Improvements in Telephonic Transmitters.
Year: 1894

page_text: This print is in accordance with the original Specification as it stands after
Amendment (under Section 18 of the Patents, &c. Act, 1883), as allowed by
the decision of the Comptroller General of the 16th day of April 1896.
Date of Application, 5th Mar., 1894
Complete Specification Left, 1st Dec., 1894-Accepted, 5th Jan., 1895
PROVISIONAL SPECIFICATION.
Improvements in Telephonic Transmitters.
66
CHARLES ADAMS-RANDALL, Mattapoisett," 1, The Avenue Bedford Park,
London, W. Electrical and Mechanical Engineer, do hereby declare the nature of
this invention to be as follows:-
This invention relates to improvements in apparatus for the transmission of
articulate speech and other sounds, electrically, and more particularly relates to
improvements in that class of apparatus in which granulated carbon or other
similar material is used, such as the "Hunnings" transmitter and others.
The object of the invention is to so improve, construct and adapt such apparatus,
that a current of greater energy or force may be employed than heretofore with
this class, and a wider and greater range of variation of the current passing through
the apparatus be obtained, whereby it becomes more effective, practical and
reliable for telephonic transmission, especially over long circuits and ocean cables.
To this end, the invention as now conceived by me consists generally in the use
of a suitable diaphragm either of carbon or carrying or vibrating a carbon
electrode, which, in either case forms a part of the circuit, and which I term the
diaphragm-electrode.
The diaphragm is suitably held in any of the well known ways, and preferably
in a horizontal position. Suitably suspended over the diaphragm, in independent
sections, and insulated from each other and from the diaphragm-electrode, and
upon separate supports or on a support common to all, I provide tubes, cylinders
or cups, preferably of metal or carbon, arranged to be electrically connected to a
battery or other source of electric power, and arranged to be adjustable to and
from the diaphragm-electrode, or arranged to be supported near the same, but
without touching it, the intervening space between the supporting piece or pieces,
or the lower edge of the tube or tubes, and the diaphragm-electrode being filled
with a soft cushion, or washer or washers of leather, felt, cotton or similar
substance, openings being made in such cushion opposite to the open end of the
tube or tubes. The tubes are arranged to contain, support or carry a certain
desirable quantity of granulated carbon, or graphite, or both, thus making a
variable electrical contact between the tubes and the diaphragm-electrode.
I have found, that by the use of a suitable weight resting by gravity or spring
pressure upon the loose carbon, or by the use of sharply pointed metal pins.
supported in the loose carbon, and in contact with the diaphragm-electrode, or by
the use of about 25%, more or less, of silver or other metal filings added to the

page_text: carbon, that a greater amount of current or electric energy is conducted there-
through and varied thereby, and I preferably use the carbon or graphite, and
silver combined.
To prevent the "packing," or hardening of the loose conducting material,
I secure to the diaphragm-electrode, or otherwise, in sections or distinct divisions
corresponding to the number and position of the tubes, pointed metal pieces of cone
or other shape, or perforated or sieve-like partitions of thin sheet metal that pass
within and nearly through the tubes, which when vibrated act to disturb the
granular mass, and prevent "packing" "of the same, and also acts to increase the
variable contact between the tubes and the diaphragm-electrode.
There are other and various forms of construction under this sectional plan, or
method, and I do not limit myself to the exact descriptions herein, though preferred
by me now.
In use, one, or a number of tubes may be used simultaneously, each tube being
connected to its respective battery, or to a section of one main battery, each being
connected to the same pole or side of the battery, the opposite pole or side, of the
respective batteries, or the several sections of the main battery being connected to
the "return wire, whether main line or local.
"
Under this method, the total effective working-current, or thereabouts from a
battery of many cells, may be passed through a transmitter with a varying force,
without danger from "sparking," and without harshness or unpleasant disturbing
noises at the "receiver," the total current over the circuit, main line or local,
equalling approximately the current passed through one tube multiplied by the
number of tubes employed, whereby electric energy equal to that employed in
telegraphy, can be utilized, and telephoning upon or over long lines or circuits, or
over ocean cables becomes possible and practicable.
Dated this Fifth day of March 1894.
Improvements in Telephonic Transmitters.
CHARLES ADAMS-RANDALL, of " 'Mattapoisett," 1 The Avenue, Bedford
Park, W., London, Electrical and Mechanical 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 relates to improvements in apparatus for the electrical trans-
mission of articulate speech and other sounds, and more particularly to that class
of apparatus in which granulated carbon or other similar material is used, all of
which will be best understood by reference to the drawings and following description,
in which,
Fig. 1. represents a plan view of a transmitter constructed with seven sections,
and showing the batteries and connections therewith.
Fig. 2. represents a sectional view of Fig. 1. on the line X. X.
Fig. 3. represents a sectional view of Fig. 1. on the line X'X'.
Fig. 4. represents a sectional view of Fig. 1. on the line X*X*.
Like figures represent corresponding parts.
In the drawings the numeral 1. Fig. 2. represents the bottom of a box or case,
in which is secured a suitable mouthpiece P. (shown broken off). An aunular
ring 2. is held upon the base 1. by means of screws S. and S2, Fig. 1. the screw S³
passing through an elongated slot T. in the ring, so that the ring, and the parts
carried thereby, may be moved to and fro, when loosely held. The ring 2. is
provided with a recess, in which rests a washer 3. of felt or other similar material,
upon which is placed the diaphragm 4. which is held in place in any suitable

page_text: manner, but as shown, by ring 12. and spring fingers 13. 14. secured to ring by
screws 15.
The supporting piece-17, of vulcanite, is adjustably held over the diaphragm
and secured to the ring by four screws 16. passing loosely through it into 2, the
four screws 16¹ fitting into 17. and resting upon 2. whereby the position of 17. is
determined by the adjustment of the eight screws.
The piece 17. is provided with a number of openings, which I term sections of
the transmitter, of which there may be any required number, seven being
shown, 5-6-7-8-9-10-11. the different sections and the parts therein
contained being shown in Figs. 2. 3. and 4. The piece 17. is provided on one side
with a covering or washer 18. of felt, cotton-wool, leather or similar material,
which rests with suitable pressure upon the diaphragm when the piece 17. is.
adjusted in proper position, said soft covering having openings therethrough
corresponding to the openings in 17. The openings or sections in 17. are in some
cases provided with metal tubes, clearly shown at 5. 6. 7. 8. and 10, and in other
cases the tubes are dispensed with, as at 11. and 9, each section forming or carrying
electrodes electrically connected to their respective batteries.
I have shown in the several sections various ways of producing a variable
contact of the electrodes. In sections 5. 6. 7. 8. and 10. I employ metal tubes
which contain granulated carbon, (shown by small dots) surrounding metal or
carbon contacting-pieces, which may be of various forms of construction. In
section 5. Fig. 2. a cap or cover 21. is provided to which is secured two or more
downwardly projecting pins 22. said caps and pins being free to be rotated, if
desired for the purposes of adjustment, in the particles of carbon surrounding
them.
In section 6. the carbon surrounds a cone or other shaped piece of metal or
carbon 26, secured to the diaphram 4, a cap 27. being provided to firmly close the
tube to keep the material in place.
In section 7. the granulated carbon surrounds an adjustable screw 31. held in the
cap 32.
In section 8. the carbon surrounds and is contained within a tubular shaped piece
of wire gauze 33, resting upon the diaphram 4.
In section 10. the granulated carbon is separated or arranged in layers by
circular pieces of wire gauze 37.
In section 11. a single piece of coiled wire 38. is used, insulated from but resting
upou the diaphram and surrounded by the loose material.
In section 9. the tube is also dispensed with and a coiled wire 34. used instead,
surrounding a smaller coil 35, both insulated from the diaphragm, but resting
thereon, the granulated carbon being contained within the coils which are held
in place by the cap 36. In these various forms the metallic contact-pieces serve
to increase the surface and pressure-contact, and also serve to prevent the packing
of the loose carbon.
There are other and various forms of construction under this sectional method,
using granulated carbon resting by gravity upon the diaphragm and I do not limit
myself to the exact descriptions herein.
In use, one, or a number of sections, may be employed simultaneously.
By reference to Figure 1. the circuits and connections will be understood. The
electrode of section 5. is connected by wire 25. to its battery 5ª, and section 6. to
battery 6^, by wire 28, the other sections being connected similarly to their
respective batteries; the connection with each section being from the same pole or
side of the battery, the currents from the several batteries passing through the
various sections to the diaphram, or the electrode carried thereby, thence to the
ring 2; the total current from the various batteries passing therefrom as a whole,
back to the opposite pole or side of the batteries over wire 19, which circuit may
include the primary wire of an induction coil, or several of them, (not shown) in
the manner well known, or, the current may pass direct, from the ring 2. to the
main line L. by wire 191, the batteries being connected to earth at E, in either case

page_text: all of the current passing from the batteries through the transmitter without
"sparking" or harsh noises.
I sometimes employ, for the purpose of insuring a better contact at the
electrodes, fine particles of silver, platinum or other metal mixed with the
granulated carbon.
Having thus fully described my invention, what I claim as new and desire to
secure by Letters Patent, is,
1st. In a granular gravity contact telephonic-transmitting-apparatus the com-
bination of a series of independent battery-electrodes, a series of batteries, one for
each electrode and connected therewith, a diaphragm or vibrator, serving as an
electrode and connected to the opposite side of all of the batteries through main or
local circuit, whereby currents from the several batteries may pass independently
to the transmitting-apparatus and pass therefrom back to battery over local or main
line circuit, substantially as shown and described.
2nd. A telephonic-transmitter having two or more independent sections, each
:section containing or carrying fixed independent battery-electrodes, or contacts,
a diaphragm or other vibrator, serving as an electrode and arranged opposite
the battery-electrodes, granulated carbon or similar material interposed between
the independent electrodes and the diaphragm-electrode, for obtaining a proper
talking-contact between such electrodes, substantially as shown and described.
3rd. In a telephonic-transmitter, the combination of a containing box or case,
the diaphragm holder secured thereto, a diaphragm, preferably forming a part of
the circuit, suitably held in the said holder, an adjustable non-conducting piece,
supported over the diaphragm, arranged to carry one or more fixed independent
battery-electrodes, having means for connection with independent batteries, the
contact between the independent electrode or electrodes and the diaphragm-
electrode being obtained by the gravity-contact of loose granulated material,
such as carbon, filling a hole or holes formed through a thick washer of felt
cotton wool or like material one opposite each independent electrode substantially
as shown.
4th. A telephonic-transmitter having, in combination, a case or box, a diaphragm
of carbon 4, a diaphragm holder 2, two or more clamps 13. 14. holding the
diaphragm, a non-conducting-piece sectionally divided 17, supported opposite the
diaphragm and adjustably secured by the screws 16. 16. 161 16' and arranged to
carry two or more independent battery-electrodes such as 5. 21. 22. 22. or 7. 31. 32.
granulated carbon or other suitable material interposed between the independent
battery-electrodes and the diaphragm-electrode, a sectionally divided washer of
felt, cotton-wool or like material 18. secured to 17. and arranged to rest upon the
diaphragm 4. holding the loose material in place, all constructed and arranged
substantially as herein shown and described.
Dated this 1st day of December, 1894.