Improvements in Electrical Sound Producing Apparatus.
Year: 1892

page_text: Date of Application, 1st Feb., 1892
Complete Specification Left, 31st Oct., 1892-Accepted, 28th Jan., 1893
PROVISIONAL SPECIFICATION.
Improvements in Electrical Sound Producing Apparatus.
ARNOLD BEAUMONT WOAKES 78, Harley Street, London, W. Aural Surgeon,
do hereby declare the nature of this invention to be as follows:-
The object of this invention is to produce an apparatus, answering the purpose
of a bell, gong, or sirene, that can be conveniently worked by the electric current
supplied for the purpose of public or private electric lighting, but it is adaptable to
current obtained from other sources & may in addition be used for any purpose in
which a musical note is or in which musical notes are required.
For the above purpose I make use of an apparatus similar in all essential details
to the ordinary telephone receiver or any of its modifications.
When the service supply is an alternating current this apparatus alone suffices
for the production of a loud sound, but it may be advantageously combined with
any sound intensifying apparatus. If mounted upon a sounding-board the sound is
greatly increased. The coil of the electro-magnet must be of sufficient resistance
and insulation to admit of forming a bridge between the two main leads of the
service supply, the amount of resistance of this coil being inversely proportional
to the quantity of current that is required to work a particular apparatus at a
particular intensity of sound. The vibrating medium may be of a stronger or
thicker nature than that required for the transmission or reception of articulate
sounds, & instead of being of disc shape it may consist of:-
(a.) A sheet of iron or steel, of any desired shape & of any degree of thickness,
fixed at one or more points in a variable magnetic or inductive field, & if desired
the vibrating surface may be enlarged by the addition of any non-magnetic
material.
(b.) A strip of iron or steel of any desired shape, or a steel or iron wire or wires,
suspended in a similar field, the sound varying with the degree of tension applied
to the ends of the strip, wire, or wires as the case may be.
(c.) A wire, rod or tube, in the shape of a coil or otherwise, placed in a similar
field.
In any case one or more electro-magnets may be used, & either one or both poles
may be made to act upon the vibrating medium; or two or more vibrating media
may be combined in one apparatus, the notes being in unison or otherwise.
When the service supply is a continuous current a similar apparatus to any of
the above may be employed, and the necessary variations in the strength of the
magnetic field brought about by introducing into the circuit any known form of
intermitting or alternating apparatus. The alternating or intermitting mechanism
may be placed in any convenient part of the circuit, on the sound producing
apparatus itself, or it may occupy position of the bell-push. In the latter case, at
the same time that the current is turned on & by a continuation of the motion, the
current is alternated or intermitted by a special form of apparatus.
Instead of employing the above, when the supply is continuous, a rapid
interrupter alone may be used, other vibrating media being dispensed with. The
shape or form of the vibrating portion of the intermitter may be adapted to the
tone or character of the sound that is required, while any form of sound intensifier
may be employed as before.
Dated this 30th day of January 1892.

page_text: ⚫ COMPLETE SPECIFICATION.
Improvements in Electrical Sound Producing Apparatus.
ARNOLD BEAUMONT WOAKES 78, Harley Street, London, W. Aural Surgeon
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 :-
This invention relates to the production of sound by the aid of a powerful
electric current, such as that supplied for the purpose of electric lighting. The
principle of the apparatus, by which this sound is produced, is based upon that of
the ordinary telephone receiver, &, consists, in its simplest form, of a disc of thin
sheet iron placed in front of one of the poles of an electro-magnet the coil of which
is traversed by a powerful alternating current of electricity or a current in which a
rapid number of interruptions are made.
The pitch of the note produced, under ordinary circumstances, corresponds with
the number of alternations or interruptions in the current supplied to the apparatus;
the timbre depends chiefly upon the material of which the vibrating diaphragm & the
body of the apparatus is composed; & the intensity greatly upon the strength
of the magnetic impulses, but, I find that, if the diaphragm whilst vibrating be
allowed to strike against some fixed body, a comparatively loud sound can be
obtained with much less expenditure of energy than is otherwise the case.
On account of the diaphragin having to withstand considerable strain, it must
be constructed of such a material, &, attached to the body of the apparatus in such
a manner that it is not readily distorted by use, it should be capable of vibrating
freely & should be of a material possessing an agreeable timbre. If composed of
a very thin material, or of a material lacking rigidity, it should be capable of being
tightened at the margins, &, if of a non-magnetic material, it must have soldered
or otherwise attached to it, a piece of magnetic material, opposite the pole of the
electro-magnet. In order to regulate the distance of the diaphragm from the
electro-magnet the latter may be arranged to screw in or out, or, preferably,
the same end may be attained, by fixing an adjustable screw to that portion of the
diaphragm opposite the pole of the electro-magnet, arranged in such a manner that
the magnetic centre of the diaphragm, or a portion of it, may be screwed near to
or further from the pole of the electro-magnet.
An apparatus possessing the above requirements is represented in the drawings.
Fig. 1. being a vertical section of the apparatus.
Fig. 2. a plan of the diaphragm and its attachments.
The letters A A represent the framework of the apparatus, of wood or other
suitable material.
B represents the iron core.
C C is a coil of insulated wire.
E represents a diaphragm of thin brass.
D Da (brass) ring over which the diaphragm is capable of being stretched.
G is a (brass) ring to which the circumference of the diaphragm is soldered.
FF is a ring (of wood) attached to the framework of the apparatus by the
screws O by tightening which the diaphragm may have the necessary amount
of tension applied to it.

page_text: it is attached to the base-board P P P P from which it is insulated by a piece of
asbestos mill-board R. R.
S occupies the position of a double pole bell push & safety fuse.
The point N may consist of wood or any other material, metalic or otherwise.
If desired it may be omitted & the plate K arranged to strike against the iron core
itself, or the striking point may be in the screw J.
The apparatus as above described may be constructed of a great variety of
materials, metalic or otherwise. Thus P P P P may be of a fireproof material,
such as slate or earthenware. A A & F F may be of wood, metal, earthenware,
vulcanite & the like. If the ring F F & the diaphragm E be constructed of metal,
the latter may be soldered to the under-surface of the former in which case the
ring G may be dispensed with. The diaphragm E may also be constructed of any
suitable resonant or other material capable of vibrating, either metalic or non-
metalic. It may be of any convenient form or shape & may be attached at its ends
or circumference in any convenient manner.
In order to utilise both poles of the electro-magnet a diaphragm may be fixed
opposite both poles, or the magnet may be of "horse-shoe" shape so that both
poles operate on one diaphragm.
The point N may be placed on either side of the diaphragm & instead of being
itself a non-musical body may be replaced by a bell, gong, tube, rod or other
musical or sound emitting body.
In other cases a body of a musical nature may be attached to the diaphragm
itself: thus, if a wire gong, as used in a clock be attached to the centre of the
diaphragm E by one end, as the diaphragm vibrates and strikes against N, the
gong will give a note that will modify the sound of the apparatus.
In some cases the diaphragm may be dispensed with & either one or both poles
of an electro-magnet may be made to vibrate a musical body, such as the tongue
of a reed instrument or a wire gong, in which cases, as before, the intensity of the
sound is greatly increased by providing a fixed striking point.
In another class of apparatus either one or both poles of an electro-magnet
traversed by an alternating or rapidly interrupted current of electricity may cause
to vibrate in unison with the alternations or interruptions in the magnetic field a
point or hammer suspended or fixed in any convenient manner and arranged to
strike rapidly a sound emitting body, such as a tube, bell, gong, wire & the like.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:
1. An apparatus capable of emitting sound, operated by a powerful alternating
or interrupted current of electricity, based upon the principle of the telephone;
also varieties of the same principle, substantially as described, capable of emitting
musical sounds distinguishable from one another, when employing a current of a
fixed number of alternations or interruptions.
2. A method of intensifying a sound produced by a body constructed wholly or
in part of a magnetic material placed in an alternating or interrupted magnetic
field, by causing this body to impinge, whilst vibrating, upon some fixed body or
bodies of either a musical or mute nature.
3. A musical or sound emitting body caused to emit sound by being struck by a
rapidly vibrating hammer or other body that is caused to vibrate by being situate
in an alternating or rapidly interrupted magnetic field.
1
1000
A. B. WOAKES.