Improvements in Telephonic Apparatus and Switches.
Year: 1892

page_text: Date of Application, 7th July, 1892
Complete Specification Left, 6th Apr., 1893-Accepted, 2nd June, 1893
PROVISIONAL SPECIFICATION.
Improvements in Telephonic Apparatus and Switches.
GEORGE LEE ANDERS of 33 Peak Hill Gardens, Sydenham, Electrician, and
WALTHER KOTTGEN of 10 Jeffrey's Square St. Mary Axe, London E.C.
Merchant do hereby declare the nature of this invention to be as follows:-
The improvement consists in a circular switch contained within the microphone
case or mounted upon a circular base carrying the microphone for connecting and
disconnecting any one of a number of outlying stations or for connecting with each
other any two of these outlying stations as may be desired.
The base containing the switch and microphone operates as a holder for the
receiver, the whole forming a single concentric devise for the purpose of telephonic
communication. The holder for the receiver consists of a bevelled yoke into
which the receiver drops and operates the necessary contact.
Dated this Sixth day of July 1892.
GEO. L. ANDERS.
W. KOTTGEN.
COMPLETE SPECIFICATION.
Improvements in Telephonic Apparatus and Switches.
GEORGE LEE ANDERS, of 33, Peak Hill Gardens, Sydenham, Electrician, and
WALTHER KOTTGEN, of 10, Jeffrey's Square, St. Mary Axe, London, E.C.,
Merchant, 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 :-
The object of this invention is to provide a micro telephone and switching device,
suitable more particularly for use in private houses, offices, hotels, and like places,
and adapted for the purpose of inter-communication by an individual in a room or
office with any one of a group of rooms or stations connected thereto, and effectually
preventing any other station overhearing the conversation carried on between the
two stations connected together for the time being.
The switchboard provided for this purpose is combined with the apparatus and
obviates the necessity of the intervention of a central office switchboard, being
worked by means of a plug by the person wishing to make communication, and, as
will be seen from its operation and construction hereafter described, the apparatus
is also adapted for more extended and public use.
In the accompanying drawings
Fig. 1 represents a vertical section through the complete apparatus.
Fig. 2 shows a back view on line x in Fig. 1, after removal of base plate.
Fig. 3 is a front view of switchboard on line.
Fig. 4 is a vertical section of the latter.
Fig. 1.
Fig. 5 is a front view of apparatus after removal of receiver.
Fig. 6 is also a front view of apparatus after further removal of front plate
and transmitter diaphragm.
Fig. 7 is a side view of the apparatus.
Fig. 8 is a side view of the receiver.
Fig. 9 is a front view of the receiver, with diaphragm and mouthpiece removed.
Fig. 10 is a section through the case of the receiver.
Fig. 11 is a diagram of the circuits through three stations connected together in
accordance with the foregoing.
The main body 2, constructed of insulating material, and containing the

page_text: principal parts of the apparatus, is screwed on to the vulcanite base plate 1 which
serves as the switchboard containing brass-plates 3, sunk therein, the number of
which correspond with those of the number of stations it is desired to put into
connection (here fourteen). The plate 4 carries a contact screw 5, whilst plate 3ª
is provided with stud 45. Into the back of main body 2 ring 9 is sunk flush with
the surface, said ring 9, containing fourteen holes, being held in position by the
projecting ends of brass blocks A B. E F which together with blocks CD are
screwed on to surface 10. There is also on surface 10 a pivoted block 13 of
insulating material to which is fastened a metal strip 14 a part of which is
turned down (Fig. 1) in such a manner beneath block 13 that a metallic contact is
made between it and the pivot screw 15. Blocks B, E F are out of contact with
ring 9 through thin plates of insulating material between them.
To metal block A a spring 16 is fastened which causes the ring 9 to be held in
such a manner that stud 12 rests against pin 45 of plate 3ª, and at the same time
pin 11 keeps block 13 in such a position that the right hand side of the metal
strip 14 (Fig. 2) is held in contact with block F. In this position of ring 9 it
will be seen that the holes 17 in same are out of line with the same number of
holes 17 in plate 3 (Fig. 2). As soon however as plug G is inserted into one of
the holes of the instrument, the holes of ring 9 are caused to be brought into
line with the holes 17, and the ring 9 is shifted in such a manner, that pin 12, as
well as 45, and one end of metal strip 14 are removed from contact with block F,
whilst the other end of metal strip 14 is brought into contact with block E. On
withdrawing the plug G the ring is brought back into its normal position by
spring 16.
The ringing key is rivetted on to ring 9 by means of a forked strip 18, the long
arm 19 of which is bent over, as shown in Figs. 1 and 2, and forms one of the
contacts of ringing key 9. When push button 21 is operated, piece 19 is forced
into contact with stud 4, and completes the battery circuit to ring a distant bell.
In its normal position arm 19 is in contact with pin 22 which passes through ring 9
without being in contact therewith, the ring having been cut away beneath arm 19
for the purpose. The other end of pin 22 is attached to a switch spring 23
(Figs. 1, 5, 6).
There is a central hole through body 2 in which is placed the transmitter
microphone, consisting of two hard carbon blocks hollowed out cup shaped, and
between which is placed fine carbon 25. To prevent the powder from falling out
of the cup shaped carbon blocks, a short piece of india rubber tubing 26 is drawn
over them of the carbon blocks 24, the rear one is fastened by screw 29 to
plate 27 one arm of which is screwed on to block C, whilst the front carbon block
is fastened by screw 30 to the diaphragm 31 which is connected with contact 33 by
a wire 47, passing from screw 30 on to it.
The fine carbon used loosely in this manner we have found to be of great
advantage, as it may be used in any position, but other forms of microphones may
also be employed.
In front of the diaphragm and for the protection of same there is a perforated
cover plate 35 around a portion of which is fixed a projecting bevelled yoke 37
(Figs. 1 and 5) to hold the receiver, the mouthpiece 38 of which, being of insulating
material, having a correspondingly bevelled flange to engage therewith. When in
position the receiver presses on the nose 34 of strip 23 which projects through
front plate 35, and as seen from Fig. 1, makes contact with strip 32 which latter
is in contact with block B (Fig. 6) by screw 32ª; if the receiver is removed from
the yoke, spring strip 23 makes contact with retaining piece 33, contact with
curved strip 32 having been broken.
The receiver case is composed of parts 42, 43, 44 containing an ordinary bent
magnet 39 which carries at each end soft iron pole pieces to hold bobbins 40, and,
as will be seen from Fig. 2, only two wires W W are employed to connect the
receiver with blocks CD.
In operating the telephone the receiver is first removed from the yoke, plug G is

page_text: placed into the desired hole, and the ringing key 19 pressed down. In doing so
the circuits through the instrument are as follows, reference being made to Fig. 11
in which No. 1 is the calling station which has made connection with station 2 :
The current is from battery wire 50 to block E, from here to contact 4, and, the
key 19 being pressed down, from 19, 18 to ring 9, from which through the plug G,
and by line wire II arrives at station No. 2. The receiver here being in the
instrument, and spring strip 23 being consequently pressed down on contact 32 (as
is shown at station 3) the path of the current is from plate 3 to stud 45 which is
in contact with pin 12, from pin 12 to ring 9, from this to key 18, 19, contact 22,
from contact 22 to switch spring 23, contact 32 and block B to bell; the latter
rings and the current passes on to block F, and through wire 52 to earth or return
wire 49. The bell having been rung, station 2 removes the receiver, when the
current passes from plate 3ª by studs 45 and 12 to ring 9, by key 18 and 19 to
contact 22, switch spring 23, contact 33, and wire 47 to microphone-from the
latter through 27 to block C, wire W, through receiver 43 to block D, wire 54,
strip 14, block F, wire 52 to earth or return wire 49.
In the foregoing it has been shown, that the current passes from block E to
contact 4, when key 19 is pressed down, so that the whole current passes through
the wires. It will however be seen that there is also a current passing from
block E, by 14, 54, D, W, 43, C, 27, through microphone, 47, 33, 23, 22, 19, 18, 9,
and by plug G into line wire, if the former is placed into one of the holes. The
current passing in this way through the receiver and the microphone may however
be found not to be sufficiently strong to ring the bell of the station called up, and
it is therefore always desirable to press down the ringing key.
As will be seen from the diagram, a wire is required for each station, and that a
return and battery wire of one polarity only is required, so that the entire number
may be represented by the symbol N + 2, instead of, as is usual, N + 3, in which
N represents the number of stations, 3 being one return and 2 battery wires of
opposite polarity.
It will also be seen that by this system there is no possibility of overhearing a
conversation between any two parties, as by removing the receiver from the
transmitter there is no current in the apparatus of the party attempting to listen.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is:
1) A microphone and receiver mounted upon a base in combination with a
circular intercommunication switch concentrically arranged within the said base,
the intercommunication switch being adapted to be operated by means of a plug
being inserted in any one of a concentric row of holes arranged around the
microphone in the manner and for the purpose set forth.
2) An intercommunicating ring switch provided with a series of holes, a corre-
sponding series of terminal or line plates having similar holes, the holes in the
ring being normally forced out of line with the holes in the terminal plates, so that
the ring will make contact with its own line plate, and the rocking spring will
make contact between either the bell or telephones as desired. The holes in ring-
switch and terminal plate being adapted to receive a plug which forces the two
sets of holes into line with each other, thereby making contact between the ring
and the desired line terminal, at the same time breaking contact between the ring
and its own line terminal, while the rocking spring breaks contact with return
terminal, and makes contact with battery terminal in the manner and for the
purpose set forth.
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"
1 1000
GEORGE LEE ANDERS.
WALTHER KOTTGEN.