Improvements in Transmitters for Telephones.
Year: 1891

page_text: Date of Application, 1st July, 1891
Complete Specification Left, 29th Mar., 1392-Accepter, 30th Apr., 1892
PROVISIONAL SPECIFICATION.
Improvements in Transmitters for Telephones.
We, JAMES RADCLIFFE of Ordsall House, Retford, in the County of
Nottingham, Gentleman, and JAMES ERNEST SPAGNOLETTI of The Poplars,
Aberdeen Place, in the County of London, Electrical Engineer, do hereby
declare the nature of this invention to be as follows:-
:-
This invention has for its object improvements in the construction of telephones
which are provided with carbon transmitters for the purpose of reducing the
susceptibility of the microphone to noises and to vibrations which are not caused
by the air waves produced when the instrument is spoken into for the purpose
of transmitting messages while at the same time the adjustment of its parts
increases its sensitiveness to air waves produced by the voice when speaking into
the instrument.
A. diaphragm of metal or other suitable material is employed which is put into
vibration in the usual manner by the air waves caused by the voice. To the back
of the diaphragm is attached a small disc or button of carbon or other suitable
material.
A permanent horse shoe magnet is placed in a plane parallel to the
plane of the diaphragm or in some other convenient position at a suitable distance
behind the diaphragm and insulated from it. A metallic non-magnetic bar is fixed
across the two limbs of the magnet and at right angles to them and to this bar is
attached the fulcrum or support upon which a metallic lever is free to swing
through a small angle. One end of this rocking lever is provided with a light
piece of soft iron which acts as the armature for the perinanent magnet. The
other end of the rocking lever is provided with a screw the end of which is
preferably tipped with carbon and comes in contact with the carbon disc or button
attached to the diaphragm. The angle through which the lever is able to rock is
regulated by the position of the aforesaid screw and the movement of the lever
produced by vibrations of the diaphragm causes variations in the distance between
the armature and magnet poles and so causes currents to flow through the circuit
of which the microphone forms part, the quantity of the currents varying according
to the greater or less pressure between the carbon disc and the point of the
screw,
The attraction of the armature by the permanent magnet causes the screw to be
pressed constantly against the carbon disc upon the diaphragm and so controls the
amplitude of the vibration of the diaphragm and also prevents external noises from
so easily affecting the instrument.
Dated tIIS
JOHN P. O'DONNELL,
2, Great George Street, Westminster, London S. W.,
Agent for the said Applicants.
COMPLETE SPECIFICATION.
Improvements in Transmitters for Telephones.
We, JAMES RADCLIFFE of Ordsall House, Retford, Nottingham, Gentleman,
and JAMES ERNEST SPAGNOLETTI of The Poplars, Aberdeen Place, London,
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 :—
This invention has for its object improvements in the construction of telephones
which are provided with carbon transmitters for the purpose of reducing the

page_text: susceptibility of the microphone to noises and to vibrations which are not caused by
the air waves produced when the instrument is spoken into for the purpose of
transmitting messages while at the same time the adjustment of its parts increases
its sensitiveness to air waves produced by the voice when speaking into the
instrument.
A diaphragm of metal or other suitable material is employed which is put into
vibration in the usual manner by the air waves caused by the voice. To the back
of the diaphragm is attached a small disc or bution of carbon or other suitable
material.
A permanent horse shoe magnet is placed in a plane parallel to the
plane of the diaphragm or in some other convenient position at a suitable distance
behind the diaphragm and insulated from it. A metallic non-magnetic bar is fixed
across the two limbs of the magnet and at right angles to them, and to this bar is
attached the fulcrum or support upon which a metallic lever is free to swing
through a small angle. One end of this rocking lever is provided with a light
piece of soft iron which acts as the armature for the permanent magnet. The
other end of the rocking lever is provided with a screw the end of which is
preferably tipped with carbon and comes in contact with the carbon disc or button
attached to the diaphragm. The angle through which the lever is able to rock is
regulated by the position of the aforesaid screw and the inovement of the lever
produced by vibrations of the diaphragm causes variations in the distance between
the armature and magnet poles and so causes currents to flow through the circuit
of which the microphone forms part, the quantity of the currents varying according
to the greater or less pressure between the carbon dise and the point of the
screw.
The attraction of the armature by the permanent magnet causes the screw to be
pressed constantly against the carbon dise upon the diaphragm and so controls the
amplitude of the vibration of the diaphragm and also prevents external noises from
so easily affecting the instrument.
In order that our invention may be better understood and more readily carried
into effect we will proceed to describe the drawing hereunto annexed. The same
letters refer to the same parts in the several figures of the drawing.
Figure 1 is a side view partly in section of the transmitter.
Figure 2 is a back view of the transmitter.
Figure 3 is an enlarged view of Figure 1 reversed the section being through A-B
Figure 2.
a is the small button or disc of carbon at the back of the diaphragm; 6 is the
permanent horse shoe magnet; c is the metallic non-magnetic bar fixed across the
two limbs of the magnet at right angles to them; d is the metallic rocking lever
fulcrumed to the non-magnetic bar as shown; e is the armature for the permanent
magnet, and is the carbon tip at the end of the screw attached to the other end of
the rocking lever.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim is—
1. In an instrument for transmitting electric impulses by sound the combination
with a microphone of a permanent magnet and armature for the purposes of tension
regulation, substantially as hereinbefore described and as illustrated on the accom-
panying drawing.
2. In an instrument for transmitting electric impulses by sound the employment
of a permanent magnet and armature substantially as and for the purposes herein
set forth.
Datal thin 90th Love of Mo), 100
JOHN P. O'DONNELL,
Agent for the said Applicants.