IMPROVEMENT IN ELECTRO-MAGNETIC APPARATUS ESPECIALLY APPLICABLE TO TELEGRAPHIC INSTRU- MENTS
Year: 1884

page_text: COMTUMIE DIECIFICATION,
I, HERBERT JOHN Haddan, of 67, Strand, in the City of Westminster, Civil
Engineer, do hereby declare the nature of my invention for IMPROVEMENT IN
ELECTRO-MAGNETIC APPARATUS ESPECIALLY APPLICABLE TO TELEGRAPHIC INSTRU-
MENTS and in, what manner the same is to be performed, to be particularly
described an ertained in and by the following statement :-
This inve
for use in
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meanwhil
It is we
relates to an improvement in electro-magnetic apparatus designed
ally closed circuit, such for instance as telegraph sounders, Morse
and other instruments which are in active use at intervals and
ale with the battery current traversing their coils.
own that as such instruments have heretofore been constructed, with
a single coilir each magnet core and placed in normally closed circuit, there is
more electricity and battery material used when an instrument is doing no work,
than when it is in active operation. Take for instance, the case of a telegraph
sounder placed according to the common practice in a normally closed local circuit.
A message received on the sounder and translated into Morse characters for the
purpose of inspection will show that while the instrument was in active operation
receiving the message, the local circuit was closed but little more than half the
time, consequently the quantity of battery material used up while the instrument
was doing this work, was nearly one half less than is consumed during an equal
period while it is idle. A similar condition exists in the employment of other
electro magnetic apparatus.
It has seemed to me repugnant to the economical use of energy that more of it
should be exerted to hold an apparatus out of use than is used to actuate it for
accomplishing its functions, and the object of this invention is to reverse the
heretofore prevailing conditions of closed circuit working of electro magnets by
providing an improved construction of apparatus whereby the least battery
material is consumied while the least productive work is being done.
With this object in view, the invention consists in certain novel construction and
combinations of devices which will be hereinafter described and illustrated in the
accompanying drawing in connection with a telegraph sounder.

page_text: In the drawing, Fig 1 is a plan view of a telegraph sounder provided with this
improvement. Fig 2 is a vertical section of the same on the line xx of Fig 1.
Fig 3 is a vertical cross section on the line y y of Fig 1. Fig 4 is a diagram
illustrating the principle of the apparatus.
The letter A indicates the electro magnet. B its armature, C the armature lover
provided with front and back stops, as usual, and D is the retracting spring for
holding the armature against the back stop. The magnet and the supporting
post E and bracket E' stand upon metallic baso F. Upon each of the cores A¹ of
the magnet are arranged two coils, one indicated by the letter a being a coil of low
resistance arranged directly upon the core, while the other b is a coil of much
higher resistance surrounding the coil a. The similar coils on the two cores are
connected together in the usual manner and both have one terminal connected to a
binding post P by wires wand w' respectively, the coils b having their opposite
teriniuals connected to a binding post P¹ by a wire w³ and the coils a have their
opposite terminal connected by a wire w³ with a contact post Q provided at its
upper end with an adjustable contact point q arranged in the path of a contact
spring c attached to the rear end of the armature lever. The armature lever must
bo electrically connected with the post P, as for instance, through the supporting
standards E metallic base F and wire w. The terminal wire w of the fine wire
coils may connect with the base F and have their connection with the post P
through the wire w.
Supposing the sounder to be used with a local battery having a resistance of one
unit, including the resistance of the conductor connecting it with the sounder, the
coils a of low resistance should have about the same resistance namely, one unit.
I prefer to make these coils of wire of such size that they will each occupy about
half the space of the bobbin. The coils b have a resistance about thirty tiines that
of the coils .a. It will be seen from the drawing that when the armature is
attracted by the magnet, there is between the contact spring c, and contact point q
a break in the circuit through the coils a of low resistance, but these circuit closing
and breaking devices do not affect the circuit through the coils of high resistance,
except that by their action in closing circuit the current will be shunted or short
circuited from said coils of high resistance in a great measure, that is the current
will be divided between the two sets of coils in inverse proportion to their
resistances. In other respects the coils of high resistance are worked precisely like
the coils of an ordinary sounder.
The action and purpose of the circuit breaking devices will be understood by
considering the successive positions of the different parts of the apparatus while the
sounder is operating in response to the makes and breaks of circuit during the
transmission of a message. As represented in the diagram Fig 4, the sounder is
Bupposed to be connected in a local battery circuit by wires and the local circuit
closed by the usual relay as shown at R. The current is now passing only through
the coils b of high resistance, which sufficiently magnetize the cores to cause them
to hold the armature lever upon its front stop against the force of the retracting
spring, but these coils would not sufficiently magnetize said cores to cause them to
attract the armature promptly if the lever were against its back. When the relay
breaks the local circuit the armature is drawn away from the magnet poles by the
retracting spring and the contact spring c strikes the contact point g thus closing
the break through the coils a of low resistance. No current passes until the relay
closes the local circuit, at which time nearly the whole current from the battery
passes through the said coils but only for an instant as the circuit through the coils
of low resistance is again broken when the cores under the vigorous action of these,
coils promptly attract the armature and cause the lever to strike its front stop
while throwing the spring c up out of contact with the point q. The current now
goes only through the coils of high resistance which are sufficient to hold the
armature down as before explained.
These coils are of such great resistance that they greatly retard the consumption
of material in the local battery and a great saving is thus effected as it will clearly

page_text: he seen that the least amount of battery material is consumed while the sounder is
idle or doing no effective work.
Besides the saving of battery material effected by my improvement the sounder
can be worked more rapidly in consequence of the coils of lower resistance being
cut out before the armature reaches its position nearest the poles as a great degree
of demagnetization of the cores result from such cutting out, only such polarization
remaining as is effected by the fine wire coils. This slight polarization is quickly
lost when the operator opens his key to commence his next signal, and in con-
sequence of this the armature can be worked much nearer to the poles without
danger of "sticking," and therefore be much sooner magnetized to the degree
necessary to overcome the resistance of the retracting spring.
The extra current induced in the coils of high resistance at the time of breaking
the circuit through the coils of high resistance being in the same direction as the
primary current at the instant the armature reaches its nearest position to the
poles tends to bring the armature lever promptly and firmly to its front stop.
While I have now described this invention in connection with a telegraph
sounder, it will be obvious that it may be applied to electric magnetic instruments
designed for uso on normally closed circuit, and I therefore claim broadly,
1st In an electro-magnetic apparatus, the combination with an electro-magnet
having one or more cores surrounded by two coils of different resistances, of
automatic circuit controlling devices for closing the circuit connection through the
coil or coils of least resistance immediately following the breaking of the circuit
including the coil or coils of higher resistance, whereby the closing of the circuit
causes the current to pass through the coil of low resistance, and immediately open
circuit the same and leave the high resistance coil or coils in circuit substantially
as set forth.
2nd In an electro-magnetic apparatus for use on normally closed circuit, an
electro magnet having separate energizing coils of different resistances in com-
bination with an armature lever and circuit closing and breaking devices operated
thereby, the connections being essentially as shown, whereby when a battery
circuit is closed through the coils of, higher resistanco the armature lever will be
held toward the magnet cores and the circuit through the coils of less resistance
will be broken, and on the breaking of the circuit through the coils of higher
resistance the armature lever will be retracted by its spring and temporarily close
the connection through the coil of less resistance so that the armature will be again
attracted when a battery circuit is closed through said low resistance coils.
3rd In an electro-magnetic instrument, an electro magnet provided with a
retractile arinatare and having its cores wound with two coils circuits of widely
different resistances, in combination with an electric circuit adapted to be opened
and closed and an automatic circuit closing and breaking devices arranged to break
the coil circuit of low resistanco when the armature is attracted, substantially as
described and for the purpose sot forth.