IMPROVEMENTS IN TELEPHONIC TRANSMITTERS
Year: 1888

page_text: Date of Application, 7th Feb., 1888
Complete Specification Left, 7th Nov., 1888
Complete Specification Accepted, 21st Dec., 1888
1, THOMAS LAURIE of Wellside Terrace, Falkirk, in the County of Stirling, North
Britain, Electrical Engineer do hereby declare the nature of the said invention for
IMPROVEMENTS IN TELEPHONIC TRANSMITTERS to be as follows:-
This Invention relates to improvements in telephonic transmitters. The main
object in it is to dispense with diaphragms, sounding boards, tympanums or analogous
sounding bodies. This is effected under the first head by means of a piece or disc of
carbon with a hole through it and divided into two separate parts, by having a piece
of fibre or any other insulator between the two parts. The piece or disc of carbon is
also fluted and upon this is laid a ball or other suitably shaped pieco of carbon so
that the sound waves of the speaker's voice may have access to it freely. This
arrangement is connected with the transmitter, so that whenever the transmitter is
spoken into the sound waves play upon the loose ball or other shaped loose piece. of
carbon and as it is very light it oscillates and makes and breaks contact upon its
fluted base. Each of the pieces of fluted carbon of which the disc is composed are
connected by a metallic (preferably a copper covered wire leading to a battery line)
wire and receiver. The sound waves are carried through the receiver and line wire
to the receiver at the other end of the system.
Under the second head, instead of using a disc having a fluted hole in it, the loose
ball or other shaped loose piece of carbon is made to act as one of the electrodes.
The ball or other shaped loose piece of carbon is placed upon an aperture. There are
two or more pencils of carbon suspended loosely from a point nearly vertical above
the ball or other loose piece of carbon and resting or rubbing on the said ball or piece
of carbon. When the transmitter is spoken into the sound waves pass through the
aperture to the ball or other loose piece of carbon which rapidly oscillates according
to the velocity of the sound waves and rubbing or striking against the pencils. The
metallic connections are, one wire carried or connected from the pencils, and the
second or return wire from the ball. Two wires may be used for the pencils, one
connected to each separately. This system is connected on to the line and thence to
the receiver. It is not necessary that all the electrodes may be of carbon. One of

page_text: the electrodes may be of carbon and the other of platinum or of any other good
conductor of electricity. The principal feature in this invention is that all the
electrodes are in a free and loose position so that the sound waves may cause them to
be set into a state of oscillation or rubbing action against one another.
It is also to be understood that it is immaterial which of the electrodes in both
systems is presented to the sound waves, but it is preferred to arrange them as herein
described.
Dated this 6th day of Wahnura 1000
ST. JOHN V. DAY,
115, St. Vincent Street, Glasgow,
Petitioner's Agent
Improvements in Telephonic Transmitters.
I THOMAS LAURIE of Wellside Terrace, Falkirk in the County of Stirling, North
Britain, Electrical Engineer, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
My Invention relates to improvements in telephonic transmitters for the trans-
mission of speech or other sound by means of electricity. In the transmitters
constituting my Invention, diaphragms, tympanums, sound boards or other analogous
rosonant bodies which have hitherto been used in connection with a carbon microphone
or a microphone of other material are dispensed with. In transmitters as hitherto
constructed it has been the practice to have cither one or more of the electrodes
or contents rigidly fixed or pressing firmly against diaphragins or other resonant
or non-resonant material while the other electrode or electrodes is or are loose.
In the transmitters constituting my Invention, instead of one or more of the
electrodes being fixed as hitherto, all the electrodes are carried, pivoted hinged or
suspended loosely, so that when the waves of the voice or other sounds strike or
impinge on the electrodes these waves set all the clectrodes in a state of motion or
oscillation.
In order that my Invention may be properly understood and readily carried into
effect, 1 have hereunto appended one explanatory sheet of drawings in the several

page_text: Figures of which corresponding parts are marked with the same letters of reference
of these drawings. Figure 1, is a vertical section shewing one form of the electrodes
of my improved transmitters.
Figure 2, is a plan corresponding to Figure 1.
The lower electrode consists of a circular disc of carbon A, B, having a conical
hole C, bored therein. This disc A, B, is divided across its diameter as shewn more
especially at Figure 2, and the space between the portions A and B, is filled with a
thin strip of insulating material D. The conical hole C, is fluted or notched as shewn
at Figure 2, and by virtue of this fluting or notching it presents a number of sharp
contacts all round its circumference, so that when the upper electrode, namely the
ball E, of carbon or other suitable material is placed in the conical hole C, it comes in
contact with these numerous sharp points. This feature is an important one as it
admits of a very light ball being used for the second electrode which will accordingly
be easily oscillated or varied by the action of the sound waves upon it without the risk
of losing or having bad contact and consequent disturbance from sparking which
might otherwise happen if the circumference of the hole U, were left plain or by the
ball E, not being truly sphorical or losing its truly spherical shape. A light metallic
connecting wire is led from each of the two electrodes A, and B, and connected in tho
usual manner with a battery, line-wire, induction coil, and any of the usual forms of
telephonic receivers.
At Figure 31, I have shown the manner of mounting my improved telephone
transmitter. It consists of a block W, W, of wood, load, iron, brass or other suitable
material, in which a circular recess or check is formed to receive the electrodes A, B,
and in which recess or check the electrodes A, B, rest loosely with the carbon ball E,
loosely resting in it, a suitable entrance mouthpiece or aperture S, S, is formed in the
block W, W, for the purpose of converging the sound waves towards the electrodes.
Into the recess or check in the block W, W, it is found advantageous to insert a
socket R, of rubber or any other suitable material and I then place the electrodes A, B,
and the carbon ball E, loosely into this socket as shewn in the drawing, Figure 31.
This socket R, may either be fixed rigidly to the block W, W, or it may likewise rest
loosely in its receptacle or recess. The recess containing the electrodes A, B, and E,
may be covered with a cap J. When speaking into the mouth-piece S, S, the sound
waves pass up the tube or aperture proceeding from the said mouthpiece and strike or
impinge upon the loose electrodes A, B, and E, or, but not necessarily on the socket R,
in which these parts rest, thus causing the electrodes to rapidly move or oscillate up
and down and thereby cause the necessary variations in the current of electricity
passing through the electrodes.
With regard to the conical hole C, in the disc A, B, this need not be bored com-
pletely through the disc as shewn and described with reference to Figures 1 and 2,
but the lower part of the hole may be closed as shown at Figures 3 and 4.
In place of the upper electrode E, being spherical or ball shaped as shewn at
Figures 1 and 3, it may be a simple conical plug as shewn at Figures 5 and 7.
The plug E, may be grooved or fluted and may rest against the smooth circular
surface of the conical hole C, or the conical hole C, may be fluted as in Figures 1
to 4, in which case the surface of the conical plug E, is not grooved or fluted but a
continuous conical surface.
Figures 7 and 8, are respectively a vertical section and plan of my electrodes
corresponding to that shown at Figures 5 and 6, but wherein the hole in the lower
electrode A, B, is closed at the bottom.
At Figure 9, is shewn a vertical section and Figure 10, a plan of the moveable
electrodes for my telephonic transmitters in which a flat circular disc E, forms the
upper electrode and which rests in a circular recess formed in the lower electrode A, B.
The under part of the upper electrode E, may be grooved or fluted as shewn so as
to provide a number of contact points resting against the bottom of the recess in the
lower electrode A, B, or the bottom of the lower electrode A, B, may be grooved or
fluted in which case the underside of the upper electrode E, is smooth and rests against
the numerous contact points thus provided on the lower electrode.

page_text: At Figures 11 and 12, are shewn views of the upper and lower electrodes of my
improved transmitter but wherein the hole (, shewn at Figures 9 and 10, is dispensed
with.
At Figures 29 and 30 is shewn another modification of my electrodes but in place
of adopting a ball or other shaped piece resting in the lower electrodes A and B,
granulated or powdered carbon E, may be substituted and laid loosely into the hole C,
which in this case is preferably closed at the bottom.
At Figure 13, is shewn in transverse section and in Figure 14 in plan, a pair of
moveable electrodes illustrating a slight modification of this part of my Invention.
The two electrodes A and B, each consist of two semicircular or nearly semicircular
pieces, portions projecting from the upper one of which overlap the other or lower
electrode. As will be seen on referring to Figure 13, the part B, is checked out at
its underside and is the overlaping portion which enters and rests in a check formed
in the upper part of the piece A. The action of this modification is slightly different
from those before described with reference to Figures 1 to 12, but with another
improvement to be hereinafter described, its action is similar and it may be explained
thus. The sound waves which pass through the mouth-piece or opening at the under-
side of the electrodes A, and B, cause them to oscillate and to rise up at the centre.
This action also causes the parts A, and B, to run together at the line of contacts F,
which may either be a continuous line or divided up into the series of grooves or
flutes as indicated by the dotted lines at Figure 14. To insure perfect contact the
electrode B, has its under surface slightly inclined so that it does not rest against the
bottom of the recess in which the electrodes are carried, excepting at its outer
extremity, whilst the opposite point F, namely the point or line of contact therefore
necessarily rests upon the outer electrode A.
Figures 27 and 28, shew an arrangement similar to Figures 13 and 14, but in
place of having two semicircular pieces A and B, two or a series of pencils are made
to overlap one another in a similar manner to Figures 13 and 14. Each series may
be connected as shewn in Figures 27 and 28.
At Figures 15 and 16, the lower electrode A, B, is shewn as formed with an
upwardly projecting orifice at its centre and wherein the upper electrode E, is formed
with a short pin-like projection for maintaining the electrodes in their proper relative
positions.
At Figures 17 and 18, an arrangement similar to that illustrated by Figures 15
and 16, is shewn but with the exception that the hole in the lower electrode A, B, is
closed at the bottom.
It is to be understood that the upper projecting orifice of the lower electrode A, B,
may be fluted or grooved across its top as shown to provide several points of contact
with the upper electrode E, or the surface of the said upwardly projecting orifice may
be left smooth in which case the under surface of the upper electrode E, is fluted or
grooved to provide sucl. several points of contact.
At Figures 19 and 20, are shown in transverse section and plan respectively
another arrangement of the moveable electrodes of my improved transmitters. In
this arrangement, the lower electrode A, B, is formed with two little recesses in it,
diametrically opposite to each other and the upper electrode consists of a carbon ball E,
having a short piece of carbon projecting at oach side of it and resting in the afore-
said recesses as shown. In place of the ball being of carbon it may be of any other
-suitable material, having a small bar of carbon inserted through the ball. The
projecting pieces, either the carbon of the ball or a bar of carbon passing through
a ball of other material, lio loosely in the recesses cut in the lower electrode A, B,
or the ball E, may be of carbon and a small bar of carbon or equivalent material
inserted loosely through the ball as shewn by the dotted lines across the section of
ball in Figure 20. The ball in this case would form one electrode and the parts A, B,
connected together would form the other electrode, while the carbon rod would serve
to complete the circuit. It would in this case likewise be preferable to keep the ball E,
in such a position so as not to touch or be in electrical contact with the parts A, B,
except through the bar passing through the ball.

page_text: The electrodes shown at Figures 21 and 22, correspond to those shewn at Figures 19
and 20, excepting that there is no aperture in the centre of the bottom of the lower
electrode A, B.
At Figures 23, and 24, there are shewn in vertical section and plan another modifi-
cation of the electrodes for my improved transmitters. This consists of a small
circular frame A, A, of wood, brass, iron, lead or any other suitable material having
pins of carbon, 1, 2 and 3, screwed into it and projecting loosely into holes in the
ball of carbon E, which is the upper electrode. The frame A, A, has an opening
through its centre so that the sound waves may strike directly or impinge upon the
ball as well as on the frame A, A, whereof both the ball E, and frame A, A, are set
into a state of rapid motion or oscillation. One wire may be connected to the ball and
another wire to all the pencils 1, 2, and 3.
An arrangement similar to that illustrated at Figures 23, and 24, is shown at
Figures 25 and 26, but in which the opening in the lower part of the frame A, A, is
dispensed with.
At Figures 32 and 33, there are shewn in vertical section and plan another modifi-
cation of my electrodes for my improved transmitters. This consists of a circular
piece of carbon A, B, divided across its diameter by a wedge shaped hole C, into two
semicircular pieces A, B, and in this hole is placed a bar E, of carbon or any other
suitable material. When used in a telephonic transmitter, one wire may be connected
to the piece B, and the other to the piece A, as shewn in Figures 32 and 33 the bar E,
completing the circuit. There is no insulating material D, required in this modifi-
cation, because the hole traverses from one extremity of the circle to the other,
therefore the air operates as the insulator instead at D, and on account of the
pieces A. and B, being hinged they cannot make electrical contact.
An important feature in connection with the improvements constituting my Inven-
tion as hereinbefore described and shewn at Figures 1 to 33 inclusive, consists in not
only having the parts A, and B, united by insulating material as described and laid
loosely in a socket suitable for their reception, but I have found there is still a
further improvement which consists in hinging the carbon piecos A, and B,
Figures 1 to 22 inclusive, with cloth, metal or any other suitable material at the
points H, H, when these pieces A and B, are thus hinged together the insulating
strip D, remains fixed to one of the pieces only and is free to move relatively with the
other piece A or B, or in place of hanging the pieces A, B, at H, H, they may be
binged loosely by a thin strip of cloth or other suitable material laid and cemented or
otherwise fixed across the underside of the division of the pieces A, B, shewn by the
dotted lines in Figure 2. It is evident that the pieces A, B, may operate without
hinging and a like good result may be obtained by simply laying the pieces A, B,
loosely into the socket made for their reception but the hinging is preferable in so far
as it is a means of keeping all the parts in their relative places when sound waves are
projected against the pieces A or B, they are rapidly projected, vibrated or oscillated
up and down across their middle at the situation of the hinge and this causes a
rubbing action to take place between the parts A and B, of the lower electrode and
the upper electrode E, Figures 1 to 22, and 27 and 28, and 32 and 33 inclusive. By
these last mentioned arrangements the sensitiveness of the transmitter is considerably
increased. The frames shown in Figures 23, 24, 25 and 26, may for the same
purpose be hinged at H, H, or the two halves of the frame A, A, may be united
by a hinge at C, C, or the two halves may be divided and allowed to lie loosely
without a hinge, but the adoption of the hinge materially serves to keep them in
place as before explained.
I desire to explain that it is immaterial which of the electrodes in the arrangements
of transmitters hereinbefore described and shewn on the annexed drawings is presented
to the sound waves as either or both may be successfully subjected thereto although
I prefer them arranged as shewn in the drawings. It is also to be understood that
in place of using the number of electrodes hereinbefore described and shown on the
drawings as applied to telephonic transmitters constructed according to my Invention,
the number of these electrodes may be increased.

page_text: Having now particularly described and ascertained the nature of my said Inven-
tion and in what manner the same is to be performed, I wish it to be under-
stood that I do not confine myself to the employment of carbon for all the electrodes.
as for instance one of the alectrodes may be of platinum, iron, brass, steel, copper,
zinc, lead, or any other suitable conductor of electricity or the arrangement may be
reversed, namely one electrode of platinum, iron, brass, steel, copper, zinc, lead, or of
any other suitable conductor of electricity, whilst the remainder of the electrodes
or a portion thereof may be of carbon. I also wish it to be understood that I do
not confine myself to the precise shape of the electrodes shown in the drawings as
the shape is not essential but may be considerably varied whilst still embodying my
said improvements; nor is it important how the sound waves enter to the electrodes
so long as the entrance is made which shall give the best effect; nor do I entirely
depend on gravitation for the pressure of one electrode upon another as a spring or
similar arrangement may be, applied for this end; nor do I confine myself to the
manner of electrically connecting up the electrodes as this may be done in a variety
of ways all well known; nor is it important as to the shape of the receptacle in
which the electrodes are placed as shewn in Figure 33, but what I claim as my
Invention is :-
1. In a telephonic transmitter, the arrangement of all the electrodes in a free and
loose hinged or suspended position so that the waves of sound passing into the
transmitter cause all the electrodes to be set into a state of rapid motion or oscilla-
tion, thereby causing one electrode or set of electrodes to have a rubbing action or
motion against or upon the other electrode or set of electrodes without the inter-
vention of diaphragms, tympanums, sound boards or other analogous resonant
bodies substantially as hereinbefore described and shewn at Figures 1 to 12,
15 to 26 and at Figures 29 and 30 32 and 33 of the annexed sheet of
drawings.
2. The arrangement of electrodes as shewn at Figures 13 and 14, and 27 and 28
consisting of two electrodes A and B, constructed according to either manner set
forth and in which one electrode B, rests partly on or in the electrode A, the lower
part of B, being inclined as shewn to insure perfect contact at F, between A, and B,
the electrodes being caused to rise upwards at their centre parts by the sound waves
striking or impinging against them, substantially as hereinbefore described.
Dated this 6th day of November 1888.
ST. JOHN V. DAY,
115, St. Vincent Street; Glasgow,
Applicant's Agent.