Improvements in and connected with Telephone Transmitters:
Year: 1893

page_text: Date of Application, 18th Feb., 1893-Accepted, 20th May, 1893
COMPLETE SPECIFICATION.
Improvements in and connected with Telephone Transmitters:
I, ERHARD LUDWIG MAYER, of 11 Billiter Square, London, in the County of
Middlesex, 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 :-
In the Complete Specification (hereinafter referred to as my prior Specification)
filed in pursuance of my application (conjointly with Alexander Chalmers Jameson)
for Letters Patent dated the 23rd day of August 1892 and numbered 15,194, I
refer to a class or type of telephone transmitters which I term double-cycle,"
transmitters; and I also therein refer to the form of induction coil used with
transmitters of this type or class, that is to say, induction coils having two primary
windings and one secondary winding. Freeman's transmitter, and certain tran-
smitters patented by La Société Générale des Telephones of Paris, (No. 10,231
of 1885 and No. 7331 of 1891) are examples of the double cycle class of
transmitters.
In my said prior Specification, I describe what I have termed a four-cycle
transmitter, the said four-cycle transmitter being joined up with induction coils
of the same kind, and in the same manner, as in the case of double-cycle transmitters.
My present invention embraces (a) a combination of parts constituting a new or
improved double-cycle transmitter, and (6) an arrangement of circuits for use with
double-cycle transmitters or with my four-cycle transmitter.
My new or improved double-cycle transmitter is shown in Figure 1 of the
accompanying sheets of drawings, where it will be seen that it differs from my four-
cycle instrument, illustrated in Figure 3 of my prior Specification, simply in the
fact that the roof-shaped presser is divided so that its two halves shall be insulated
from one another, and in the fact that the weight presser is not of conducting
material. This figure also illustrates an arrangement of circuits constituting a part
of my present invention. It will be seen that this arrangement of circuits differs
from that hitherto employed with double-cycle transmitters in that instead of the
wire from one pole of the battery splitting up into two branches, each branch including
in its circuit one of the two primary windings of the induction coil, the circuits are
so arranged that there is no branching. Instead thereof two independent circuits
start from each pole of the battery, and remain separate and distinct throughout
their length, as will be readily seen in the figure. For convenience of comparison
of this figure with Figure 3 of my prior Specification, I have given the several
parts the same letters of reference, except that I now indicate the two halves into
which the roof-shaped presser is divided by the letters F1 and F'.
The action of my apparatus is as follows: When movement inwards of the
diaphragm takes place (from left to right of the figure), the inertia of the movable
pieces causes increased pressure between the front movable piece and the front fixed
piece and decreased pressure between the rear movable piece and the rear fixed
piece, so that the current traversing the primary winding which has the front pieces
in circuit will be increased, and that traversing the primary winding which has the
back pieces in circuit, will be decreased. In a similar manner, movement of the
diaphragm in the other direction will cause increased pressure between the rear
movable piece and the rear fixed piece, and decreased pressure between the front
movable piece and the front fixed piece, so that the current traversing the primary
winding which has the rear pieces in circuit will be increased, and that traversing
the primary winding which has the front pieces in circuit will be decreased.
It will be seen from the above that the roof-shaped presser being divided and

page_text: the weight presser being a non-conductor, the two circuits remain distinct, and that
there is no shunt cycle of operations as in the four-cycle instrument specified in my
prior Specification.
..
For the purpose of more clearly demonstrating wherein that part of my invention
which consists in the arrangement of circuits differs from the arrangement of
circuits hitherto employed, I have omitted the induction coils from the following
figures, but I shall indicate in what parts of the primary circuits the primary
windings of the induction coil would be.
Figure 2 illustrates diagrammatically an ordinary type of double-cycle transmitter
such as is well-known, arranged in circuit in the usual manner. H is the battery
as before and M M are the points where the primary windings of the induction
coil would naturally be in circuit. It is to be noted that two separate wires might
be led from the pole of the battery up to the carbon piece D, but the circuits
would not then be separate and distinct as in my invention, because D, being
common to the two circuits, and being a conductor, would form a common part of
both circuite.
Figure 3 is a diagrammatic representation of my invention inserted for the
purpose of comparison with Figure 2, and wherein it will be seen that to come
within my invention, the construction of the transmitter must be such that no part
of the transmitter shall be common to the two circuits. To apply therefore my
invention of the arrangement of circuits to a transmitter of the form shown in
"Figure 2, a part of the said transmitter would have to be divided into two parts,
insulated from one another as is shown at d in Figure 3, where it will be seen that
the carbon piece D' is split down the middle, and the two halves insulated from one
another. In this case the primary windings of the induction coil would naturally
be inserted either at the points M M, or at the points M¹ M'. It will be seen
that so far as the arrangement of circuits is concerned Figure 3 is identical with
Figure 1.
Figure 4 illustrates the application of my arrangement of circuits to a four-cycle
instrument. The action in this case will be readily understood, as it differs from
that described with Figure 1 solely in the fact that the presser weight E being of
"conducting material, the shunt cycle of operations is added to the ordinary cycle
of operations in a double-cycle transmitter. In this case the primary windings of
the induction coil would naturally be placed at the points MT M'.
that if they were placed at the points M M, a part of the current would not
traverse the primary windings at all, as there would be a complete circuit from
pole through F¹, D', E, D, F, 1.
It is obvious
In the figures hereinbefore described, I have shown the circuits in use with a
single battery, although the said circuits are distinct throughout their entire length.
It is obvious that instead of employing an induction coil with two primary windings
and one secondary winding as hereinbefore set forth, I may employ two separate
induction coils of the ordinary kind, that is to say each with one primary winding
and one secondary winding. When I adopt the plan of using two ordinary
induction coils as aforesaid, I place a primary winding of each ordinary induction
coil in each of the two separate and distinct circuits, and I connect the secondary
windings of the two ordinary induction coils together either in series or in
multiple are.
It will be seen that all the parts constituting that part of my invention which
consists of my new or improved double cycle transmitter, are supported upon or
from the centre only of the diaphragm. A great delicacy of action is thus
obtained..
It is not necessary that both a roof-shaped presser and a weight presser should
be employed, but I prefer to employ both.
1 desire it to be understood that when I use my arrangement of circuits in
connection with a four-cycle instrument, it is not necessary that the circuits should
- be absolutely separate and distinct, as is the case when my arrangement of circuits

page_text: is employed with a double cycle instrument. Thus in Figure 4 it will be seen that
the weight presser being a conductor, the circuits cannot be said to be entirely
distinct and separate as in the case of a double-cycle transmitter.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. The improvement in telephone transmitters consisting of the new or improved
form of double cycle transmitter, substantially as set forth.
2. The improvement in telephone transmitters, consisting in the combination of
two fixed pieces, two movable pieces, and a presser, the said presser consisting either
of a weight presser or of a roof shaped presser, and being either divided or of non-
conducting material, so that the current cannot be shunted from one movable piece
to the other through the said presser.
3. The improvement connected with telephone transmitters, which consists in
supporting the whole of the microphone elements of a double cycle transmitter
from the centre of the diaphragm, substantially as set forth.
4. The improvement connected with telephone transmitters consisting in the
arrangement of circuits, substantially as set forth with reference to double-cycle
transmitters.
5. The improvement connected with telephone transmitters consisting in the
arrangement of circuits substantially as set forth with reference to four-cycle
transmitters.
נית
حرم1
AT
2000
•
E. L. MAYER,
Per J. G. Lorrain, M. Inst. E.E., M. Inst. M.E.,
Norfolk House, Norfolk Street, Strand, London, W.C.,
Chartered Patent Agent.