IMPROVEMENTS IN MAGNETO GENERATORS OF ELECTRICITY
Year: 1883

page_text: "
LETTERS PATENT to Martin Benson of N° 52 Chancery Lane London for an
Invention of "IMPROVEMENTS IN MAGNETO GENERATORS OF ELECTRICITY
Communicated to him from abroad by James Pleasants Stabler of Sandy
Spring in the State of Maryland United States of North America Electrician.
COMPLETE SPECIFICATION filed by the said Martin Benson at the Office
"
of the Commissioners of Patents on the 11th October 1883.
MARTIN BENSON of N° 52 Chancery Lane London.
IMPROVEMENTS IN
MAGNETO GENERATORS OF ELECTRICITY." Communicated to me from Abroad by
James Pleasants Stabler of Sandy Spring in the State of Maryland United States
of North America-Electrician
The object of my invention is to vary the strength of the current at will without
changing the speed of the armature and without the interposition of resistance in
the line current for that purpose In an individual call apparatus for telephonic
purposes (Patented by me October 5th 1882 N° 4740) I have two magneto generators
of different strength, the current from either being applied to the line at will; that
of the weaker, a "to-and-fro" current, taken off without a commutator and that of
the stronger being applied by means of make and break contacts arranged to take
off a current in one direction only.
My present invention consists of a magneto generator the bobbin wire of which
is so wound that by means of proper contacts, either the intensity or quantity of
the current taken from it may be varied at will without changing either the speed
of its revolution, the intensity of the magnets field or the resistance of the external
circuit I am enabled by this means to dispense with one of the generators
heretofore used.
It is well understood that the intensity of a magneto current depends upon the
length of the bobbin wire of the generator armature and that the quantity of said
current depends upon the cross sectional area of said wire. Thus by winding the
wire of the said bobbin or bobbins so that the current may be taken off at different
points as to its length the intensity may be correspondingly varied and by winding
the bobbin or bobbins with several wires one or more of which may be connected
with the line, the quantity of the current may be varied, Thus it is possible to

page_text: vary both the intensity and quantity or to vary the intensity with a given quantity
or to vary the quantity with a given intensity
I am aware that a magneto generator has been constructed with a series of
separate armatures and bobbins arranged around a single axis of revolution and
that separate currents have been taken from such a generator by coupling said
armature armature bobbins in separate series, each series having its own commutator
contact or collector This is in effect a series of separate generators the single
members whereof are separately able to give off single currents only and it
therefore differs from my invention which caused the single member to give off
several currents. I am also aware that a revolving armature comprising two
cylindrical bobbins has been wound with loops taken out at different corresponding
points on each of said bobbins said loops being provided with contacts, either pair
of which may be connected with the line and return circuit for the purpose of
varying the intensity of the current, But that armature differed from my present
invention because, the helices at the two poles of said armature constitute parts of
a single circuit and give but a single current whereas in my invention the helices
at the opposite poles of the armature are provided with an intermediate ground or
return connections and therefore constitute parts of separate circuits and give off
separate and independent currents.
Fig. 1. is a plan view of an armature showing a typical arrangement of the
bobbin wires for variations as to intensity.
Fig. 2. is a longitudinal section showing the contact connections for variations as
to quantity.
Fig. 3. is a full plan of an armature as I have constructed it--the wires being
omitted
Fig. 4. is a perspective view of my commutator key
Fig. 5. is a side elevation of the same.
Fig. 6. is a plan of the same with the electrical connections added.
Referring now to the Drawings A is an ordinary "Seimens" armature with two
coils. The wires of the several coils are approximately of the same length. If it
is designed to vary the intensity of the current the loops b b¹ of the wires w¹ w¹
are taken out and separately placed in electrical connection with contacts e e¹ on
the armature spindle, while the outer terminals are electrically connected with the
contacts d d so that said loop contacts e e¹ may become terminals and the current
may be taken off from either of said contacts d'd¹ or e e¹ at will and, the effective
length of wire being thereby varied, the intensity of the current will be
correspondingly varied. It will be understood that the circuit is completed by
giving the inner terminals of all the wires or bobbins a ground connection as at a,
common to them all through the spindle of the armature and its frame or through
a suitable contact spring provided for that purpose.
To vary the quantity of the current connection is made with one or more of the
bobbin wires by means of suitable contacts say t t¹, and having a return conductor
common to them all the quantity of the current is in proportion to the number of
said wires so connected.
The above is a typical description of my armature. For the purpose of my
individual call herein before alluded to I do not require variations as to intensity
and therefore for convenience the following particular description will be confined
to the structure of the armature &° as I now employ them for variations as to
quantity, but the same structure precisely may be employed to vary the intensity,
the electrical connections only being changed as described above, Contacts d, d¹.
and e e¹ will not again be alluded to.
B B are the field magnets, C is the frame, and D is the armature spindle.
The spindle D is perforated transversely to receive an insulating plug G and from
its extremity it is bored axially to receive another insulating plug or bushing h
which projects outwardly beyond the end of the spindle to receive and support the
rings k. . to which are attached the contacts t, f, in different planes of revolution
'so as to make 'contact with the separate springs FF. The insulating plug h is

page_text: bored axially and the cavity extends into the plug g, so that a metallic pin i, may
extend through said bushing h into and past the centre of the plug g but not
entirely through said plug. The pin is split lengthwise through its centre to a
point beneath the ring k and then the portion is cut off and separated from the
portion i by a strip m of some insulating material.
The connection screws K K¹ are inserted endwise into the plug g and their ends
severally brought into electrical contact with the separate parts i, ¹. The outer
terminals of the bobbin wires w wll are then respectively attached by solder or
other suitable means to the screws K K' Each of the rings k, l, is placed upon the
bushing hand in electrical connection with the pin i and the part respectively
by means of the screws n n¹. The contacts t t¹ I find it convenient to make in the
form of lateral extensions or fingers projecting from the rings k, l, respectively to
engage with the contact springs F F at the proper times during the revolution of
the armature spindle. The outer terminals of the bobbin wires w¹ wll being thus
separately connected with the contacts t t¹ the currents may be taken off by the
contact springs F F¹ from one or both and jointly or separately used as may be
desired.
To operate the motor magnets of my individual call instrument I make
permanent contact with the end of the pin i by means of the spring p and thus
obtain a "to and fro" current from one of the bobbin wires. When said motor
magnets have moved the travelling switch to the proper point and it is desired to pass
a stronger current to the line L then the "to and fro" current by way of the
spring p is switched off and the two currents by way of the springs F F¹ are
switched to the line L thus giving twice the quantity of the "to and fro" current.
This is conveniently done by means of a key Q pivoted to a post q. My patent
heretofore referred to described a central office instrument a part of which is in the
ground circuit of the generator A. That central office instrument is herein
designated by the letter R, and the ground circuit by the letter H and I find it
convenient to place the key Q and its contact post S in the same ground circuit.
At its rear end said key is provided with an elastic spring extension and a
ground post S is provided with a contact for said spring and properly placed so
that said contact will be closed when the front end f of the key is depressed and
opened when the front end is raised The object of this is to close the break which
exists at R in the ground circuit H of the generator by the same movement of the
key Qwhich connects the outer terminals tt' of the armature helices on the line.
The key bears an insulating button u forward of its pivot and a switch spring v
passes under said button making contact at its free end with the line post w, when
the key is free, and breaking said contact when said key and spring are
depressed. The post w is in electrical connection with the spring p and therefore
when contact is closed with the spring the "to and fro" currents may pass to the
line L.
A second spring y is so placed that its free end is beneath the spring v but not
in contact therewith until contact of said spring v with the post w is broken.
The spring y is in electrical connection with the commutator spring F¹
Beneath said spring y there is a contact screw Z in electrical connection with
the commutator spring F
When the key Q is depressed contact with the post w is broken and afterwards
closed with the post S. Electrical contact of springs v, y, and pin z is made by the
further depression of said key Q and the combined or quantity current of single
direction from both bobbin wires w¹ w¹¹ is passed to the line.
Having now described the construction and operation of my invention to which
I have given the name "The Stabler Variable Current Magneto Generator”
I disclaim all other generators now in use. What I claim as new is:-
1. An armature for a magneto generator having its bobbin wire or wires divided
into several sections electrically by means of loops connected with independent
commutator or contacts substantially as described whereby the current may be
varied either as to intensity or as to quantity or both as set forth:

page_text: .2 In a Magneto generator an armature the opposite poles whereof are provided
with separate helices so wound as to give off a coincidently currents in the same
direction one terminal of each helix being connected with the ground or return
current and the other terminal of each being connected with the line commutators.
3. An armature for a magneto generator the bobbin wire whereof is at its middle
of length connected with the ground or return circuit and at one or more points of
its length between its terminals and said ground connections, in electrical connection
with corresponding independent commutator contacts, whereby the intensity of the
coincident currents may be varied at will.
4 An armature for a magneto generator the bobbin wire whereof is in several
strands w¹ wll one corresponding terminal of each being permanently connected
with the return conductor at a, and the other corresponding terminals being
severally connected with the pin i and insulated portion and the commutator
rings k, l, and contacts t, t, connected therewith combined with the commutator
springs F F¹ and p substantially as and for the purpose set forth.
5. The combination of a magneto generator provided with commutators whereby
"to and fro" currents or single direction currents may be taken off at will a
commutator key Qin the return circuit provided with an elastic extension r for
making contact with the post S and the switch spring and contact line post w
and the single direction current contacts y, z, adjusted to make contact with the
switch spring when depression of the said key Q has broken its contact with
post w.
In witness whereof I the said Martin Benson have hereunto set my hand and
seal this Sixth day of October in the year of our Lord 1883.