IMPROVEMENTS IN TELEPHONE TRANSMITTERS
Year: 1885

page_text: F
I, CHARLES MOSELEY of the Chapelfield Works Manchester in the County of
Lancaster Indiarubber Manufacturer, do hereby declare the nature of my invention
for IMPROVEMENTS IN TELEPHONE TRANSMITTERS and in what manner the same
is to be performed, to be particularly described and ascertained in and by the
following statement :—
"
This Invention relates to Improvements in Telephone Transmitters and these
Improvements consist in enclosing the variable resistance or "tension regulator'
within a chamber or cell so as to exclude dust and the action of changes in the
condition of the atmosphere; in constructing the tension regulator in such a
manner that speech and other sounds may be faithfully reproduced in the receiving
telephone whether such sounds are produced in close proximity to or at a con-
siderable distance from the transmitting telephone and in a method of or arrangement
for producing variations of resistance in the tension regulator corresponding with
the vibrations of the tympan or diaphragm produced by sound.
And in order that this Invention may be more readily understood and carried
into practical effect I have hereunto appended a sheet of Drawings marked
with letters of reference, similar letters denoting similar parts in the various
figures.
Fig 1 represents in vertical and Fig 2 in horizontal section through A. B Fig 1
the tension regulator attached to a diaphragm or tympan the whole being enclosed
within a box shown in dotted outline.
Figs 3, 5, 6 and 7 represent vertical sections through the tension regulator and
diaphragm showing modifications in the details of construction and connection
between the tension regulator and diaphragm or tympan. Fig 4 represents
a back view or plan of the tension regulator mounted upon the diaphragm or
tympan.
The tension regulator consists of two carbon electrodes c and g having granulated
carbon i between them. I prefer that these electrodes should be of hard gas retort
carbon and that they should be square in plan but compressed carbon may be
employed and any other convenient shape may be adopted. The granulated
carbon, to obtain the best result, must be clean gas retort carbon crushed and
passed through two sieves all that is passed by the finer meshed sieve and all that
vill not pass through the coarser meshed sieve being rejected, the object being to
btain grains of approximately equal size. Two suitable sieves for the purpose
D

page_text: would be one having thirty meshes to the inch and one having forty meshes
to the inch but other numbers of meshes may be used if they do not vary
considerably from those given.
The front electrode c and the back electrode g are connected by some pliable
medium as hereinafter described in such a manner that they may to a limited
extent vibrate independently of each other. In Fig 3 the front electrode c is
cemented or otherwise secured to a thin sheet of indiarubber or to a sheet of
vellum, parchmentised paper or other similar suitable material f. Upon this sheet
and surrounding the electrode c is also cemented or secured a frame e shown in
dotted lines in Fig 4. The cavity thus formed is then slightly more than half
filled with the granulated carbon and the back electrode g is cemented or secured
to the frame e. The back electrode g may be formed of a plate or disc of carbon
having in plan the outside form and dimensions of the frame e or it may be a
similar plate or disc of wood, vulcanite, metal or other suitable material having the
carbon electrode inlaid in its inner surface as shown in dotted lines at g Fig 3.
When the containing cell is of the full dimensions of the frame e the front
electrode c should be somewhat sinaller than the inside of the frame but not so
much smaller as to permit the grains of carbon to penetrate between the electrode
and the frame. The frame c is by preference made of brass or other metal in
which case its inside edges should be insulated with varnish, paraffined paper or
other suitable material as indicated at d Fig 3. The cell box or chamber containing
the tension regulator may be cemented or secured to the diaphragm a directly, as
shown in Fig 6 or it may be cemented or secured to a disc or plate b which is
attached to the diaphragm as shown in Figs 3, 5 and 7. I prefer in all cases to
mount the tension regulator above or below the centre of the diaphragm in such a
manner that the lowest part of the granulated carbon is approximately in the same
horizontal plane as the centre of the diaphragm as shown in the Drawings.
Instead of making the back electrode c of nearly equal dimensions with the
inside of the frame e I may make it considerably smaller as shown in Fig 5. In
this event I surround the electrode with a strip or raised edge of parchment,
cardboard or other suitable material. The heighth of this border or edge should
be such that it does not quite touch the back disc or electrode g but comes near
enough thereto to prevent the passage of the granulated carbon which is contained
within the cavity formed by the front electrode c and its border or edging. In all
cases the disc b when it is employed should be somewhat smaller than the inside of
the frame e.
Instead of making the pliable connection between the front and back electrodes
by means of the sheet fI may make it by substituting for the metal or equivalent
frame e Figs 3 4 and 5 a ring or frame of vulcanized indiarubber cut nearly through
so as to form two rings or frames connected together at their inner edge as shown
in Figs 6 and 7.
When the frame e is circular in plan I prefer to fix upon one of the electrodes a
shelf or partition r the width of which is slightly less than the distance between
the electrodes as hereinbefore described in reference to the raised edge or border d
Fig 5. The upper space or cavity is then slightly more than half filled with the
granulated carbon as shown in Figs 6 and 7.
The connections may be made in the usual manner by means of wires n n¹
attached to the electrodes c g. These wires are indicated in Figs 1. 2 and 3 but are
omitted from the other Figs for distinctness. The usual method is more fully
shown in Figs 1 and 2 in which n and n¹ represent the wires connected to the
poles of the local battery this circuit including also the tension regulator and the
primary coils of the induction coil m. One end o of the secondary wire of
the coil m is connected to line and the other end p to earth. The containing box is
indicated atk k and the mouthpiece at L.
I do not limit myself to any precise dimensions but the inner diameter of the
frame or ring may advantageously be about 18 millimeters and the distance betweer
:

page_text: the electrodes about 2 millimeters the remaining relative dimensions being about as
indicated on the Drawings. Neither do I limit myself to the precise materials or
substances for the constituents of the containing cell or chamber hereinbefore
specified or the particular forms set forth, nor do I claim the use of carbon
in the tension regulator. For ordinary purposes and for long distance telephony
I find that the form and arrangement herein before described and illustrated
in Fig 5 yields the best average results. The other forms are suitable for short
circuits.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what
I claim is
(1) As a variable resistance or tension regulator for a transmitting telephone the
use of the carbon electrodes c g in combination with the granulated carbon i and
the frame or ring e substantially as hereinbefore described and set forth and as
illustrated on the accompanying sheet of Drawings.
(2) As a variable resistance or tension regulator for a transmitting telephone
the use of the carbon electrodes c and g in combination with the granulated
carbon the frame or ring e and the pliable base or sheet f substantially as.
hereinbefore described and set forth and as illustrated on the accompanying sheet
of Drawings.
(3) As a variable resistance or tension regulator for a transmitting telephone
the use of two carbon electrodes having granulated carbon between them within
a closed chamber or cell the whole being mounted upon or secured to the diaphragm
substantially as hereinbefore set forth and described and as illustrated on the
accompanying sheet of Drawings.
(4) In a variable resistance or tension regulator for a transmitting telephone
the use of the raised edge or border & substantially as hereinbefore set forth and
described and as illustrated in Fig 5 of the accompanying Drawings.
(5) In a variable resistance or tension regulator for a transmitting telephone
the use of the shelf or partition r substantially as hereinbefore described and set
forth and as illustrated in Figs 6 and 7 of the accompanying Drawings.
(6.) In combination with a variable resistance or tension regulator for a trans-
mitting telephone the use of the disc b substantially as hereinbefore set forth and
as illustrated in Figs 1, 2, 3, 5 and 7 of the accompanying Drawings.
Dated this twenty eighth day of January & D 1885