US295742A - Daniel drawbatjgh - Google Patents

Description

(No Mbdel.)

DJDRAW -BAUGH. TELEPHONE TRANSMITTER;

No. 295,742. Patented Mar. 25,1 84.

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UNITED STATES PATENT "O FICE.

DANIEL DRAWBAUGH, or EBERLYS MILL, PENNSYLVANIA, ASSIGNOR TO,

THE rnornn s TELEPHONE COMPANY, on NEW YORK.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 295,742, datedlVLarch 25, 1884.

Applicationfiled November 19, 1883. (No model.)

T0 at whom it may concern:

Be it known that I, DANIEL DRAWBAUGH, of Eberlys Mill, Cumberland county, Pennsylvania, have invented a new and useful Improvement in Telephone-Transmitters, of

. of a suitable substance in pulverized form,

mixed with a binding material, to produce a plastic or semi-liquid mass capable on drying of hardening. I have found it to be quite sufficient for all practical purposes to apply a thin coating or layer of this compound over the surfaces of any pieces of conducting material,

is the box or case.

and then, when said coating is hardened, to place the two surfaces in contact and in circuit. l

Referring to the drawings, Figure l is a front view of a telephone-instrument in which my invention is embodied, one of the diaphragms in saidflinstrument being removed. Fig. 2 is a vertical section on the line as 00. Fig. 3 is a face view of one of the conductingplates coated partially with my electrode compound. Fig. plates coated with the electrode compound and placed in contact, substantially as in the instrument. Fig. 5 is a rear view of the front diaphragm. i

Similar letters indicate like parts.

.A is the back board of the instrument; B

O is the front cover, having a moutlrorifice. D is the rear cover, also having a central orifice. E is the front diaphragm. F is the rear diaphragm. G G are blocks of wood or other material, supporting the instrument'at a distance from the back board, A. By this construction sound-waves impinge upon the diaphragm E directly, and upon the diaphragm F after reflection from the back board, A, thus vibrating both diaphragms relatively in opposite directions simultaneously. The electrodes are arranged between the two diaphragms, one electrode being fixed to the rear diaphragm, and having an inclined upper surface, and the other one resting upon said inclined surface by grav- 4 shows two conducting ity, and receiving motion from the front diaphragm, E. This general construction of instrumentthat is to say, with two diaphragms and two electrodes arranged between them has already been fully set forth by me in other applications, and therefore is not herein specifically claimed.

To therear diaphragm, F, and at about its center, I secure a block of wood or other suitable material, H, upon which I attach by a screw, as shown in Fig. I, or in any other convenient way, a metal plate, I. This plate is covered or coated with what I have already designated as my electrode compound, which I may prepare in the following way: I pulverize gascarbon finely and mix it with what is known as rubber-varnish that is to say, pure rub ber dissolved in bisulphide of. carbon-so as to form a pasty mass, which I prefer should not be so thick as to prevent its flowing from the brush. I do not limit myself to any particular consistence of this mixture, because it maybe desirable in some cases to haveitthick or viscid and in others thin and flowing. I'

have found, however, that it is more convenient to make the compound not much thicker than ordinary varnish, so that it can be applied easily with the brush.

I do not limit myself to any particular binding material--such as rubbervarnish-because I may use other agglutinating mixtures in place thereofsuch, for example, as shellac dissolved in alcohol, or even ordinary glue, or copal-varnish, or Chinese Japan varnish. All of these substances give good results; but I think, in practice, it is best to useamaterial which does not absorb moisture, as does glue, and which will cause the compound to dry and harden quickly through the evaporation of a volatile-constituent-such, for example, as alcohol or bisulphide of carbon.

Referring now to the drawings, Fig. 3 shows the metal plate I partially covered with the electrode compound. The plate may be wholly covered 5 but I think the results are a little better when it is partially covered, substantially as here shown.

J is another metal plate covered with my electrode compound used substantially the same way. To the back of this plate. is so cured a projecting piece, L, also of metal,

having a curved outer edge. On the diaphragm E, I secure'two pieces of wood, M, With a space between them, into which space enters the curved edge of the projecting piece L, as shown in Fig. 2. These pieces M prevent lateral displacement of the upper electrode, J L, which rests upon the lower electrode by gravity. I find it preferable to make the angle of inclination of the electrode I about forty-five degrees.

The circuits in the instrument proceed as follows: from the battery to the binding-post 1, by the wire a, to the induction-coil N, through the primary of said coil, by the wire b, to the plate I, through layers of electrode compound to .the plate J, projection L, and thence by the wire 0, connected to said projection, and to the contact-plate P, thence to the spring and contact-plate Q, and thence by the wire 01 to the binding-post 2, and back to the battery. The secondary coil of the induction coil N connects, by wires 6 e, to the-line binding-posts 3 and 4, and from said wires 6 e branch wires f f extend to the binding-posts 2 5 5 and 6, to which a receiving-instrument may be attached. The spring contact-piece Q overlaps the plate P, and has a rectangular downward projection, so that when the ring of a receiving-instrument is placed over the arm B, said contact-plate Q, is raised and the circuit between the parts P and Q is broken.

S is 'a bar for holding the induction-coil M in place. Said inductioncoil passes through an opening in the rear diaphragm, F, and is secured to the back board, A. The vibrations of the diaphragms are communicated to the electrodes, so that the latter cause modifications of the current passing through them.

I do not limit myself to two electrodes provided with a coating of finely-divided conducting material mixed with an agglutinating substance, inasmuch as I have used one electrode consisting of a plate of metal or other conducting material combined with a second electrode coated as described. The plates coated may be either of conducting or non-conducting material. In thelatter case electrical circuit-connection is established directly with the coating.

I claim as my invention- 1. In a telephone-transmitter, electrodes consisting of flat plates having their surfaces in contact, the said surfaces beingcovered with a hard, thin coating of finely-divided conductof a thin stratum of finely-divided conducting material, combined with an agglutinatin g substance, substantially as described.

3. A telephone electrode or resistance-varying conductor for telephone-transmitters, consisting of a plate covered with ahard, thin coating of finely-divided conducting material, combined with an agglutinating substance, substantially as described.

' 4- In a telephone-transmitter, electrodes consisting of metallic plates or surfaces provided with a hard,thin coating of finely-divided conducting material, combined with an agglutinating substance, the said coated surfaces being in contact, substantially as described.

5. In a telephone-transmitter, electrodes consisting of metallic plates having their surfaces partially covered with a hard, thin coating of finely-divided conducting material, combined with an agglutinating substance, the coated portions of said plates being in contact, substantially as described.

6. In a telephone-transmitter, and rigidly attached to a support, an inclined plate or surface coated with a mixture of finely-divided material and agglutinating substance, in combination with a movable plate similarly coated and pressing by gravity upon said inclified surface, and a diaphragm acting upon said movable plate, substantially as described.

7. In a telephone-transmitter, the combination of the diaphragm E, guides M, plate J, coated with a mixture of finely-divided conducting material and agglutinating substance, and having a projection, L7 similarly coated plate, I, and an inclined support for said plate I, substantially as described. 7

8. In a telephone, the combination, with the diaphragm and the fixed support carrying the inclined electrode, of the loose plate having a surface of conducting material resting upon the fixed electrode, and a projection in contact with the diaphragm, substantially as described.

DANIEL DRAVVBAUGH,

Witnesses:

FRED. M. OTT, M. W. JACOBS.

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