US1113499A

US1113499A - Sound-magnifying appliance for telephonic and telegraphonic purposes.

Info

Publication number: US1113499A
Application number: US83267614A
Authority: US
Inventors: Harald Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 1914-04-18
Filing date: 1914-04-18
Publication date: 1914-10-13
Anticipated expiration: 1931-10-13

Description

Y H. SMITH. v SOUNDIVIGNWYING APFLIANCE FOR TELEPHQNIC AND IELEGFH'ZMC Awucnion riz/au mags. wir;A

l, l 13,499. IDL-wanted Gail. 2.213. l'..

HARALD SMITH, 0F MAGDEBURG, GERMANY.

SOUND-MAGNIFYING APPLIANCE `FOR TELEPHONIE AND TELEGRAPHONIC PURPOSES.

Specification. of Letters Patent.

Patented Oct. 13, 1914.

Application filed April 18, 1914. Serial No. 832,676.

To all whom t may concern.'

Be it known that I, HARALD SMITH, a citizen of the German Empire, residing at Magdeburg, in Germany, have invented certain new and useful Improvements in Sound- Magnifying Ap liances for Telephonie and Telegraphonic urposes, o-f which the following is a specification. p

The object of this invention is to provide improved means for increasing the sound emitted by telephone receivers or produced by so-called talking magnets, the invention being applicable both to ordinary telephone systems andjn systems with electromagnetic talking apparatus (telegraphones).

I use a diaphragm adapted to be vibrated by electromagnetic means, with microphones at each side of the diaphragm, comprising caj'tbon ballsplaced within insulators which do not touch the diaphragm, so that the latter can vibrate freely across its entire diameter from wall to wall of the box containing same. I electrically connect the microphones at opposite sides of the diaphragm to two groupsof induction coils, so that the current from the microphones on one side flows through the self-inductive coils in the opposite direction to the current flowing through thev other coils from the microphones on the other side. In this con-` nection I have found that it is not necessary to provide the induction coils with secondary windings, but that better results are obtained by dispensing with secondary coils and connecting the telephone between the coils through which the current flows in opposite directions as described.

The invention is illustrated in the accompanying drawings, in which- 1 Figure 1 is a diagram of one installation in vertical section embodying my invention; Fig. 2 is a diagram showing another installation. Fig. 3 1s a sectional view of a detail, and Fig. 4 is a detail plan view showing three pairs of microphones on one side ot' the diaphragm and arranged in parallel.

Referring in the first instance to Fig. 1, 1 designates a Vdiaphragm of carbon, arranged ina box 2`of lead or other metal, which is for practical purposes free from vibration. At opposite sides of the membrane are placcd'microphones 3, each consisting of a `cup of electrically insulating material, such as vulcanitc, with its cavity faci g the diaphragm and containing a bloc 4 of carbon and two layers of small carbon balls 5 on the'said block. The microphone cups are spaced from the diaphragm, so that the latter can vibrate. An iron rod or core 6 fixed to the diaphragm de ends from the latter into a solenoid coil its downward movement being limited by an adjustable screw 8. The rod 6 and screw 8 are polarized by means of an electromagnet 9 of cylindrical shape, ha'ving pole-pieces 10, 11, with holes for passage of :the rod 6 and screws 8 respectively. Above the diaphragm, outside the box there is another solenoid 12, with a core13 extending into the box and alined with the rod 6. The solenoid 13 is connected by a wire 121 to the screw 8, and by a wire 1211 to one terminal of a battery 14, and the dia hragxn is connected by a wire 15 to the otlier terminal of the battery. It' the parts 6 and S come into contact, and tend to make the diaphragm stick they close the circuit dcgcribed, and the core 13 pulls the diaphragm ree.

The microphones 3 are connected to cach other in pairs. Two groups of induction coils 16 and'l'? are provided, and the three pairs of microphones (see Fig. 4) on one side of the diaphragm are connected by wires 18 to tlie coils 16, the three pairs on the other side being connected to the coils 17 by wires 19. As-shown in Fig. 1, the wires 18 are joined to the right hand ends of the coils 16, and the wires 19 are joined to the left hand ends of the coils 17. The opposite ends of the two groups of coils are connected by wires 2O and 21 respectively to one terminal of the battery 14. Condensers 22 and '23 are connected to the coils 16 and 17 re spectively, at the ends where connection made to the

wires

18 and 19, and these cor.- densers are connected by wires 24 and Q5 re- Lmectively to a telephone 26. i t

vWhen the apparatus is in use, downward u'lovemcnt of the diaphragm increases the resistance of the microphones 3 above it, andf thus reduces'the current in the coils 16, but increases the currentl in the coils 17. Upward moyement of the diaphragm eiiects the currents in the opposite sense. The variations of current strength, due to movements of the diaphragm, produce induced currents in the coils. I have found that the secondary circuits need not be taken through separate coils, but that the coils 16, 17 may be used therefor, a secondary circuit being, for example, formed as follows z-Coil 16, wires 20, 21', coil 17 condenser 23, wire 25, telephone 26, wire 24, condenser 22, and back to the coil 16.

F ig. 2 slows two of the sound magnifying applia ces arranged in series. One of these appl'ances is similar to that shown in Fig. 1,'an hasL a diaphragm 11, solenoid 71,

battery 141, and induction coils 161, 171, together with the respective microphones, connections and condensers. The other appliance consists of a. similar combination of elements, including a diaphragm 1", solenoid 7, battery 14 and induction coilsl 16 and 17. vThe solenoid 7 is in the secondary circuit of the first-mentioned appliance, and consequently induces vibrations of the diaphragm l, which affect the currents in the coils 16a and 17. These currents excite a talking magnet 30, which acts on a magnetic steel wire 31.

Fig. 3 shows a preferred form of construction of the microphones. A metal cup 34 is screwed by means of a shank 35 to the box containing the diaphragm, part of this box ibeing shown at 2', and the shank is made fast by means of a nut 36, enabling the cup to be easily detached. The cup contains the carbon block 4, on which are placed the carbon balls, and the latter lie in and between rings 33, so that the balls are supported in columns, consisting of vertical series of balls resting one upon the other. This prevents the balls from becoming jammed.

The operation of the arrangement shown in Fig. 1 will be largely understood from the foregoing description, together with the followingr explanation. Assuming the diaphragm 1 of electrical conducting material to be moved upwardly, causing the carbon balls 5 of the microphones 3 on the upper side of diaphragm 1 to be brought more closely together, thereby reducing the resistance and increasing the current in one direction through the respective circuits including the three wires 18, coils 16, back through battery 14 to the diaphragm 1. At the same time the currents through the respective circuits of the three pairs of microphones 3 on the lower side of the diaphragm 1 are reduced due to the increased resistance, by virtue of the carbon balls 3 of the microphones on the lower side of the diaphragm 1 being more separated from one another, whereby such reduced currents pass through the respective coils 17 in the direction opposite to the direction of the currents passing through the coils 16, the circuit through coils 17 including the condensers 23, battery 14, lower microphones 3 and Wires 19.

It will be noted that the respective coils 16 kare connected in parallel with the respective coils 17 through the battery 14 and diaphragm 1. The connection of the telephone receiver 26, or talking magnet 30, or like electro-responsive device, is such that the respective coils 16 and condensers 22 are connected in series with the respective coils 17 and condensers 23. -By reason of the inductivelyl related coils 16, 17, being wound in opposite directions, the magnetization is kept low thereby effecting a high amplification of the voice currents. Similar actions and interactions between the microphones 3, coils 16, 17, condensers 22, 23, and the electro-responsive device 26, take place when the diaphragm 1 moves downwardly, in which. case thev current through the respective coils 17 is greater than the current through the respective coils 16.

What I claim as my invention and desire to secure byl Letters Patent of the United States is:--v f 1. In apparatus for the purpose set forth, a diaphragm, microphones at opposite sides of said diaphragm, a coil connected at one end to a microphone on one side of said diaphragm, a coil inductively related to said coil and connected at one end to a microphone on the other side of saiddiaphragm, a source of electric energy, means connected with said source and connecting said-coils in parallel, an electro-responsive device, and means connected to said electroresponsive device and connecting said coils in series.

2. In apparatus for the purpose Set forth, a diaphragm, microphones at opposite sides of said diaphragm, a coil connected at one end to a microphone on one side of said diaphragm, a coil inductively related to said coil and connected at one end to a microphone on the other side of said diaphragm, a source of electric energy, means connected with said source and said diaphragm and connecting said coils in parallel, an electro-responsive device, and means connected with saidelectro-responsive device and connecting said coils in series.

3. In apparatus for the purpose set forth, a diaphragm, microphones at opposite sides of said diaphragm, a coil connected at one end to'a microphone on one side of-said diaphragm, a coil inductively related to said coil and connected at its end opposite to said one end to a microphone on the other side of said diaphragm, a source of electric energy, means connectedwith said source and said diaphragm and connecting said coils'inl parallel, an electro-responsive device, and means connected with said electrorcsponsive device and connecting said \\c0ils in series. i

4. In apparatus for the purpose set forth,

a diaphragm, two groups of microphones.

inductivcly related to said group of coils and connected oppositely to the group .of micropl'loncs on the other side of said dia- `phra, ,'m, a source of electric energy, means -coiinccted with said source and said 'dia- ,liragm and connecting said rst named 'group of coils and said second named group a coil connected at one end to the microprone at one Side of said diaphragm, a coil connected at one' endto the microphone at the other. side of 'said diaphragm, means electrically connecting the other ends of said coils to each other, an electric soundproducii'ig appliance, and means including condensers connecting said sound-producing appliances to said coils.

6. In apparatus for the/purpose set forth the combination of a diaphragm, a solenoid on' one side of said diaphragm, an iron rod attached to said diaphragm extending into said solenoid, an iron abutment alined with said rod in said solenoid to limit the vibration of the diaphragm, an annular group of electro-magnets surrounding said solenoid,`

pole pieces on said eleetromagnets embracing said rod and said abutment respectively, microphones at opposite -sides of said diaphragm, a coil connected at one end to the microphone at one side of said diaphragm,

'a coil inductively related to said coil connected at one end to the microphone at the other side of said diaphragm, a source of electric energy, and means connected with said source and said diaphragm and connecting saidcoils in parallel.

7. `In apparatus for the purpose set forth thecombination of a diaphragm, a solenoid on one side. of said diaphragm, an iron rod attached to said diaphragm extending into said solenoid, an iron abutment alined with said rod in said solenoid to limit the vibration of the diaphragm, an annular group of electromagnets surrounding said solenoid, pole pieces on said electromagnets einbracing said rod and said abutment respectively, microphones at opposite sides of said diaphragm, a coil connected at one end to the microphone at one side of said diaphragm, a coil connected at one end to the microphone at the other side of' said diaphragm, means electrically connecting the other ends of said coils tov each other, a second solenoid on the other side of Said diaphragm, a core in said second solenoid aliped with vthe rod attached to the diaphragm, and means whereby con- .tact of the last mentioned rod with the iron abutment establishes an electric circuit 8. In apparatusifor the purpose set forth the combination of two groups of elements,

each comprising a diaphragm, microphones at opposite sides of said dia hragm, a solenoid, anY iron rod attache connected at one end to a microphone atene side of said diaphragm, a coil inductively related to said coil-connected at one end to a microphone at the other side of said diaphragm, ascurce of electric energy, means connected to said source and connecting the coils of the two groups in parallel, and means for connecting the solenoid of one of said groups with the coils of the other group of elements.

9. In apparatusfor the purpose set forth,-

to said dia'- phragm extending into said solenoid, a colli a diaphragm of conducting material, two

groups of microphones respectively on opposite sides of said diaphragm, two groups of inductively interrelated coils, the coils of one group being connected to the microphones on one side of said diaphragm and the coils of the other group being oppositely connected to the microphones on the other side of said diaphragm, a source of electric energy, means connected with said source and said diaphragm and connecting the coils of said two groups in parallel, an electro-responsive device, and means connected with said *electro-responsive device connecting said coils in series.

10. In apparatus for the purpose set forth, a diaphragm, groups of microphones at op- /posite sides of said diaphragm, the microphones of each gro-up being arranged in parallel, groups of inductively related coils, the coils of one group bein microphones on one side of said diaphragm, the' coils of the other group being oppositely connected to the microphones ,on the other side of said diaphragm, condensers con. nected to said groups of co1ls,.a source of electric energy, and means connected with saidsouree and 4connecting said groups of coils in parallel.

connected to the 11. In apparatus for the purpose'set forth,

a diaphragm of conducting material, groups of microphones at opposite sides of said daphragm, the microphones 'of each group being arranged in parallel, groups of indue tively related coils, the coils of one group being connected to the microphones on one side of said diaphragm, the coils-of the other group being oppositely connected to the microphones on the other side of diaphragm, condensers connected'tosaid groupf of coils, a sourceof electric energy, and

means connected with said source and said diaphragm and connecting said groups of coilsin parallel.

. 12 In apparatus for the purpose set forth, a diaphragm, two groups of microphones disposed respectivelv on the opposite side of CTY group bein connectedin'paallel, a coil connected to t e group Aof microphones onone coils in series.' side of said diaphragm, a coil iductively re lated to said coil and oppositely connected to the group of microphones on the other side of said diaphragm, a. source offelectric energy, an electrofresponsive device, and means connected with" seid' eleetxpoo-Iiesponsive device and connecting said groups of In witness whereof I have signed. this specification in the presence of two. witnesses.

` HARALD SMITH.

Witnesses: -v

HENRY EYOLEY, lL. OCHLMANN.