IMPROVEMENTS IN ELECTRIC TELEPHONES
Year: 1884

page_text: ALAN A CAMPBELL-SWINTON Engineer 43 Grove street Newcastle on Tyne do
hereby declare the nature of my invention for IMPROVEMENTS IN ELECTRIC
TELEPHONES to be as follows:-
This invention relates to improvements in Electric Telephones by which sounds
are electrically transmitted and reproduced at a distance.
In the transmitting portion of the apparatus there is no diaphragm or
tympanum.
Two or more suspended pendula carrying pieces of some conducting material are
employed, and under the varying pressure of the sonorous vibrations of the
atmospheric air are pressed with more or less force upon one or more other
conducting bodies, and thus regulate the strength of an electric current flowing
through the apparatus so that the fluctuations in this current are in unison with
and in amplitude proportional to the afore' mentioned sonorous vibrations.
In the receiving apparatus there is a horse-shoe permanent magnet carrying two
soft-iron pole pieces of circular or eliptical cross-section, fitted with bobbins of
insulated conducting wire. The pole pieces are inclined towards one another so as
to include an angle approaching to a right-angle, and their outward, sectional
extremities being semi-circular and close to one another together form a plane
figure approaching to a circle.
In close proximity to the semicircular extremities of the pole pieces, but without
touching the same, is fixed an iron or steel diaphragm which is not held down all:
round the edge but at three or four places only.
In order to convey the sonorous vibrations produced by the receiving diaphragm
to the ears of the operator acoustic tubes may be employed and in some cases
these tubes are attached to swinging arms which support the tubes, and with the
help of springs press their outward extremities against the ears of the operator.
Dated thin 10th day of th
1001

page_text: I ALAN A. CAMPBELL-SWINTON Engineer of 43 Grove Street Newcastle on
Tyne do hereby declare the nature of my invention for "IMPROVEMENTS IN
ELECTRIC TELEPHONES" and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following stateinent :-
66
This Invention relates to improvements in Electric Telephones by which
sonorous vibrations or sounds are transmitted electrically and reproduced at a
distance, and has reference to telephones wherein the transmitter or that
portion of the instrument by which the vibrations are received and transmitted is
based upon the principle discovered in 1861 by Philipp Reis, namely that of
employing regulators of the electric current, which regulators are controlled by
the sonorous atmospheric vibrations, produced by the human voice, these current
regulators consisting of loose or separable contacts between two or more portions
of conducting material, these contacts offering more or less resistance to the passage
of the electric current flowing through them according to the varying degrees of
pressure brought to bear upon them by the variations in the atmospheric sonorous
vibrations.
In an instrument arranged or constructed according to my Invention, I dispense
with the diaphragm or tympanum generally employed in the transmitters of
telephonic instruments for collecting or intercepting the sound, waves or vibrations
and I employ instead thereof a number of suspended pieces or tongues constituting
pendula, each carrying a contact piece which contact pieces when the said pendula
are under the influence of varying pressures, due to the sonorous vibrations of the
atmosphere, are pressed with a correspondingly varying force upon another
conducting body or conducting bodies, and by this varying force of pressure,
correspondingly regulate the strength of the electric current passing through the
instrument so that the fluctuations or variations in the electric current are in
unison with and in amplitude proportional to the sonorous vibrations of the
atmosphere.
And in order that my Invention my be properly understood I will proceed to
describe the system mode or manner in or under which my Invention may be
carried into effect reference being had to the accompanying drawings premising
however that I do not limit myself to the precise details shewn in and described
with reference to the drawings as they may be varied without departing from the
nature of iny Invention.
Figures 1 and 2 are respectively a transverse section and a front view of an
apparatus constructed according to my Invention.
A. A represent a number of pieces which may be called the body parts of the
pendula They carry small portions of conducting material a and are suspended
by flexible wires or strips a² of conducting material extending over or through the
body parts of the pendula so as to be in electrical connection both with the
conducting pieces a and a conducting plate or continuation B attached to a board
or support C. which is inclined so that the contact pieces a rest upon a conducting
rod or plate The inclination of the support C may be conveniently varied by
turning the screw c upon which rests the triangular piece c² fixed to the support C.
the said support C. being hinged to the casing of the instrument as shewn clearly
in the drawings-The spring d serves to convey the electric current from the
binding screw e to the conducting piece B and at the same time serves to keep
the support C. in its adjusted position by causing the piece c³ to bear against the
Screw C.

page_text: The passage of the electric current through the instrument is by the binding
screw e, the spring d, the plate B, the wires or strips a' the pieces a and rod b and
by the other binding screw f with which the rod 6 is electrically connected.
The operator speaks before the mouth piece G which may be provided with
a curtain H of wire gauze, paper or cloth or equivalent material to prevent the
entrance of dust.
Under the influence of the varying vibrations caused by the voice of the
operator the pendula vibrate, thereby causing corresponding variations in the
pressure of the contacts a a upon the rod b-The resistance of the contacts are
thus correspondingly varied and the strength of the electric current (which flows
through the contacts between a and b in parallel circuits (owing to each contact
being a distinct path for the current) is therefore correspondingly varied.
By varying the inclination of the support the degree of pressure primarily
existing between the contacts a and b can be varied as desired to suit loud or soft
talking and to suit the distance at which the operator stands from the mouth
piece.
Provided that the materials be arranged for conducting and non-conducting in
accordance with the foregoing requirements I do not limit myself to the use of any
particular materials. However I may state that it is found that satisfactory
results are obtained if the body portions of the pendula A be made of wood,
vulcanite, cork papier-maché, aluminium or similar light material and if the wires
or strips a forming the electric connection between the plate B and the contacts a
be of light wires or of metal foil and if the contacts a and b be of carbon,
platinum or iron, but it is to be understood that I do not limit myself to these
materials as it is quite evident that they may be considerably varied.
Figure 3 is a transverse section and figure 4 a front elevation of another
arrangement according to my Invention-Figure 5 is a front view of the support.
shewing clearly the arrangement of the contacts, the pendula being omitted but,
their position being indicated by dotted lines.
The arrangement shewn in these figures is similar to that shewn in figures 1
and 2 except that the body parts A of the pendula are suspended by strips or
ribbons a² not necessarily of conducting material as the said strips are not in this
arrangement included in the circuit.
The pieces of conducting material a a are attached to the pendula and each
conducting piece bears upon two other conducting pieces b b¹ which are connected
alternately to conducting plates x and y one of which is in electrical connection
with the binding screw for the entering current the other plate being in
connection with the binding screw by which the current leaves the instrument,
the pieces a forming the means whereby the current passes from one plate to
the other.
There are thus in this arrangement two contacts for each pendulum.
The guard Z is provided to prevent the pendula from shifting when the
instrument is being moved from place to place-Small pins or stops may be
fastened onto the pendula to prevent them from passing up and down past the
guard Z.
Figure 5 is a view corresponding to Figure 5 shewing a modification wherein
the contacts b b¹ and a are connected together in series in place of in parallel
circuits The way in which this is effected is clearly shewn in the figure, the
adjacent pairs of contacts b being electrically connected by the strips and the
adjacent pairs of contacts b¹ being electrically connected by the strips y-The
contacts a bridging the space between each pair of contacts b and b¹-R and S
indicate the electric connection for the entering and leaving current-It will be
evident that this arrangement and that shewn in figure 5 may be combined so as
to form an arrangement wherein there are several parallel circuits each consisting
of two or more contacts in series.
In figure 6 is shewn an arrangement similar to the one shewn in Figures 3. 4
and 5 except in that, the position of the pendula relatively with the speaking

page_text: orifice is reversed so that the operator speaks on to the sides thereof which bear
the contact pieces a the contacts b 61 and conducting strips x y being supported by
a bracket C. The pendula are shewn as being supported from the casing of the
instrument.
.
In figure 7 the contacts a are shewn as consisting of small conducting balls or
short cylinders attached to the pendula, these balls or cylinders forming bridges
between two parallel conducting rods b b¹-In order that the balls or cylinders a
may press evenly on both the rods b b the said balls or cylinders a may be
attached to the pendula by some flexible material (such as india rubber for
example) so as to ensure their coming into proper contact with both of the
rods.b b¹.
All the arrangements shewn may be employed with any telephone receiver in
the ordinary method with or without an induction coil-That is to say the
transmitter may be put in direct circuit with a galvanic battery the line and the
receiver or receivers, or the transmitter may be put in circuit with the battery
and the primary of an induction coil, while the receivers and line are connected in
circuit with the secondary of the induction coil-Or the line may be in the
primary circuit and the induction coil be placed at the receiving end.
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
1st In electric telephones the combination in the transmitting portion of the
instrument of what I have hereinbefore termed pendula, and loose or separable
contact makers constituting electric current regulators or controllers, substantially
as and for the purpose hereinbefore described.
2nd The several arrangements of telephonic transmitting apparatus, substantially
as herein before described with reference to the several figures of the accompanying
drawings.
Date : 1942
"A...hạn 1001