IMPROVEMENTS IN AND RELATING TO SWITCH BOARDS OR APPARATUS FOR CON- " and in NECTING CIRCUITS AND SIGNALLING IN TELEPHONE EXCHANGE SYSTEMS
Year: 1885

page_text: I THOMAS JOHN HANDFORD of 42 Southampton Buildings in the County of
Middlesex Patent Agent do hereby declare the nature of this invention for
IMPROVEMENTS IN AND RELATING TO SWITCH BOARDS OR APPARATUS FOR CON-
" and in
NECTING CIRCUITS AND SIGNALLING IN TELEPHONE EXCHANGE SYSTEMS
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
This Invention relates to what are known as switch boards, the same being
apparatus which are used in telephone exchange systems (chiefly at central stations)
for placing any required two of a series of circuits in connection and also for calling
attention when one subscriber or other person desires to converse with another;
and the Invention consists of improvements in and in connection with apparatus of
this description whereby the space required for the apparatus is reduced and its
construction is simplified and a saving is effected in the time necessary for working
the signalling apparatus.
"
"
or may
One part of the invention relates to the means of connecting subscribers, on
various boards of a series of switch boards, together. For this purpose in lieu of
using connecting strips, the several switch boards are connected together by means
of contact points which may be of the type known as spring-jacks
consist simply of a piece of metal having a cavity for the reception of a plug
carried on the ends of conducting cords. These contact-points are inserted in
apertures provided in any suitable part of each switch board, by preference in a
sloping shelf at the bottom thereof, the number of such apertures being regulated
by the number of subscribers for which the switch boards are constructed. The
contact-points of the several switch boards are connected together in sets electrically
say for example the No 1 contact points of all the boards are connected together,
similarly the No 2 contact points are connected together, and so on with the
remainder. It will thus be seen that the several switch boards are in electrical
27

page_text: connection by means of the connected sets of contact-points precisely as if they
were united by means of connecting strips equal in number to the connected sets
of contact points whilst economy of space and facility of application are obtained.
Figure 1 of the accompanying drawings is a diagram perspective view of a series
of switch boards placed in electrical connection with each other according to this
part of the invention. This figure also illustrates in part other improvements
hereinafter referred to, and which are more particularly shewn in Figures 2 and 3
these figures representing sections of a switch board with diagrams of the various
instruments and their connections.
A A A A³ (Figure 1) represent a series of switch boards each provided with
spring jacks; B, or equivalent devices used in switch boards for the reception of
plugs for the purpose of placing two subscribers of one and the same board in
communication with each other. It is sometimes required, however, to place a
subscriber of one switch board in communication with a subscriber of another
switch board and therefore an electrical connection between the several boards is
necessary. This is accomplished according to the present invention by means of
auxiliary sets of contact points C Figure 1 (which may be of the character shewn
at Z in Figures 2 and 3 to be presently described) inserted in apertures in a sloping
shelf D or in any other convenient part of the switch boards. The contact points C
of the several switch boards are connected together in sets electrically, say for
example all the contact points marked a are connected together as shewn by the
dotted lines C¹ and in a similar manner all the contact points marked bare
connected together and so on with the remainder. The several switch boards being
thus in electrical connection by means of the connected sets of contact points C,
two subscribers on different boards may then readily be placed in connection. Let
it be assumed, for example, that it is desired to connect subscriber 51 on board A¹
with subscriber 200 on board A³; one plug E of a conducting cord F, is inserted in
the jack No 51 on board A¹, as represented, and the other plug E¹ of that cord is
inserted, as shewn, in one of the auxiliary contact points (say the contact point a)
of the sloping shelf or other portion of board A¹ set apart for effecting intercom-
munication between the several boards. At board A³ a similar operation is
performed, as indicated, with another conducting cord G, one of its plugs (H) being
inserted in the spring jack 200 on that board and the other plug (H) being inserted
in the contact-point of the sloping shelf or equivalent part on board A³, corresponding
to the contact point used at board A¹ viz: the contact point a in the example
illustrated.
By this arrangement also facilities are afforded for connecting together three (or
any other number of persons not exceeding the number of switch boards employed)
who may wish to hold a conversation together.
A series of contact points Z is further provided at the side of each switch board
the same being all connected by wire P (Figures 2 and 3) with the operating key
so that the attendant may be at all times in a position to communicate with the
greatest possible despatch with any subscriber by the act of inserting plug No 1 of
a conducting cord Z¹ in the spring jack B corresponding to such subscriber, the
plug No 2 of the said cord being inserted in one of the contact-points Z. In the
drawing Figure 1, subscriber No 151 on board A³, is represented as in communi-
cation with the attendant. Figure 2 shews diagramatically the connections of
circuit when the subscriber calls the attention of the attendant and Figure 3 shews
the connections when the attendant has joined up for speaking with subscriber.
The invention further relates to that portion of the switch board or apparatus 5
which is used for signalling or calling the attention of persons when it is desired
to hold a conversation. It has been customary sometimes to use for giving the
audible signal, a device known as a magneto-electric bell which operates with an
alternating current, the hammer of the device striking alternately two bells proper
arranged one at each side thereof. As however it is sometimes desirable to employ 5
a battery for sounding the bell it is then necessary to provide means for alternately
changing the course of the current so as to obtain the required alternating effect.

page_text: For this purpose, a device is used known as a "pole-changer" which is brought
into circuit, and by which under the action of electro-magnets excited by a battery,
the required alternating current is obtained. Now this part of the invention has
reference to a peculiar key having multiple contacts for throwing the pole changer
and the line battery which operates the bell into circuit simultaneously.
This part of the Invention is illustrated more particularly in Figure 3 of the
drawings. I is the transmitter, I¹ the transmitter battery, K the receiving telephone,
K the switch, L the pole-changer (shewn only diagrammatically its construction
being well known) M₁ M³ the terminals from the battery M which sets the pole
changer in action, N the line battery with its terminals N' N2, O the key, 1, 2,
plugs of a conducting cord Z' before referred to, P¹ P main circuit from line through
key O, telephone and secondary coil to earth, Qlocal circuit of pole changer,
R connections of line or signal battery with key O, pole changer I, and carth,
S inducing circuit comprizing battery I', diaphragm contacts and primary coil,
T earth wires. The key O is provided with contacts 01 02 03. In the normal
condition of the parts illustrated in the drawings the key is on contact O' and off
the other contacts 02 03 and the home telephone is in circuit and the pole changer L
and line battery N are out of circuit. By depressing the key O, however, contact
is broken at Oi so as to cut the home telephone out of circuit and contact is made
at 02 03 by which the battery M for working the pole changer L is brought into
circuit and the line battery N for sounding the bell is also thrown into circuit
simultaneously therewith. The pole-changer L is then vibrated and the current
travelling alternately in opposite directions the two bells are sounded alternately.
A single action of one key is therefore sufficient to set the pole changer in
motion and at the same time to connect the calling battery to the subscriber's line,
instead of keeping the pole-changer constantly in motion involving a rapid dete-
rioration of the instrument and absorption of battery power.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is
1st The employment of contact-points or spring-jacks connected up substantially
as set forth for placing a series of switch boards in electrical connection substantially
as and for the purpose herein before described.
2nd The peculiar key with its connections in combination with a pole-changer
substantially as and for the purpose herein before described.
3rd The use of contact-points or spring jacks Z at the side of each switch board,
which are all in electrical connection with the centre of the key, and by means of
which the attendant is at all times in position to communicate with the greatest
possible despatch with any subscriber, substantially as herein before described.
Dated this 24th day of January 1885