Improvements in Telegraphic Transmitting Instruments.
Year: 1897

page_text: Date of Application, 21st Oct., 1897
PROVISIONAL SPECIFICATION.
Improvements in Telegraphic Transmitting Instruments.
We, GEORGE DRAPER and WILFRID GAYE, both of Winchester House, Old Broad
Street, in the City of London, do hereby declare the nature of this invention
to be as follows:-
This invention relates to transmitters in which a "curbing" current is sent
after each signalling current and its object is to make the duration of the signal-
ling and curbing currents and the period between the cessation of the first and
the application of the second independent of the length of time during which the
operator holds down the key.
For this purpose the key is made to close two circuits one through the line
and the other a local circuit through an electro-magnet whose armature in its
movement actuates a contact maker by which the signalling circuit is broken and
the curbing circuit is first closed and then broken, the time during which the
circuits remain closed as well as that between the breaking of the first and the
closing of the second being dependent solely on the adjustment of the parts and
not on the time during which the local circuit is held closed by the operator.
Preferably two keys are provided one for positive and the other for negative
signals the arrangement being as follows: -Each key is divided into two parts
insulated from each other, one part of each being connected to the corresponding
part of the other and to one pole of the local battery. The other parts of the keys
are connected respectively to the line and to earth and normally rest upon a con-
tact plate A common to them both. When either of the keys is depressed it is
lifted off the plate A and its two parts come respectively into contact with two
plates B and C. The plate C is connected to the other pole of the local battery
so that when either key is depressed the circuit through the local battery is closed.
The plate A is connected to a lever carrying a spring contact working between
two terminals connected respectively to the poles of the signalling and curbing
batteries whose other poles are connected to the plate B. A blade on the armature
of the electro-magnet in the local battery circuit normally holds the contact
against the signalling terminal, when however the local circuit is closed and the
magnet attracts its armature the blade drops into a notch in the lever and the
latter being pulled by a spring carries its contact against the curbing terminal
the further movement of the armature however carrying the blade past the notch
and forcing the lever back again so that its contact is clear of both terminals.
When therefore the key connected to the line is first put down the circuit is
from the line battery, through the plate B, the depressed key, the line, earth, the
other key, the plate A, and the notched lever back to the battery whilst when
the key connected to earth is put down the circuit is from the signalling battery,
through the plate B, the depressed key, earth, the line, the other key, the plato A
and the notched lever back to the battery. In either case the local battery circuit
is closed causing the electro-magnet to attract its armature so shifting the lever

page_text: as above described breaking the line circuit after a fixed time dependent on the
adjustment of the parts and first closing and then after another fixed time break-
ing the curbing circuit.
The terminals between which the spring contact on the lever works are carried
on a slide whose position is determined by a tangent screw so that the length of
time the contact remains against each terminal can be adjusted.
Further adjustments can be obtained by making each terminal movable on the
slide and providing means for altering the tension of the springs acting on the
lever and armature.
Total this 21st day all station 1007
Improvements in Telegraphic Transmitting Instruments.
We, GEORGE DRAPER and WILFRID GAYE, both of Winchester House, Old Broad
Street, in the City of London, 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 transmitters in which a "curbing" current is sent
after each signalling current and its object is to make the duration of the signal-
ling and curbing currents and the period between the cessation of the first and
the application of the second independent of the length of time during which the
operator holds down the key.
For this purpose the key is made to close two circuits one through the line
and the other a local circuit through an electro magnet whose armature in its
movement actuates a contact maker by which the signalling circuit is broken and
the curbing circuit is first closed and then broken, the ume during which the
circuits remain closed as well as that between the breaking of the first and the
closing of the second being dependent solely on the adjustment of the parts and
not on the time during which the local circuit is held closed by the operator.
Preferably two keys are provided one for positive and the other for negative
signals the arrangement being as follows:-
Two batteries of suitable strength are provided the positive pole of the one
(hereafter referred to as the main battery) and the negative pole of the other
(hereafter referred to as the curb battery) being connected by way of the ter-
minals F F to the contacts X Y (Figure 1) mounted upon the springs S2 S3:
their other poles are connected together and by way of the terminal F (Figure 2)
to the contact plate H¹ (Figures 2 and 3).
The cable is connected by way of the terminal F6 (Figure 2) to the bridge J
in which is pivotted the lever K³ (Figures 2 and 3) and the earth is connected by
way of the terminal F7 to the bridge in which is pivotted the lever K.
These levers consist of two parts V₁ and V2 and V3 and V4 (Figures 2 and 3),
V being insulated from V2 by the ebonite piece E¹ and V³ from V4 by a similar
piece E. The parts V2 and V4 are connected together by a piece of suitably flexible
wire and in like manner to the terminal F8.
The contact plate H2 (Figures 2 and 3) by way of the terminal F is connected
to one pole of any suitable battery the other pole being by way of the terminal F
(Figure 1) connected to one side of the electro magnet M the other side of which

page_text: is connected by way of the terminal F" to the terminal F8 (Figure 2). The
levers K K carry on their ends light springs Z Zª (Figures 2 and 3) with suit-
able contacts attached.
The lever L (Figure 1) is delicately pivotted in the metal base at C and the
3 terminal F2 being uninsulated from the base is in connection with the lever L.
To this terminal 1 is connected the terminal F5 which is the connection for the
contacts D³ (Figures 2 and 3).
A general plan of the connections is shown in Figure 8.
The connections being thus made the apparatus functions in the following
manner.
At the beginning of the depression of the lever K by the operator, the spring Z
rises and makes contact with D¹, this sends a positive current from the main
battery into the cable, when however the part Va of the lever K' makes contact
with the plate H2 (Figures 2 and 3) the circuit is closed in the electromagnet M
Figure 1 and the armature A is drawn over.
Attached to the armature is a lever B furnished with a tapered steel end R
(Figure 1), when the apparatus is in its normal position at rest this occupies a
position indicated in Figure 1 at the top of a small recess in a cam G attached to
the lever L which is thus held in contact with the contact X.
During the transit of the armature the end R of the lever B passes across the
recess and the lever L becomes free to respond to the tension of the spring S¹ and
passes over to the contact Y, this condition is indicated in Figure 4 and results in
a negative current passing into the cable.
At the completion of the transit of the armature (the distance of which is
governed by the adjustable stops 1" 12) the end of the lever B reaches the other
side of the recess and forces back the lever L. into a position clear of the con-
tacts X and Y (Figure 5).
On the release of the lever K¹ the lever 13 responds to the tension of the spring S
(the amount of which is regulated by the screw adjustment) and regains its normal
position.
Similarly on the depression of the lever K2 a negative current passes into the
cable followed by a positive one.
It may be preferred to reverse the connections on the terminals F1 and F2 or
those on F and F5 in which case the processes described are obviously reversed.
The curbing effect is dependent upon (1) the relative strengths of the main
and curb batteries (2) the length of period of contact with the cable of one and the
other and (3) the interval elapsing between cessation of the current from the main
and the application of that from the curb. The first of these conditions is attained
by an arrangement of suitable battery power in each case, and the second by the
mounting of the contacts X Y on an ebonite platform Q (Figure 1) capable of
movement in a straight line in either direction by means of a very fine tangent
screw adjustment T (Figures 1 and 7).
Thus a movement of the platform from right to left would result in the cable
getting a shorter contact with the main and a longer one with the curb battery,
than it had before such a movement was made, and a movement in the opposite
direction would have a reverse effect.
The contacts X Y have also independent adjustments for the same purpose; in
the screw stops P3 P4, as the levers WW2 carrying the springs on which are
mounted these contacts are capable of being revolved about the screws N N, which
when the right adjustment is obtained may be screwed up so as to fix the
levers WW³
The length of period of contact with the main battery may also be varied by
the position of the tapered end R of the lever B upon the cam G, also by the
amount of tension of the spring S, greater tension giving longer contact and
vice versa.
This period may also be varied by the adjustable screw contacts D' D² (Figures 2
and 31

page_text: The length of period of contact with the curb battery may be varied also by the
amount of tension of the spring S¹ greater tension giving longer contact and vice
versa.
The adjustment of the tension of this spring (which is effected by the milled
headed screw T) also controls the period of time elapsing between the conclusion
of contact with the main battery and the beginning of that with the curb.
The cam G on the lever L is preferably constructed of some antifrictional alloy.
In cases where it is desirable to prolong the contact with the main battery
beyond what the above mentioned adjustments are capable of doing, we may shape
the cam G in the form shown in Figure 6, in this case the normal position of
the lever L is upon the contact Y but the tapered end R of the lever B will in the
descent of the armature A force the lever L over to the contact X: in Figure G
is indicated the position of the lever L when the lever B is midway in its transit.
Normally the tapered end R is above the projection; at the end of the transit
of the lever B it is below it and the lever L is clear of X.
In cases where such a cam is employed we prefer to attach the tapered end R
to the lever B by a light steel spring as shown in Figure 6.
It is obvious that under these conditions the main and curb battery poles on the
contacts X Y must be reversed.
To still further prolong the contact with the main battery we prefer to so arrange
that the making of contact between H³ and the parts V2 V4 of the levers K' K³
shall close the circuit in another electromagnet the armature of which is so
arranged that it shall close the circuit in the electromagnet M.
We may sometimes so shape the cam G that the normal position of the lever
is clear of both contacts X and Y, but on the depression of either K¹ or K³, in the
transit of the lever B. the tapered end R may first cause the lever L to make con-
tact with the main battery then with the curb and finally leave it in a position
clear of both.
In some cases the apparatus is employed in conjunction with a condenser of suit-
able capacity which is inserted in the circuit between the cable and the bridge J¹:
only one battery is employed for signalling, one pole of it being connected to the
contact X and the other to the contact plate H¹ and the contact Y, see Figure 9.
At the beginning of the depression of either of the levers K¹ K² the condenser
becomes charged positively or negatively according to which of the levers is de-
pressed, and an impulse passes into the cable, the amount of the charge and
the consequent impulse depend upon the length of period of contact between the
lever L and the contact X a period which, as has been shown, is controlled by the
various adjustments.
Contact being made on arrival of either of the parts V2 V4 of the levers K' K²
upon the plate H2, the tapered end R of the lever B passes across the recess in the
cam G permitting the lever L to be drawn over to the contact Y, this discharges
the condenser and a curbing impulse, or one in an opposite direction to that of
the charge, passes into the cable.
The amount of this impulse is controlled by the length of period of contact
between the lever L and the contact Y and this period is as has been shown
adjustable. Or one pole of the battery is connected to the contacts 1' 1)² (through
a resistance coil if preferred) and the other to the contact plate H', the bridge Ja
connection being unchanged.
The other side of the condenser is of course connected to the cable.
The general plan of connections for this arrangement is given in Figure 10.
Having now particularly described and ascertained the nature of our said in-
vention and in what manner the same is to be performed, we declare that what
we claim is:-
1. A telegraphic transmitting instrument in which the key closes two circuits
one through the line and the other through an electro-magnet whose armature in

page_text: its movement actuates a contact maker by which the signalling circuit is broken
and the curbing circuit is first closed and then broken.
2. The combination with the subject matter of Claim 1 of the lever L cam G
and lever B substantially as described.
3. Telegraphic transmitting instruments substantially as described and illus-
trated in the drawings.