Improvements in Telephonic Transmitters.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in Telephonic Transmitters.
I, ALEXANDER MARR of 9 Repton Street, Manchester in the County of Lancaster,
Electrical Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention relates to an improved construction of telephonic transmitter, by the
use of which greatly improved results are obtained with a smaller battery power than
is at present generally necessary.
Such instruments, constructed according to these improvements, may have a vertical
or a sloping diaphragm, which is made of thin sheet carbon. I will describe an
instrument with a vertical diaphragm, this being the form at present more generally
required. The diaphragm is clamped, by a leather ring, or a ring of equivalent
material which acts as a damper, on the front of a casing or box, a mouthpiece being
arranged in front of the diaphragm. In the box there is a carbon block with a
sloping top, the angle between the sloping top and the diaphragm being preferably
about 60 degrees. In the upper surface of the carbon block two cavities are formed
with semicircular cross sections by preference. Of these, one, nearer to the
diaphragm, may be from three eighths to half an inch wide at the top where it is
bounded by concentric lines convex to the diaphragm. The other cavity is circular
in plan and is situated in the concavity of the first named cavity, or further from the
diaphragm. Both cavities are filled with small carbon pellets.
Just above, and just clear of the top of the carbon block, and parallel therewith,
there is a thin sheet carbon electrode, the lower end of which is secured to the
diaphragm, the attachment being strengthened if desired, by an angle block or fillet
through which an additional connection may be made by a spring between the
diaphragm and the electrode.
In the front of the carbon block there is arranged a buffer of indiarubber or like
material at about opposite to the centre of the diaphragm, with which it acts as a
damper.
The electric circuit through the instrument includes the diaphragm, the electrode,
the carbon pellets, and the carbon block, the diaphragm and the electrode being
constructed as already hereinbefore described, of thin sheet carbon.
If it is not essential that the diaphragm should be vertical, the electrode may be
omitted and the diaphragm be arranged in its place over the sloping top of the carbon
block.
DL:
1984
W. E. HEYS & SON,
Agents for the Applicant.

page_text: Poponic Transmitters.
I, ALEXANDER MARR, of 9 Repton Street, Manchester in the County of Lancaster,
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 :-
This invention relates to an improved construction of telephonic transmitter by the
use of which greatly improved results are obtained with a smaller battery power than
is at present generally necessary.
Such instruments constructed according to these improvements may have a vertical
or a sloping diaphragm which is made from thin sheet carbon.
Figure 1 of the accompanying drawings represents a cross section of an instrument
with a vertical diaphragm. Figure 2 represents a front elevation of the saine
instrument with the mouthpiece and diaphragm removed and with the carbon pellets
absent. This form, or the hereinafter described modification of it, is that which is
more generally required. The carbon diaphragm D, is secured upon the front of the
box or casing B, by the mouthpiece M, between which and the diaphragm there is
a leather, indiarubber or other similar ring R, acting as a buffer or damper. Within
the box, that is to say at the back of the diaphragm, there is a carbon block A,
having a sloping top, the angle between the sloping top and the back of the diaphragm
being preferably about 60°. In the upper surface of the block there are formed two
cavities (C', which may be variously shaped. The figures shew the shape which I
prefer to employ, both cavities being semicircular in cross section. The ends of the
cavities may be closed by walls of any suitable material whatever, such as the
material of the block itself or, if the cavities are cut right through, the ends made be
made up with strips of ebonite, cardboard or the like cemented on the sides of the
carbon block. Practically equal results are obtained if the upper cavity, instead of
being curved as shewn, is circular in plan and semicircular in cross section, that is to
say, if it is a hemispherical cavity. The cavities may be from three eighths to one
half of an inch wide at the top. Both of the cavities are nearly, but preferably not
quite filled with hard carbon pellets.
Just above, and just clear of the carbon block, there is a thin sheet carbon
electrode E, the lower part of which is secured to the diaphragm, the attachment
being strengthened if desired, by an angle block F, and an additional electric
connection between the diaphragm and the electrode may be made by a spring such
as S. In front of the carbon block there may be arranged a buffer G, of india-
rubber or other like material at about the centre of the diaphragmn, with which it acts
as a damper. The electric circuit through the instrument includes the carbon
diaphragm D, the carbon electrode E, the carbon pellets in the cavities CC, and the
carbon block in the order named, the circuit terminals being connected with the
carbon diaphragm and with the carbon block respectively. If the carbon block be
attached to the box or casing by means of a screw or screws, they may be employed
for adjusting the position of the block
If it be not essential that the diaphragm should be vertical, the carbon electrode E
may be omitted and the diaphragm be arranged in its place over the sloping top of
the carbon block.
If the modification represented in cross section by Figure 3, be placed in a sloping
position, it will practically be the instrument last referred to, that is to say one
having its carbon diaphragm arranged in its place over the sloping top of the carbon
block. Such an instrument is intended to be used in a fixed position, but a
duplication of one of its parts, that is to say the cavities in the carbon block, makes
it adapted perfectly for hand use. This duplication is shewn in the figure which

page_text: represents four cavities. The upper two of these may be precisely similar to those
represented by Figure 2; the two lower ones are also similar, but reversed, that is
to say the centre of their curvature would be at some distance below the bottom of
the carbon block instead of above it.
The box or casing may have any convenient shape, as may also the carbon block,
provided the conditions of construction hereinbefore described are observed.
It is intended that in use the cavities in the carbon block should not be quite filled
with the carbon pellets.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In a telephonic transmitter, the combination and arrangement with a sheet
carbon diaphragm, of a sheet carbon electrode attached at an angle to the back of
the diaphragm and a carbon block having recesses containing carbon pellets which
come into contact with the sheet carbon electrode; substantially as hereinbefore-
described and as illustrated by the accompanying drawings.
2. In a telephonic transmitter, the combination and arrangement with a sheet
carbon diaphragm, of a block forming an electric conductor and having recesses.
containing carbon pellets which come into contact with the diaphragm ; substantially
as hereinbefore described and as illustrated by the accompanying drawings.
3. Telephonic transmitters constructed substantially as hereinbefore described and.
as illustrated by the accompanying drawings.
Dated this imot daw of AAD 1907
W. E. HEYS & SON,
Agents for the Applicant..