IMPROVEMENTS IN TRANSMITTING AND RECEIVING TELE- PHONES
Year: 1883

page_text: LETTERS PATENT to Charles William Hayes and Seth R Beckwith both of
Washington in the District of Columbia and United States of America for
an Invention of "IMPROVEMENTS IN TRANSMITTING AND RECEIVING TELE-
PHONES Communicated to them by Myron Leslie Baxter of Aurora in the
county of Kane and state of Illinois in the United States of America
COMPLETE SPECIFICATION filed by the said Charles William Hayes and
Seth R. Beckwith at the Office of the Commissioners of Patents on the
8th May 1883.
17
CHARLES WILLIAM HAYES and SETH. R. BECKWITH both of Washington in
the District of Columbia and United States of America. IMPROVEMENTS IN
TRANSMITTING AND RECEIVING TELEPHONES Communicated to us by Myron
Leslie Baxter of Aurora in the County of Kane and State of Illinois in the United
States of America.
The first part of our invention relates to transmitting telephones and has for its
object to provide means whereby the limit of variation in the strength of a voltaic
current may be greater than at present. This refers to the undulatory current
used. for generating a current for the transmission of speech telephonically and
which as is well known is the result of a variation gradual in its nature from
strong to weak and vice versa. When the current sent to line is due to magnetic
induction from a permanent magnet the variation to which it owes its existence is
effected by strengthening or weakening said magnet, but when said current is
derived from a galvanic battery by induction the variation is produced in the
primary or direct battery current, To the latter class our invention pertains.
In common with other transmitters we use in ours the vibrating diaphragm
carrying or actuating a metallic stud in unstable contact with a piece of hard or
soft carbon or carbonaceous material which is attached to a freely suspended bar,
and an induction coil for producing the intense intermittent induced secondary
current and these either singly or in combination in their well known forms We do
not claim. In all the battery transmitters with which we are acquainted the limit

page_text: of variation is very narrow and consequently the strength of the induced current is
small. Our object is as heretofore set forth to increase the variation (without
actually breaking the current) and consequently to send to line a much more
powerful induced or secondary current to work upon the distant receiving tele-
phone, overcoming resistance leaks and extraneous induction incident to long lines.
To effect this we make use of the devices shown in figures 1, 2 and 3 of the
accompanying drawings. Figure 1 being a plan view of the inside of the door of
the transmitter, Figure 2 a vertical section of the door through the line x. x
figure 1 and. Figure 3 a vertical section of the induction coil through line x. x
figure 2. A is the door of the transmitter, a the orifice through which the sounds
to be transmitted obtain access to the diaphragm B which is surrounded at its
periphery by the soft rubber binding b³ and held in position by the clip b' and
the presser spring b with its soft rubber covered end b². From the block h is
suspended from the pointed screws jj (passing through the threaded lugs i i) The
swinging bar C carrying the carbon button d, nuts c and c' and the bolt c², From
the centre of the diaphragm projects the metallic stud p in suitable contact by
gravity with the carbon button d, The suspended bar C may be of soft iron.
throughout its entire length or of other magnetic material or as is shown it may be
terminated only with the soft iron or other magnetic material D.—E F and G
represent the induction coil which in addition to its ordinary function serves as
hereafter fully described to vary the pressure between the metal stud p and the
carbon button d. One pole of the battery (which is not shown) is connected to the
butt or hinge m and the other to the hinge n the course of the current being from n
to f¹ thence through the convolutions of the primary coil F thence to f thence
through the metal diaphragm B to the metallic stud p (or if a non-conducting
diaphragm be used by a wire connecting with p) and thence to the battery
through the carbon button d the suspended bar B, the pointed screw j the lug i
and the hinge m The secondary coil G is wound upon the primary coil F for
economic reasons. It may be disregarded if a complete induction coil properly
connected with the line be introduced into the primary circuit between either of
the hinges and the battery. With the secondary coil G removed we have simply a
straight electro magnet E F included in the circuit and controlling the pressure
between the electrodes pa. In order to so adjust the carbon button & with relation
to the bar C that when the electro magnetic controller E F is not exerting any
attraction the contact between the electrodes shall be by gravity very slight and
just sufficient to establish the current through the helix F the bolt c² is screwed in
or out of the bar C carrying with it the nut c¹ and the attached carbon button &
and the nut c is then turned down to act as a check nut for holding it firmly in
position. This contact should be as stated slight, and should be regulated after the
transmitter box or case is secured in position. The operation of our invention is a
follows, Supposing a given current from the battery to be following the attractive
force exerted upon D by E will cause a firm contact between p and d which will
be approximately the means of pressure or of surface contact. If now a heavy
impulse thrusts forward the stud p against a the result will be quite different from
that observed when the suspended bar B is held in place merely by gravity or by
a spring. Instead of being carried away by its momentum, thus breaking the
circuit the bar C is held in close contact by the increased attractive force of core E
such increased attractive force being due to a stronger current operating upon it
and such stronger current is obtained by the increased contact between p and d by
the thrust of p against d, For this reason more ample vibration can be given to
the diaphragm without breaking.
The pressure however at the end of the excursion is considerably less than that
quickly succeeding the initial thrust the then greatly increased attractive force
of E having been to a great extent overcome by the momentum of C but enough
force still remains in E to secure on the retreat of the diaphragm and stud Ρ actual
contact. This contact however rapidly diminishes almost to the point of disruption
at the extreme point of retreat as will be understood by considering the mutual

page_text: action of pressure between the electrodes and attractive force of core E one acting
upon the other and being in turn acted upon by the other. In practise we find
that a proper relation (easily determined by experiment) between the battery, the
coil F and the space between E and D gives a combination by which very loud
sounds are perfectly transmitted and also one by which the faintest are also sent
to line with equal facility and this without further adjustment. To provide
however for different conditions of the battery, we make the core E movable
within the coil F so that it may at will and without opening the transmitter box
be adjusted at a greater or less distance from D. By our transmitting telephone,
telephony through very long lines, heretofore impossible is rendered practicable,
and upon short lines a great advantage in distinctness and volume of tone is
obtained, the vibration of the diaphragm in an ordinary receiving telephone being
so greatly amplified as to be distinctly heard at a distance of several feet. Even
better results are obtained from receiving. telephones constructed with special
reference to the duty required. The reason of this marked superiority is in the
fact that a stronger induced current is derived from the greater range of variation
in the primary current from the battery. It should perhaps be clearly stated
that we use a stronger battery than is used ordinarily or can, in ordinary trans-
mitters be used to advantage for the following reasons As the induced current
sent to line has a strength proportioned to the degree of variation in the battery
current it is clear that the induced current due to a battery of 10 volts varied to
9 volts would be no more powerful than one due to a battery of 2 volts varied to
1 volt. It is also clear that the induced current due to a battery of 5 volts varied
to 1 volt would be much more powerful than one due to a battery of 10 volts
varied only to 9. volts. It will be observed that the electro magnetic attraction
governing the pressure between the electrodes is not exerted directly upon the
diaphragm but upon a freely suspended bar carrying one of the electrodes, also
that the attraction is exerted upon the longer arm of a lever of the second kind
the pressure being thereby multiplied. By this arrangement a helix opposing less
resistance to the battery current can be used than would be the case were the
pressure applied direct as less attractive force is required to produce the same
pressure. The use of permanent magnets acting by attraction or repulsion to
control, to a certain extent, the movements of the electrodes is not new and is
objectionable for the reason that when not provided with an inducing coil said magnets
exert a constant force like that due to a spring or gravity and even when furnished
with an inducting coil they do not act as completely and powerfully as a soft iron
core, because as is well known a steel bar whether used as a core or an armature
cannot be as powerfully acted upon by a coil and also because the difference in
magnetic tension under wide variations in the battery current cannot be as great
as with a soft iron core whose power has a range from maximum to zero. Another
important difference lies in the fact that the electro magnetic core is not in contact
with any of the moving parts of the transmitter and when once brought to a
proper adjustment remains stationary. As with this arrangement we do not
utilize any motion of the core to act inductively (electrically) upon a secondary
wire, our primary helix is wound next to the core, thereby realizing its maximum
effect and by placing our electrode upon a disconnected part we are able, to make
of our electro magnet, the primary of an efficient induction coil.
་
The second part of our invention relates to improvements in telephone receivers
especially adapted for use in conjunction with our improved transmitter. It will
however be understood that other forms and constructions of receivers may be used
in conjunction with said transmitter and we do therefore not desire to limit
ourselves to the exclusive use of the receiver which we will now describe referring
to figures 4, 5 and 6. Figure 4 is a vertical section of a receiving telephone made
in accordance with our invention-Figure 5 is a plan view of the same with ear
piece E left off. Figure 6 is an enlarged vertical section of the coil and a part of
the magnet and shows a modification of the coil. A is the stock or holder made
of woot, hard rubber or any other suitable material, with ear piece E attached in

page_text: any convenient manner for clamping and securely holding by its periphery the
vibrating iron diaphragm C, B is a U shaped permanent magnet to one leg 6' of
which the aforesaid diaphragm C is attached by a screw c, clearly shown in figure 1.
By this arrangement a stronger magnetic effect is produced between the pole b and
the diaphragm C,-D is the actuating or inducing coil consisting of concentric
parts d d d hereafter more fully described. ee are the connecting wires con-
necting the parts & and d² with the binding posts a a Fis a set screw for securely
clamping the magnet in place in the stock A at a proper distance from the vibrating
diaphragm 6. Currents of electricity entering and departing by the binding
posts a a actuate the compound inducing coil D to produce audible vibration of
the diaphragm. The object of this part of our invention is to provide a more
perfect receiving telephone and one in which vocal sounds including speech shall
not only be increased in volume but also be rendered more clear, smooth and
natural, While our receiver may be used to advantage with ordinary transmitters
it is intended especially for use with the form of battery transmitter hereinbefore
described. The features of our receiving instrument which we believe to be new
and which we claim are those belonging essentially to the compound actuating
coil D. This coil is made up as follows:-Its central portion d of fine insulated
copper wire, the part d' of fine insulated iron wire or iron ribbon and the part d²
of fine insulated copper wire. A current of electricity entering at one of the
binding posts and reaching first the outer end of the copper-wire coil d² traverses
successively throughout all the convolutions of coils d² d' and d passing from the
latter to the other binding post. The object of the iron coil d is to afford in
addition to the central magnetic core b a tubular electro magnet made up of the
'wire or ribbon itself so that this coil while it acts as an inducing helix to the
central magnetic core is itself acted upon and rendered magnetic by the action of
the copper wire coil d³ and to a considerable extent reacts upon itself to produce
the same result. Its effect upon the diaphragm is obvious, it amplifies the vibration.
At figure 1 this portion of the coil is shown as wire and in figure 3 as ribbon. The
ribbon being merely a flattened wire we regard the two as equivalents. In use
we make the ribbon exceedingly thin so as to get inductive effect from the current
but while more magnetic effect is obtained from the ribbon greater inductive effect
is obtained from the wire. In either case it is to be understood that the material
be it ribbon or wire is covered by an insulator With regard to our iron wire or
ribbon coil we do not wish to be understood as confining ourselves to soft iron as
steel may be used with advantage.
We are aware that a helix of copper wire without a core may in a manner
be considered a magnet, but its magnetism is strongest in its vacant centre, being
due to the lines of force (so to speak) set up by electric currents and not to the
magnetic condition of the particles of the metal of which it is composed. The iron
coil however becomes truly magnetic. It may here be remarked that the size of
the iron wire used is greater than that of the copper their cross sectional areas
being proportioned approximately to their relative conductivities.
Having thus fully described our invention we claim as new the following :—
1 The combination of the suspended bar C carrying one of the electrodes
attached to the adjusting devices c c c³ with the vibrating diaphragm carrying
the other electrode and the electro magnetic controlling device all operating
substantially as described and for the purpose specified.
2nd The vibrating diaphragm carrying one of the electrodes in combination with
the suspended bar C and the bolt c² carrying the other electrode and the check
nut cas and for the purpose specified.
3rd The electro magnetic controlling device operating in the manner described
in combination with the suspended bar C, the bolt c² carrying one electrode and
the check-nut o and the vibrating diaphragm carrying the other electrode as and
for the purpose specified
4th The bolt carrying the carbon button d and the check nut c in combination
with the suspended bar C as and for the purpose described.

page_text: 5th In combination with an iron diaphragm arranged at right angles and in
proximity to one pole of a permanent magnet, said magnet exerting an attractive.
influence at or near its centre, an inducing coil for varying the said attraction
composed partly of copper and partly of iron for the purpose specified.
6th In combination with a vibrating iron diaphragm arranged at right angles
and its centre in proximity to one pole of a permanent magnet and rigidly
attached near its periphery to the other pole of the same magnet, an inducing coil
composed partly of iron and partly of copper for the purpose specified.
7th In combination with a vibrating iron diaphragm, a cylindrical electro-
magnet made up of convolutions of iron ribbon the same being surrounded by a
helix of copper wire and enclosing another helix of copper wire and one pole of a
permanent nagnet.
8th A compound inducing coil consisting of a cylinder made up of a continuous
insulated iron ribbon surrounded by a helix of copper wire and acting by attraction
upon a superposed iron diaphragm and by electrical induction upon one pole of a
permanent magnet located within said cylinder substantially as described.
9th In combination with a vibrating iron diaphragm and a permanent magnet
arranged at right angles thereto and exerting a magnetic attraction upon the same
at or near its centre, an inducing helix of iron ribbon surrounding and in electrical
connection with another inducing helix of copper wire.
10th In combination with a permanently magnetic core and an iron diaphragm,
an inducing coil consisting of two helices of insulated copper wire arranged
concentrically and having between them a helix of insulated iron ribbon
substantially as described and for the purpose specified.
11th In combination with a vibrating iron diaphragm arranged at right angles
with its centre in proximity to one pole of a permanent magnet and rigidly
attached near its periphery to the other pole of the same magnet, an inducing helix
of iron ribbon surrounding and in electrical connection with another inducing
helix of copper wire
12th In combination with a vibrating iron diaphragm and a permanent magnet
arranged at right angles thereto and exerting a magnetic attraction upon the same
at or near its centre, an inducing helix of iron ribbon surrounding and in electrical
connection with another inducing helix of copper wire, said helix of iron ribbon
acting by virtue of electric currents traversing its insulated convolutions to vary
the aforesaid magnetic attraction and at the same time to produce within its own
substance a tubular electro-magnet.
In witness whereof we the said Charles William Hayes and Seth R Beckwith
have hereunto set our hands and seals this twenty third day of April in
the year of our Lord, One thousand Eight hundred and Eighty three."