Improvements in Telegraph Keys.
Year: 1897

page_text: Improvements in Telegraph Keys.
I, ALFRED CHRISTOPHER ROBINSON, of 4A, Talbot Road, Forest Gate, in the County
of Essex, Telegraph Clerk, do hereby declare the nature of this invention to be as
follows:-
This invention relates to improvements in telegraph keys whereby the operator is
enabled to switch from duplex to simplex and vice versa by simply moving a switch
connected with the key independently of any other switch, the arrangements being
such that when the said switch connected with the key is moved so as to switch from
duplex to simplex the key may be used as a double or single current simplex key, and
when the said switch is so moved the galvanometer remains in circuit and shows a
deflection when a current is sent or received, but the relay of the circuit is not
affected by the sending current; also when the key is in position for duplex it may
be used either for double or single current working. In the arrangements under
this invention the same set of instruments is used whether the key is switched to
duplex or simplex, but the rheostat or resistance coils and the condenser, which are
used for duplex telegraphing, are switched out of the circuit when the switch con-
nected with the key is moved from duplex to simplex. When, however, the said
switch is moved from simplex to duplex the rheostat or resistance coils and the
condenser are brought into circuit, and the galvanometer indicates when a balance is
obtained, in the usual way, namely by remaining unaffected when a current is sent
into it by the sending station, but shows that this balance is destroyed when a current
is received.
In order to effect the above objects I employ arrangements of the following
character:-
The switch connected with the key is provided with three ways, the first two of
which are for working simplex, the first for receiving and the second for sending.
The third way is for working duplex. When working simplex I prefer to provide a
stop whereby the switch is prevented from being moved into the duplex position,
but when it is required to work duplex this stop can be removed to allow the switch
to be moved into the duplex position and then be replaced so as to prevent the switch
being moved back into either of the simplex positions until it is required to change
from duplex to simplex again when it can be removed and replaced after the change
has been made.
When the key is in its normal position and the switch is in position for sending a
current, either duplex or simplex, the positive current of the sending battery is con
nected to earth and the negative current to the line by means of contact springs.
When, however, the switch is in position for receiving simplex, these currents are
disconnected from the line and earth by devices connected with the switch which
open the circuits through these springs.
When the key is in its normal position and the switch is in position corresponding
to duplex working the sending current passing as follows; the positive current from
the battery goes to earth through one of the aforesaid springs and the negative
current goes through the other spring to the galvanometer where it splits, one
Price 8d71

page_text: portion going through the galvanometer relay, key, and rheostat or resistance coils to
earth, and the other through the galvanometer relay and key to the line, and the
received current through the key galvanometer, relay, and rheostat or resistance coils
to earth.
When the key is in its normal position and the switch in the position for sending
simplex the sending battery is connected to earth and to line in the following
way
The positive current from the sending battery goes through say No. 1 of the
aforesaid springs to earth, and the negative current through the other, say No. 2
spring; and the galvanometer and key to the line, deflecting the galvanometer in
its course but not affecting the relay. Then on depressing the key the positive
current from the sending battery goes through No. 2 spring to the line, deflecting
the galvanometer in its course but not affecting the relay, and the negative current
goes through No. 1 spring to earth.
When the key is in its normal position and the switch in the position for receiving
simplex the devices connected with the switch raise both the aforesaid springs and
thereby disconnect the sending battery from both line to earth, and the received
current then goes from the line through the key, the galvanometer and the relay to
earth actuating the galvanometer and relay in its course.
I provide the key with certain terminals in addition to those generally attached to
what is known as a double current key. To one of these terminals I attach the wire
carrying the sending current to the galvanometer, to another the wire carrying the
current from the relay to other terminals for duplex working or to earth for simplex
working. To another of these extra terminals I attach the wire carrying the current
from the galvanometer to the line. This latter terminal and its connections, together
with the arrangements of the various roads open to the sending current, enable me
to insulate all the roads by which the sending current could be split when the switch
is in the sending position for simplex working, and to connect the one which takes
the current through the galvanometer only in one direction, namely to the line.
When working duplex the received current is taken to the relay by means of a loop
connecting a part of the switch to the contact post corresponding to the receiving
position for working simplex.
It will be seen that by the above arrangements, when the switch is in the sending
position for working simplex and the key is connected to the line and to earth, the
relay is not affected although the galvanometer is deflected when a current is sent
into the line wire.
improvements in Telegraph Keys.
I, ALFRED CHRISTOPHER ROBINSON, of 4a, Talbot Road, Forest Gate, in the County
of Essex, Telegraph Clerk, 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 telegraph keys whereby the operator is
enabled to switch from duplex to simplex and vice versa by simply moving a switch
connected with the key independently of any other switch, the arrangements being
such that when the said switch connected with the key is moved so as to switch from
duplex to simplex the key may be used as a double or single current simplex key, and
when the said switch is so moved the galvanometer remains in circuit, and shows a

page_text: deflection when a current is sent or received, but the relay of the circuit is not
affected by the sending current, also when the key is in position for duplex it may be
used either for double or single current working. In the arrangements under this
invention the same set of instruments is used whether the key is switched to duplex
or simplex, but the rheostat or resistance coils and the condenser, which are used for
duplex telegraphing, are switched out of the circuit when the switch connected with
the key is moved from duplex to simplex. When, however, the said switch is moved
from simplex to duplex the rheostat or resistance coils and the condenser are brought
into circuit, and the galvanometer indicates when a balance is obtained, in the usual
way, namely by remaining unaffected when a current is sent into it by the sending
station, but shows that this balance is destroyed when a current is received from the
distant station.
In order to effect the above objects I employ arrangements of the following
character:
The switch connected with the key is provided with three ways, the first two of
which are for working simplex, the first for receiving and the second for sending.
The third way is for working duplex. When working simplex I prefer to provide a
stop whereby the switch is prevented from being moved into the duplex position, but
when it is required to work duplex this stop can be removed to allow the switch to
be moved into the duplex position, and then be replaced so as to prevent the switch
being moved back into either of the simplex positions until it is required to change
from duplex to simplex again; when it can be removed and replaced after the change
has been made.
When the key is in its normal position and the switch is in position for sending a
current, either duplex or simplex, the positive current of the sending battery is con-
nected to earth, and the negative current to the line by means of contact springs.
When, however, the switch is in position for receiving simplex, these currents are
disconnected froin the line and earth by devices connected with the switch which
disconnect these springs from their contact pieces.
When the key is in its normal position and the switch is in position corresponding
to duplex working the sending current passes as follows; the positive current from the
battery goes to earth through one of the aforesaid springs and the negative current
goes through the other spring, to the galvanometer where it splits, one portion going
through the galvanometer, relay, key, and rheostat or resistance coils to earth, and
the other through the galvanometer, relay and key to the line and the received
current through the key, galvanometer, relay, and rheostat or resistance coils to
earth.
When the key is in its normal position and the switch in the position for sending
simplex, the sending battery is connected to earth and to line in the following way:-
The positive current from the sending battery goes through say No. 1 of the aforesaid
springs to earth, and the negative current through the other, say No. 2 spring and
the galvanometer and key to the line, deflecting the galvanometer in its course but
not affecting the relay. Then on depressing the key the positive current from the
sending battery goes through No. 2 spring to the line, deflecting the galvanometer in
its course but not affecting the relay, and the negative current goes through No. 1
spring to earth.
When the key is in its normal position and the switch in the position for receiving
simplex the devices connected with the switch raise both the aforesaid springs and
thereby disconnect the sending battery from both line and earth, and the received
current then goes from the line through the key, the galvanometer and the relay to
earth actuating the galvanometer and relay in its course.
I provide the key with certain terminals in addition to those generally attached to
what is known as a double current key. To one of these terminals I attach the wire
carrying the sending current to the galvanometer, to another the wire carrying the
current froin the relay to other terminals for duplex working or to earth for simplex
working. To another of these extra terminals I attach the wire carrying the current
from the galvanometer to the line, This latter terminal and its connections, together

page_text: with the arrangements for insulating the other roads open to the sending current
enable me to pass the current through the galvanometer only in one direction, namely
to the line.
When working duplex the received current is taken to the relay by means of a loop
connecting a part of the switch to the contact post corresponding to the receiving
position for working simplex.
It will be seen that by the above arrangements, when the switch is in the sending
position for working simplex and the key is connected to the line and to earth, the
relay is not affected although the galvanometer is deflected when a current is sent
into the line wire."
.:
And in order that the said invention may be fully understood I will now proceed to
describe the same with the aid of the accompanying two sheets of drawings, in which
Figure 1 shows diagrammatically a key constructed in accordance with my invention,
and adapted more especially for working with an unsplit battery and Figure 2 shows
a similar key adapted for working with a split battery.
In each of these figures the rheostat and condenser are marked a, the differentially
wound relay and galvanometer b and c respectively, the battery d, the transmitting
key e, and the beforementioned switch, 17.
The switch 17 is provided with three ways, that is to say it can be placed in three
different positions marked respectively 14, 2 and 3^, the first two of which, shown
by.dotted lines, are for working simplex, the first, 14, for receiving, and the second, 2^,
for sending; the third way 34, shown by full lines, is for working duplex. The
switch 17 is connected at f. to a bar g which is pin-jointed to arms h and i pivotted
respectively at 16 and 15. The free end of the arm makes contact with the contact
pieces 12, and 7, and the free end of the arm i with the contact pieces 11, 14 and 2.
So that when the switch 17, is in position 3^, as shown in full lines, the arms h and i
make contact with 7 and respectively; when the switch 17 is in position 2ª the
arms h and i make contact with and 14 respectively; and when the switch 17 is in
position 1 the arms h and i make contact with 12 and 11 respectively. The contact
pieces 12, 7, 11, 14 and 2 are connected to the various terminals of the key by
conductors which are represented by dot and dash lines, and the contact piece
insulated and is not connected electrically, with any other part of the key.
* is
In order to prevent the switch being moved from the simplex into the duplex
position, or vice versu by inadvertance I prefer to provide a stop pin Y which takes
into a hole in the guide piece Y¹ of the switch handle, by this means the switch is
prevented from being moved into the duplex postion unless it is required to work
duplex, in that case the stop pin Y is, removed to allow the switch to be moved into
the duplex position, as shown by full lines in the several figures, and then replaced,
as shown, so as to prevent the switch being moved back into either of the simplex
positions, until it is required to change from duplex to simplex, when it can be
removed, and replaced after the change has been made. It is obvious that any other
suitable device may be employed for locking the switch in position.
It will be understood that the transmitting key e illustrated in Figure 1 is supposed
to be constructed as a double current key, while the transmitting key e illustrated in
Figure 2 is supposed to be constructed as a single current key.
Referring now more particularly to Figure 1, assuming that the double' current
transmitting key e is in its normal position making contact with the two contact
pieces at C and W, and the switch 17 is in position for sending a current into the
line, either duplex or simplex, that is to say in either position 3ª or 24, the positive
current of the sending battery d is connected to earth through A, C, R, spring or
strip N, D, and E. When the switch 17 stands in the 3 position for. sending or
receiving duplex the negative current passes through V, W, Q, spring or strip
2

page_text: When under these circumstances, the transmitting key e is depressed the contacts
at C, W, are broken and those at X B are closed, then the positive current of the
sending battery d passes by A, B, Q, spring or strip
and the negative current by V, X, R, spring or strip N, D, E, to earth, and the
galvanometer c and relay 6 are not actuated because the current passing through
them is split and balanced.
When a current comes from the distant station while the switch 17 is in the 3* or
duplex position, it comes from the line through 1, 15, i, 2, 11, 3, 4, J, I, H, K, L,
M, 5, 6, 16, h 7, 8, 9, 10 through the rheostat to earth actuating both the
galvanometer c and relay b because this current passing through them destroys the
balance.
Assuming next that the transmitting key e is in its normal position, and the
switch 17 in the 2 position, that is to say for sending simplex, the arms h and i
being thereby brought into contact with and 14 respectively, the negative current
from the sending battery d passes through V, W, Q, P, F, G, H, I, 13, 14, 15, 1 to
the line deflecting the galvanometer c but not affecting relay b. When under these
circumstances, the transmitting key e is depressed the switch 17 being still in
the 2 position, the positive current goes from the battery d to A, B, Q, P, F, G, H,
I, 13, 14, 15, 1, to the line deflecting the galvanometer c, but not affecting the
relay ; and the negative current from the battery d to earth through
V, X, R, N, D, E.
Assuming lastly that the transmitting key e is in its normal position, and the
switch 17 in the 1ª position, that is to say for receiving simplex, the bar g will have
been moved to the left by the switch 17 and the studs T S or other suitable device
connected with the switch will have raised the contact springs or strips N and P
respectively clear of the contact pieces D, F thereby cutting out the sending battery d
altogether, and bringing the arms hand into contact with 12 and 11 respectively. The
current coming from the distant station passes through 1, 15, 11, 3, 4, J, I, H, K, L,
M, 5, 6, 16, h, 12, E to earth, actuating the galvanometer c and relay 6 because the
current passing through them is unbalanced.
In the arrangement of key illustrated in Figure 2, the negative current from the
sending battery d is disconnected from the line when the switch 17 is in the 1ª or
simplex receiving position by the end 17 thereof coming under, and raising the
contact spring NP free of the contact piece D F. The contact between NP and DF
remains unbroken so long as the switch 17 stands in the 3* or 2* position, namely for
duplex sending or receiving, or for simplex sending.
When the transmitting key e is in its normal position, and the switch 17 is in
the 34 position for sending current duplex, the sending current takes the following
course: the positive current of sending battery d goes to earth from any, desired
point of the battery. The negative current goes from the battery to V, D F, NP,
A, e², e², G, H,
I, J, 4, 3, 11, 2, i, 15, 1, to line
K, L, M, 5, 6, 16, 7, 8, 9, 10, to earth through the rheostat a.

page_text: and relay not being actuated
balanced.
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MICH
Curren passing onge
.
The received current from line passes through 1, 15, i, 2, 11, 3, 4, J, I, H, K,
L, M, 5, 6, 16, h, 7, 8, 9, 10 to earth through the rheostat a actuating both the
galvanometer c and relay because the current passes through them destroys the
balance.
When the transmitting key e is in its normal position, and the switch 17 in
the 2 position for sending current simplex, the sending current takes the following
course. The positive current from battery & goes to earth from any desired point
of the battery. The negative current goes from the battery through V, D F, N P,
ele, G, H, I, 13, 14, i, 15, 1 to line, deflecting the galvanometer c in its course
but not affecting the relay b.
When the transmitting key e is depressed contact is broken at e¹ and established
at es, the negative current goes to earth at the battery, and the positive current goes
through A, e³, e², G, H, I, 13, 14, i, 15, 1 to the line, deflecting the galvanometer c
in its course, but not affecting the relay b
When the transmitting key e is in its normal position, and the switch 17 is in
the 1 position for receiving current simplex, the end 17% of the switch 17 passes
under and raises the spring NP clear of the contact piece D F so that there is now
no road for the negative current from the battery to line, and the positive current is
also interrupted because the road A, e³, is broken at 3. But the received current
from the distant station takes the following course :-froin line through 1, 15, 1, 11,
3, 4, J, I, H, K, L, M, 5, 6, 16, h, 12, E to earth actuating both relay band
galvanometer c.
In some cases it may be found desirable to insert a rheostat or resistance coil
between the battery d and the terminal A to prevent leakage of current through the
said battery when the switch is in position for receiving current duplex from a
distant station.
Telegraph keys constructed as above described can be readily applied to duplex
telegraphy on what is known as the "Bridge" principle.
If it is required to employ the above described apparatus for single current work-
ing it is only necessary to connect one pole of the sending battery d permanently to
earth in the usual way.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
First. In a telegraph key the use of a three-way switch so constructed and con-
nected with the said key that when the said switch stands in one position the key
can be used simplex to receive a current from a distant station; when the said switch
stands in another position the key can be used simplex to send a current to a distant
station; and when the said switch stands in yet another position the key can be used
duplex both to send a current to and to receive a current from a distant station, sub-
stantially as described.
Second. In a telegraph key intended to work either simplex or duplex, a three-way
switch so constructed and combined with the key that when the transmitting key is
in its normal position and the said switch stands in position for sending a current
either duplex or simplex one end of the sending battery is connected to earth by
means of a contact spring or strip and the other end thereof to the line by means of
a contact spring or strip but when the switch is in position for receiving simplex the
connections through such springs are broken by devices connected with the said switch,
substantially as described with reference to Figure 1 of the drawings.
Third. In a telegraph key intended to work either simplex or duplex a three-way
switch so constructed and combined with the key that when the transmitting key is
in its normal position and the said switch stands in position for sending a current
either duplex or simplex, one end of the sending battery is connected to earth at
the battery and the other end to live through a spring or strip and the key; but

page_text: when the switch is in position for receiving simplex the connection to line through
the said spring or strip is broken by the said switch, substantially as described with
reference to Figure 2 of the drawings.
Fourth. A switch for a telegraph key intended to be used either duplex or simplex,
so constructed and connected with the transmitting key, galvanometer, relay and
rheostat with or without a condenser that when the said switch is in position for
receiving simplex the current received from the distant station actuates the galvano-
imeter and relay; when the said switch is in position for sending simplex the current
sent to the distant station actuates the galvanometer but not the relay; when the
said switch is in position for sending duplex the current sent to the distant station
does not actuate the galvanometer and relay and when the said switch is in the same
position, but receiving the current coming from the distant station actuates the
galvanometer and relay, substantially as described.
Fifth. A telegraph key and switch for telegraphing either duplex or simplex, con-
structed and operating substantially as described.
Dated this 4th day of February 1898
A. C. ROBINSON.
Per W. H. Beck, Agent,
115, Cannon Street, London, E.C.