Improvements in Voltmeters..
Year: 1891

page_text: Date of Application, 15th July, 1891
Complete Specification Left, 11th Apr., 1892-Accepted, 14th May, 1892
PROVISIONAL SPECIFICATION.
Improvements in Voltmeters..
We, ALFRED HERBERT DYKES of 3 Mount Terrace, Charlton, and' WILLIAM
BENISON HIRD of 2 Mount Terrace, Charlion in the County of Kent, Electrical
Engineers, do hereby declare the nature of this invention to be as follows:-
Our invention relates to a simple and inexpensive construction of voltmetor in
such a manner as to avoid the errors resulting from residual magnetism, from
variations of temperature, and from external magnetic influences, and to present a
scale that can be easily read. For this purpose, in a narrow space between the
poles of a permanent horse shoe magnet we introduce the edge of a coiled bobbin of
insulated wire, made in the form of a thin disc and fixed on an eccentric axis which
carries an index and is held in the zero position by an adjustable spring or by a
weight, this axis being parallel to the plane of the magnet. According as the
electric current which passes through the coil has greater or less electromotive
force, the bobbin is drawn more or less in between the magnet poles in opposition to
the spring or weight, its index pointing to the volts on a suitable scale.
In a modified form of the instrument, the bobbin is in the form of a rectangle,
having its axis passing through it lengthwise and supported in bearings in a position
perpendicular or parallel to the plane of the horse shoe magnet.
The limbs of the magnet near their ends are internally hollowed so as to allow
the bobbin to move more or less round between them, in opposition to the spring or
weight, according to the electromotive force of the current passing through the coil
of the bobbin, which is shewn by the index on the axis pointing to the scale of
volts.
Dated this 15th day of T... 1001
ABEL & IMRAY.
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Voltmeters.
We, ALFRED HERBERT DYKES, of 3, Mount Terrace, Charlton, and WILLIAM
BENISON HIRD, of 2 Mount Terrace, Charlton in the County of Kent, Electrical
Engineers, do 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 :-
.
Our invention relates to a simplo and inexpensive construction of voltmeter in
such a manner as to avoid the errors resulting from. residual magnetism, from
variations of temperature, and from external magnetic influences and to present a
scale that can be easily read. For this purpose we construct a voltmeter as we
shall describe referring to the accompanying drawings.
Fig. 1 being a front view and Fig 2 a vertical section of the instrument,
Fig. 3 is a part front view shewing one modification and
Fig. 4 is a front view of another modification.
Referring first to Figs. 1 and 2, in a narrow space between the poles N S of a
permanent horse shoe magnet we introduce the edge of a coiled bobbin B of
insulated wire, made in the form of a thin disc and fixed on an axis A eccentric to
the bobbin but parallel to the plane of the magnet. This axis carries an index I
and is held in the zero position by suitable weights W for which an adjustable
spring might be substituted. According as the electric current which passen
Price 8d |

page_text: .
through the coil of B has greater or less electromotive force, the bobbin B is drawn
more or less in between the magnet poles N S in opposition to the weights W, its
index pointing to the volts on a suitable scale S.
In the modified forms of the instrument shewn in Figs. 3 and 4 the bobbin B is
in the form of a rectangle like what is known as the Siemens Harmature having its
axis A passing through it lengthwise and supported in bearings in a position which
in Fig. 3 is perpendicular to the plane of the horse shoe magnet and in Fig. 4 is
parallel thereto.
The limbs of the magnet near their ends N S are internally hollowed, so as to
allow the bobbin to move more or less round between them in opposition to a volute
spring V to an extent depending on the electromotive force of the current passing
through the coil of the bobbin B, which force is shown by the position of the
index I on the scale of volts S.
In order to suit different ranges for the instrument and different scale graduations
the forms of the pole pieces may be varied.
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed, we declare that what we
claim is:-
1. A voltmeter consisting of a horse shoe permanent magnet having introduced
between its poles a disc shaped bobbin coiled with insulated wire and mounted on
an eccentric axis having suitable counterweights and index, arranged and operating
substantially as described with reference to Figs. 1 and 2.
2. The modified forms of voltmeter in which a coiled bobbin of H form is
arranged to rotate between the hollowed poles of the magnet substantially as
described with reference to Figs. 3 and 4.
Dated this 11th dev of Annil 1900
ABEL & IMRAY,
Agents for the Applicants.