Regula Electric Currents.
Year: 1894

page_text: Date of Application, 31st Aug., 1894
Complete Specification Left, 31st May, 1895-Accepted, 6th July, 1895
PROVISIONAL SPECIFICATION.
Regulating Electric Currents.
LESLIE BRADLEY MILLER of 2 Gray's Inn Road, London Electrical Engineer
do hereby declare the nature of this invention to be as follows:-
My improved apparatus consists of a choking coil or transformer wound with
wire in one long spiral in order that there should be as little difference of potential
as possible between neighbouring convolutions. The shape of core most convenient
is the ring pattern and in this case I scratch off the insulating covering from the
surface of all the wires on the outside of the ring and arrange a switch so that
when turned round on a centre its end makes a rubbing or scratching contact on
the bare surface of the wire, and more or less convolutions can therefore be put in
circuit with a lamp or other apparatus with which it may be connected. By
lengthening the axis of the switch by means of a tube to which a lampholder is
fixed, the apparatus forms a convenient table lamp for carrying a lamp the light of
which can be reduced by merely turning round the upright stem in the fixed base.
Dated this 30th day of August 1894.
LESLIE BRADLEY MILLER of 2 Gray's Inn Road, London Electrical Engineer
does hereby declare the nature of this invention and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:-
My improved apparatus consists of a choking coil which can be inserted in any
alternating current circuit, and employed to regulate the current. It is chiefly
intended to be used for reducing the light of a single incandescent lamp, and takes
the place of an ordinary switch.
It is constructed as follows:-Round a ring of laminated soft iron a layer of wire
is wound in one long spiral so that there is a gradual rise of potential from one end
to the other. As usually constructed the inner diameter of the iron ring is
approximately half of the outer diameter, and the wire on the inside two layers in
depth, and one layer on the outside. To prevent undue heating owing to the turns
which come under the rubbing contact being short circuited it is preferable to wind
turns which come next to one another on the outer circumference on the top of one
another on the inner circumference, but in the case of fine wire having a considerable
resistance per turn compared to the volts per turn this is not essential. The wire
may also be made from a metal or alloy, such as brass or German silver, having a
higher resistance than copper.
The wire should be insulated with cotton or silk in the usual manner and so
wound that the outer surface is without any irregularities. The insulating covering
should then be stipped or burnt off the surface of a narrow band round the ring,
and over this the end of a spring arm should rub, the rubbing portion being made
small and narrow so as to short circuit as few turns as possible. The rubbing arm

page_text: is attached to a knob by which it can be moved from one place to another on the
surface of the wire; or in the case of the table lamp afterwards described, to the
upright of the lamp.
The same arrangement can be employed as a regulating transformer by winding
the secondary turns in the same way as described for the choking coil; or the
choking coil winding may be used as primary and the volts of a secondary
wound over a portion of it regulated by varying the ratio of the turns.
Referring to the annexed drawings Figure 1 is a plan of the choking coil with
the cover removed, and Figure 2. a sectional view of the same.
4 is the
1 is the iron laminated ring wound with wire, 2 is the thumb knob carrying the
spring arm 3, with its end pressing on the bared surface of the wire at 6.
position where the spring arm breaks the circuit, 5 is an insulating base.
Referring to Figure 3, which shows an elevation of the choking coil arranged
in the base of a table lamp, the thumb knob 2 is replaced by the vertical stem of
the lamp but the other arrangement of parts holds good.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
(1.) The improved choking coil constructed arranged and operating substantially
as described, and shown in the drawings annexed.
(2.) The combination of a table lamp with a choking coil arranged in its base
substantially as described and shown in the drawings annexed.
Dated this 30th day of May 1895.
LESLIE B. MILLER.