Improvements in Telephones.
Year: 1890

page_text: Date of Application, 2nd May, 1890-Accepted, 7th June, 1890
CODEL DELE
Improvements in Telephones.
We, WILLIAM VOGEL, Civil Engineer, and GARY G. CALKINS, Merchant, both of
Chicago, in the County of Cook and State of Illinois, United States of America, 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 improvements in telephones of that class in which vocal
or other sounds are transmitted electrically by undulations in an electric current
produced by the inductive action of a vibrating armature upon a core which is sur-
rounded by the coils in circuit with the line wire. The invention consists in the
matter heroinafter described and pointed out in the appended claims.
The accompanying drawings show an apparatus embodying my invention, including
transmitting and receiving instruments at both ends of a wire over which the electric
impulses are transmitted, said instruments being shown in section for the purpose of
illustrating their interior structure.
Both of the instruments illustrated are alike and a description of one will apply to
both, similar letters of reference being used upon the instrument at both ends of the
line.
As shown in said drawing, A is a metal rod or core made of soft iron and to one
end of which is secured a disk B of non-metallic substance. is a cap also of non-
metallic substance which forms a mouth-piece and is secured at its margins to the
edges of the disk B, preferably by a screw joint. D is a diaphragm which is sustained
by being clamped at its edges between the disk B and cap C, the middle of the
diaphragmn being sustained opposite the end of the core A. E is a coil of wire sur-
rounding the core A and in circuit with a line wire F. Said line wire F is connected
with the terminals of a battery or other generator C and its ends ff are connected
with the ground as shown. H is a second coil surrounding the core E exterior to
the coil E, said coil H being placed in a local circuit I, of which I' is the battery or
generator. The coils E and H are oppositely wound, or in other words, are so
disposed that in the passage of electric currents through both coils, magnetic poles of
opposite polarity will be formed at the adjacent ends of the coils. J is an exterior
casing attached to the cap C and surrounding the coils E and H. Said casing is
conveniently secured in place and the core A is additionally supported by means of a
screw passing through the end of the casing and entering the end of the core.
a tube leading from spaces between the disk B and the diaphragm D, outwardly
through the casing and provided with an ear piece K', said tube being flexible so
that the ear piece may be placed to the ear at the same time the mouth is held
opposite the mouth piece of the instrument.
K is
Under a well understood law of electro-dynamics if the intensity of an inducing
current is varied, a current will be induced in a secondary coil which is inverse when
the intensity of the inducing current increases, and direct when the intensity of the
inducing current diminishes. When thereforo, the intensity of the current in the
local circuit coil H is varied by the inductive action produced by the vibration of the
diaphragm opposite the end of the core A, corresponding variations will take place in
the current traversing the main line coil E, and such variations will be transmitted
to the coil E of the receiving instrument and by inductive action will set up indula-
tions in the local circuit coil H of such receiving instrument, and thereby produce
variations of intensity in the magnetic field produced by the said local circuit coil,
which will produce vibrations in the armaturo of the receiving instrument corre-
sponding with those of the armature of the transmitting instrument.
A telephonic apparatus of the character described, transmits vocal and other sound
with great clearness and volume, a result thought to be due to the fact that the local

page_text: circuit coils maintain, in the soft iron cores, magnetic poles of high intensity, and
that the electric impulses. arising in the main line, coils, from the inductive action of
such local circuit coils are of corresponding strength or intensity and thereby act
with a strong and positive attractive force upon the armature of the receiving
instrument.
The particular arrangement of the local circuit and main line coils herein illustrated
is not essential, and said coils, may be disposed relatively to each other in any manner
adapted for the inductive action, of one coil upon the other.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:
A telephonic transmitter or receiver, comprising a main line coil, a local circuit
coil, a soft iron core, and a vibrating arinature or diaphragm, substantially as
described.
WILLIAM VOGEL.
GARY G. CALKINS.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicants.