Improvements in Telephone Annunciators.
Year: 1893

page_text: Date of Application, 4th Feb. 1893-Accepted, 11th Mar., 1893
COMPLETE SPECIFICATION.
Improvements in Telephone Annunciators.
I, ALFRED WHALLEY of Mount View, Helsby, near Warrington, in the
County of Cheshire, Electrical 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 :-
My invention relates to telephone annunciators shielded with a tube of iron
either to increase their self-induction, their sensitiveness, or to reduce the
induction between adjacent annunciators.
Instead of placing the iron tube or shield over the usual form of horse-shoe
electro-magnet which carries its own armature, I prefer to support the armature
from the end of the tube placed as a shield over the horse-shoe electro-magnet.
This is more especially convenient for metallic circuit systems in which the centre
of the winding of the wire of the annunciator's electro-magnet has to be connected
to some form of either speaking or testing apparatus, permitting communication
or tests to be established by the operator over speaking circuits without disturbing
the balance of the lines. In this case I establish connection with the centre of
the electro-magnet's wire, either through the yoke to which each core is screwed,
by soldering one end of the wire forming each helix to its own core, the other
end being joined to a form of bent soldering tag described later; or I connect
up the two helices to each other in the usual way, and bring out of the tube
an independent third (central) connection from the electro-magnet. The iron
shield affords space for enclosing a small resistance coil as well as the electro-
magnet in case the circuit to which the central connection is made requires one
of such for each annunciator.
I find that a brass-cased iron tube offers advantages in the construction of
shielded annunciators as the supporting ears for the armature or brackets for
adapting the annunciator for relay working can be soldered to the brass case-
avoiding the use of screws.
In adapting a shielded telephone annunciator for relay working, I provide two
insulated contact-screws supported by brackets fixed to the iron tube or shield,
and provide also two metallic springs, or one broad one, fixed to the armature
and making contact with the two insulated contact screws, when a current works
the armature. These relays are useful when a bell is required to be rung, but
only so long as the calling current' is working the annunciator.
In find also that if an iron ring of width and thickness equal to about twice
the thickness of the iron tube be mounted at its armature end the sensitiveness
of the annunciator is much increased.
To avoid having to cut the electrical connection of the annunciator before the
shield or tube can be removed, I provide two or three slots in the tube at the
yoke end, through which pass soldering tags connected to the wires of the electro-
magnet.
Several of these improvements are applicable to shielded annunciators whose
electro-magnets consist of a central core and helix surrounded by an outer tube
of iron.
Fig. 1, is a vertical section of a double helix annunciator shielded according to
my improvements, but showing one of the helices and cores in section. The iron
ring is not shown here.
Fig. 2, is a horizontal section of an unwound double helix electro-magnet with
tube of iron. The iron ring is here shown in section.
Fig. 3, is an elevation of the yoke end of the electro-magnet, and tube in Fig. 2,

page_text: the line XX passing through the centres of the two cores. The iron ring is not
shown here.
Fig. 4, is a plan of the annunciator in Fig. 1.
Fig. 5, is a front elevation of the annunciator in Fig. 1.
Fig. 6, is an elevation of the armature end of a complete shielded electro-magnet,
with armature &c., but not fixed to the plate carrying the annunciator drop.
In the several figures p. p, is the plate supporting on one side the drop or
shutter, and on the other the shielded electro-maguet, armature &c.
c. c, are the cores of a double helix electro-magnet.
h. h, are the helices of the same.
y, is the yoke of the electro-magnet, to which the two cores and also the iron
-tube are attached.
t, is the tube or shield of iron which may be either entirely of iron, or internally
of iron, and externally of brass.
a, is the armature of the annunciator pivotted or supported from the tube or
shield.
1, is the lever connected to the armature, whose free end normally holds up the
drop.
s.s, are the slots in the iron tube at the yoke end provided for the passage of
the soldering tags.
o. o, are the soldering tags passing through the slots s. s, in the iron shield to the
helices to which they are electrically connected. These tags may be conveniently
insulated from the iron shield by thin india-rubber rings slipped over them.
u. u, are the insulating supports provided for the soldering tags towards the
armature end of the shield.
r. r, Fig. 2, shows the iron ring mounted at the armature end of a shielded
annunciator to increase its sensitiveness.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The construction of double helix annunciators with an iron tube or shield
enclosing the electro-magnet and supporting the armature.
2. The combination with a double helix electro-magnet of an iron tube enclosing
the same, and the armature supported by the tube.
3. The construction of annunciators shielded with brass-cased iron tubing.
4. The construction of annunciator shielded by an iron tube which is thickened
either in one piece, or by the addition of an iron ring, at the armature end.
5. The method described of arranging that the iron tube of shielded annunciators
can be removed without disturbing the electrical connections.
6. The combination of an iron shield or tube, a double helix electro-magnet,
placed inside the shield and having three electrical connections to the same and the
armature supported by the iron shield.
7. The construction of a combined shielded annunciator, and relay, the armature
and one portion of the relay contacts being pivotted or supported from the iron
tube under the control of the current passing through the electro-magnet of the
annunciator, and the other portion of the relay contacts being supported from the
iron tube by brackets or lugs.
8. The combination of an electro-magnet, the iron tube surrounding the same,
the armature with relay contacts supported by the iron tube, the brackets or lugs
with relay contacts supported also by the iron tube, the lever projecting from the
armature, and the annunciator drop normally held up by the lever and adapted to
be released therefrom when the armature is moved.
Dated this 24th day of January 1893.
ALFRED WHALLEY.