IMPROVEMENTS IN TELEPHONE TRANSMITTERS
Year: 1884

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I WILLIAM ROBERT LAKE, of the firm of Haseltine, Lake, and Co, Patent.
Agents, Southampton Buildings, in the County of Middlesex do hereby declare
the nature of said Invention for "IMPROVEMENTS IN TELEPHONE TRANSMITTERS
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 that class of telephone transmitters wherein the
changes of pressure upon a carbon block, cause it to offer different resistances to
the passage of an electric current, so as to vary its strength in unison with the rise
and fall of vocal utterances.
The said Invention has for its objects to simplify the construction of instruments
of this class; to render them more compact and durable than heretofore; to
regulate the force of contact of the electrodes and to increase the electro-motive
force of the induced currents; and it accordingly consists in the novel construction,
combination and arrangement of parts as hereinafter described.
In the accompanying Drawing
Figure 1 is a vertical section of a telephone transmitter embodying this
Invention.
Figures 2 and 3, are respectively a perspective view and an elevation showing
details.
Figure 4 is a vertical section of the transmitter.
Figure 5 is a similar view showing a modification.
Figure 6, is a perspective view and
Figure 7, a sectional view of another modification.
A indicates a box or casing having a hinged lid a to which is suitably secured a
diaphragm B having a platina or other electrode b attached thereto. On each side
of the said electrode, and secured to the diaphragm B, are brackets or supports C
which have an upward inclination, as shown, so that when the carbon-block D is
placed thereon it automatically maintains its contact with the electrode b.
.
ו...D

page_text: 61 indicates another electrode secured to a bar e fastened to the ends-el, el of an
induction. coil E, the core e² of which is pivotted at f to a nut F engaging with a
screw G, having a shoulder g and bearings g', g' in an arm or bracket H secured to
the door a or one of the sides of the box A.
The core e² is cut away at c³, or at its lower end which is in line with a soft iron
or other bar I capable of being magnetized. This bar is threaded at i and is
supported by the door a so as to be adjustable to and from the end o³ of core e².
By turning the screw G the nut F is adjusted thereon to regulate the contact of
the electrode 61 with the carbon-block D, and such initial contact is duly
maintained by the gravity of the induction coil E, while the pivotal connection of
the latter permits it to yield to the vibrations of the diaphragm B.
J indicates the local battery or generator in circuit with the electrodes and the
primary of the induction coil E, and 1 the line which leads to the secondary
circuit of such coil and is suitably grounded as shown at 2.
The operation is as follows that is to say:-The initial adjustment of the
screw G being made for obtaining corresponding contact of the electrodes, the
bar I is adjusted until its end nearly, but not quite, makes contact with the
end es of core e².
The sound waves vibrating the diaphragm B, the latter varies the strength of
the battery current and sets up corresponding induced currents in the secondary
circuit of the coil E in the customary manner, and correspondingly magnetizes the
core which in turn is proportionately attracted by the bar I, and thereby
regulates the force of contact of the electrodes, in unison with the vibrations of the
diaphragm, to obtain a more efficient variation in the battery current, or, in other
words, the coil E is not only an induction coil but also acts as a governor for
regulating the force of the contact of the electrodes.
The variations of the magnetic charge induced in the core e³ not only variably
magnetize the bar I for regulating the force of contact of the electrodes, but also,
as they disappear, intensify the disappearing currents in the primary circuit of the
induction coil E, and thereby proportionately strengthen the currents induced in
the secondary coil, whereby the electro-motive force of such induced currents is
greatly increased.
It will be noticed that the carbon block. D is loose upon the supports C, and
presents diametrical points for contact with the electrodes, as more plainly shown
in Figures 2 and 3, but, if desired, the said block may be suspended between the
electrodes in any suitable manner.
If a tube K is attached to box A, as represented in Figure 1, the instrument may
be used as a receiver as well as a transmitter, the receiving sound waves being
produced by the vibration of the end es of core e³ to and from bar I. If desired a
reflector L with opening L' may be used as a substitute for the tube K, as
indicated in Figure 6.
In Figure 5 I have represented the Invention as applied to a portable or hand
transmitter, wherein the screw G and appurtenances are dispensed with, a spring
being substituted therefor. The carbon block D rests within a recess on the bar e,
and the core e³ is provided with an adjusting screw M having an insulated end m.
The casing A has an ear piece, as shown.
In Figure 7, I have illustrated a modified arrangement of the primary and
secondary circuits of the induction coil E, in which arrangement the tube or ear
piece is secured to the bar I. Such construction causes the received articulations
to be more distinct or pronounced, by reason of a part of the secondary circuit
being wound next the core e².
While I have shown the supports C having inclined sides, in order that the
gravity of the block D may be utilized to maintain its contact with the electrodes b,
yet I do not confine the Invention thereto, as the said supports may be right-angle
brackets and the box A tilted forward at its upper front end to cause the gravity
of the said block to advance it towards and maintain contact with electrode b. So,

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too, while I have represented screw and spring mechanism for causing the core
and coil E to maintain contact of the electrode b¹ and block D, yet I do not limit
myself thereto, as any other suitable mechanism or appurtenances that will
accomplish such result may be substituted therefor, the said coil being; in all cases,
provided with or carrying the electrode b¹.
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. A telephone transmitter composed of a diaphragm having an electrode and
an induction coil carrying another electrode, and arranged to maintain and regulate
the force of contact of the said electrodes, as set forth.
Second. A telephone transmitter having a diaphragm and an induction coil freely
suspended, and carrying an electrode so as to regulate its force of contact with the
said diaphragm or another electrode, as set forth.
Third. In a telephone transmitter, the combination of a diaphragm and an
adjustably suspended or supported induction coil carrying an electrode in circuit
with the said diaphragm substantially as shown and described.
Fourth. The combination of the diaphragm B carrying the electrode b and a
carbon block D, and an induction coil E supporting an electrode b¹, substantially as
set forth.
Fifth. The diaphragm B having the electrode 6 and brackets CC on each side of
the said electrode, substantially as set forth.
Sixth. In combination with the diaphragm B, the brackets C C and carbon
block D, substantially as shown and described.
Seventh. The transmitter diaphragm B carrying a freely supported or suspended
block or button D, substantially as set forth.
Eighth. The combination of a diaphragm carrying an electrode, a suspended and
adjustable induction coil having an electrode, and a carbon block between the said
electrodes, substantially as set forth.
Ninth. The combination of a diaphragm, an induction coil E, interposed
electrodes between the said diaphragm and coil, and the bar I, substantially as
set forth.
Tenth. In a telephone transmitter, the combination of a diaphragm and an
induction coil arranged to regulate the force of contact of the electrodes and increase
the electro-motive force of the currents induced in the secondary circuit of said
coil, substantially as set forth.
Eleventh. The combination of the diaphragm B, the induction coil E having the
core e², the electrodes between the said diaphragm and coil, and the bar I, as.
set forth.
Twelfth. The combination of the diaphragm B, the induction coil E having the
core e² and an electrode in circuit with the said diaphragm, the bar I, and the ear
piece or tube K, substantially as shown and described.
Thirteenth. The combination of the diaphragm B, the pivotted or suspended
induction coil E having the core e* and an electrode, and the adjustable bar I,
substantially as set forth.
Fourteenth. The combination of the diaphragm B, the pivotted and adjustable
induction coil E, the interposed electrodes, and the adjustable bar I, substantially
as shown and described.
Fifteenth. The combination with the induction coil E, of the core e³, the nut F,
the screw G, and electrode b¹, substantially as shown and described.
Sixteenth. In a telephone transmitter, a suspended and adjustable induction
coil carrying an electrode, substantially as set forth.
Seventeenth. The combination of the diaphragm B carrying the electrode b and
brackets CC, the adjustable induction coil E having the electrode 6¹, and the
carbon block D supported upon the said brackets and presenting diametrically
opposite points of contact for the electrodes, substantially as shown and described.

page_text: 3 Eighteenth. In a telephone transmitter, an induction coil having an electrode
and a core, in combination with a bar I, whereby the force of contact of the
electrodes is regulated, substantially as set forth.