4 Sheets-Sheet 5 Nov. 7, 1939.

' R. KIMBALL MULTIUNIT RADIO RECEIVING SYSTEM Filed July 3, 1937 4 Sheets-Sheet 4 b w r 35 mt T SQ 3 F352.

p IB N Patented Nov. 7, 1939 warren stares PATENT OFFEQE MULTIUNIT, RADIO RECEIVING SYSTEM Raymond Kimball, Hollywood, Calif.

Application July 3, 1937, Serial No. 151,897

19 Claims.

This invention is a radio receiving system pro viding for selectively controlled intercommunication among a plurality of inter-related stations.

One of the objects of the invention is to provide a system of the character mentioned characterized by a plurality of inter-related radio receiving stations and means selectively controllable at each of said stations for establishing oral communication with any one of the other stations. A further object is to provide simple means for temporarily converting the sound reproducing element of any station into a microphone and placing it into communication with the sound reproducing element of any other station of the system. A further object is to provide means at each station for selectively effecting temporary interruption of radio reception at any of the other stations of the system.

The invention will be hereinafter fully set forth and particularly pointed out in the claims.

In the accompanying drawings,

Figures 1, 2, 3 and 4 are diagrammatic views of a corresponding number of portions of the radio receiving system, it being understood that all of them are part of a single lay-out and should be regarded as assembled in joint relation as one larger complete plan, with Figure 2 at the right of Figure 1 and Figures 3 and 4 below Figures 1 and 2 respectively.

Referring to the drawings, A diagrammatically illustrates a program power-supply-contrcl device of the type provided with means controllable from a distance for making and breaking the circuit to the various tuners and amplifiers of the system. B indicates an intercommunicating power supply device having means controllable from a distance for establishing intercommunication between control stations. C represents an amplifier controllable from a distance for amplifying intercommunication between stations. D is a transformer for reducing the usual 110 volt power current to a 6 volt power supply.

Any number of stations may be employed, each with its duplicated control devices and loud speaker, four of such stations, located in separate rooms, being shown for purposes of illustration. The several stations are represented by panel boards CP CP (3P and 3 respectively, each provided with circuit closing devices and wiring, all to be described in detail later. The circuits and method of control are identical in each instance, except that the circuit closing devices carried by panel boards CP and CP are illustrated as of the push button type and those of panel boards CP and CP are of the rotatable gang switch type. The panel boards may be of the portable type or of the fixed wall type, the push button controls being preferably used with the portable type CP and (JP and the gang switch being preferably carried by the fixed wall type CP and GP.

The main lead-in wire a is connected by a branch wire 28 to the program power supply A, by a branch wire 2!, to the intercommunicating power supply B by wire M and is also directly connected with the transformer D. Leading from the intercommunicating power supply B is a wire 22 to which is connected the fixed contact rv of each of'a series of relays #lil, #ll, #l2 and #13 respectively. Leading from the program power supply is a wire 23v which by means of a wire 24 is connected to the fixed contact 1 of each .of relays #M, #i and #lfi. Each relay #14 and #l5is provided with two sets of contacts, namely one set consisting of a fixed contact 1' and a movablecontact s, and the other set consisting of a fixed contact 0 and a movable contact o. The two movable contacts are so connected as to move together. All of said relays #ll), #H, #l2, #l3, #l4, #l5, and #IG have their movable contacts 8 suitably connected with a return wire 25, which in turn isconnected by a wire 26 to the main return wire b. Contact 0' of each relay id and #I5 is connected with the wire 28. Contact 0' of relay #14 is connected with Wire I28 by Wire 123 and contact 0' of relay #I5 is connected to wire l2? by wire 38.

Each of the coils of the respective relays #lll, -#ll, #l2, #l3, #l4, #IE has one terminal connected with a common feed wire 28, which in turn is connected to the output side of transformer D, by wire 29. The circuit connections with the other terminals of said coils will be described later in connection with the detail description of the respective control stations.-

The intercommunicating power supply B is so constructed that the circuit to wire 2N and its connections is normally broken, said circuit being closed, however, upon the actuation of any one of the relays #10, #l l, #IE and #53. It will be observed that the fixed contact r of each of these relays. is connected with the wire 22 and that the movable contact 3 of each relay is connected with the return wires 25 and 26.

In addition to the relays above described there is another group of relays arranged in pairs, to wit, #1 and #2, #3 and #d, #5 and #6, and #1 and #8, each having two fixed contacts, 8,, s and a movable contact 5 The fixed contact s of each relay #I, #3, #5 and #1 is connected to a common wire 28 Each fixed contact 8 of relays #I, #3, #5 and #1 is connected with the movable contact 8 of relays #2, l, #6, #8, respectively. Each fixed contact s of relays #2, #4, #6, #8, is connected to a common Wire 28 The movable contacts s of each relay #I, #3, #5 and #1 is connected with a wire I06 leading to a loud speaker, one for each control station, relay #1! being connected with LS of control panel CP', relay #3 with LS of P relay with LS of CP and relay #1 with LS of GP. Each loud speaker is also connected by wire I01 with wire 39. The fixed terminal .9 of relay #2 is connected with amplifier AM by wires I03 and IUS I04, s of relay #4 is connected with amplifier AM by wires I08, I09, II 0, s of relay #6 is connected directly with amplifier AM by wire H2, and s of relay #8 is directly connected with amplifier AM by wire H2 and H4.

One end of the coil of relay #I is connected to a terminal of the coil of relay #II], by means of a wire 38, said last-mentioned wire being also connected with conductor I I8. In a similar manner a terminal of coil of relay #3 is connected to a terminal of the coil of relay #II by means of wire 3|, said wire also being connected with conductor I25, a terminal of the coil of relay #5 is connected with a terminal of the coil of relay #I2 by wire 32 which wire is also connected with conductor I25; and a terminal of the coil of relay #1 is connected with a terminal of the coil of relay #I3 by a wire I23 which wire is also connected with conductor I21. Each of the other terminals of the coils of relays #III, #I I, #I 2 and #I3, as before stated are connected with the transformer wire 29 by wire 28.

One terminal of the coil of relay #2 is connected with conductor II1 by a wire H1 one terminal of the coil of relay #4 is connected with conductor H9 by a wire B one terminal of the coil of relay #6 is connected with conductor I22 by a wire I22 and one terminal of the coil of relay #8 is connected with a conductor I23 by a wire I23 The portable control panel CP is provided with a plurality of diagrammatically illustrated switches P P, P P P P P P P P P P preferably in the form of push buttons. Push button P which is the on-oil button, has one terminal 11 connected to a terminal of the coil of relay l5 by means of conductors 35, 36 and 31 the other terminal of said coil being connected with the ground wire 28. The movable contact 0 of relay I5 is connected to a pilot light L by means of wire 38, I21, 40, said light being grounded by wire AI in any suitable manner. Thus, the pilot light is illuminated when the relay I5 is in one position.

Relay #I5 is the on-off power supply for CP. It is of the pulsating type, operating one way on the first impulse and returning to its normal position on the second impulse. The construction of the relay is such that the life of the pulsation is not a factor in the operation of the system.

Any number of radio tuners and amplifiers may be employed but for purposes of illustration four tuners RT, RT RT, and RT*, and a phonograph amplifier one for each control panel, and four individual station amplifiers AM, AM AM and AM are shown.

Located at a convenient position is relay #9 one terminal of the coil thereof being connected with wire 28 by wire 21*, the other terminal being connected with wire H6 by wire 6*. This relay is provided with two sets of contacts t, t, t and u, u u Contacts 25, t, u and u are fixed and contacts t and u are movable and so connected as to operate in unison. Fixed contacts t and u are connected by wire '6 with the input of intercommunicatii g amplifier C. The input of amplifier C is also connected with wire 39 by a wire ".5 Fixed contacts I" and u are connected by means of a wire 1%, to the output of amplifier C. The output of amplifier C is also connected with wire 39" by wire 21. The movable contact u is connected by wire 25 with wires 28 and movable contact t is connected by a wire u with Wire 28*.

The radio tuners and amplifiers all receive their operating voltages from the common program power supply A by means of wire 45 leading from the latter, and having a branch wire 46 connected with amplifier AM the respective amplifiers AM AM and AM also being connected by wires 41, 48 and 49 respectively. Supply wire is also connected with a branch wire 50 leading to radio tuners numbered RT and RT respectively, radio tuner RT being connected with the phonograph amplifier AM by means of a wire 5|. Tuners RT RT RT and RT are connected by suitable wires 52, 53 and 54 respectively Leading from the antennae ANT is a wire 55 which is connected by branch wires 56 with the respective tuners as shown. Each of the radio tuners is provided with circuit wires (1, d respectively, said circuit wires of tuner RT being connected with line wires 60, 6I respectively, the circuit wires d, d of tuner RT being connected with wires 52 and 63, wires 11', d of RT being connected with wires 54, 55, wires d d of RT being connected with wires 56, S1 and wires (1, d of RT being connected with wires 68, 69. The phonograph amplifier AM is connected by branch wires d (1 with the wires 10 and 1| and is also connected by suitable circuit wires 12 with the phonograph pick- up F. Wires 12, 13, 14 and 15 are dead wires and are only to be used in the event that it is desired to increase the number of tuners.

Leading from the wire a is a branch wire 16 which is connected to one side of the phonograph motor G, the other side of said motor being connected by means of a wire 11 to contact s of the relay #I'I. The other contact 1' of relay I1 is connected through the wires 21 and 26 to the wire 12.

Assuming that it is desired to tune in on any desired program at station CP, the on-01f button P is depressed, thereby closing the circuit from transformer D via wire 29, wire 28, coil of relay #I5, wires 31, 36 and 35, contacts p, p of switch P wires 38 39 and 46 to transformer D. As the coil of relay #I5 is energized contacts r and s of said relay are brought into engagement, thereby closing a circuit from main input conductor a, wire 20, program power supply A, wire 23, contacts r, s of relay #I5 and return through wires 21 and 26 to return wire b. Operation of relay #I5 also closes a circuit from transformer D, through wires 29, 28, contacts 0, o of relay #I5, Wires 38 and 4!], pilot light L, wires 4!, II to ground.

Current passing through program power supply A by reason of closing of the circuit through relay #I5 connects the main power line a with wire 45 in a manner well understood in the art.

Any one of the five program selector buttons,

wardlyfor selection of a radio and button P" is pressed downwardly for selection of phonograph program. Each of said program selector switches has four contacts as, :c, x and m respectively, connected to the output of its corresponding radio tuner or the phonograph. The contact 3: of button P is connected with the wire 6 I by means of a wire 89 and the contact a: of that switch is connected with the wire 69 by means of a wire M. In a similar manner, the contacts: of each of the switches P P P P, P are respectively connected by wires 82, 88, 89, 86 and 90 with the respective wires, 62, 64, 66, i3 and 68 and the contacts x of said switches are connected with the wires 63, 65, 51, H, 69, respectivelyby wires 87, 83, '84, 9! and 85, respectively, thereby placing tuner R'I under the control of switch P the tuner RT under the control of switch P ,the tuner RT under the control of switch P the tuner RT under the control of switch P the tuner RT under the control of switch P and the phonograph amplifier under the control of switch P With the buttons of the program seiector switches in the top or open circuit positions, dummp load resistors R are arranged across the respective tuner or phonograph output circuits. Each resistor is equal to the input impedance of the room amplifier. When any program selector button is depressed, the dummy load resistor of that particular switch is disconnected from the tuner circuit and the output of the program channel is connected through to the volume control VC Contact 3: of each button is connected with the volume control by wire 39 and contact r is connected to ground by wire ll One side of the volume control V0 is connected by wire it!!! to amplifier AM the other wire llll from said amplifier being grounded through the ground wire 4 I. In the case of the station CP the output line is to the amplifier AM as stated. In a similar manner amplifier AM is connected with the portable station CP and the amplifiers AM? and AM are respectively connectedin a similar way to the respective stations CP and CP.

One side of the'output of each amplifier AM AM AM and AM is connected by means of a wire 92 with the common ground wire 39. The other-side of the output of amplifier AM is connected by means of wires S93, H13 and W4 to contact s of relay #2.

While relays #l and #2 are in normal or off position the circuit will be through contacts s', s of relay #2, wire I95, contacts 5', s of relay #l, and wire I96 to speaker LS, and return by wire I01 which is connected to the ground Wire 39. The other side of amplifier AM is connected by wires H38, H33 and H9, relays #4 and #3 which in the ofi position of the relays connects with the speaker LS through its wire Hit, the return wire In! of said speaker being connected to ground wire 39. In a similar manner, the terminals of relays #5 and #6 are placed in circuit with LS bywires H2, 105*, E96, l3! and 39; and the terminals of relays #l and #8 are placed in circuit with SP by wires 2 i95, lllii, l9? and 39. Each pair of relays #l and #2, #3 and #4, #5 and #6, and #1 and #9 are intercommunicating relays and have no bearing on the program reproduction other than to cut it off when the intercommunica- 'tion system is being used.

The portable control 0P has an interlocking device I on all intercommunication selector buttons P P P P and all program selector buttons P", P P P P and P This interlocking device is so arranged in a manner well understood in the art, that when any of the above mentioned buttons is depressed, it will be locked down until another button is depressed, whereupon the first button is released and the second button locks down. Devices of this type are very common and 5 it is not considered necessary to illustrate this type of device in detail. The two topmost buttons P and P of the i2 button control are disconnected from the interlocking device so that they do not lock down while depressed. I Each control station in the form of the invention illustratedis provided with '12 circuit closers. For instance, on control board OP twelve push buttons are shown, the button P being the press-to-talk button which functions to reverse 15 the input and output of the inter-communication amplifier by the operation of relay #9, setting up the calling speaker and the speaker whichis being called alternately as microphone and reproducer. which is pressed to initiate or terminate the radio reception and to start or stop the normal radio reception functions. of the system. Buttons P P P and P are the calling or selector buttons for u the inter-communication system, one for each 5 station on the system, P being out of use. By means of these buttons, the loud speakers at the respective stations may be selectively disconnected from the various amplifiers. For instance, the

button P controls the amplifier AM for loud BO speaker LS button P controls amplifier AM for loud speaker LS button P controls the amplifier AM for loud speaker LS button P is an extra intercommunication selector button and would normally be unconnected as shown or connected 35 to an extra station. The button 2 controls the phonograph motor through relays-ll as follows: Depression of said button closes a circuit from transformer D, wires 29, 28, ll coil of relay #ll,

wires E22, IZI, Il contacts l'l l'i' .wires l'l 40 and 4 ii to ground. By energizing the coil of relay #ll circuit is closed by contacts 7, s of said relay through wires '36, phonograph motor G, wires 11, 27, 26 and b.

Upon the depression of the button P, circuit is 45 closed from the transformer D through the wires 29, 28, 21 and the coil of relay #9, wires l W21 l6, 6 the contacts of P, and wires tile, 39, 4!),- back to transformer D. Thus, the coil of relay #9 is energized so that the movable members 5 and a of said relay are shifted in such a manner as to reverse the connections of the" sound reproducer LS, and which ever of the reproducers I (LS LS or LS may be in the circuit due to selection by depressed buttons P P or P, from 55 the input to the output of the inter-communication amplifier. f

Assuming that a person in the room where control panel CP' is located is desirous of communicating with the person in the room where 60 'control panel CP is located, he will first depress the calling button P which is the proper button to reach station'CP Depressing of the button P will close a circuit from transformer D via wires 29, 28, coil of relay #IO, wires 30, H8, IN, '65

15h, 'l5l contacts o and o of button. P and return to transformer D by wires 49 39, and

- lll "The energizing of relay #ll! closes a circuit through the intercommunication'power supply B so that power is furnished to the inter- 7o communication elements of the system. Simultaneously, a circuit is also established from transformer D via wire 29, coil of relay #6, wire l22 contacts 2:, o of button P and wires 'IEI 40 39 and 40 to the transformer.

The push button P is the on-off button #20 At the same 7 5 time another circuit is established from the transformer D via wires 29,. 28 and 21 coil-of relay #l, wires-30, H8, IEI, l5l contacts 12 o of button P and wires IEI 40 39, 40 to D. It will be observed that when the coil of relay #6 is energized the movable contact s is moved out of engagement with the fixed contact a and engages the contact 8, thereby cutting out the amplifier AM The energizing of the coil of relay #l shifts the movable contact 5 of that relay out of engagement with contact s thereby breaking the circuit at these contacts and bringing contacts 8 and 3 into engagement, thereby breaking the normal circuit to loud speaker LS and so connecting the latter with the intercommunicating amplifier C that the connections to the loud speaker LS must pass through the contacts of relay #9. The circuit will now be from the intercommunicating amplifier C through wires 2%, u, W, 28 27*, contacts .9 and s of relay #2 and to loud speaker LS through wire I05, relay #I to wire I06. At the same time circuit is established by relay #9 through wires 15 contacts t, F, wires 14 28*, H 3, contacts 8, S of relay #5 and wire I06 to loud speaker LS on control panel CP By the foregoing changes, loud speaker LS is now made to function as a'reproducer and loud speaker LS is functioning as a microphone, so that the person at control board CP is listening in to the room in which loud speaker LS is located, i. e. at control board CP Relay #9 normally functions to reverse the speakers which may have been placed in circuit therewith from the input to the output of the intercommunication amplifier C. Before the person at control board CP may talk and be heard through the loud speaker LS he must first press the pressto-talk button P on his control panel CP'. Normally, the circuits through the relay #9 are connected with the output of the intercommunication amplifier C. Energizing of the coil of relay #9 shifts the movable contacts 15 and u so as to connect the speakers with the input and output of the intercommunication amplifier in the reverse order of the normal circuits above described. A conversation may then be carried on by the originator of the call pressing the but ton P while talking, and releasing it while-listening. It will, of course, be understood that through the operation of the relays #l and #6 as just described, the programs, if any, which are being produced through speakers LS and LS are completely out off while the conversation takes place, and that when the intercommunication selector switch P is returned to normal position the programs originally being produced at both stations are replaced.

The arrangement of the circuits is such that any person at any one of the stations 0P, 0P, 0P CP may selectively communicate with any one of the other stations of the group by merely depressing the proper button P, P or P as the case may be, and operating the button P as above described. For instance, by depressing the button P the coils of relays #i, #l', #8 and #I3 are energized so as to close the circuit through intercommunicating power supply B, to cut out amplifier AM*, and to place speakers LS and LS in communication. The power circuit is closed by relay !3, and the amplifier AM is cut out by the operation of relay #8. Relay #2 functions .as has already been described in connection with the intercommunication between stations I and 2 Speakers LS and LS are connected by depressing button P thereby closing the power circuit through relay #ll, cutting out the amplifier AM? and connecting the speakers with the intercommunicating amplifier C as already described, through relays #3, #2 and #9.

The modified form of control employed in connection with the fixed wall-type panel as illustrated in connection with station CP preferably comprises four switch contact disks E E E and E secured to a rotatably mounted shaft E so that they may be actuated as a gang. In a similar manner, a two disk gang switch having contact disks E and E is provided, the same being mounted on shaft E All of the switches are shown in off position. Switches E and E are for program selection, switches E and E7 are for intercommunication control, and E designates a press-to-talk switch.

Program selector disk E is provided with six contacts arranged to engage terminals of wires 26!], 2!, 202, 293, 204 and 205, the other terminals of which are respectively connected with wires 60, 62, 64, 66, 68 and 18. Disk E is also provided with six contacts arranged to engage terminals of wires 209 20W, 202 263 2M and 295 the other terminals of which are connected with wires (ii, 63, 65, 6'5, 69 and- TI. Dummy resistors 206 similarto those shown on panel CP' may be provided.

Plate E which is the phonograph on and oif switch, contains six contacts which are selectively brought into engagement with one terminal of a wire 26'], the six contacts corresponding to the positions of said disk when rotated with shaft E The other terminal of wire 20'! is connected with wire 52! so as to be placed in circuit with the coil of relay #Il whereby the latter may be caused to function in the same manner as described in connection with push button P Plate "E cooperates with the power on-ofi switch E Said plate is provided with six contacts corresponding to the number of positions of the disk when rotated with disks E and E so that at least one of a plurality leads 298 is at all times in engagement with a contact. Leads 298 are connected with a wire 209 the other end of which is connected to wire I24 so as to control the circuit to coil of relay #IS. Closing the circuit through any of the leads 2288 establishes a circuit from transformer D, wires 29, 28, coil #16, wires 125, I2 3, 289, switch E wires 2, 39, 438* to transformer D. Relay #16 closes circuit from program power supply A via wires 23,

21 contacts r, 8, wires 21, and 25 to return wire b. One terminal of switch E is connected with disk E by wire 2H], and said last mentioned wire is connected with wire 39 by means of a wire 2H. The other terminal of switch E is connected by a wire 212 with wirel IS. The operation of switch E is the same as that already described in connection with switch P.

Disks E and E are each provided with four active contacts corresponding to the number of stations in the system. The contacts of disk E are arranged to engage terminals of wires H5, H6, 2i"! and 2H8, respectively. The other ends of said wires are connected respectively with wires H7, H9, !22 and H3. The contacts of disk E are all connected to leads 219 connecting with one terminal of the wire 220 the other terminal of which is connected with wire I26. The circuits are the same as heretofore described in connection with push buttons P F, P and P The advantages of the invention willcbe readily understood by those skilled in the art to which it appertains. For instance, it will be observed that very simple and efiective means is provided for oral intercommunication between any two stations of a multistation receiving system without in any manner disturbing the normal functions of any of the other stations. A further advantage is that just as soon as the temporary constructing and using the same, although without attempting to set forth alloi the forms in which it may be made, or all of the forms of its use, what is claimed is:

l. A multiunit radio receiving system comprising a plurality of receiving units o-peratively connected with a radio receiving circuit, each unit including a sound reproducing device and its cir cuit, an intercommunication power circuit means commonto all of said receiving. units, means selectively controllable at each unit for "connecting the sound reproducing device of the same unit and the sound reproducing device of any other preselected unit with said intercommunication power circuit, and means associated with each unit for changing the direction of current fiow through its sound reproducing device and-the preselected sound reproducing device while'said devices are included in said intercommunication power circuit. i

a 2. A multiunit radio receiving system. comprising a plurality of receiving unitsoperatively connected with a radio receiving circuit, each unit including a sound reproducing device and its circuit, an intercommunication power circuit means common to all of said receiving units, means selectively controllable at each unit for disconnecting the sound reproducing device of that unit and of any other preselected unitfrom their respective circuits, said means also including means for connecting the said two sound reproducing devices with said intercommunication power circuit simultaneously with the breaking of the sound-reproducing circuits, and means controllable at each station for reversing the direction of current flow through said two sound reproducing devices while the latter are connected with said intercommunication power circuit.

3.. A multiunit radio receiving system comprising a plurality of receiving units operatively connected with a radio receiving crcuit, each unit including a sound reproducing device and its circuit, an intercommunication power circuit means common to all of said receiving units, means selectively controllable at each unit for connecting the speaker of the same unit and the speaker of any other preselected unit with said intercommunication power circuit, means associated with each unit for changing the direction of current flow through its sound. reproducing device as wellas the sound-reproducing device of the preselected unit, while they are included in said intercommunication power circuit, and

means .for connecting said intercommunication power circuit with a source of electrical energy simultaneously with the interruption of the. normal current flow through the sound reproducing devices.

4'. A multiunit radio receiving system, comprising a plurality of receiving units operatively connected with a radio receiving circuit, eachunit including a sound reproducing device and its circuit and a plurality of program-selection'devices,:.10 means for controlling the volume of selected program reproduction, an intercommunicationpower circuit means common to all ofsaid receiving units, control means associated with each unit for disconnecting the sound reproducing deviceof the same unit as well as the sound reproducing device of any other preselected unit from the program selection means, means controllable at each unit for connecting the sound reproducing device of the same unit and the sound I'GPI'OdUC-gfio ing device of the preselected unit with said intercommunication power circuit, and means associated with each unitforv changing the direction of current fiow through the sound reproducing devices while the latter are included in said inter-.7 5 communication power circuit.

5. A multiunit radio receiving system comprising a plurality of. receiving units operatively connected with a radio receiving circuit, means providing a normal amplifier circuit for each unit ao a sound reproducing'device associated with each unit and included in the normal amplifier circuit of thesame unit, an intercommunication power circuit means common to all of said receiving units, means providing" an intercommunication 3-5 amplifier circuit connected with said intercommunication power circuit and also connected with the several normal amplifiercircuits of. the respective units, means selectively controllable at each unit for disconnecting. the sound reproducing .40 device of the same unit from its normal amplifier circuit and also disconnecting the sound repro-- ducing device of any other; preselected unit from its normal amplifier circuit, said selective means also including means for connecting said disconnected sound reproducing devices-with said intercommunication amplifier circuit, and means associated with each unitfor changing the direction of current flow through its sound reproducing device and the preselected'sound reproducing device while said devices are included in said' intercommunication amplifier circuit.

6. A multiunit radio receiving system comprising a plurality of receiving unitsoperatively connected with a radio receiving circuit, means pro- ,5 5

viding a normal amplifier circuit for eachunit, a

sound. reproducing device associated with each unit and included in the normal amplifier circuit of the same unit, an intercommunication amplifier circuit means common to all of said receiving units, means for breaking each of said normal amplifier circuits, means for connecting each sound reproducing device to thcintercommunication amplifying, circuit, means at each circuit for controlling the circuit breaking means 5 of its amplifier circuit and the connecting means of the sound reproducing device of any other preselected unitwith said intercommunication amplifier circuit, and means associated with each unit for changing the direction of current fiow 7 0 through the soundreproducing device of the same unit and also through the preselected sound reproducing devicewhile said devices are included in said intercommunication amplifier circuit. {7 5 7. A multiunit radio receiving system comprising a plurality of receiving units operatively connected with a radio receiving circuit, means providing a normal amplifier circuit for each unit, a sound reproducing device associated with each unit and included in the normal amplifier circuit of the same unit, an intercommunication amplifier circuit means common to all of said receiving units, means for breaking each of said normal amplifier circuits, means for connecting each sound reproducing device to the intercommunication amplifier circuit, means for connecting said intercommunication amplifier circuit with a source of current supply, means at each unit for controlling the circuit breaking means oi. its amplifier circuit and for controlling the connecting means of the sound reproducing device of any other preselected unit with said intercommunication amplifier circuit, and also for controlling the means for connecting the intercommunication amplifier circuit with said source of current supply, and means associated with each unit for changing the direction of current flow through the sound reproducing device of the same unit and also through the sound reproducing device of any preselected unit while said devices are included in said intercommunication amplifier circuit.

8. A multiunit radio receiving system comprising a plurality of receiving units operatively connected with a radio receiving circuit, each unit including a sound reproducing device and its circuit, an intercommunication power circuit means common to all of said receiving units, means at each unit for breaking the circuits of the sound reproducing device of the same unit, and also for breaking the sound reproducer circuit of the sound reproducing device of. any other preselected unit, means for connecting the disabled sound reproducing devices with said intercommunication power circuit, a common control means associated with each unit for simultaneously actuating the means for breaking the said sound reproducer circuits and the means for connecting the disabled sound reproducing devices with the intercommunication power circuit, and means associated with each unit for changing the current flow through the sound reproducing device of the same unit while the previously disabled sound reproducers are connected With said intercommunication power circuit.

9. A multiunit radio receiving system comprising a plurality of receiving units operatively connected with a radio receiving circuit, each unit including a sound reproducing device and its circuit, an intercommunication power circuit means common to all of said receiving units, a relay controlling said intercommunication power circuit, said relay having reversing contacts, means associated with each unit for breaking the first mentioned sound reproducer circuit of said unit, means associated with each unit for connecting one terminal of its sound reproducing device with said relay, means at each unit for actuating the circuit breaking means of the sound reproducer circuit of the same unit and the sound reproducer circuit of any other preselected unit, and means associated with each unit for energizing said relay so as to reverse the normal fiow of the current through said intercommunication power circuit and the sound reproducing devices connected therewith.

10. A multiunit radio receiving system comprising a plurality of receiving units operatively connected with a radio receiving circuit, each unit including a normal amplifier circuit and a sound reproducing device in said circuit, an intercommunication amplifier circuit means common to all of said receiving units, a relay having reversing contacts connected with said intercommunication amplifier circuit, a circuit breaker connected with one terminal of each sound reproducer circuit and also connected with said relay, means associated with each unit for actuating the circuit breaker in the circuit of the loud speaker of the same unit and also for operating the circuit breaker in the circuit of the loud speaker at any other preselected unit, and means associated with each unit for energizing said relay, so as to selectively reverse the current fiow through said sound reproducing devices while they are connected with said intercommunication amplifier circuit.

11. A multiunit radio receiving system comprising a plurality of receiving units operatively connected with the radio input circuit, an amplifier circuit for each unit including a normally closed circuit breaker, a sound reproducing device for each unit including a circuit having a normally closed circuit breaker connected with one of its terminals, an intercommunicating power circuit means common to all of said receiving units, an intercommunication amplifier connected with the first mentioned amplifier circuits and also with said intercommunication power circuit, a reversing relay connected with said intercommunication amplifying circuit, means connecting said reversing relay with the circuit of each sound reproducing devices, means associated with each unit for operating the first mentioned normally closed contacts to break the circuit to the sound reproducingdevice of the same unit, to break circuit to the sound reproducing device of any other preselected unit, and also to break the amplifier circuit of said preselected unit, and control means associated with each unit for actuating said reversing relay, whereby the flow of current through the sound reproducing devices may be reversed while said devices are connected with said intercommunication power circuit.

12. A multiunit radio receiving system comprising a plurality of receiving units operatively connected with a common radio input circuit, each unit including a reproducing device and its operating circuit, a volume control circuit for each unit, normally closed contacts connected with one of the terminals of each of said sound reproducing devices, an intercommunication amplifier circuit means common to all of said receiving units, normally closed contacts in each of said sound reproducer circuits, a reversing relay having reversing contacts connected with the intercommunication amplifier circuit, means for connecting said relay contacts with a terminal of each of the sound reproducing devices, means for operating the circuit breakers to break the circuit to the sound reproducing device of said unit and to connect the same with said relay, and also to selectively break the circuits to the sound reproducing device of any other preselected unit,

terminals connected with a sound reproducing circuit, a volume control circuit for each unit, a pair of relays associated with each unit, one of said relays of each unit being so connected with a terminal of the sound reproducing device of the same unit as to normally maintain a closed circuit to the latter, the other of said relays being connected with the volume control circuit of the same unit, an intercommunication amplifier circuit means common to all of said receiving units,

a relay having reversing contacts connected with said intercommunication amplifier circuits, means connecting the contacts of said relay with the contacts of each of said pairs of relays, so as to break the normal circuit to the affected sound reproducing device of that unit and also to break the normal volume control circuit of the preselected unit, and to establish circuit connections with the intercommunication amplifier circuit, and means associated with each unit for actuating the reversing relay of the intercommunication amplifier circuit, whereby flow of current through the sound reproducing device of a unit may be controllably reversed.

14. A multiunit radio receiving system comprising a plurality of. receiving units operatively connected with a common radio input circuit, a sound reproducing device for each unit having terminals connected with a sound reproducing circuit, a volume control circuit for each unit, a reversing relay, a set of relays for each unit, one being a speaker control relay and the other a control relay, said last mentioned relays each having two fixed contacts and one movable contact, the movable contact of the speaker control relay being connected with one terminal of the sound reproducer circuit of the same unit, one of the fixed contacts of the speaker control relay being connected with the movable contact of the volume control relay, the other fixed contact of the speaker control relay being connected with a terminal of the reversing relay, one fixed contact of the volume control relay beim connected to the opposite side of said reversing relay, and the other fixed contact of the volume control relay being connected with the volume control circuit of the same relay, a single operating device at each unit having means controlling the circuits to the speaker control relay of the same unit and the volume control relay of any other preselected unit, so as to break the speaker control and volume control circuits of the two last mentioned relays and to place them in circuit with the reversing relay, and means associated with each unit for energizing said reversing relay whereby flow of current through the previously disabled sound reproducing devices may be controllably reversed.

15. In a multistation system, a plurality of program-selector units, means selectively controlled at each station for operatively connecting the station with any one of said program selector units, while the selected unit is operatively connected with any or all of the other stations, and in such manner that the sound-volume-producing-functions of said selected unit remain practically unimpaired irrespective of the number of stations connected therewith.

16. In a multistation system, a plurality of program-selector units, a plurality of operating circuits for the respective units there being one circuit for each unit, a'plurality of circuit closers at each station selectively controlling all of said circuits, said circuits and'their circuit closers being so arranged that any one of the programselector units may be selectively connected with any station while the selected unit is operatively connected with any one or' all of the other stations, and in such manner that the sound-volume-producing-functions of the selected unit remain practically unimpaired irrespective of the number of stations connected therewith.

17. In a multistation system, a plurality of program-selector units, means selectively controlled at each station for operativeiy connecting the station with any one of said program selector units, while the selected unit is operatively connected with any or all of the other stations, and in such manner that the sound reproduction functions of the various stations remain prac tically unimpaired irrespective of the number of stations connected therewith.

18. In a multistation system, a sound-reproducing element at each station, a plurality of program selection units, selective means at each station for operatively connecting the sound reproducing element with any one of said program selection units while said unit is operatively connected with any or all of the other stations, and

, in such manner that the sound-volume-produoing functions of the selected unit remain practically unimpaired irrespective of the number of stations connected-therewith. l

19. In a multistation system, a sound-reproducing element at each station, a plurality of program selection units, selective means at each station for operatively connecting the sound reproducing element with any one of said program selection units while said unit is operatively connected with any or all of the other stations, and in such manner that thesound-volume-producing functions of the various sta ions remain practically unimpaired irrespective of the number of stations connected therewith.

RAYMOND KIMBALL.

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