An Improved Microphonic Transmitter.
Year: 1896

page_text: .Date of Application, 21st Jan., 1896
Complete Specification Left, 19th Oct., 1896-Accepted, 9th Jan., 1897
An Improved Microphonic Transmitter.
I, Captain PHILIPPE CHAROLLOIS, of No. 31 Rue Bergere, Paris, in the
Republic of France, do hereby declare, the nature of this invention to be as
follows:-
The invention relates to a microphonic transmitter characterised by the special
method adopted in its construction, and one, in fact, which I have already applied,
in a general way, to various telephonic apparatus; such method consisting in
moulding the constituent parts of the transmitter in the very substance or body of
non-conducting material of which the supporting case or cage of the apparatus is
formed; whereby the said constitutive parts are arranged or gathered up in groups
or series, in a manner so simple and convenient, as to reduce the cost of the
apparatus to a minimum not hitherto attained.
The transmitter hereinafter described has for its main feature the employment of
either granulated carbon, or graphite or plumbago in scales, arranged to gyrate or
move between two plates or tablets of carbon of any suitable construction, the
compression of which plates, occasioned by the vibrations of the membrane or
diaphragm, causes the primary current passing through the microphone to vary in
strength. The method of construction, however, which mainly constitutes my
invention, is equally applicable to any transmitters, for instance apparatus, in which
the connections are surrounded by a ring consisting of a solid insulating substance
which fixes them in the desired position. It may therefore be applied to microphonic
transmitters other than those with granules; such as instruments with carbon or
like rings, for the purpose of constructing them with the maximum economy,
efficiency and safety against all kinds of possible irregularities.
The apparatus mainly consists of an egg-shaped case obtained by casting &
plastic insulating substance in a mould; such substance being mouldable at the
time of the formation of the case, but having the property of hardening afterwards
to a condition resembling marble or ebonite.
In the material of the casing, thus moulded, are embedded all the metallic
connections, provided for the passage of the primary current through the membrane,
the upper carbon block, the granulated carbon or the like, the internal carbon
tablet and, finally, the telephonic station.
The metallic connections comprise the following parts:-A stout copper hoop or
ring embedded in the material of the casing and serving as a support for the
membrane and ensuring electrical communication with the upper block, either
direct, or through the medium of small plates or scales made integral with the
membrane. A segment of a circle embedded in the material and serving to form
the electrical connection with the lower carbon tablet, through the medium of a
hin plate and the piece, made of copper and assuming the shape of a washer about
wo millimetres deep, embedded in the material of the casing and carrying a screw-.
hreaded or tapped aperture in the centre.
The case or cage is screw-threaded thereby affording a means for securing the
nembrane in position by means of a tightening ring provided at its inner periphery
with a screw thread enabling it to receive and hold the trumpet.
The membrane or diaphragm may be made of metal, ebonite or any other

page_text: substance according to the more or less intense sound or tone to be obtained. The
upper carbon, provided with concentric grooves or recesses, so as to constantly
ensure close contact with the graphite, is "cupped" within a cylinder of celluloid
or any other insulating material. The carbon,. thus fitted with its cylinder, is
secured to the centre of the membrane or diaphragm by the aid of a screw and nut.
The granulated carbon or graphite is provided in quantities sufficient to fill up the
said concentric recesses of the upper carbon and even slightly in excess of the
amount strictly requisite for filling those recesses. A screw-threaded rod, terminates
at one end in a small plate of a diameter less than that of the cylinder. On to this
rod, by means of a screw, is secured the carbon tablet separated from the said plate
by a flannel or cotton wool washer, the diameter of which is equal to that of the
cylinder and which serves to close in or retain the granulated graphite. A counter
nut serves to fix the screw-threaded rod in position after the final adjustment of
the apparatus. A cap or cover is secured to the case by three screws.
I also provide two columns or posts for the admission of the current supply:
Passing through the said posts are screws, the front ends of which are of conical
or bevel shape and adapted to engage in apertures of corresponding shape-provided
for their reception in the case; such screws serving to retain the terminal posts-;
while counter nuts are adapted to ensure the stability of the said screws.
The complete mechanism is adjusted in the following manner.
The granulated plumbago or carbon is first placed in the cylinder; whereupon
all the parts-are-arranged in their proper positions and, in each case, moved right
home. The transmitter is then placed upon pillars or columns, and the apparatus
is tested by the ear, the carbon tablet supported by the screw-threaded rod being
moved further backwards.or forwards as the case may be, by the operation of the
said,screw:
When the apparatus has been properly adjusted, the counter nut is screwed
tight and the adjusting or set screw is covered over with the cap. or dome. which
need,not,.after that, be at any time again displaced...
The improved microphonic transmitter offers the advantage of being extremely
simple in its construction, which enables it to be manufactured and supplied to the
market at such a small cost as may safely be said not to have been attained
hitherto; while, on the other hand, it transmits sound in a perfectly audible
mapner in all directions, it being, for this purpose, made revolvable upon a pivot.
It will be understood that the shapes, dimensions and proportions of the several
parts or devices which go to form the complete arrangement, the materials of which
they are made.and, indeed, the.construction of the accessory parts, may be varied
according to circumstances or requirements..
An Improved Microphonic Transmitter.'
I, Captain PHILIPPE CHAROLLOIS; of 'No. 31, Rue Bergère, Paris, in the
Republic of France; 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:
The invention relates to a microphonic transmitter characterised by the special
method-adopted.in its construction, andsone, in fact, which I have already applied,
in a general way, to various telephonic apparatus; such method consisting in 5

page_text: moulding the constituent parts of the transmitter in the very substance or body of
nou-conducting material of which the supporting case or cage of the apparatus is-
formed; whereby the said constitutive parts are arranged, or gathered up in groups
or series, in a manner so simple and convenient, as to reduce the cost of the
apparatus to a minimum not hitherto attained.
...
The transmitter hereinafter described has for its main feature the employment of
either granulated carbon, or graphite or plumbago in scales, arranged to gyrate or
move between two plates or tablets of carbon of any suitable construction, the
compression of which plates, occasioned by the vibrations of the membrane or
diaphragm, causes the primary current passing through the microphone to vary in
strength. The method of construction, however, which mainly constitutes my
invention, is equally applicable to any transmitters.
The invention will be best understood by reference to the accompanying drawing,.
in which
Figure 1 is a front elevation of the improved transmitter ;
Figure 2 is a plan or top view of the same, with a portion of it broken away.
Figure 3 is an elevation, partly in section on line 1-2 Figure 2;
Figure 4 is an inverted plan or bottom view of the vibrating plate and its
carbon:
Figure 5 is a sectional plan of the apparatus, the section being taken on line 3-4-
Figure 3; and
Figures 6 to 9 are detached detail views.
Like letters of reference designate identical parts in the several figures.
The apparatus mainly consists of a case A obtained by casting a plastic insulating-
substance in a mould; such substance being mouldable at the time of the formation
of the case, but having the property of hardening afterwards to a condition
resembling marble or ebonite.
In the material of the casing, thus moulded, are embedded all the metallic-
connections B C and D, provided for the passage of the primary current through
the membrane H, the upper carbon block I, the granulated carbon or the like L,.
the internal carbon tablet O and, finally, the telephonic station.
The metallic connections comprise the following parts:-A stout copper hoop.
or ring B embedded in the material of the casing and serving as a support for the.
membrane and ensuring electrical communication with the upper block, either
direct, or through the medium of small plates or scales such as b, made integral
with the membrane H. A segment of a circle C embedded in the material and
serving to form the electrical connection with the lower carbon tablet O, through
the medium of a thin plate c and the piece D, made of copper and assuming the-
shape of a washer about two millimetres deep, embedded in the material of the
casing and carrying a screw-threaded or tapped aperture in the centre.
The case or cuge A is screw-threaded at E, thereby affording a means for-
securing the membrane H in position by means of a tightening ring F provided
at its inner periphery with a screw thread enabling it to receive and hold the
trumpet G.
The membrane or diaphragm H may be made of metal, ebonite or any other
substance according to the more or less intense sound or tone to be obtained. The
upper carbon I, provided with concentric grooves or recesses, so as to constantly
ensure close contact with the graphite, is "cupped" within a cylinder K of
celluloid or any other insulating material. The carbon, thus fitted with its cylinder,.
is secured to the centre of the membrane or diaphragm H by the aid of a screw or
the like h. The granulated carbon or graphite L is provided in quantities.
Bufficient to fill up the said concentric recesses of the upper carbon and even
slightly in excess of the amount strictly requisite for filling those recesses.
screw-threaded rod, terminating at one end in a small plate M' of a diameter less-
than that of the cylinder. To this rod, by means of a screw P, is secured the
carbon tablet O, separated from the said plate M by a flannel or cotton wool
washer X, the diameter of which is equal to that of the cylinder K and which.
M is a

page_text: serves to close in or retain the granulated graphite. Qis a counter nut serving to
fix the screw-threaded rod M in position after the final adjustment of the apparatus.
R is a cap or cover secured to the case by three screws. S S' are two columns or
posts for the admission of the current supply. Passing through the said posts are
screws T T', the front ends of which are of conical or bevel shape and adapted to
engage in apertures of corresponding shape provided for their reception in the case
and ensuring the feed of the current, while V V' are counter nuts adapted to ensure
the stability of the said screws T T¹.
The complete mechanism is adjusted in the following manner.
The granulated plumbago or carbon is first placed in the cylinder; whereupon
all the parts are arranged in their proper positions and, in each case, moved right
home. The transmitter is then placed upon pillars or columns, and the apparatus
is tested by the ear, the carbon tablet supported by the screw threaded rod M
being moved further backwards or forwards as the case may be, by the operation
of the said screw M.
When the apparatus has been properly adjusted, the counter nut Q is screwed
tight and the adjusting or set screw is covered over with the cap or dome R which
need not, after that, be at any time again displaced.
The improved microphonic transmitter offers the advantage of being extremely
simple in its construction, which enables it to be manufactured and supplied to the
market at such a small cost as may safely be said not to have been attained
hitherto; while, on the other hand, it transmits sound in a perfectly audible
manner in all directions, it being, for this purpose, made revolvable upon a pivot.
It will be. understood that the shapes, dimensions and proportions of the several
parts or devices which go to form the complete arrangement, the materials of which
they are made and, indeed, the construction of the accessory parts, may be varied
according to circumstances or requirements.
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 :-
The improved process of construction of a novel microphonic transmitter,
characterized by the combination of the elements or constituent parts above specified,
substantially as described and illustrated in the accompanying drawing.
Dated this 19th day of October 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.