APPARATUS FOR INDICATING THE PROPER WORKING OF ELECTRICAL ANNUNCIATORS
Year: 1884

page_text: COMPLETE SPECIFICATION.
I, JAMES KENNETH DOUGLAS MACKENZIE, 25 Queen Anne's Gate Westminster,
Electrical Engineer do hereby declare the nature of my Invention for "APPARATUS
FOR INDICATING THE PROPER WORKING OF ELECTRICAL ANNUNCIATORS" and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The object of my Invention is to provide a means by which the proper working
of an electric bell or other annunciator is indicated at the distant push or contact
or at other desired place where the sound of the bell or annunciator cannot itself
be heard which means shall be automatic simple and inexpensive. The person
operating the push or contact will thus be certain that the bell is ringing and that
the circuit is in proper working order.
The means I employ according to my Invention for obtaining this result consist
in employing the well known property of iron which is that of. emitting a sound
when magnetised or demagnetised.
For this purpose, 1 arrange an electro magnet in the annunciator circuit, the
core of which is magnetised and demagnetised when the contact is made and the
said circuit is acting properly and in combination with this I use a piece or disc of
iron which may form part of the core magnetically and which emits sounds as the
core is magnetized and demagnetized.
In carrying my Invention into effect I may take a box preferably round formed
of iron of any convenient size and fasten to the inside of the bottom a small core
of soft iron almost the height of the box. Around this core of soft iron I place a
bobbin or helix of wire which forms part of the annunciator circuit. Over the
other end of the soft iron core but not touching it and fastened to the edge of the
box I place a disc. of thin iron forming a lid or cover and also preferably the
opposite pole of the soft iron core. The box is thus closed completely. The two
ends of the wire forming the before mentioned bobbin or helix are led out through
and insulated from the side of the box and are connected in the circuit of the
annunciator. When contact is made in the circuit the current flows round the
bobbin or helix of my indicator along the line around the electro magnets of the
annunciator through the break and make arrangement and back to the source of
electricity. Whilst the current is flowing it magnetizes the core of soft iron and
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page_text: each time the circuit is interrupted or broken by the break and make arrangement
of the annunciator the magnetism of the soft iron core is lost and a sound is given
out. When the break and make arrangement again completes the circuit tho
magnetism of the coro is renewed and a sound is again given out and this sound
caused by the magnetisation and demagnetisation of the iron continues to be given
out so long as the bell is being rung-I prefer to polarize the lid as hereinbefore
mentioned as the effect is thereby increased.
If the annunciator failed to act or the circuit be not completed the core would
not become magnetised and therefore no sound would be given out by my indicator.
I combine my indicator with any contact maker or ordinary bell push or pull.
And in order that my said Invention may be fully understood I shall now
proceed more particularly to describe the same and for that purpose shall refer to
the several Figures on the annexed Sheet of Drawings the same letters of reference
indicating corresponding parts in all the Figures.
Figure 1 represents in section and Figure 2 in plan an apparatus arranged
according to my Invention and is shewn in combination with an ordinary contact
maker. A is the iron box. B the bottom to which is attached the soft iron core C
around which is the bobbin or helix E D is the iron lid or cover of the box A
and attached thereto opposite the end of the core C. F F are the two contact
springs and P is the push. Figure 3 is a theroretical diagram of connections
showing the bell and battery. In Figure 3 when F F are joined the current flows
from the battery round the bobbii or helix E to the bell round the magnets
through the make and break arrangement and back to the battery thereby
polarizing the core C and the lid D and causing the said lid to emit a sound. The
make and break arrangement of the bell now comes into action and the circuit is
interrupted thereby demagnetizing the core C and the lid D and causing it again
to emit a sound. I find that this sound caused by demagnetization is louder than
that caused by magnetization and therefore my apparatus is capable of being used
as a means of transmitting messages orally.
This interrupted and intermittent sound is kept up so long as the contact
between F and F is maintained and the battery current lasts. Other electrical power
than that produced by batteries may be used and the instrument may be combined
with any apparatus in which electric bells are used such as telephone call bolls.
I have shewn in the Drawing the lid of the box as connected with the core so ELS
to be polarized thereby but I do not necessarily limit myself to this.
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-
First. The use in the circuit of an electrical annunciator of an electro magnet
capable of being magnetized and demagnetized by the circuit of the annunciator
in combination with an iron disc box or its equivalent substantially as and for the
purpose hereinbefore described.
purpose encore describeu,
Dated this 27th day of May 1884.
J. KENNETH D. MACKENZIE.
J. Henry Johnson,
Agent for the said James Kenneth Douglas Mackenzie.