An Improved Telephonic Plant for Private and Domestic Use.
Year: 1892

page_text: Date of Application. 25th July, 1892-Accented, 27th Aug., 1892
COMPLETE SPECIFICATION.
An Improved Telephonic Plant for Private and Domestic Use.
I, JULES CERPAUX of 3 Rue d'Artois, Brussels in the Kingdom of Belgium,
Electrician, 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 consists in the construction, arrangement and combination of parts
of a complete telephonic plant or system for domestic or private use, the main
advantage of which is that, to suit this purpose, the arrangements employed are
considerably simplified and made more economical, especially for places already
provided with electric bells, such as hotels, business establishments, private
dwellings etc.
The invention may be divided into three main parts: the telephone, the micro-
phone and the switch-board. As will be seen from the accompanying drawings the
telephone consists of a case containing a coil connected with a special armature
consisting of a double-armed soft iron core. The core is so screwed as to be
adjustable, so that it may be brought into contact more or less closely with the
vibrating diaphragm. The magnet is contained in the telephone-handle fitted to
the case by a soft iron screw which secures the short arm of the double-armed core
and serves as a commutator or switch between the magnet and the armature of the
coil. The other end of the telephone-handle carries a pin also made of soft iron
and serving to close and keep up the circuit when required. This telephone is
hooked to a special microphone formed by a series of carbon styles the ends of
which rest in graphite bearings applied against the vibrating diaphragm of the
microphone and in an inclined position as shown in the drawings.
I have
These styles or pencils will not produce any objectionable crackling or hissing
noise which more or less interferes with the sound of the speaker's voice.
added to the microphone a small induction-coil serving for suppressing the hissing
which generally occurs and for increasing the power of the voice as owing to the
provision of this auxiliary coil the current which carries the voice is no longer a
direct current but an indirect one. The main line wire passes through the coil.
From the drawings the course taken by the currents will be readily understood by
any skilled person. It is therefore unnecessary more fully to describe it here. The
contact made by the hook, when the telephone is hooked to the microphone, forins
the circuit for the bell, the current passing through the central binding-post; while
when the telephone is removed for use, the bell circuit is broken, and the spring
detent with which the telephone-hook is connected takes up its position against the
contact which forms a telephone circuit when placed in communication with the
main wire. Thus the same line which serves for the bell is also ntilized for
the telephone by a simple arrangement of contacts or switches whereby the main
wire is made to be the negative pole instead of as before the main line. This
special combination of the telephone with a bell-wire necessarily requires a peculiar
switch-board which I propose to arrange as follows: the board consists of a plate
of copper or any other good conductor of electricity; this plate itself serves as a
switch or commutator in combination with a contact-key or switch proper whereby
the circuit is opened or closed as desired, the conductors or hell-wires being
connected to that plate which in the normal condition is the negative pole. This
plate is enabled to receive the switch-key by being provided with perforations the
number of which exceeds by one the number of conductors connected to the plate.
This plate forms the cover of the switch-board, which has the appearance of a box
or case of dry wood or ebonite, the wall of which, on the opposite side to that
where the perforated plate is arranged, carries a series of spring-controlled metal

page_text: tongues adapted to form a continuous contact with the apparatus whether for the
bell or for the telephone and to be used as a switch-board. These tongues touch
contacts connected with the line-wires and are removed from the said contact when
a key is inserted into one of the perforations of the perforated plate. The key
pressses upon one of the tongues and intercepts the call-current (which becomes a
negative current passing through the copper plate owing to its connection with the
key) and this negative current passes through the corresponding wire of the said
plate. The line-wires therefore no longer form lines of communication, but
negative poles, so that conversation may be transmitted from one or more points at
a time according as one or more keys are inserted into the perforations of the
switch-board.
To facilitate the comprehension of the foregoing, I shall now refer to the
drawings in which
Figure 1 is a front elevation of the microphone and Figure 2 a sectional side
elevation of the same. A is the vibrating diaphragm or plate. B is one of the
carbon pencils mounted in the bearings bb. C is the indication coil. D is the line-
wire and D' D are respectively the induced wires leading to the telephone. E is
the telephone-hook.
Figure 3 is an elevation of the apparatus the bottom-plate of the microphone
being removed. The same letters of reference refer to the same parts as in the
other figures. F is the positive wire leading from the carbons to the binding-post
of the battery. G is the bell or call-wire leading from a contact spring G₁ to the
binding-post of the bell-wire. H is the tongue whereby the circuit is closed when
the telephone is removed from the hook E which is in contact with the tongue of
the main line E¹.
Figure 4 is a section on line A B Figure 3.
Figure 5 is a front view of the switch-board represented by way of example as
having three communication orifices and two key carrying steps. I is the switch-
board. are the orifices for the insertion of the switch-key or pin (Figure 9).
LL' are the steps or offsets for carrying the keys.
Figure 6 represents the bottom wall of the switch-board case, provided with
contact tongues which are to be operated by the key in order to break or make a
circuit for telephonic communication. J is a bottom-plate of insulating material.
Kare counter-tongues connected with the binding-post L of the call devices, while
other counter-tongues K are similarly connected with the binding-posts of the line-
wires L. The negative wire M leading from the switch-board I passes through a
binding-post M' to the negative pole of the battery.
Supposing now that the key is inserted into the hole No. 3 of the switch-board,
the corresponding tongue K is thereby moved out of contact with K and the call-
current being interrupted the line becomes negative, the key which is then
connected with the switch-board, forming a connection with the telephone. The
same will take place whatever the position of the hole into which the switch-key is
inserted.
Figure 7 is a vertical section through the centre of the switch-board or box.
Figure 8 is a plan of the said box.
Figure 10 is a front view of the telephone with its steel handle forming a magnet
and electrically connected with the armature N (Figures 11 and 12) having two
arms at right angles and upon which is adjustably secured the core of the
coil P.
Figure 11 is an elevation of the telephone, the vibrating plate being removed.
Figure 12 is a transverse section thereof and
Figure 13 is a section of the cover or lid of the telephone.
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
A telephonic system or plant for private or domestic use mainly consisting of a

page_text: microphone a telephone and a switch-board the whole constructed and operating
substantially as described and illustrated in the accompanying drawings.
¡L:- ozal, dow of Il 189
W. P. THOMPSON & BOULT,
Agents for the Applicant.