TRANSMITTERS, OR MICROPHONS
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by the said Louis Jacobson at the Office
of the Commissioners of Patents on the 12th July 1881.
LOUIS JACOBSON, of Berlin, Prussia.
TRANSMITTERS, OR MICROPHONS."
"IMPROVEMENTS IN BATTERY-TELEPHONS,
Telephons at present in use have the great inconvenience of rendering the speech
transmitted by them too feeble. By my Invention this inconvenience is done
away with, so that it is possible to transmit vocal sounds to greater distances.
My Invention refers to what are called battery telephons or transmitters, or (as
they are sometimes called) "microphons."
The Invention consists in applying a tube to the casing or box of the transmitter
into which the sounds are spoken, so that the undulations are concentrated and
fall upon the diaphragm of the transmitter with much more intensity than in the
ordinary apparatus. By this arrangement the loudness of the words sounding from
the receiver on the receiving station is enormously increased.
The casing of the microphon containing the accessories, such as the induction
coil with primary and secondary wire, switch, etc., etc., is provided with a metallic
tube.
The diaphragm carrying the fluctuating contacts is fastened at the proper
distance to the lid of the box by means of a small frame or simply by means
of small bushes and screws which may be placed near the corners of the diaphragm,
or more or less towards its middle, or both towards the middle and in the
corners.
It is obvious that the form, material, size, shape, etc., of the diaphragm and the
tube, as well as the nature or number of the fluctuating contacts may be varied,
and I wish to be understood that I do not limit myself to the above specified
details. Some characteristic improvements of the tube however are of greatest
importance to obtain the transmission of perfectly articulate speech.

page_text: For using very sensitive microphons, and when the organ of the person speaking
into the transmitter is very loud and shrill, it often happens that the reproduced
sound at the receiving station becomes very harsh, accompanied by disagreeable
by-noise.
To obviate this I have made arrangements so that only a part of the undulations
of the air in the tube produced by the speaker fall upon the diaphragm, while the
other part is led off or escapes.
I shall describe hereafter several forms to obtain this effect.
I may provide the tube with an opening at the side which can be more or less
opened or closed by a slide. The more it is opened the more undulations escape
and the transmitted sounds become more distinct though a little weaker.
Instead of one opening I can apply two or more placed opposite to each other or
to any other part of the tube.
According to another arrangement the tube is hinged to the lid of the microphon
and can be moved in the hinges away from the lid. In order to secure the tube in
the position a person may find well adapted to his voice, a toothed or notched spring
may be used to receive the lower edge of the tube in its notches, or a screw passing
through a nut projecting from the lower edge of the tube may be employed, the
foot end resting in the lid of the apparatus by means of a ball joint.
I can also move the whole tube more or less away from the opening in the lid.
A rod firmly attached to the lid carries the tube by means of a bush sliding on the
said rod and provided with a set screw to retain the tube at any desired distance
from the opening.
By another arrangement I can move the tube away from the opening in the lid,
but in another direction. It consists in attaching the tube on a plate sliding in
guides fastened on the lid of the instrument.
In the normal position the sounds fall full upon the diaphragm, but when the
plate with the tube is shifted aside the sounds can only in part fall upon the
diaphragm.
Another mode of deadening the harsh yelling of the transmitted speech consists
in covering the inside of the tube with flannel or similar soft fabrics, also varnish
may be used advantageously for this purpose. To draw off the condensed
respiration I can apply a small pipe at the lowest point of the opening in the lid
of the instrument to lead the condensed water out.
In order to obtain a free and easy manipulation of the mouthpiece I can make
use of a rubber hose in lieu of the stiff tube, or I can make the said tube in several
parts and connect them by pieces of flexible hose. The tube or hose need not be
attached on the lid of the instrument, but can be fastened just as well on any side
or even on the bottom of the box. The diaphragm may be placed on one side of
the box and the tube on another if desired.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Louis Jacobson in the Great Seal Patent Office on the
11th January 1882.
LOUIS JACOBSON, of Berlin, Prussia.
TRANSMITTERS, OR MICROPHONS."
"IMPROVEMENTS IN BATTERY-TELEPHONS,
The telephones now and hitherto in use have the great inconvenience that the
speech transmitted by them is too feeble. My Invention by which this
inconvenience is obviated, and by means of which it is possible to transmit vocal
sounds to greater distance than heretofore, refers to so called battery-telephones or
transmitters, or as they are called sometimes, microphones.
The Invention consists in applying a tube or hose of special construction to the
casing, frame, or box of the transmitter, into which tube or hose the sounds are
spoken, so that the undulations are concentrated and fall upon the diaphragm of
the transmitter with much more intensity than in the ordinary apparatus.
By this arrangement the loudness of the words emitted from the receiver at the
receiving station is enormously increased, and also the greatest part of the
extraneous noise in the room, etc., is prevented falling on the diaphragm and
irritating the speech.
The accompanying Drawings represent my improvement in several forms. The
casing of the microphone containing the induction coil with primary and secondary
wire, switch, etc., etc., is provided with a metallic tube a, Figure 1.
The diaphragm b (made of wood, cork, metal, or any other material) carrying the
fluctuating contacts c is fastened in the proper position and distance in the lid of
the box by means of a small frame d, as in Figure 1, or simply by means of small
bushes e with screws, as in Figure 3, which may be placed near the corners of the
diaphragm, more or less towards its middle, or both towards the middle and in the
corners.
It is obvious that. the form, material, size, and shape, etc., of the diaphragm and
of the tube, as well as the nature or number of the fluctuating contacts may be
varied, and I wish it to be understood that I do not limit myself to the above
specified details. Some characteristic improvements of the tube or hose however
are of the greatest importance to obtain the transmission of perfectly articulate
speech without any disturbing noises.
In using very sensitive microphones, and when the organ of the person speaking
into the transmitter is very loud or shrill, it often happens that the reproduced
sound at the receiving station becomes very harsh, accompanied by disagreeable
bye-noises.
To obviate this I have made arrangements by which I can bring about that only
part of the undulations of the air in the tube produced by the speaker (which
part can be made large or small according to momentary want or pleasure) fall
upon the diaphragm, while the other part is led off or escapes. Besides these
arrangements. the tube or hose allows the admitted words to be loud or soft at
pleasure, I shall describe hereafter several forms to obtain this object, referring to
Figures 1-8 of the accompanying Drawings. I may provide the tube with an
opening in the side, which can be more or less opened or closed by a slide f,
Figures 1 and 2. The more it is opened the more undulations escape, and the
transmitted sounds become more distinct though a little weaker.
Instead of one opening I can apply two or more, placed opposite to each other
or to any other part of the tube.
Figures 3 and 4 show an arrangement according to which the tube is hinged to
the lid of the microphone, and can be moved in the hinges g away from the lid.

page_text: In order to secure the lid in the position a person may find well adapted to his
voice, a toothed or notched spring h, Figure 3, may be used to receive the lower
edge of the tube in its notches, or a screw i, Figure 4, passing through a nut k
projecting from the lower edge of the tube may be employed, the foot end resting
in the lid of the apparatus by means of a ball joint l.
Figure 5 shows an arrangement to move the tube more or less away from the
opening in the lid. A rod m firmly attached to the lid carries the tubes by
means of a bush n sliding on the said rod m, and provided with a set screw to
retain the tube at any desired distance from the opening.
Figure 6 is also an arrangement to move the tube away from the opening
in the lid, but in another direction. The tube is carried by a plate p sliding in
guides o fastened. on the lid of the instrument, the said lid being provided with a
round hole of about the same size as the section of the tube or hose.
In the position, as shown in Figure 1, the sound waves fall full upon the
diaphragm; but when the plate p with the tube is shifted aside, as in Figure 6, the
sound waves can only in part fall upon the diaphragm.
Another mode of deadening the harsh yelling of the transmitted speech consists
in covering the inside of the tube with flannel or a similar soft fabric; varnish may
also be used advantageously for this purpose.
To draw off the condensed respiration, I can apply a small pipe at the lowest
part of the opening in the lid of the instrument leading the condensated water off.
In order to obtain a free and easy manipulation of the mouth piece I can make
use of a flexible hose in lieu of the stiff tube; or I can make the said tube in
several parts and connect them by a piece or pieces of flexible hose, as represented
by Figures 2 and 3.
The tube and hose need not be attached on the lid of the instrument, but can
be fastened just as well on any side or even on the bottom of the box. Besides,
the diaphragm can be placed on one side of the box and the tube on another.
In place of rigid tubes I can employ hoses as already stated, and in order not
to have the sounds absorbed by the soft material I make the hose rigid by inserting
wire springs or by other convenient means. I prefer to arrange the mouthpiece
of the tube or hose detachable, so that everybody can use his own mouthpiece.
Instead of employing one tube or hose of the construction above described, I can
make use of more than one, uniting into one tube or hose carrying the mouthpiece,
as shown in Figures 7 and 8.
Figure 7 represents three different diaphragms in connection with the three
branches of the tube, the fluctuating contacts being connected by electric conducting
wires. Figure 8 shows one diaphragm in connection with the three branches of
the tube, leading to three different parts of the diaphragm.
Figures 9, 10, 11, and 12 illustrate several modes of arranging the connections
of the fluctuating contacts in the circuit. The wires or conducting threads or
strings can be led to A, A, from the positive pole, and to D, D, from the negative
pole, as in Figure 9; or in order to decrease the electrical resistance to C, C,
from the positive pole, and to A, A, and D, D, from the negative pole, as
indicated by the dotted lines, Figure 9; and finally, in order to increase the
electrical resistance to a from the positive pole and to d from the negative pole,
as shown in Figure 10.
xin Figure 9 and y in Figure 10 are electric connecting wires or threads con-
ducting electricity between the fixed contacts C, C, or a¹, d
In Figures 11 and 12 these wires are dispensed with by uniting the fixed
contact C, C, (Figure 9) and a¹, d, (Figure 10) into one respectively.
As the electric resistance of the transmitter is always pretty considerable I
employ induction coils of a construction shown in Figure 13, wherein a is the
primary and b the secondary coil.
The
I surround the secondary coil b by a third coil a¹ of one or more layers forming
part of the primary coil, and being connected with the wire of said coil a.
free ends of this divided inside and outside coil a, a, are connected with the battery

page_text: and the transmitter, the ends of the secondary coil b are connected with the wires
of the line or with the receiver.
The fluctuating contacts can be made of coal or any other conducting material.
I have found, for instance, that iridium and alloys containing this metal give good
results; I also compose the contacts of more than one conducting material, for
instance, of coal and metals. I sometimes make also changes in the form, the
constructions, and number of the fluctuating contacts.
The moveable parts of the fluctuating contacts may be weighted in order to
prevent the transmitted speech from being accompanied by disturbing noises. To
prevent the diaphragm from getting warm, I can isolate it against the fluctuating
contacts by the interposition of asbestos paper, or asbestos paste board, or any
other bad conductor of heat.
Having now described the nature of my said Invention, and in what manner
the same is to be performed, I declare that I claim in battery telephones, tran-
smitters, or microphones,
First. The employment of a tube in combination with a piece or pieces of flexible
hose for the purpose specified, through which tube the undulations of the air
occasioned by the sound to be transmitted are concentrated and fall upon the
diaphragm with increased intensity, as set forth.
Secondly. The employment of tubes or hoses, or tubes combined with hoses
provided with adjustable arrangements to lead off a portion of the sound waves
without their falling upon the diaphragm or to let escape such portion to be regu-
lated as may be desirable, as described.
Thirdly. The employment of hoses provided with spiral wires or other stiffening
appliances in order to prevent the soft sides absorbing too much of the undulations,
as set forth.
Fourthly. The manner of securing the diaphragm on the lid or casing of the
apparatus by means of small bushes, being placed either near the corners or more
to the middle, or both near the corners and the middle of the diaphragm, sub-
stantially as shown and described.
Fifthly. The employment of asbestos paper, asbestos paste board, or any other
bad conductor of heat between the diaphragm and the fluctuating contacts, in order
to prevent the diaphragm from getting warm, as set forth.
Sixthly. The arrangement of the fluctuating contacts, as described with reference
to Figures 9, 10, 11, and 12.
Seventhly. The arrangements of the connections of the fluctuating contacts in
the circuit, in the manner described and shown in Figure 9 by dotted lines, and in
Figures 10, 11, and 12 by full lines.
Eighthly. The employment of metal clothed threads or strings for bringing the
fluctuating contacts into the electric circuit, as described.
Ninthly. The employment of induction coils constructed as specified and shown
with primary coil arranged inside and outside the secondary coil, as set forth.
Tenthly. For the manufacture of the fluctuating contacts I claim the use of
iridium or alloys containing iridium, as set forth.
Eleventhly. The employment of weights to the moveable parts of the fluctuating
contacts represented in Figures 9, 10, 11, and 12, in order to prevent the
transmitted sounds from being accompanied by disturbing noises.
In witness whereof, I, the said Louis Jacobson, have hereunto set my hand
and seal, this Second day of January, in the year of our Lord One
thousand eight hundred and eighty two.
LOUIS JACOBSON. (L.S.)