IMPROVEMENTS IN TELEPHONE REPEATERS
Year: 1885

page_text: I, CHARLES ARTHUR ALLISON, of the firm of Allison Brothers, of 52 Chancery
Lane, London, in the County of Middlesex, Patent Agents, do hereby declare the
nature of said invention for "IMPROVEMENTS IN TELEPHONE REPEATERS" and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
My invention consists in a repeater for use in telephone circuits for reproducing
in one circuit the signals transmitted over another, the instrument being con-
structed and adapted for uses analogous to those of the ordinary telegraphic
repeaters. Inasmuch as the invention resides chiefly in the mechanical construction
of the repeating apparatus, I will explain the same by reference to the accom-
panying drawings in which,―
Fig. 1 is a plan view of the repeating apparatus.
c
Fig. 2 is a side elevation of the same, with certain parts removed, and Fig. 3 a
diagram of the circuits and arrangement therein of the apparatus in a telephone
system.
The repeating apparatus is mounted on any suitable form of base A and is
composed of the parts described below.
.
B, is a sensitive electro-magnet before the poles of which is pivoted a polarized
armature C. The magnet or armature is provided with the usual means of
adjustment, such as an adjusting screw a passing through post b and connected
with the cross bar or back armature ċ.
From the centre of the armature C extends at right angles a light arm or bar D,
on either side of which is an adjustable stop e by means of which the vibration or
play of the armature is limited.
Facing the electro-magnet B, is a permanent magnet E, resting on a suitable
support and adjustable by means of a screw F. Close to one pole of this magnet
is a post G, mounted on the base A, and at the other pole is a corresponding
post H
Each post is properly formed for holding two pins f, g, in vertical line. These
pins serve as bearings for light metallic blades K, K³, to each of which is attached
.

page_text: an iron or steel armature at right angles. The pins f. f. may pass through the
armatures, and the armatures are separated from one another by washers. The
attractive force of the magnet exerted upon the armatures tends to draw the
blades K, K¹, together. They are held apart, however, by an insulating plate M,
carried by the arm D, in the edges of which plate are inserted metal strips h, k, 5
upon which the blades K; K', make contact.
Adjustable spiral springs m, m, are connected to opposite sides of the bar D, for
adjusting its position.
The base A contains six binding posts, by means of which the connections are
made. Posts 1 and 2 are then connected with the magnet B, and to them the 1
incoming line wires are connected.
Post 3 is connected by wire n with the post G, and post 4, by wire o with the
The circuit from wire n to
pin f, in post G, which pin is insulated from the post.
wire o is therefore made from the pin f, through blades or strips K, the metal edge
of plate M, on the arm D, thence through blades K¹, back to the post G..
Posts 5 and 6 are similarly connected with the post H.
Referring now to Fig. 3 which is a diagram illustrative of the manners of
operating and using the above described apparatus.-A transmitter is used
consisting of a lever A³, pivoted at its centre and divided into two parts which are.
insulated from each other. Upon bars a' on the ends of this lever, rest pivoted
metal strips B¹, C¹. The vibration of the lever which is produced by the vibration
of a diaphragm D', connected with it, varies the contact pressure between the
strips B, C, and the bars a¹, so that if the strips be connected up in branches of a
circuit E and these branches carried in opposite directions around the core of an
induction coil, magnetic changes will take place corresponding to the vibrations of
the lever, and impulses of current will be developed in the secondary coil and line
wire F¹.
These impulses acting upon the magnet B, produce vibrations of the lever or
arm D, but a movement of arm D, produces with the blades or strips K, K¹, the
same effect as lever A¹ with the strips B₁, C₁, so that if the strips K, K¹, of each
post G, H, be included in separate circuits or branches of a circuit that pass around
the core of an induction coil, the magnetic conditions of the core will be disturbed
by the vibrations of the arm D, and current impulses reproduced in the line H¹,
corresponding to those received by magnet B, from the line F¹, but stronger.
In the same way these reproduced impulses may again be repeated and loud and
distinct signals or words transmitted over. long lengths of wire.
°
The moving metallic parts, such as the blades K, K¹, the plates h, k, and even
the arm D, I prefer to make very light, using preferably aluminium.
The purpose of the permanent magnet is solely to maintain a certain degree of
pressure between the strips K, K¹, and the plates h, k. In consequence of the use
of a number of strips K, K¹, the magnet is much more practicable than springs or
similar means, as the force exerted upon the armature is more uniform. It is
very desirable to use a number of strips K, K', instead of single strips, as better
contact is assured. By using two sets of strips for each circuit or branch, the
operation of the device is greatly improved, as the change in contact resistance
takes place at two points in the circuit simultaneously.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I wish it to be
understood that I do not claim broadly herein the multiple contacts, but I declare
that what I claim is
1st A telephonic repeater consisting of an electro-magnet and having a polarized
vibrating armature and connected with one circuit, in combination with pivoted
strips or blades held in contact with a projection from the armature and connected
with a second circuit as set forth.
2nd A telephone repeater consisting of an electro-magnet and vibrating armature
connected with one circuit, in combination with pivoted strips or blades carrying

page_text: armatures, a permanent magnet acting upon said armatures for holding the strips
in contact with a projection from the vibrating armature, and circuit connections
through said strips, as set forth.
3rd A telephonic repeater consisting of an electro-magnet and polarized vibrating
armature connected with one circuit, in combination with two sets or groups of
pivoted strips or blades bearing upon a projection from the polarized armature, and
circuit connections through said strips, as set forth.
.
4th The combination with an electro-magnet, a vibrating polarized armature
pivoted in face of the poles of the magnet, an arm extending from the centre of
the armature and two insulated metal plates carried by said arm, of two sets of
pivoted strips or blades carrying armatures, a permanent magnet acting upon the
armatures to hold the strips in contact with the insulated plates carried by the
vibrating arm and circuits connecting with the strips or blades in the manner
specified.
5th The combination with an electro-magnet, a vibrating polarized armature
pivoted in face of the poles of the magnet, an arm extending from the centre of
the armature, and two insulated metal plates carried by said arm, of two sets of
pivoted strips or blades carrying armatures, a permanent magnet acting upon the
armatures to hold the strips in contact with the insulated plates on the vibrating
arm, circuits through the pivoted strips, and an induction coil the primary coil of
which is formed by the wires of said circuits, as and for the purpose set forth.
Dated this 8th day of September 1885.