Improved Electrical Signalling Apparatus for Transmitting Commands and the like.
Year: 1897

page_text: Date of Application, 7th May, 1897-Accepted, 13th Nov., 1897
COMPLETE SPECIFICATION.
Improved Electrical Signalling Apparatus for Transmitting
Commands and the like.
I, CHARLES DENTON ABEL, of No. 28 Southampton Buildings, Chancery Lane, in
the County of London, Consulting Engineer, and Chartered Patent Agent, do hereby
declare the nature of this invention (as communicated to me from abroad by
Allgemeine Elektricitäts-Gesellschaft of Schiffbauerdamm No. 22 Berlin,) and
in what manner the same is to be perforined, to be particularly described and
ascertained, in and by the following statement:-
Electrically operated signalling apparatus for transmitting commands and the like
as heretofore employed, are more or less unreliable in their working, in consequence
either of the use of interpolated mechanical devices, or on account of variations in
the potential difference, when their action depended upon changes of resistance
effected in the transmitting instrument.
The present invention relates to a construction of electrical signalling apparatus
whereby such unreliableness is entirely obviated.
I will describe the invention with reference to the accompanying drawing, in
which Figure 1 shews a plan and Figure 1^ a vertical section of one form of the sending
and receiving instruments.
For the above purpose the transmitter consists of a resistance coil a closed in itself,
which is supplied with current at two diametrically opposite points by a moveable
sliding contact arm b b b² rotated by means of a moveable lever c, and connected by
leads with the source of current.
At three points d₁ d₁ d, situated 120° apart this current is taken from the
resistance coil and is conducted by means of three leads e¹ e² e³ to the receiving
instrument.
The latter consists of an arrangement of three, or of a multiple of three
coils ffaf, in the magnetic field of which is a magnet g with pointer
an axis on which it can revolve freely.
The coils are here arranged perpendicularly to the axis.
mounted on
Figure 2 shews a plan and Figure 2 a vertical section of another construction of
receiver in which a system of six (or it might be three, or other multiple of three)
coils are arranged with their axes parallel to the axis of rotation of the magnet.
The connections of the circuits are such that the three leads el e and e³ are
respectively connected to coils situated at an angle of 120° to each other. The other
ends of these coils are connected by leads with the entering ends of the diametrically
opposite coils, the other ends of which are connected together by a ring shaped
conductor .
Referring to Figs. 1 and 1^, the action of the apparatus is such, that a current
supplied by means of the opposite sliding contacts 61 and 62 to the resistance «, is so
distributed through the leads e¹ ees and the receiver coils f f f³, that the latter
constitute a magnetic field whose direction always corresponds to that of the contact
arm band hand lever c of the transmitter.
In the position shewn at Fig. 1, for example the positive current enters at 61 and
divides in such manner that one part passes through the two half coils of a directly
to the opposite negative contact be. This part of the current has no influence upon

page_text: the action of the apparatus and by a suitable proportioning of the resistance of a can
be made so small so to be negligable.
The other portion of the current entering at passes through the branch at d² to
the lead e and through this to the receiver, where it first passes through coil, this
taking place, in the arrangement shewn, in the direction from inside to outside;
assuming for example that the winding of this coil as also that of coils f¹ and f³ is
such that, if the current flows from inside to outside a south pole is produced at the
inside, (a north pole being consequently produced at that point if the current flows
in the contrary direction) then an inner south pole will consequently be produced in
this instance. On issuing from into the ring conductor, the current divides into
two branches flowing through coils f¹³ in the direction from without to within, and
consequently producing inner north poles. The current then passes through leads e¹
and back to the sending instrument, where it passes through the two parts d¹²
and db back through to the negative pole of the current generator.
The north poles of f¹ and f3 and the south poles of f now form the components
of a magnetic field, whose direction will be the same as that of coil f, so that the
magnety and index will also assume that position, and the latter will therefore
have exactly the same position as b and c of the sending instrument.
If now bande be turned until 2 is brought to d¹ then the positive current
entering at will divide into two parts which will flow through till they reach
the branches and d³, passing thence through the leads e² and es to the receiver.
In the latter the currents will pass through coils f2 and f in the direction from
within to without, thus forming inner south poles; from f³ the currents pass into
the ring conductor and, joining, pass thence through the coil from outside to
inside, producing an inner north pole, and finally the current passes from f¹ through
el and to b² and so back to the current generator.
The poles of f f f will thus form the components of a magnetic field the direction
of which will correspond to the position of b, c, and which will bring g and into
a corresponding position.
By the order of succession of the connections of the points d', d², ³, with the
coils fff, this shifting can be made to take place in the same direction as in the
transmitter, or in the opposite direction, at will.
On further rotation of the contact lever b in the transmitter, the respective
operations and changes of the current are repeated in the coils of the receiver, so that
a complete rotary field is produced which always moves in a synchronous manner
with the transmitter lever.
As only these variations of resistance affect the direction of the magnetic field
whilst the strength of the same, that is to say the strength of the current introduced
(into the circuit), has no appreciable effect upon this direction, the accuracy of the
indications of the pointer is in this invention independent of variations in the
potential of the current used.
In apparatus for giving orders, with reply, the transmitter of the one apparatus is
connected to the receiver of the other apparatus. It is also possible, without further
trouble, to operate from one transmitter any desired or varying number of receivers
simultaneously.
Obviously the arrangement may also be such that in the receiver there is provided
a fixed permanent magnet g, whilst the coils which are then provided with a
pointer, have their movement in the field of this constant magnet.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
Electrically actuated signalling apparatus consisting of a transmitting instrument
and a receiving instrument, of which the transmitter consists of a closed wire coil
which is supplied with current by means of two diametrically opposite rotatable
contacts, while the coil is connected by means of three leads situated 120° apart
with a receiver or receivers consisting of three coils or groups of coils arranged so as

page_text: to act upon a central rotatable magnet with pointer in such manner that each
variation of resistance in the transmitter caused by the change of position of its lever,
corresponds to a certain position of the pointer in the receiver, quite independent of
any variations in the tension of the current supplied substantially as described.
Dated this 7th day of May 1897.
ABEL & IMRAY,
Agents for the Applicant.