Improvements in Microphones.
Year: 1891

page_text: Date of Application, 21st May, 1891
Complete Specification Left, 19th Feb., 1892-Accepted, 21st May, 1892
TRUVISIONAL SEMIFICATION.
Improvements in Microphones.
I. CHARLES HUELSER of the firm of Huelser & Co., Temple Chambers, London,
International Patent Agency, do hereby declare the nature of this invention, a
communication to me from abroad by Caesar Vogt of Posen, in the Empire of
Germany, Electrician, to be as follows:-
This invention relates to carbon cylinder microphones and has for its purpose to
attain greater distinctness in the reproduction of the sounds than is the case in the
systems hitherto known.
The improvements essentially consist in lifting the carbon cylinders, surrounded
by an iron casing, by means of an adjustable magnet support without touching the
cylinders, thereby preventing the carbon dust from "packing," allowing of a free
vibration of the diaphragm and producing a more uniform action of the apparatus.
The magnet support mentioned above consists of two symmetrically joined
horse-shoe-shaped magnets having at their poles two pole shoes. This double horse
shoe magnet with its two pole shoes is adapted to be approached to or removed
from the carbon cylinders of the microphone by means of two vertical screws
connecting the magnets with the microphone. The microphone cylinders are
surrounded in their middle with an iron casing and thereby placed under the
permanent influence of the magnet poles, which are arranged opposite the cylinders.
By the approaching or removal of the magnet support by means of the said
screws, the carbon cylinders are lifted up in their bearings corresponding to the
adjustment.
By the magnet support allowing through its adjustability the carbon cylinders to
be lifted in any desired degree without contact, it is possible to give the carbon
cylinders, without mechanical contact, a librating but immovable position inde-
pendent of influences of temperature or climate. The pivots of the cylinders are
thereby caused to be in miniinal contact with the carbon bars, so that the coal dust
cannot settle between the carbon contacts, and the diaphragm remains absolutely
untouched and unimpaired in its vibrations. Consequently sounds which require
fewer vibrations are reproduced with the same distinctness as sounds requiring
more vibrations.
The improved device can be applied to any carbon cylinder microphone.
Dated this 20th day of May 1891.
COMPLETE SPECIFICATION.
Improvements in Microphones.
I CHARLES HUELSER, of Temple Chambers, London, Putent Agent, (a com-
munication to me from abroad by Caesar Vogt, of Posen, Germany, Electrical
Engineer) 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:-
None of the microphones hitherto known attains the desired object, viz. to
clearly reproduce all similar sounds uttered therein and particularly hissing or
whizzing sounds.
In the microphones first constructed which were practically useless and hence are
now entirely abandoned, the carbon electrodes pressed one against the other and

page_text: hence formed a good deal of soot which produced strong, troublesome noises, while
in microphones of later construction in which the abovementioned defects were
sought to be remedied by raising the carbons, the object was not entirely attained
as this raising was effected by a mechanical contact i.e. by a brake. This brake
action was injurious as it pressed upon the carbons and the membrane so that the
soot from the carbons produced when speaking, was firmly held between the
contacts, free oscillation of the membrane being thus impeded. Moreover this
raising of the carbons by mechanical means i.e. by a brake, was influenced by
fluctuations in the temperature, and other meteorological conditions and hence
could not act uniformly for a very long time.
The arrangement which I have discovered and which applies to microphones
wherein carbon cylinders are used, remedies all the above defects, the raising of the
carbons which are enclosed in an iron casing, being effected without touching them
by an adjustable magnetic support. Thus the carbons are in a well poised position,
there is the smallest possible friction between their axis and themselves, whereby
the carbon soot formed, as is the case in microphones wherein carbon cylinders are
used, cannot remain between the contacts, but becomes volatilized to a certain
extent so that the membrane cannot be touched. As shown in Figs. 1 and 2 of
the accompanying drawings, the magnetic support consists of two horse shoe
magnets m. m² at the poles of which are placed the armatures p. The whole of
this double horse shoe magnet with its two armatures, can be brought in close
proximity to or separated from the carbon cylinders k. f of the microphone, by
means of the two screws s. S. The microphonic carbons are covered centrally with
an iron casing and are hence under the permanent influence of the poles of the
magnet which are placed opposite the same. By causing with the aid of the
screws s. s the magnetic support to advance or recede, the position of the carbons
will be raised according to adjustment.
As owing to its mobility, the magnetic support allows of the position of the
carbons being raised without any possible contact, this arrangement is an improve-
ment upon all those heretofore constructed, that is to say, the position of the
carbons is perfectly poised, and yet cannot be displaced, being moreover free from
the influence of temperature and other meteorologic conditions, while the axis of
the carbons develope but the smallest amount of friction with the latter, whence
results that the carbon soot formed, cannot remain between the contact joints of the
carbons, but is to a certain extent volatilised.
Furthermore the membrane remains absolutely untouched and hence cannot be
impeded in its vibrations so that it will even receive hissing or whizzing sounds in such
a manner that the ear may at once and unmistakably perceive the difference between
the consonants 66
111 "in mail, and "n" in nail, and "J" in Jack, and "ch" in
cheque for instance. Another advantage of this arrangement is that the membrane
is thoroughly free to vibrate so that sounds which produce few or slower vibrations
such as 'F', are transposed with the same accuracy in the currents through the
contact of the carbon electrodes, as those producing more or quicker vibrations
such as s.
In contradistinction with microphones such as hitherto constructed, it matters
not with my improved microphone, whether people speak in close proximity to it
or at a distance therefrom, or whether they speak loud or in whispers.
In all such cases the speech is heard clearly, distinctly, and is undisturbed by
any foreign noises.
The above described arrangement can be applied to all microphones in which
carbon cylinders are used.
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
In microphones wherein carbon cylinders are used, a magnetic contrivance or

page_text: support for raising the carbon cylinders without coming into contact therewith,
substantially as herein described and showu.
HUELSER & Co.,
131, Temple Chambers, E.C.