Improvements in Electrical Signalling Apparatus.
Year: 1894

page_text: Date of Application, 18th Sept., 1894
Complete Specification Loft 15th June. 1805 Accented
3rd Aug 1805
PROVISIONAL SPECIFICATION.
Improvements in Electrical Signalling Apparatus.
THE PHONOPORE COMPANY LIMITED, of Faraday House, Charing Cross
Road, London W.C. and EDWARD WYTHE SMITH, also of Faraday House
Charing Cross Road, London, W.C. Electrical Engineer do hereby declare the
nature of this invention to be as follows:-
Our invention consists of an improved means of calling attention to telephones
or signal apparatus which is not directly connected to the line wire in the ordinary
way, but by means of a condenser, phonopore or other induction device. The
vibratory currents used in such cases are not of sufficient strength or duration to
work a bell, or other instrument for calling attention, directly. We overcome
this difficulty by a relay consisting of a permanent magnet having soft iron poles
with coils wound on the poles, similar to the type known as "Hughes magnet.'
In front of this we arrange an armature so adjusted with a spring that the
permanent magnetism is just strong enough to hold the armature away from a
contact stop against the action of the spring; if, however, the armature is released
from the magnet it touches the contact stop and remains there.
The action is as follows:-The calling station sends vibratory currents to line.
At the receiving station these currents are caused to pass through the winding of
the relay magnet by means of the particular induction device employed. This
causes the armature to tremble, which, by the action of the spring, flies back to the
contact stop, thus completing the circuit of an electric bell. Whilst the armature
of this bell is attracted to its magnet, it closes another circuit thereby causing a
current to pass through a winding of the relay magnet of such strength and
direction as to pull the armature away from the contact stop and bring it back to
the pole pieces. The armature will not remain against the pole pieces, so long as
vibratory currents continue to pass through the coils, but will continue to fall back
against the contact stop each time it is replaced, thereby causing each time a
stroke of the bell.
Dated this Eighteenth day of September 1894.
Improvements in Electrical Signalling Apparatus.
THE PHONOPORE COMPANY LIMITED and EDWARD WYTHE SMITH,
5 Electrical Engineer, of Faraday House, Charing Cross Road London W.C.
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 :—
Our invention consists in an improved means of calling to telephone or other
apparatus which is not directly connected to the line wire in the ordinary way, but

page_text: With such
by means of a condenser, phonopore coil, or other induction device.
apparatus vibratory currents are employed, which currents, in most cases, are not
of sufficient strength or duration to ring a bell, or work any other form of
instrument for calling attention directly.
"3
By the expression "vibratory currents we mean currents of short duration in
either or both directions following one another in rapid succession.
To apply such vibratory currents to the working of call apparatus we employ a
relay constructed as shown Fig. 1, where M is a permanent magnet with soft iron
pole pieces forming cores on which are wound coils of wire a, a, b, b, Fig. 1, similar
to the form known as "Hughes magnet." In front of these bobbins we arrange a
soft iron armature A supported at one end by a pivot with a spring f, the other
end being free to move between the stop S and contact screw C. The spring f,
Fig. 1, tends to keep the armature away from the magnet, but it is so adjusted
that, when the armature is placed against the stop S, it will remain there, the
spring being not quite strong enough to pull it away against the attraction of the
over to the contact
magnet. But, if the armature is released, the spring will pull
screw C, and will hold it there, the pull of the magnet on the armature being much
less in this position than when it is against the stop S.
The bobbins a, a of the magnet M are connected by the wires t, t to the
condenser or other induction apparatus employed in such a manner that the
vibratory currents received from the line affect the magnet and make the armature
tremble so that, owing to the action of the spring, it flies off the stop S and makes
contact with the screw C, thus closing the circuit of the battery X through the
magnet of the bell in, causing a stroke of the bell. When the spring on the bell
armature Qtouches the stop K a second local circuit is completed, the battery Y
sending a current through the coils b, b of the magnet M of such strength and
direction as to strengthen the magnet to such an extent that it will pull back the
armature A. from the contact C to the stop S. When the armature A leaves
the contact C the bell circuit is broken and the armature Q springs back. If
vibratory currents continue to pass through the coil a, a of the magnet M the
armature A will be again released, when the bell armature Q leaves the contact K,
this will cause another stroke of the bell and so on; the bell armature will continue
to vibrate until the vibratory currents in the coils a, a of the magnet M cease and
allow the armature A to remain on the stop S.
A modified disposition is shown in Fig. 2, the armature A being mounted on the
spring and fitted with a light spring p, which increases the duration of the
electrical contact with C.
Also, in Fig. 2, there is only one winding on the magnet M, the coils a, a
forming part of both the vibratory current circuit t, t and the circuit of the local
battery Y.
We prefer to use the instrument, thus shown, Fig. 2, fixed vertically, the
armature A hanging pendulumwise. Under these conditions we find it convenient
to carry the armature on the spring the adjustment being made by turning the
pillar Puntil the tendency of the spring is to bring the armature A to the
contact C, being, however, not quite strong enough to pull it off the magnet M.
Fig. 3 shows the arrangement together with a phonopore coil, described in
Patent No. 4506 of 1885. When the push R is pressed the circuit of the battery Z
is closed through the primary r, r of the phonopore coil and the vibrator V, which
induces vibratory currents in the secondaries j, j which are connected to the line
and earth. When the vibratory currents are received, they pass through the coils
of the magnet M and cause the bell to ring. The connecting wires L and E go to
line and earth.
In Fig. 3 the apparatus is shown so arranged that the same coil is used for
speaking by telephone and to generate and receive the vibratory currents for
working the call. The hook switch H closes the circuit of the microphone
battery Z through the primary r, r and the microphone N in the ordinary way.
It is also arranged to cut out the telephone receiver n when down, and to cut ou

page_text: the coils of the magnet M when up. The phonopore coil may be replaced by an
ordinary induction coil with a break, a condenser being interposed in either or both
of the secondary branches.
When using our invention to give the call signal for a harmonic telegraph, we
employ it constructed as described with reference to Fig. 1 or Fig. 2. We
interpose the coils a a of the magnet M in the circuit of the harmonic relay used,
and then the currents received from the calling station actuate our apparatus in the
manner described.
Before replying the operator switches our call apparatus out of circuit, by short
circuiting the coils a a, or by a switch worked by hand, similar to the automatic
switch H (Fig. 3); and, after the telegraph message is finished he switches the call
apparatus again into the circuit.
We do not confine ourselves to the exact disposition or design of the parts
described; the various parts being capable of modification without altering the
action of the arrangement. Instead of the signal being produced on a bell, it may
be given by any other known form of instrument giving visual or audible signals
by the motion of an armature similar to Q.
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 :-
1. The combination of a relay nd bell or similar instrument with the relay
armature A and the contacts C and K substantially as and for the purpose
described.
2. The combination of a relay and bell or similar instrument with the relay
armature A and the contacts C and K, substantially as described, with instruments
using vibratory or intermittent electric currents, such as telephones and harmonic
telegraphs substantially for the purpose described.
3. The combination of a coil, microphone, relay and bell with the necessary keys
and contacts substantially as described with regard to Fig. 3.
Dated this 7th day of June 1905
THE PHONOPORE COMPANY, LIMITED,
CHARLES ISAAC, Secretary.
E WYTHE SMITH.