US1543992A - Woody - Google Patents

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US1543992A US1543992DA US1543992A US 1543992 A US1543992 A US 1543992A US 1543992D A US1543992D A US 1543992DA US 1543992 A US1543992 A US 1543992A
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    • H04R19/00Electrostatic transducers
    • H04R19/01Electrostatic transducers characterised by the use of electrets
    • H04R19/016Electrostatic transducers characterised by the use of electrets for microphones


June 30, 1925.

H. H. C. DUNWOODY TELEPHONE TRANSMITTER AMPLIFIER AND REPEATER Filed Oct. 25, 1924 0 6 9 l6 /7 E 'flf gwuwnto'c X726 63 fizuzzaaady.

d V (krona/u;

Patented June 30, 1.925.



may H. c. 'nUNwooDY, or 'wasnme'ron, DISTRICT or COLUMBIA.


Application filed October 25, 1924, Serial No. 745,812.

To all whom it may concern:

Be it known that I, HENRY H. C. DUN- woonY, a citizen of the United States, residing at \Vashington, in the District of Columbia, have invented a certain new and useful Improvement in a Telephone Transmitter Amplifier and Repeater, of which the following is a specification.

My. invention relates broadly to telephone apparatus, and more particularly to the con- 4 struction ofa device for varying the conductivity of an electrical circuit in accordance with speech vibrations for operation in conjunction with modulation systems, telephone transmission circuits, and amplifier and repeater system of telephonic currents.

One of the objects of my invention is to provid a telephone apparatus arranged to operate in circuit with a local source of energy of relatively. large otential for producing relatively large uctuations in energy in accordance with voice vibration to insure accuracy and distinctness in the transmission of speech.

Still another object of my invention is to provide a construction of telephone apparatus wherein 'soundvibrations cause variation in the current values in a circuit through the increase or decrease in pressure over a relatively large surface area and between a relatively large number of microphonic contacts Still another object of my invention is to provide; a construction of sound vibration current controlling device wherein a pair of metallic discs are employed each having a plurality of instruck projections arranged to contact on opposite sides of a carbon disc providing a plurality. of microphonic con-.

tacts through the sound vibration current controlling device for effecting the variation of a relatively large telephonic current.

Stillanother object of my invention is to provide a construction of sound control current variation device wherein a pair of magnetized plates having a plurality of instruck projections therein are arranged on opposite sides of a diaphragm forming a plurality of microphonic contacts with the surface of the diaphragm, the metallic plates being normally magnetized in such manner that the several rojections consistently tend to attracteac 1 other through the said diaphragm, the plates bein carried in such position that sound vi rations impressed thereagainst tend to vary the pressure between the plates and the'diaphragm, causing variation in the energy controlled by the device. 1

My invention finds particular application in modulation circuits in telephone control systems, including line wire telephony, radio, and carrier wave line wire telephony, and the apparatus thereof operates effectively as a repeater and an amplifier of telephonic currents as will be hereinafter described in detail.

My invention will be more fully understood by reference to the accompanying drawings, wherein:

Figure 1 is a cross-sectional view taken through a telephone transmitter employing the apparatus of my invention; Fig. 2 is a plan view looking at one of the plates in the telephone apparatus of my invention; Fig. 3 is a partial cross-sectional view illustrating the disposition of, the instruck proj ections over the surface of one of the plates; Fig. 4 is an enlarged cross-sectional view illustrating the arrangement of plates on opposite sides of the diaphragm and indicating the magnetized projections on the plates; Fig. 5 is a diagrammatic view illustrating the arrangement of the apparatus of my invention in a telephonic modulation control circuit; Fig. 6 is a diagrammatic view showing the apparatus of my invention employed for the amplification of telephonic currents; and Flg. 7 is a diagrammatic view showing the use of the apparatus of my invention in a repeater circuit for telephone systems.

Referring more particularly to the drawings, reference character 1 designates a housing for a telephone transmitter supported by lug 2 in the rear thereof enclosed by a front cover'portion designated at 3 which carries the telephone mouth piece 4. Arranged within the transmitter casing 1 I provide an annular casing 5 having a screw threaded portion 6 and a shoulder '7. The tele hone apparatus abuts against the shoulder and is secured in position by an annular screw threaded ring 8 suitably adjusted in an axial'direction by a socket wrench insorted in sockets 9. The telephone apparatus includes plates 10 and. 11 each hav ng a plurality of mstruck projections 12 and 14 projecting from the p ane of the plates but integral with the 'material thereof. The plates 10 and '11 may be constructed of a a magnetized nickel alloy permanently retaining a large amount of magnetism. Each plate is magnetized in such manner that the projections of one plate assume a polarity opposite to the polarity of the projections o the other plate. The projections 14 of plate 10 are magnetized to form north poles, while the projections 12 of plate 11 are magnetized to form south poles. .The

plates 10 and '11 are positioned within the annular member 7 and supported by the smooth wallportion 15 thereof with a car-. bon diaphragm 16 disposed between the projections 12 and 14. The plates 10 and .11 are each provided with angle members 17 and 18 of insulated 'stri material bearing .u on the peripheral sur aces of the carbon 'aphragm 16 at points spaced one from another'about the circumference thereof. The strips 17 and 18 have suificient resilient qualities to normally position plates 10 and 11 in the desired relationshi with respect to diaphragm 16. The securing means 17 and 1 8" also provide terminals for conductors 19 which pass into the telephone apparatus throu h a slot 20 into annular ring 5 and are 1e out to the associated circuits through cable 21. When em loyed as a telephonic transmitter or modullitorof telephomc currents, plates 10 and 11 are connected in circuit w1th a local source of energy 22 and a primary winding 23 of a modulation transformer 24. The secondary winding 25 of the transformer 24 delivers the modulated energy to the control circuit as represented cner which is safel handled through multitude of microp onic contacts in the telephone apparatus, I may amplify the energy' at intervals in ,a line wire system as represented in Fig, 6 where incoming enerand produces a response in .tele hone reby reference character 29 is arranged'adjm cent the telephone receiver'28 where the telephone transmitter 30 collects sound vibrations reproduced by receiver .28 and causes the sound vibrations to be impressed upon the microphonic contact system com prising plates 31 and 32 with the interposed carbon 'aphragm 33. The plates 31 and 32 are connected-in circuit with an independent-source of energy 34 and a primary microphonic contacts provided by in Flg. 5. By reason of the relatively large in winding 26 is transferred to a wmding' winding 35 of transformer 36 causing energy of large amplitude to be delivered to'secondary winding 37 from which it is passed to the line for transmission.

When employing the telephone apparatus of my invention in a repeater circuit I utilize an arrangement as illustrated in Fig. 7- where the line wire system 39 includes windings 40 and 41 inductively related to windings 42 and 43. The repeater comprises primary and secondary windings 44 and 45 connected in circuit with local battery 46. The windings operate u on solenoid plunger 47 which is positione against plates 10 and 11 by means of adjusting device 48. The plates 10 and 11 include the plurality of microphonic contacts as hereinbefore described, and are placed on opposite sides of carbon diaphragm 16 and con nected in circuit. with local battery 49'and windings 42 and 43. The windings 44 and 45 are electrically arranged in regenerative relationship with respect to the plurality of lates 10 and 11 so that sound vibrations w ich impinge against metallic plate 11 cause the setting up of electrical impulses which are reamplified through windings44 and 45 and then impressed on the line wire circuit 39. It will be observed that I provide a great number of microphonic contacts in the telephone circuit enabling the energy which is 'to be usefully employed to be divided among a great many individual circuits and the energy of the several circuits integrated in a common control circuit for the transmission of telephonic energy.

While I have described my invention in certain particular embodiments, I desire that it be understood that modifications may be -made and that no limitations upon the invention are intended other than are imposed by the scope of the appended claims.

What I claim and desire to secure by Letters Patent of the United States is as follows: a

1. Telephone apparatus, comprising in combination an annular casing, an annular supporting member within said casing, and

means carried within said annular supporting member for eifecting a variation in an electrical current under the influence of sound vibration comprising a pair of per-.

10 contacts carried t ereby, whereby said.

plates normally tend to attract each other and exert a predetermined pressure upon.

said diaphragm.

2. Telephone apparatus, comprising in combination an annular casing, an annular supportin member within said casing, a

pan of p ates carried in said supporting member, each of said plates having a plutions on the opposite plate being magnetized l'ality of projections extending toward each at the opposite polarity whereby said plates other, a diaphragm positioned intermediate normally tend to attract each other and 10 said plates and contacting with the exterior exert a predetermined pressure upon said 5 surfaces of said projections, the projections diaphragm.

on one of said plates being permanently magnetized inone. polarity and the projec- HENRY H. C. DUUODY.

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