An Improved Device to be used as an Indicator, Signal or Relay in connection with Telephone Switch Boards and other Analogous Apparatus.
Year: 1897

page_text: Date of Application, 12th Jan., 1897
Complete Specification Left, 12th Oct., 1897--Accepted, 12th Feb:, 1898
An Improved Device to be used as an Indicator, Signal or Relay in
connection with Telephone Switch Boards and other Analogous
Apparatus.
I, PARNELL RABBIDGE, Electrician, of Glendearg, William Street, Double Bay,
Sydney, in the Colony of New South Wales, do hereby declare the nature of this
invention to be as follows:-
This invention relates to telephone switch boards and the like and has for its
object the construction' of an indicator, signal or relay which is intended to replace
the shutter indicator ordinarily in use with telephone switch boards. The inven-
tion may however be employed for other similar purposes, but in the following
specification it is described more particularly in connection with telephone switch
boards..
Upon the poles of a magnet of preferably horseshoe shape are arranged pieces
of soft iron, one of which is either permanently attached to one pole or formed
integral with it, the other piece is so arranged that while being in contact with the
second pole of the magnet it is free to slide to and fro through the latter. The
appearance given to the magnet with these cross pieces is somewhat similar to
that of the letter "U", the sliding piece being of such length that it may be
drawn in by the attraction of the fixed piece so that the ends of the two may
touch, though if desired a stop or collar may be arranged on the sliding piece to
prevent the two poles coming actually in contact.
•
Between the arms of the magnet and so as to surround the ends of the cross
pieces which project on the inside, is arranged a bobbin carrying a coil of wire
the ends of which are in communication with a distant instrument. A spring is
arranged upon the outer end of the sliding cross piece of the magnet the action
of which is to tend to force the sliding piece away from the other pole of the
magnet, the magnetic attraction of the other pole is however sufficiently strong
to overcome this tendency until a current is sent through the coil, when the poles
of the magnet being temporally demagnetised the spring is free to act and
cause the sliding piece to fly out. Directly the current flowing through the coil
is shut off the poles of the magnet again exert their influence and the sliding
piece is again drawn in.
The whole of the above described device is enclosed in a casing which is provided
with a suitable opening on the front side through which can pass a button or
other device mounted upon the end of the sliding cross piece in such a manner as
to attract attention when the latter is moved. Contact pieces are also arranged
on the interior of the casing adjacent to this opening, so that upon the current
being passed through the coil and the sliding piece with the button being caused
to fly out in the manner above described, a suitable shoulder formed upon the
sliding piece comes in contact simultaneously with the two contact pieces on the
casing and throws into action a relay which may be arranged to operate a bell
other signal

page_text: The movement of the sliding cross piece may if desired be arranged to operate
some other signalling device which will remain in a certain position until replaced,
such a device may comprise a shutter which is normally retained by a catch upon
the end of the sliding piece but upon the movement of the latter is free to fall
down, or a shutter may be operated in some other convenient manner.
It is obvious that this device may be employed in connection with many
appliances where it is required to transmit a signal for the purpose of attracting
attention.
Dated this 12th day of January 1897
BOULT & WADE,
Agents for the Applicant.
An Improved Device to be used as an Indicator, Signal or Relay in
connection with Telephone Switch Boards and other Analogous
Apparatus.
PARNELL RABBIDGE, Electrician, of Glendearg, William Street, Sydney, in the
Colony of New South Wales, do hereby declare the nature of this invention and
in what manner the same is tn he performed, to be particularly described and
ascertained in and by the following statement: —
This invention relates to telephone switch boards and the like and has for its
object the construction of an indicator, signal or relay which is intended to replace
the shutter indicator ordinarily in use with telephone switch boards. The inven-
tion may however be employed for other similar purposes, but in the following
specification it is described more particularly in connection with telephone switch
boards.
Upon the poles of a magnet of preferably horseshoe shape are arranged pieces
of soft iron, one of which is either permanently attached to one pole or formed
integral with it, the other piece is so arranged that while being in contact with the
second pole of the magnet it is free to slide to and fro through the latter. The
appearance given to the magnet with these cross pieces is somewhat similar to
that of the letter "U", the sliding piece being of such a length that it can be
drawn in by the attraction of the fixed piece so that the ends of the two may
touch, though if desired a stop or collar may be arranged on the sliding piece to
prevent the two poles coming actually in contact.
Between the arms of the magnet and so as to surround the ends of the cross
pieces which project on the inside, is arranged a bobbin carrying a coil of wire
the ends of which are in communication with a distant instrument. A spring is
arranged upon the outer end of the sliding cross piece of the magnet the action
of which is to tend to force the sliding piece away from the other pole of the
magnet, the magnetic attraction of the other pole is however sufficiently strong
to overcome this tendency until a current is sent through the coil, when the poles
of the magnet being temporally demagnetised the spring is free to act and
causes the sliding piece to fly out. Directly the current flowing through the coil
is shut off the poles of the magnet again exert their influence and the sliding
piece is again drawn in.
The whole of the above described device is enclosed in a casing which is provided
with a suitable opening on the front side through which can pass a button or
other device mounted upon the end of the sliding cross piece in such a manner as
to attract attention when the latter is moved. Contact pieces are also arranged

page_text: according to this invention.
Fig. 2 a side elevation of the apparatus shown in Fig. 1, the containing box
alone being in section, and the parts in their relative positions when the signal
has been given.
Fig. 3 a diagram illustrating the simplest form in which the apparatus can be
constructed.
Fig. 4 a vertical longitudinal section of an alternative form of indicator,
Fig. 5 a side elevation of the same apparatus, the parts being in a different
position the containing box being in section, and
Fig. 6 an end elevation of the apparatus shown in Fig. 5.
Like letters refer to like parts throughout these drawings.
In Figs. 1 and 2 A is a U-shaped permanent magnet whose poles are marked N
and S respectively, and C and D are the two parts forming the soft iron armature
to the magnet, in this instance they are cylindrical in shape, but any convenient
shape may be used.
Of these two pieces C is fixed so as to be immovable relatively to the permanent
magnet, through one of whose poles N, it passes transversely in the direction of
the other pole S. This piece C may be affixed to the pole of the magnet itself
or may be fixed as shown in Figs. 1 and 2 to the box 13 which contains the whole
apparatus and to which the magnet is secured also. The box B should be made
preferably of non-magnetic material.
The other of the two armature pieces I passes freely through a hole in the
pole S similar to that in the pole N through which the piece C projects. The
two pieces thus form when in the position shown in Fig. 1 a practically continuous
cylinder, bridging the gap between the two poles and so fulfilling the function
"armature or keeper."
of an
"
The movable piece D is conveniently made longer than the piece C and carries
on its extremity remote from C a push-button or similar device or any convenient
indicator E and also a flange or other stop or check E¹ which serves the double
purpose of limiting the outward movement of the push E and of completing the
electric circuit between the springs e, el as and for the purpose hereinafter described.
The button E and stop E' may be formed of the same piece of metal as the armature
piece Dor may be formed of any suitable material, it being only necessary in
the event of the stop E¹ being of an insulating material to secure upon the face
thereof a ring of conducting material or its equivalent which will effect the closure
of circuit between the contacts e e¹.
F is a spring in compression which tends constantly to force the movable
armature piece D out and away from the piece C, but which is not strong enough
to effect this when the two adjacent ends of the two armature pieces have been
brought into contact, say by hand, and adhere under the influence of the magnet A.
Around the armature pieces and between the poles of the magnet is wound a

page_text: coil of wire G of such an internal diameter as not to impede the movements of
the armature piece D. This coil is so wound and so connected electrically as
to oppose the magnetic flux through the armature pieces C and D due to the
magnet A, and when the effect of this is sufficiently powerful to allow the spring F
to assert itself, the piece I flies out under its influence in the direction indicated
by the arrow F and assumes the position indicated in dotted lines in Fig. 1 or
in full lines in Fig. 2. The push E then protrudes through a hole B¹ formed for
the purpose in the wall of the box B, its motion being limited by the stop E¹.
When in this position the stop E¹ makes connection between the contact springs e, e¹
which are connected as shown to a local circuit containing a bell H and a battery:
so long therefore as the stop E is in this position the bell H will continue to
ring, and so attract the attention of the operator. Or the bell may be of the
single-stroke kind.
If the current in the coil G has ceased or fallen to so low a value as to be
insufficient to effect the release of the piece D, when the operator pushes in the
push E so as to bring the two adjacent extremities of the armature pieces C and D
into contact they will adhere and the push E remain out of sight until the next
signal-current traverses the coil G. The push E may bear a name or number or
any other device or inscription upon its surface; or its movement may indicate
the source of the signal or give other requisite information by means of a suitable
shutter or the like such as is shown at K in Figures 4, 5, and 6 bearing the word
"London"; the face K¹ of the shutter which bears the inscription being turned
out of sight when the two armature halves are in contact as is shown in Figure 4.
The shutter is pivotted at and there engages with it a small projection E² on
the push E which imparts to the shutter a quarter revolution thus causing the
inscription to be displayed when the push protrudes through the box as a result
of the passage of a current through the coil G, and causing the inscription to be
returned to its hidden position when the operator replaces the push.
A bell or other sonorous signal may or may not be added to the apparatus in a
similar manner to that described in reference to Figures 1 and 2; I may if
desired bush the hole in the pole S of the magnet through which the piece D
slides, with brass or other suitable non-magnetic material and this bush may at
the same time serve to retain the bobbin of the coil G in position, as shown in
Fig. 4.
A simple form of indicator constructed according to this invention is shown in
Figure 3 where the magnet A is made of springy steel and carries the armature
pieces attached one to each pole; these normally adhere as herein before described
but when the magnetic flux is opposed by the current in the coil G, the force due
to the springiness of the magnet A preponderates and the two poles carrying
with them the armature pieces C, D fly apart.
I may obviously vary the construction of the magnet and other parts of the
apparatus described in this specification without departing from the spirit of
this invention. I may for instance employ a permanent magnet of bar shape
instead of the U shape illustrated and in that case may conveniently attach polar
extensions of soft iron to take the place of the upright limbs of the U shape.
Or I may employ a compound magnet formed of several placed side by side.
Further I may affix the piece C into the magnet limb, in which case the piece
is virtually an extension of the magnet pole. I prefer however the construction
shown in which a small gap is left between the piece C, and the wall of the hole
in the magnet pole through which it passes.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what I
claim is:-
1. In an indicator, signal, relay or the like the combination with a permanent
magnet A and coil G of an armature divided into two parts whereof one is fixed
relatively to the magnet and the other movable, and means, such, for example, as

page_text: the spring F for moving one armature piece away from the other substantially as
described or illustrated in the accompanying drawings.
2. In an indicator, signal, relay or the like the combination with a permanent
magnet A and coil G of an armature divided into two parts whereof one is fixed
relatively to the magnet and the other movable, and means, such, for example,
as the spring F for moving one armature piece away from the other and contact
pieces e, el and E' substantially as and for the purpose described.
3. In an indicator, signal, relay or the like the combination with a permanent
magnet A of an armature divided into two parts such as C, D, a coil G surround-
ing the armature and spring F for separating the armature pieces with or without
an audible signal substantially as described or illustrated in the accompanying
drawings.
4. In an indicator, signal, relay or the like the combination with a permanently
magnetised spring of an armature divided into two parts and a coil & surrounding
the armature with or without an audible signal substantially as described or illus-
trated in Figure 3 of the accompanying drawings.
5. In an indicator, signal, relay or the like the combination with the apparatus
described in Claim 3 of an oscillatory device such as K, actuated by the movable
armature piece substantially as described and illustrated in the accompanying
drawings.
6. The complete electrical indicator substantially as described and illustrated
in Figures 1 and 2 or Figure 3 or Figures 4, 5 and 6 of the accompanying drawings.
Dated this 12th day of October 1897.
BOULT & WADE,
Agents for the Applicant.