IMPROVEMENTS IN INDUCTION COILS
Year: 1885

page_text: I KAZIMIR STANISLAS DEMBINSKI Officer in the Belgian Army, and resident of
Brussels in the Kingdom of Belgium do hereby declare the nature of my said
invention for "IMPROVEMENTS IN INDUCTION COILS," and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
This present application for Letters Patent has for its object the description of
the induction coil made use of in combination with the microphone described
and claimed in the Letters Patent No 7312 of the 6th May 1884; but it is obvious
that this induction coil may also be used for any other purposes.
It is represented in the annexed drawings in which:
Fig. 7 is a longitudinal section of the coil, and
Fig. 8 is a perspective view of the same.
Fig. 9 is a general view showing how a single coil is placed for the microphone,
the commutator (Inverseur de courant) and the bell.
Fig. 10 is a side view of same.
The induction coil, preferably of box wood, is formed of a core of similar
substance as thin as possible; this core ought really to be thin enough to appear
translucid. Upon this core the induction wire is wound in three series of helixes
not insulated except by the silk overcovering the wire. The latter whose
thickness is of millimeter enters the coil in a; crosses the cheek and rolls up
in joined helixes untill meeting the opposite cheek; it then rolls up in a second
series of joined helixes, until close to the first cheek; then in a third series, to go
out in B while crossing the cheek opposite that by which it entered.
The helixes of the induction wire are separated from those of the wire inducted
only by a simple sheet of letter paper which generally goes one and a half round of
the core overcovered by the induction wire. In this way a very violent induction is
obtained; but in placing the sheet of letter paper it is absolutely necessary to
extend it close up the opposite cheeks of the coil, in order that no direct contact
may exist between the induction wire and that inducted.
The wire inducted whose diameter is 27 of a millimeter enters in 8 on the
same side as the induction wire and on the same diameter as the latter; it goes
out on the opposite side à. The number of series of helixes of the inducted wire
may be any multiple of the number of series of the induction wire, that is to say,

page_text: that such number must be multiplied by 2, 3, 4, etc. The more you increase the
length of the inducted wire, the stronger the coil becomes, the induction wire
always forming three series of helixes.
In the case of very large coils however, you may increase the number of helixes
of the induction wire, provided the ratio between such number and that of the
helixes of the inducted wire follows the same proportion.
The coil represented fig. 7 and 8 is intended for telephony at long distance; for
such like coils, the most proper ratio is three series of helixes of the induction wire
and nine series of helixes of the wire inducted.
In the making of our coils, the wires are never knotted as is practised with
ordinary coils, and in order to avoid their unrolling, they cross the cheek of the
coil at the extremity of the last helix. The bars constituting the core of soft iron
may be of any thickness, but it is preferable that their diameter never exceed that
of the induction wire. With good sized coils the inside of the cheeks, may be
varnished.
Fige 9 and 10 show a general arrangement of the apparatus comprising a
microphone, a bell and commutator and the induction coil, which may be applied
upon a wall.
Here the coil is inside of the microphone box, this latter containing a single
drawer 11, with two longitudinal carbons 13, and three transversal carbons 12;
18 being the induction coil-2 is the box containing the commutator and bell.
The commutator consists of eight laminae b b, and of four springs c, d, e, f, two
of which c, d rest simultaneously upon two laminae of opposite names; and the
two others e, f, on two circular rings ġ g insulated one from the other. The
laminae of the commutator are alternately connected with the two rings. Two
supports H maintain the apparatus to which a rotary motion is transmitted by
crank i. An ordinary bell system comprising two coils, a magnet, an oscillating
armature, the bell and the pendulum is affixed to the apparatus.-The commutator
and bell are of known construction and are not claimed in this present application.
Having now particularly described and ascertained the nature of the said
invention, and in; what manner the same is to be performed, exactly as commu-.
nicated to me by my foreign correspondent, I declare that what I claim is
1st. An induction coil consisting of an uneven number of spires at least three of
induction wire not insulated, unless by the silk covering same; and of an inducted
wire separated from the latter by a sheet of letter paper, the number of spires of
the inducted wire being a multiple of the number of spires of the induction wire
and each of these wires entering on one side of the coil and taking exit on the
opposite side.
2nd. In an induction coil such as described in claim 1, an induction wire having
a diameter of 18 of /m, and an inducted wire whose idiameter is 27 of /m.
125
100
m>
100
3rd. In an induction coil the passage of the induction wire and inducted wire
through the cheeks of the coil so as to prevent the wire from knotting itself, the
entry and exit of the wires on the two opposite sides of the coil being on a like
diameter.