US508829A - Telephone teansmittee - Google Patents

Description

L t e e8 h S v lm e e h Sv 2 um E m1 .n GS EN ...1M RT OE NN EP E Tn.-Y E T d d o M o N No. 508,829. Patented Nov.14,v1898.

w/r/VESSES t m A fr0/swf Ys 'rhs NATIONAL LITHUGHAPHINQ coMPANv.

(No Model.) 2 Sheets-Sheet 2.

B. NORIBGA. TELEPHONE TRANSMITTER.

No. 508,829. vPatented Nov. 14, 189s.

ATTORNEYS me NATloNAL L ooooooooooooooooo Y.

I -UNITED STATES -PATENT OFFICE.

ELOY NORIEGA, OF MEXICO, MEXICO.

TELEPHONE-'TRANSMITTER sPEcIFIcATIoN forming pea ef Lettere Patent No. 508,829, aerea November 14,1893.

Application iled February 4, 1891. Serial No. 380.172. (No model.)

`.To a/ZZ whom i# may concern:

Be it known that I, ELOY NORIEGA, of Mexico city, Mexico, have invented a new and Improved Microphonic Telephone-Transmitter, of which the following is a specification, reference being had to the annexed drawings, forming a part thereof, in which- Figure lis a side elevation,partly in section, ofmy improved microphonic telephone transmitter. Fig. 2 is a vertical transverse section of the same. Fig. 3 is a rear elevation o f a modified form. Fig. 4 isavertical transverse section; and Fig. 5 is a front elevation of a complete telephone, including the receiving and transmitting instruments, induction coil and signaling mechanism, also showing a modified form of the transmitter. g

Similar letters of reference indicate corresponding parts in all the views.

The object ofmy invention is to provide a microphonic Vtelephone transmitter, capable of utilizing a heavy current, and of producing the variations of Vcurrent necessary for the transmissiony `of speech over long distances; also to provide atransmitter which willremain in adjustmentand work uniformly und'er all conditions.

My `invention consists in the combination with a diaphragm provided with an electrical conducting surface, a series of carbonvbars attached to the diaphragm, and bearing upon the conductin g surface, and an adjustable bar provided with a chamberV containing elastic absorbentmaterial held against the carbon bars, all las will be hereinafter more fullydescribed. Y l

The annular frame A, is provided lat the top and, bottom with arms B, B', and with aperturesafor receiving the screws by which the frame is fastened tothe telephone box.

' .Upon diametrically opposite sides of the annular frame are secured spring clips b, which extend inwardly over theV diaphragm C, and hold it in place inthe frame A. The edge of the diaphragmisinclosed in a soft rubber band c, which modifies the vibrations of the diaphragm and prevents any electrical connection betweenthe diaphragm and the frame A.

Upon the rear face of the diaphragm C is secured a thin plate of conducting material,

and to the diaphragm are bolted two` carbon bars D, D', in which are made transverse holes for receiving the ends of the carbon rods d,

which fit the holes loosely and rest normally upon the thin plate of conductingmat-erial attached to the diaphragm. The carbon bar D is provided with/a conductor e, and the carbon bar D', in a similar way, is provided with a conductor e'.

To the arm B, is attached a spring f, which extends toward the arm B', and parallel with the diaphragm C. To the springfis secured a bar E, which is provided at its upper end with a lug g, and is angled at its lower end to adapt it for engagement with the adjusting screw F. To the lug gis attached aspring h, which extends downwardly parallel with the diaphragm C, and carries a chambered bar G, in which is placed a body z', of bropus, absorbent material Which rests upon the carthe thin carbon plate'dti, attached to the diaphragm. The pressure of the absorbent material i upon the carbon rods is regulated by turning the screw F,fin one direction or the other, whichby engagingthe angled end of the bar E, causes it to move inwardly o r outwardly as required. y

The frame A is secured to the telephone box cover Z,whicheis provided with a mouthpiece I, located opposite the center of the diaphragm C. The diaphragm C is preferably made of wood, spruce having been found ,by

experiment to be the best wood for 'thepurpose. AThe diaphragm is protected against the effects of moisture of the breath or the atmosphere, by a coating of Water-proof varnish, such as shellac.

In the modifications shown in Figs. 3 and 4, the diaphragm C is clamped in a cell A', by the mouth-piece I', which screws upon the cell. To the diaphragm C are attached the carbon bars D, D', as in the other case, and the carbon rods d, which are like those already described, are pressed against the diaphragm by fibrous absorbent materialpreferably absorbent cotton contained in a case G', carried by a spring h secured to the Wall of the cell A', and the adjustment of the spring h is effected by the screw F' passing through-the back of the cell A'. The cell A' 4bon rods d, and presses them lightly against IOO may be made of metal or insulating material such as hard rubber, but in any case the back 7' of the cell must be iliade of insulating material. The binding posts e2, e3, attached to the back j, are connected electrically by liexible wires with the bars D, D. The back of the cell A in this lcase is threaded externally to permit of screwing it into the door of the casing of the telephonie apparatus.

In the form of transmitter shown in Fig. 5, the construction is the same Vas that shown in Figs; l and 2, with the exception of the omission of the bar E, the spring h, and the body t' of absorbent material, and the ends of the rods d, which are made conical and inserted in conical cavities in the carbon bars D, D. The casing J, which contains all the working parts of the telephone, with the exception of the receiver, consists of a body 7e `and a cover Z, 4the two parts being connected by the hinges m, m', m2, m3. To the inside o f the cover l is secured the annular frame A, and in the cover is placed the induction coilK.

In the body of the box is arranged a magneto-electric machine L of the usual description, also a magneto call bell M, of the kind commonly used in connection with telephones, 4and in .one side of the box case is pivoted a switchy lever N, which extends outwardly through the side of the box, and is bent upward to form a key for receiving the telephone receiver O. .The inner end of the lever N is connected with one end of aspiral spring n, the other end of which is attached to a stud o, and in the path of the inner end of the le# ver N, is arranged a contact point p, which istouched by the lever N, when the said lever is moved by the spring n after lifting the telephone receiver O from the outer end of the said lever. The body lo of the box is furnished with binding posts q, q', and the cover Z is furnished at the bottom with binding posts r, r', and at the top with binding posts s, s.

The poles of the battery P are connected with the binding posts r, 1". The binding post r is connected with one terminal of the primary wire of the coil K, the other terminal of the said primary wire being connected with the hinge m2, which is connected electrically with the stud o. The binding post r is connected with the wire e leading to the carbon bar D', and the wire e attached f to the carbon bar D, is connected with the hinge m', and the hinge is connected electrically with the contact point p, so that when the telephone receiver O is lifted from the lever N, the said lever is tilted by the spring n, so as to touch the contact point p, thus closing the local circuit.

The line circuit is from the ground Q through the binding post q', hinge m3, the secondary wire of the induction coil, binding post s', one branch of the double cord R, to and through the telephone receiver O, back to the binding post s, thence through the hinge m to the binding post q, andl through the line S to the distant station.

The signaling circuit is from the ground Q through the binding post q', .the polarized bell M, the magneto L, the armature of the magneto to the stud o, through the spring n, lever N, contact point p', to the wire extending to the binding post q, thence over the line tothe distant station.

When sounds are uttered in the mouth piece ofthe transmitter, the diaphragm is vibrated and the current in the primary circuit is varied. by the variable contact of the carbon rods d with vthe carbon lining ofthe diaphragm and with the bars D, D', and electrical impulses are generated -in the secondary Wire of the coil, which aretransmitted to the distant station, and act upon the telephone receiver to produce sounds like those made in the mouth piece of the transmitter.

Although the thin coating of -carbon ,attached tothe diaphragm sho-rt circuit-s the electrodes to some extent,still when'theelectrodes are vibrated bythe move-ments of the diaphragm, the contact of the electrodes with the thin coating of carbon varies the resistance of this part of the circuit, and thus adds materially to the efficiency of the instrument. The carbons used in my microphone are made according to one of the following formulae:

Formula No. 1.-Carbon (charcoal), fortysix per cent.; carbon (coke), forty-four per cent.; water saturated with boric acid at fty per cent., ten per cent.

Formula No. 2.-(larcon (soft charcoal), forty-six per cent.; carbon (coke), thirty-three per cent.; Water saturated'with boric acid at forty-six per cent., eight per cent.; plumbago, thirteen per cent,

Formula, lVo. 3.-Carbon', sixty-three per cent.; graphite, twenty-two per cent;.plutn hago, seven per cent.; water saturated with boric acid at fifty per cent., seven per cent.; tar, one per cent.

Formula No. 4.Garbon (charcoal), iifty per cent.; carbon (coke), fourper cent.; graphite, thirty-two per cent.; plumbago, six V'per cent.; tar, one percent.; water, five per cent.

Formula, No, 5.-Graphite, sixty-six per cent.; carbon, twenty-ve per cent.; tar, one per cent.; water, eight per cent.

FormulaNo. 6.- Carbon, sixty-six percent.; graphite, thirty per cent.; water saturated with boric acid at fifty per cent., four per cent.

, Formula No. 7.-Carbon, seventy-four per cent.; graphite, nineteen per cent.; water saturated with gum-lac and alcohol at fifty per cent.

Ido not limit myself to the formulae enn merated, nor to the quantities stated, for these can be varied as desired. Carbons made according to my method are suitable for all classes of microphones.

The carbons are prepared according to the formulae as follows: Pulverize 'it until reduced to a very ne powder, and then pass it through a fine sieve of silk or metal, so as to IOO IZO

eliminate anylumps which would be prejudicial in making the paste. The paste, which is produced by mixing the carbon with the., other substances and the Water, is submitted to a pressure which can be varied from seventy-eight to ninety atmospheres. The strips, bars or cylindrical carbons (for any form can be obtained) which are thus obtained, and which can be of'the desired size, are placed immediately in an oven of the proper form .y

The plate ofvcarbon atthe backof the diafA phragm slightly decreases the resistance of the circuit, but the principal objectot' this construction is to be able to divide or subdivide the current between the plates and the .barskof carbon,if desired. By this means three improvements in the system of carbon microphones are obtained. These are as follows: First, when the resistance of the microL phone -is excessive, the telephone messages are confused, so that articulate sounds are scarcely perceptible; this difficulty is increased With an increase of the distance over which-conversation is carried on. With the carbon plate introduced into the combination, a perfectly clear and distinct transmission is obtained over a .largely increased distance. Second, as the lpressure of the carbon plate on-the diaphragm canbe increased more or less and the pressure o f the cylinders against thelplate can be varied, and the pressureof the absorbent material ony the cylinders can be varied, amore uniform yaction may he secured, the resistance beingdivided or subdivided as abovestated, throughout the various contacts andv bodiesof carbon, thus causing a part of the current to pass through the plate,

and a part throughth'elcarbon bars.` Third, f

the absorbent porous material is inserted for .the purposeof collectingall the moisture of the carbon electrodes. Itis well known that .carbon is quite hygromatic, andconsequently carbon electrodes absorb Water easily' and with very slight changes of temperature. Wa-

.ter is prejudicial to the transmission of speech and to a cleardelivery. The absorbentmasov terial removesthewater kfrom the carbon and Having thus describiedmy invention,l

claim as new and desire to secure by Letters ,Patent- 1. -In a microphonic telephone transmitter, the combination, with a diaphragm .of nonnconducting material, of a thinconductinglin-A ing attached to the diaphragm, apertured carbon bars secured to the diaphragm, transverse Agreatlyimproves'thel action of the microphone. i

carbon rods having their ends inserted inthe apertured bars With their sides-resting upon the metal lininguof the diaphragm, and means `for pressing thetransverse carbon rods'for- Ward against the conducting lining of the diaphragm, substantially as specied.

2. A carbon electrodev `for microphones, formed ot' charcoal, coke, and a -solution of boricacid, combined in about the proportions stated.

3. A carbon' electrode for microphones,

formed of charcoal, coke, graphite, andan aqueous solution of boricacid, combined in about the proportions stated.

1 Witnesses: PEDRO NORIEGA. LUIS SANTA MARINA.

ELOY NoRIEeA. Y

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