US2160829A

US2160829A - Method and device for auxiliary transmission for telephone receivers

Info

Publication number: US2160829A
Application number: US36809A
Authority: US
Inventors: Carl W Cherry
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-08-19
Filing date: 1935-08-19
Publication date: 1939-06-06
Anticipated expiration: 1956-06-06

Description

c. w. CHERRY METHOD AND DEVICE FOR AUXILIARY TRANSMISSION FOR TELEPHONE RECEIVERS June 6, 1939.

3 Sheets-Sheet 1 Filed Aug. 19, 1935 All M M n In": ullnlll ATTORNEY June 6,1939. c w CHERRY 2,160,829

METHOD AND DEVICE FOR AUXILIARY TRANSMISSION -FOR TELEPHONE RECEIVERS Filed Aug. 19, 1935 :5 Sheets-Shet 2 'dmzo 5. Q2 65 ATTORNEY June 6, 1939. c w H Y 2,160,829

METHOD AND DEVICE FOR AUXILIARY TRANSMISSION FOR TELEPHONE RECEIVERS Filed Aug. 19, 1935 s Sheets-Sheet s INVENTOR (Am w. CHERRY avg a ATTORNEY Y Patented June 6, 1939 PATENT OFFICE METHOD AND DEVICE FOR FOR TELEPHONE RE-' TRAN SMIS SION CEIVERS AUXILIARY Carl W. Cherry, Camel, Calif. Application August 19, 1935, Serial No. 36,809

24 Claims.

This invention relates to a device and method for transmitting the signal from a usual telephone to, a point outside the usual receiver.

'Ijhe primary object of the invention is to pro- 5 vide a method whereby the signal impulses or current of a usual telephone receiver may be utilized to issue'the sound through a' receiver other than the usual receiver.

\ Another object of the invention is to provide a method for the transmission and amplifying of the diaphragm actuating impulses-or current of a usual telephone receiver so as to accomplish reception in an auxiliary receiver whereby the conversation or sound can be heard by persons to whom the signals in the usual receiver would not be normally audible.

Another object of. the invention is to provide an apparatus or device which can be attached to the usual telephone receiver so that the usual diaphragm-actuating current in the telephone receiver operates an auxiliary circuit and an auxiliary sound producing mechanism.

A further object of the invention is to provide a device and method which is applicable to a usual telephone receiver so as to allow the witnessing or recordation of the signal or sound transmitted through the telephone by the use of. the usual diaphragm-actuating impulses of said ordinary telephone.

Another object of this invention is to provide a method and device for auxiliary transmission for telephone receivers which is highly useful and simple in construction. Convenience of ar rangement, lightness and con'iparative inexpense of manufacture-are further objects which have been borne in mind in the production and development of the invention.

I am aware that some changes may be made in the general arrangements and combinations of the several devices and parts, as well as in the details of the construction thereof without departing from the scope of the present invention as set forth in the following specification, and as defined in the following claims; hence I do not limit my invention to the exact arrangements and combinations of the said device and parts as described in the said specification, nor do I confine myself to the exact details of the construccompanying drawings.

With the foregoing and other objects in view, which will be made manifest in the following detailed description and specifically pointed out in the appended claims, reference is had to the action of the said'parts as illustrated ,in the accompanying drawings for the illustrative embodiment of the invention, wherein,

Figure l is a somewhat diagrammatic view of an illustrative .embodiment of my device connected to a usual telephone receiver.

Figure 2 is an enlarged view of the attachment rest on the top of the amplifier of my device, being shown partly in section.

Figure 3 is a sectional view of a clamped attachment on a telephone receiver.

-Figure 4'is a detailed view of the coils of the usual telephone receiver and of. my attachment in their relative operative position.

Figure 5 is an end view of a telephone receiver partly in section showing a modified embodiment 15 of my device attached to the same.

Figure 6 is a perspective view of coils used in my device.

Figure 7 is a perspective detailed view of the double core of my device.

Figure 8 is a face view of a mounting disc of by device.

Figure 9 is a face view of a mounting and connection disc of my device.

Figure 10 is an end view of the attachment 25 part of my device, the cover and the coils being removed.

Figure 11 is an end view of a telephone receiver with an attachment, partly in'section and an auxiliary attachment on said receiver con- 30 nected to a remote telephone receiver.

Figure 12 is a wiring diagram of my apparatus and method showing the connection of the current of the usual telephone receiver to an auxiliary receiver.

Figure 13 is a wiring diagram of the embodiment of my invention as shown in Figure 11.

Figure 14 is a wiring diagram of. another modification of my invention, and

Figure 15 is another modified embodiment of 40 my invention. I

It is frequently desirable that the signals or voice-from the usual telephone be amplified or rendered audible outside of the usual telephone receiver. For example it is extremely important I! in many instances. that there shall be a witness or witnesses to a telephone conversation. The use of an extension telephone for such purposes is impractical because the person would have to stop the conversation until the extension receiver is lifted off the hook, furthermore a click or some noise or fading is noticeable on the telephone line as soon'as an extension is interconnected'on the line. Another example for need of some amplification is for deaf persons. 1

one of the adjustment and use to suit changing conditions and. DUIPOSGS Of use.

In my method and device I utilize the usual diaphragm-actuating current or electric impulses, of a telephone receiver by the use of an auxiliary electric circuit which is adapted to receive and transmit the usual diaphragmactuating electric impulses of a telephone receiver, and to modify said current so as to suit the pur-- pose for which the received signal or sound is used. This auxiliary circuit is adapted in some embodiments to operate when the usual dia phragm is in place. In other forms the usual diaphragm may be removed and the input elements of said auxiliary circuit are substituted therefor.

In the event it is desired that a number of persons should witness the conversation at a remote point from the usual telephone receiver, then the secondary circuit is adapted to operate a loud speaker. For the purpose of recording of the conversation this secondary circuit can reproduce the sound in the dictating tube of a so-called dictaphone or the like. In order to allow witnesses to listen in on a conversation in private the secondary circuit can be adapted to operate on one or more auxiliary earphones. For aiding persons who are hard of hearing amplified signals can be transmitted to an auxiliary earphone. The above and other uses of this method and auxiliary device are accomplished without any interference with the usual telephone service, and without any necessity of replacement of the usual telephone equipment, ex-

cepting in some cases the removal of the usual magnetic flux caused by the usual diaphragmactuating impulses of the telephone receiver, are

, placed opposite the outside face of the diaphragm,

or in some cases the diaphragm is removed and replaced by said elements. Then the secondary current so created is transmitted and modified to operate an auxiliary sound producing device. The usual diaphragm is preferably replaced by secohdary coils which coincide with and complement the usual diaphragm-actuating coils of a telephone receiver, so that theelectric impulses in the usual receiver coils induce corresponding electro-motive force in the secondary coils of my attachment. Then said induced current is suitably amplified, and the amplification controlled to suit the purpose. The modified or amplified, induced current is then conducted to one or more auxiliary diaphragm-actuating devices in auxil iary telephone receivers, or in loud speakers or in sound recording instruments, as the-case may be. It may be said, that by the above method, the usual diaphragm actuating coils of a-telephone receiver are converted into primary coils and my device completes the magnetic circuit and supplies secondary coils of a transformer and the current so induced operates an auxiliary sound producing apparatus.

My device in general includes an attachment member l8, preferably detachably connected to the telephone receiver l8. The diaphragm'is left rubber, or similar composition.

in place but is prevented, by means shown later, from vibrating. The mechanism in the attachment member I8 is connected by a cord 2| to an amplifier and loud speaker unit 22, as shown in Figure 1, or to auxiliary telephone receivers 23, as shown in Figure 11.

In detail the usual telephone receiver I9 includes an externally threaded housing 24, within which is mounted a magnet 26, and the usual electro-magnetic coils 21. Usually each of the .coils 21 has a substantially 'L shaped core 28 forming a pole of the magnet 26, the legs of which cores 28 point to the. usual diaphragm, which latter is normally held on the face of the housing 24 by an internally threaded hard-rubber, or composition ear piece 29 centrally apertured opposite said coils 21.

The attachment member |8 includes a base 3|, made of an insulating material, such as hard If the earpiece 29 has the usual perforated cover over its central aperture then an auxiliary earpiece 32, with a fully open central aperture 33 is also provided with my device to replace the usual earpiece 29.

The form of the attachment illustrated in Figures 2 and 3 includes a tubular bushing 3 with a head 36. The bushing 34 is inserted through a central hole 31 in the base 3| substantially opposite the receiver coils'2'l. Inside the bushing 34 are induction coils 3B wound around a double, or U shaped core 39, which latter in turn is so secured in place that the legs of the core 39 point toward the aperture 33. A thin-insulating disc. such as a mica-disc 4| may be placed between the coils 21 and the coils 38 when the diaphragm is removed. The bushing head 36 rests on a ring 42 and is held in. place by a suitable clamp 43. from turning by a prong 44 inwardly projecting from the ring 42 into a slot 46 cut into the outer periphery of the head 36. cated in alignment withthe center between the legs of the core 39. Therefore the legs of the core 39 can-be aligned with those of the core 28 by turning the ring 42 on the shoulder 41 of the base 3|, while the bushing 34 is removed, so that the prong 44 is in line centrally between the spaced legs of the core 28. Then the bushing 34 is clamped in place so that the slot 46 slides over the prong 44thereby locating the legs of the core 39 exactly in registry with the corresponding legs of the core 28. The ring 42 is also held fixed by the same clamp 43, as the bushing head 36. The clamp 43 is slightly resilient where it engages the head 36 to allow slight axial play of the entire bushing 34. A light spring 48 bears at one end against the center of the bushing head 36 and at its other end against an insulating cover 49 to urge the bushing 34 at all times toward the coils 28, and against the usual diaphragm, to hold the latter against the coils 28 and prevent its vibration. The cover 49 is secured to the base 3| in any suitable manner such as by screws 5|. It is to be noted that both the outer face of the base 3| and the inner face of the cover 49 are recessed to accommodate the head of the bushing, its holding means and suitable wiring. In addition the base 3| has a radial hole 52 leading from the side of the recess of said. base 3| to accommodate a suitable cord 2|, the wires of which latter are suitably connected to the ends of the respective coils 38.

The entire attachment is clamped on the earpiece 29 or 32,]as the case may be, by a spring wire clamp 54, which is journalled in the sides This slot 46 is 10-- The bushing is prevented of the base 3| andis so bent as to spring over the end of the earpiece 29 or 32 and hold the attachment in place.

Another form of auxiliary attachment is illustrated in Fig. 5. In this embodiment the usual diaphragm, and also the earpiece 29 is removed from the telephone receiver. A base 56, of suitable insulating material, is internally threaded at 51 so as to fit over. the receiver housing 24 in place of the earpiece 29. ,The other face of the base 51 is recessed at 59 to accommodate an insulating ring 59. The outer end of the ring 59 is reduced in its outer diameter and the shoulder thus produced is engaged at diametrically opposite points by the heads of retainer screws 6|, which latter are threaded into the base 56 at the bottom of the recess outside the periphery of the ring 59. The central aperture 62 of the ring 59 is in aiignmentwith a central aperture v63 in the base 56 but the ring 59 can be turned in the recess 58. The outer face of the ring 59 has a marking, such as a colored or white dot 64 thereon and a pair of threaded screw holes 66, which latter are on, a diameter at right angles to the radius leading to said marker .dot 64; Before the screws 6| are tightened the ring 59 is turned around so that the marker dot 64 appears exactly between the coils 21 of the telephone receiver I8. This can be observed as shown'in Fig. 10. Then by tightening the screws 6| the ring 59 is fixed in its adjusted position. Then on the ring 59 is secured a unit which includes a resiliently flexible disc 61 the screw holes- 69 of which are spaced to register with the screw holes 66 of the ring 59. Another aperture 69 is so located on the disc 61 that it coincides with the marker dot 64 when 1 the screw holes 69 of the disc 61 are in registry with the respective screw holes 66 of the ring 59. The disc 61 is so apertured that a diametrical strip 1| is formed in alignment with the marker aperture 69. The base of the U-shaped core 39 of the secondary coils 39 is so mounted on the strip 1| that the legs of the core 39 are equally spaced on the opposite sides of the "center line of the strip- Consequently when the coils 39 are inserted in the ring 59 and the disc 61 is turned so that respective screw holes 69 and 66 are in alignment then the marker dot 64 shows through the marker aperture 69 and the coils 39 are in exact registry with the coils 21 of the receiver. The

disc 61 is held on the ring 59 by the usual screws 12. -An insulating disc 13 is on the outer face of the disc 61 and the core 39- is secured to the strip 1| by screws 14 which extend also throughthe insulating disc 13; There are two small metal eyelets 16 in the disc 13 opposite the cut away portions of the disc 61 for the connecting and lead wires irom the coils 39. After the unit is posite each other.

thus assembled it is covered by an insulating cov-, er 11 which is suitably secured to the base 56. A hole 18 through the side of the cover 11 accommodates the usual electric cord 2|.

Either one, of the ai'oredescrlbed attachments can be readily attached to a receiver, and once the coils 39 are properly adjusted in the attachment,

The cord 2| is detachably connected to the usual terminals 19 of the amplifier unit 22. It is to be noted that the amplifier 22 has a switch8| thereon whereby the power circuit can be opened or closed at will. The amplifier 22 alsohas the usual volunie control92. On the top of the amplifier 22 is a rest or bracket 93 for the attachment l8 when the latter is not in use." This rest,

as shown in Fig. 2 is adapted for the type of attachment shown in Fig. 3, and it is made of insulating material. A central bore 64 therein accommodates the bushing 34.-' In thebore 84 is an,

automatic switch which includes a fixed contact 96 and an insulating plug 81 having a contact 98 thereon. The plug 81 slidable in the bore 94 and is normally urged upwardly bya coil spring 89 so as to urge the contact 98 into engagement with the contact 86 thereby closing the amplifier circuit therethrough. When the attachment I8 is clamped onto the bracket 83 then the bushing 34 pushes the plug 94 downwardly and holds it in its down position, thereby automatically breaking the amplifier circuit. When the attachment is removed from the bracket 93 the amplifier circuit is automatically closed. The switch 8| is used in connection with other forms of the attachment.

In operation the diaphragm-actuating impulses of the coil. 21 induce an electro-motive force in the coils 39. The induced current then'flows through the circuit of the amplifier 22, and is audible through the usual loudspeaker opening 89.

Thus the conversation can be heard by several witnesses at the same time. This "does not interthe transmission so that a person may speak from a certain distance away from the transmitter yet be clearly heard at the other end of the line. If

the loudspeaker is remote from the transmitter,

or another loudspeaker or receiver in an entirelydifferent room is connected into the circuit, the

entire two-way conversation is audible and can.

fere with the transmitter part of the telephone,--

in fact, actual practice shows that it augments ation as the type of attachment shown in Fig. 5, v heretofore described in detail. The only difference is that an externally threaded boss 92 is provided on the free face of the base 56 and instead of the cover 11 an auxiliary receiver housing 93 is threaded on said boss 92, back to back with respect 'to the base 56. In this housing is.

the usual permanent magnet 94, and receiver coils 96. The legs of the core 91' in the coils 96 point-away from'the coils 38. One of the coils 38 is connected to oneof the coils 96, by a conduit 99, as shown in Fig. 13, and the other coil of each pair is connected to the wires of acord 99, which latter leads to-the usual coils of the usual earphone 23, or any other auxiliary receiver. On the housing 92 is threadedly secured a suitable, insulating earplece l9i, which holds in place the usual diaphragm I92 at the ends of the coils 96. Thus the usual receiver l9 can be used in the customary manner/yet a' witness is enabled to listen in on the entire conversation and record it if necessary through the auxiliary earphone 23. If more than one auxiliary line'is required a'suitable amplifier may be interconnected between the coils 39 and the coils of the respective auxiliary receivers.

The attachment described'in' Fig. 11, may be used also for selective connection with a loud 18 speaker, or other-recording device requiring an amplifier, by the connections shown in the wiring diagram in Fig. 14. In this embodiment one of the secondary coils 38 is connected by a wire Another 1 plifier 22. A wire I06 shunts the wireI03 directly without amplification.

the amplifier.

over to one of-the coils 96. Wires I01 and' I08. lead respectively from the

other coils

38 and 96. f

A switch I09 is adapted 'to selectively connect the wire-I0'I either to the amplifierlead I04, or to the other wire I08. In the former case the coils 96 are inoperative because the current flows from the coils 38 through the wires I03, I01, and I04 to theamplifier and the conversation is heard through the auxiliary speaker in the amplifier circuit. On the other hand when the switch I09 closes the circuit between the wires I01 and I08, then the-auxiliary circuit flows through the coils 96 and conversation may be had in a normal way. The switch I09 isa double switch namely the second contact III therein breaks and makes the circuit between the power lines I I2 and H3 which supply the electricity for The switch I09 and contact III operate simultaneously so that when the wire I01 is connected to wire I04, the circuit through lines I I2 and H3 is also closed, and when the wires I01 and I08 are'connected then the amplifier power supply circuit is also opened. Thus the conversation can be shifted to a loud speaker or thelike at will.

The .unit shown in Fig. 11 may be also used so as to selectively connect or disconnect an ampliher in the circuit of the coils 96. This form is especially adapted to amplify the sound only when a louder signal is required in the receiver, for instance to accommodate deaf people. shown in the wiring diagram in Fig. 15, the wires H4 and H6 lead from the coils 38, and the wires I I7 and H8 lead from the coils 90 of the auxiliary receiver. The wiresllll and H6 are at all times connected to the lead-in terminals of the usual amplifier 22, and the wires I I7 and I I8 are always connected to the output terminals of the amplifier 22. A triple switch H9 is adapted, however, to simultaneously close "the circuit fromthe wire IIB to the wire Ill, and from the wire Ild to the wire H8, and also simultaneously to break the circuit in the power supply line I 2| of the amplifier, rendering the latter inoperative. In this position of the switch N9 the unit is used When the switch H9 breaks the above circuit between'the wires IIS and Ill, and H4 and H8, it simultaneously closes the power supply circuit through the power supply line I2I and the current then fiows to the wires Ill and H8 of the auxiliary coils 9% from the amplifier 22.

While the amplifier 22 may be of any suitable circuit, by way of illustration, in Figure 12, is shown the wiring diagram of an amplifier with four electron tubes I22. The coils 38 are connected to the transformer I23 of the amplifier circuit so as to impress the electric impulses flowing through the coils 38, upon the electric circuits of the grids I26 of said electron tubes. The power supply is connected through the power unit I26 to the electric circuits ofthe filaments I21 and plates I28 of the amplifying circuit. The impulse so amplified flows through the transformer I29 which impresses it on the coils or electromagnets of a loud speaker I3I, or of any sound reproducing or recording device, so as to operate a usual diaphragm in the latter.

The method and device herein described is simple and light, it is easy to attach and detach from the usual telephone receiver, without necessitating interference or connection with the telephone circuit or equipment It can be put into operation so that it will not be noticeable at the transmitter end of the line. After the initial adjustment of the auxiliary coils to align with the usual coils of the normal telephone receiver, there is no further adjustment required, therefore it can be easily handled, connected, and operated by the average layman. r

Having thus described my invention what I claim and desire to secure by Letters Patent is:

1. A device for producing amplified sound from a usual telephone receiver, comprising electro responsive means positioned in place of' the usual diaphragm of said receiver so as to be actuated by the usual diaphragm-actuating current impulses of said receiver, sound producing means to be operated by said electroresponsive means, means to transmit to said'sound producing means the action of said electro-responsive means, and an element to hold said electro-responsive means in the place of said diaphragm within the usual telephone receiver.

2. A device for producing amplified sound from a usual telephone receiver, comprising electro-responsive means actuated by the usual diaphragm-actuating current of said receiver to take the place of the diaphragm of said receiver so as to be acted upon by said current, means to amplify the action of said electro-responsive means, sound producing means to be operated by said electro-responsive means, means to transmit to said sound producing means the amplified action of said electro-responsive means, and an elementto hold said electro-responsive means in operative relation within the usual telephone receiver, and means to detachably secure said element in place on said usual telephone receiver.

3. An auxiliary device for the usual telephone receiver, comprising induction coils positioned in extension of the ends of the usual diaphragmactuating coils of said receiver, an auxiliary re ceiver adapted to convert electric current varitioned opposite to and in registry with the dia- V phragm-actuating means on said receiver so as to supplement the same into a transformer circuit, means to hold said coils in operative rela tion to said diaphragm actuating means in the place and position of the usual diaphragm of said receiver, so that said diaphragm actuating means can impress an electromotive force on said coils, an electrically actuated auxiliary diaphragm, and means to transmit said electromotive force from said coils to said electrically actuated, auxiliary diaphragm.

5. Inan auxiliary device for the usual telephone receiver comprising, an electrically actuated aum'liary receiver, and means to transmit the action of the receiving current from the usual telephone receiver to said auxiliary receiver, said meansincluding secondary coils positioned adjacent to and in alignment with the ends of the tive alignment within said usual telephone receiver.

6. An'attachment for a usual telephone receiver, comprising a housing adapted to be attached to the receiver opposite the diaphragmactuating coils of the receiver, induction coils held in the housing so as to be aligned with the coils f the receiver when the housing is in place and adapted to be impressed with an electromotive force according to the usual diaphragm-actuating impulses in said coils of the receiver, an auxiliary to and-aligned with said magnetic coils so as to bev impressed with electromotive force by the usual diaphragm-actuating impulses of said electromagnetic coils, means to hold said induction coils in operative. relation to said electromagnets, and

means connected to said induction coils to produce sound in accordance with the current in said induction coils.

8. The combination with a usual telephone receiver having electro-magnetic coils to actuate the usual diaphragm; of an attachment substituted into said receiver in place of said diaphragm, and comprising induction coils aligned with said electro-magnetic coils so as to be impressed with electromotive force by the usual diephragm-actuating impulses of said electromagnetic coils, means to hold said induction coils in operative relation to said electro-magnets, and means connected to said induction coils to produce sound in accordance with the current in said induction coils, said induction coils being so disposed thatthe cores of the induction coils when in place are in registry with the cores of the respective electromagnets in said receiver.

9. The combination with a usual telephone receiver having electro-magnetic coils to actuate the usual diaphragm: of an attachment substituted into said receiver in place -of said diaphragm, and comprising induction coils aligned with and opposite to said magnetic coils so as to be impressed with electromotive force bythe usual diaphragm-actuating impulses of said electro-magnetic coils, means to hold said induction coils in operative relation to said electromagnets, a current amplifying device connected to said induction coils, and means connected to said amplifier to convert said amplified electric current into sound.

10. The combination with a usual telephone receiver. which contains electro-magnetic coils to actuate a diaphragm, and means to fix the diaphragm at its periphery, of means to engage said diaphragm so as to prevent its vibration, induction coils adjacent said diaphragm opposite said electro-magnetic coils so arranged as to be impressed with inducedcurrent by said electro- A magnetic coils, means to actuate the diaphragm of an auxiliary receiver, and means to convey said induced current from said induction coils to said last actuating means.

11. The combination with a usual telephone receiver having a vibratory diaphragm and electro-magnetic-means at one side of the diaphragm to vibrate the latter, of means to render said dia-c phragm non-vibratory, induction means held on the side of the diaphragm so as to be with induced current by said electro-magnetic means, means to actuate the diaphragm of ,an auxiliary receiver, and means to convey said induced current from said induction means to said last actuating means. I

12. The combination with a usual telephone receiver having electro-magnetic means adapted to actuate a sound producing element, and an electrically operated auxiliary sound-producing device, of induction means held in operative relation to, said electro-magnetic means so as to be impressed with the ends of the pole pieces of induced current by. the latter, a current amplifier, and means to selectively convey said induced current to said auxiliary sound producing device directly or through said amplifier.

13. In a device of the character described the combination with a usual telephone receiver having electro-magnetic coils adapted to actuate a vibratory sound producing element, of a housing on said receiver, induction coils held in said housing opposite to said electro-magnetic coils so as to be impressed with induced current by said electro-magnetic coils, a second set of electro-magnetic coils being in registry with the said induction coils, and a vibratory sound producing element held in operative relation to said second set of electro-magnetictcoils, said second set of electromagnetic coils being connected to said induction coils..

14. In a device of the character described the combination with a usual telephone receiver having electro-magnetic coils adapted to actuate a vibratory sound producing element, of a housing on said receiv'er, induction coils held in said housing opposite to said electro-magnetic coils so as to be impressed with-induced current by said electro-magnetic coils, a second set of clcctro-mar-k netic coils being in registrywith the said induction coils, a vibratory sound producing element held in operative relation to said second set of impressed electro-magnetic coils, an amplifier, and means to selectively connect said induction coils to said second set of electro-magnetic coils directly or through said amplifier.

15. In a device of the character described the combination with a usual telephone receiver having electro-magnets therein adapted to actuate a diaphragm, of a housing on said receiver, aligned coils held back to back relatively to each other in said housing, one of said coils being adjacent to and aligned with said electro-magnets to be impressed with induced currents by the latter, a diaphragm held opposite the other set of coils in the housing so as to be actuated by the same, and means .to operatively connect said sets of coils to each other.

16. 'In a device of the character described the combination with a usual telephone receiver having electro-magnets therein adapted to actuate a diaphragm, of a housing on said receiver, aligned coils held back toback relatively to each other in said housing, one of said ,coils being 'adjacent to and aligned with said electro-magnets to be impressed with induced currents by the latter, a diaphragm held opposite the other set of coils in the housing so as to be actuated by the same, an amplifier, and means to selectively connect said coils to each other directly or through said amplifier.

17. Means to connect an electrically actuated auxiliary sound producing device to a usual telephone receiver comprising, a housing attached to the telephone receiver, induction coils in the zso housing being connected to said auxiliary sound producing device, and means in the housing to support said induction coils adjacent to and aligned with ends of the pole pieces of the usual eloctromagnets of said telephone receiver.

18. Means to connect an electrically actuated auxiliary sound producing device to a usual telephone receiver comprising, a housing attached to the telephone receiver, induction coils in the housing being connected to said auxiliary sound producing device, and adjustable means in the housing to support said induction coils adjacent to and aligned with the usual electro-magnets of said telephone receiver.

19. Means to connect an electrically actuated auxiliary sound producing device to a usual telephone receiver comprising, a housing attached to the telephone receiver, induction coils in the housing being connected to said auxiliary sound producing device, a supporting element in, the housing for said induction coils, said supporting element being adapted to be adjusted in said housing so as to hold said coils in alignment with the pole pieces of the usual electro-magnets of said telephone receiver.

20. Means to connect an electrically actuated auxiliary sound producing device to a usual tele phone receiver comprising, a housing attached to the telephone receiver, induction coils in the housing being connected to said auxiliary sound producing device, a supporting element-for said induction coils, the relative position of said supporting element and said induction'coils being constant, and adjustable means of connection between said supporting element and said housingso as to hold said coils in operative alignment with the core of the usual diaphragm actuating means of said telephone receiver.

21. Means to connect an electrically actuated auxiliary sound producing device to a usual telephone receiver' comprising, a housing attached to the telephone receiver, induction coils in the housing being connected to said auxiliary sound producing device, a supporting element inthe housing for said induction coils, the relative positiion of said supporting element and said induction coils being constant, and adjustable means of connection between said supporting visual observation of its position relatively to said I diaphragm actuating means.

22. Means to connect an electrically actuated sound producing device to a usual telephone receiver, comprising a housing attached to said receiver, a hollow support adjustably held in said housing and being adapted for visual observation of the position of said support relatively to the usual diaphragm actuating elements of said telephone receiver, and induction means connected to said sound producing device being supported on said support in a fixed relation to said support and in operative alignment with said diaphragm actuating means.

23. Means to connect an electrically actuated sound producing device to a usual telephone receiver, comprising a housing attached to said receiver, a hollow support adjustably held in said housing and being adapted for' visual observation of the position of said support relatively to the usual diaphragm actuatingelectro-magnets of said telephone receiver, a substantially U shaped core fixedly held in said support so that the open ends of said core are aligned with the core of said electro-magnet, and induction coils on said core connected to said sound producing device.

24. Means to connect an electrically actuated sound producing device to a usualtelephone receiver, comprising a housing attached to said receiver, a hollow support adjustably held in said housing and being adapted for visual observation of the position of said support relatively to the usual diaphragm actuating electro-magnets of said telephone receiver, a substantially -U port and core against said diaphragm so as to prevent the vibration of the diaphragm.

CARL W. CHERRY.