Improvements in and relating to Telephonic Switch Boards.
Year: 1891

page_text: Date of Application, 12th Mar., 1891
Complete Specification Left, 14th Dec., 1891-Accepted, 16th Jan., 1892
PROVISIONAL SPECIFICATION.
Improvements in and relating to Telephonic Switch Boards.
I, CHARLES JONATHAN PRICKETT, of 29 Gosterwood Street, Deptford, S.E.
Electrician, do hereby declare the nature of this invention to be as follows:-
My invention relates to improvements in and relating to telephonic switch-
boards and fittings and has for its object chiefly to provide efficient means whereby
a perfect contact is obtained.
In the switch board the springs are fastened to a suitably shaped strip, the top
spring instead of resting on underneath spring as ordinarily is the case has a hole
formed in it to allow the curl of the underneath spring to pass therethrough, a
portion of the metal where the hole is punched being made in the shape of a knife
edge to clean the surface of the metal cach time it is allowed to come in contact,
the strip and springs otherwise being arranged in a similar manner to other
systems. On the front of the strip pieces of metal are provided in halves with a
piece cut out so that when placed opposite each other a square hole is formed.
Each piece of metal is connected to the corresponding one on each section of board
by wires and a groove is made on switchboard within which the wires are laid and
covered by suitable material having numbers or other indications to distinguish one
from the other.
The speaking jacks are made with two flat pieces of metal insulated from one
another by suitable material, and a cover suitably shaped made of insulating
material is adapted to the end of the pieces of metal. The speaking jack where
inserted in the switch board is provided with a tongue made so as to fit in the
hole made in the springs of the strip so as to clean the surface every time it is
inserted, whereas in other systems the springs of the strip merely rest on or clasp
the front end of the speaking jack. When the speaking jack is inserted in the
hole in the switchboard it short circuits the pieces of metal aforesaid on front of
switch board so that when the operator taps with speaking plug on the other
section of board it is sufficient to indicate that the line is already in use.
The connections in the circuit of one speaking jack with the other are made by a
plug of metal inserted between two strips or plates of metal, these strips replacing
the springs usually employed.
The ring-off indicator which is inserted in the circuit between the two jacks is
provided with two coils wound on it, one coil being joined to one wire of the jack
and the other coil joins on to the other wire of the jack when the plug is inserted
between the two metal strips. The electro magnet is made of soft iron in the
shape of the letter H and the armature and shutter are the same as in other
systems, excepting that a spring is fastened on the lever of armature so that when
raised it makes contact with a screw fastened by insulating material to switch-
board and thus rings electric bell. The indicator for calling attention of operator
is wound with only one coil.
The keys for speaking are arranged in sets of three for each speaking jack. By
pressing these keys the speaking instrument which is inserted on that wire in which
the jack is inserted depresses a suitable arrangement of horizontal springs provided
with contacts and disposed under a flap adapted to switch board. One key is
marked red or in such a manner that when pressed it sends a ringing current
along the line from an ordinary magneto generator, and is cut out of circuit when
the plug is inserted between the two metal strips aforesaid, whereas in other systems
a lever is employed which makes contact with springs and is always in circuit.
Dated this 20th 1
1901

page_text: COMPLETE SPECIFICATION.
Improvements in and relating to Telephonic Switch Boards.
I CHARLES JONATHAN PRICKETT of 29 Gosterwood Street, Deptford, S.E.,
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 relates to improvements in and relating to telephonic switch
boards and fittings, and has for its object, chiefly, to provide an efficient means
whereby a perfect contact, and, at the same time, ready means of communication is
obtainable.
The apparatus in accordance with my invention which is arranged in
a similar manner to that at present in use is shown in the annexed diagramatic
explanatory drawing wherein
Figure 1 represents by vertical section three strips with springs for the reception
of the contact ends of the speaking jacks. These strips as ordinarily is the case
with multiple systems are arranged in sections, each strip being connected to the
corresponding strip of the other sections, the speaking jack being shown in position
for speaking at section 2 Figure 1. Figures 2, 3 & 4 illustrate respectively by
side, end and front elevations the indicator employed by me in carrying out my
invention, an alternative construction being shown by sectional elevation and plan
respectively Figures 5 & 6.
66
Figure 7 illustrates the contact for connecting two speaking jacks together, and
'ring off" indicator for announcing to the attendant when the line is out
of use.
a
Figure 8. is a vertical section of a keyboard arranged horizontally in front of the
switch board to enable the operator to communicate at will with any particular
subscriber.
Figure
apparatus.
illustrates the usual speaking, receiving and current generating
My improvements relate firstly, to the improved construction of the strips and
springs within which the speaking jacks are inserted; secondly, to an improved
speaking jack for use with same; thirdly, to the indicators employed, and fourthly,
to the arrangement employed for enabling the operator to communicate with two
subscribers in circuit
In sections 1, 2 & 3, Figure 1, A is the strip of non-conducting material on the
top and bottom of which are secured outer and inner springs B, C. The outer
springs B terminate at their frout in curved ends and are there formed with
openings Fas hereunder mentioned. The front ends G of the inner springs C are
bent outwards and enter openings formed in the outer springs B, as shown more
particularly in the plan view Figure 1A, the knife-like edges I of the outer springs
scraping against the curved ends G every time the jack is inserted or removed, thus
insuring good contact. Immediately in front of the curved ends of the outer
springs openings Ware formed in the switch board between the metal plates D
and E Figure 1B of the speaking jacks, as in section 2, the metals being connected to
one another in parallel by the wires 7 and 8, a groove or space between the
plates D and E serving to receive the wires 7 and 8 whilst the separating strip of
non-conducting material U is numbered to denote the opening of each subscriber.
When, as in section 2, the contact end W1 of the jack is inserted in the opening W
and between the curved ends of the outer springs B the bent ends G of the inner
springs C are disconnected from the outer springs and the current passes out to the
local exchange. The speaking jack is formed of two pieces of metal M insulated
from each other, and surrounded with an insulated cover N. The end W' of the
jack is formed with tongues X which enter the openings F in the curved ends of
the springs B and clean the contact surface every time the jack is inserted or
removed.
In the indicator Figures 2, 3 and 4,-the magnet A of which is wound with one

page_text: coil-L is the armature pivotted at M, F a lever attached to L and provided with
a catch for holding the indicator H which is pivotted at J in position. When a
current passes through indicator coil the armature I is attracted and the catch of
lever F raised allowing indicator H to fall whilst the spring E. Figure 4 is forced
into contact with the insulated screw C, the current traversing the wire 1 to
battery B connected with electric bell to wire 2 so completing local battery circuit.
The current coming in on wire 2 section 1 Figure 1 passes by wire 3 through the
springs C, B, through sections 2 and 3 and wire 5 to the brass strips O of indicator,
through magnet coil, thus attracting armature, raising lever, causing indicator to
fall and bell to ring as aforesaid, the current returning by wires 6, 4 and 1.
In the modified form of indicator, Figures 5 and 6, A is a core of soft iron which
screws into two magnets, or vice versa, and is wound with a coil of wire, so that,
when a current passes through the coil it creates magnetism in opposite directions
to the permanent magnet, so temporarily neutralising the magnetism, in con-
sequence of which the armature falls. B is the pivotted, combined indicator and
armature.
This
In Figure 9, A is the transmitter. C the receiver, B induction coil, D switch
hook, G the generator all of ordinary type. The current travels from the
battery 10 to wire 3 then through springs S into transmitter A and back through
primary circuit of B and wire 4 to battery 10. The current travels from the
secondary circuit of B to wire 5 and then to springs L M or P, Figure 8. In this
figure, K is the keyboard, and H, I, J, the keys, H being the ringing and I, J, the
speaking keys, these three keys and springs are provided for each pair of speaking
jacks and are connected up as shown with the "ring off" indicator Figure 7.
keyboard is preferably arranged horizontally in front of the switch board, whilst
the "ring off" indicator is adapted above or below the call indicator as desired.
On pressing the key I. contact is made with the spring S on to wire 9 to the plug
or speaking jack which is inserted in the springs of section 2 Figure 1, through the
upper outer spring B, out to local exchange and back to the lower outer spring B
on to wire 7 to spring O Figure 8 through contact S to spring N on to wire 6,
through receiver, so completing circuit. For the other plug or speaking jack the
current travels the same way through wire 5 to spring L and by pressing key J
contact is made with S and wire 8 to speaking jack and back to wire 7 through one
half coil of magnet of ring off indicator to wire 7 through springs O and N and
wire 6 thus completing local circuit. If desired any of the jacks may be inserted
between the wires and 6 for ascertaining if the line is in or out of use.
ringing key H-which is marked red to distinguish it from others--when pressed,
sends a current from an ordinary magneto generator G through wires .1 and 2
through contact S and springs O and P and other springs L, M, N, according to
which key is pressed. In this "ring off" indicator, Figure 7, A³ is the indicator
for enabling the attendant at the central station to ascertain when the line is out
of use.
F is a plug which is inserted between two brass strips E when the line is
connected up to enable one subscriber to communicate with another, the current
thus passing by wires 7 and 9 through two halves of magnet A through plug
contacts E and along wires 7 and 8.
The
When a subscriber desires to communicate with another the ringing current
coming in on wire 2 Figure 1 causes a numbered indicator Figures 2, 3, 4, 5, and 6
to fall. The plug F being then removed and the speaking jack Figure 1 Section 2
inserted in the subscribers opening the ringing key H is pressed and the subscriber
spoken to by way of key I. The other jack after being inserted and the other
subscriber rung up and spoken to the plug F is again inserted and the springs and
connections Figure 8 cut out of circuit the communications passing through the two
speaking jacks and plug F. When a subscriber has finished speaking a ringing
current passes through the "ring off" indicator causing indicator A³ to fall.
Should it occur that the attendant at any section of the switch board wishes to
communicate with a subscriber whose wire is engaged he first taps with the jack
and so ascertains that the wire is in use.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
First The improvements in telephonic switch boards substantially as herein set
forth.
Second-In telephonic switch boards the combination of strips A, springs B, C,
with openings F, bent ends G and knife edges I, together with the metal plates D
and E, all as and for the purposes specified.
Third In a speaking jack the combination with the insulated metallic plates M
of the knife edges X for scraping the ends of the springs B as herein set forth.
Fourth In telephonic switch boards the improvement in the indicator Figures 2,
3, 4, 5 and 6, "ring off" indicator A Figure 7 with contact plug F and key
board K Figure 8 with contact springs and keys all as and for the purposes
specified.
Dated this Twelfth day of December 1891.
JAMES STEVENSON,
20, High Holborn, London, W.C., Agent for Applicant.