Improved Means for Preventing Disturbing Action in Long Telephonic Circuits.
Year: 1890

page_text: Date of Application, 16th Jan., 1890
Complete Specification Left, 3rd Oct., 1890-Accepted, 10th Jan., 1891
PROVISIONAL SPECIFICATION.
Improved Means for Preventing Disturbing Action in Long
Telephonic Circuits.
We, EUGENE GWOSDEFF, Nobleman, and HEINRICH BUNGE, Civil Engineer, both
of Konnogwandeiski Boulevard No. 20, St. Petersburg in the Russian Empire
do hereby declare the nature of this invention to be as follows:-
In all existing telephone installations, it is considered essential to have as perfect as
possible an insulation of the line wire and circuit generally. Experience has proved
however that notwithstanding the best possible insulation, the telephonic communica-
tion over long distances can only be carried on up to certain not very wide limits
(about 250 kilometres); with greater length of line, the disturbing action induced is
so considerable that no-means heretofore proposed have been able to render telephonic
communication intelligible.
According to the present invention the disturbing influences of iron wire conductors
upon the transmission of speech are prevented by the following means.
If between the two telephonic stations A and B, Fig. 1 of the accompanying
drawings, which are cornected by the line wire L and return conductor L', the com-
munication is rendered impossible on account of the stations being too far apart, the
conductors L and L¹ are connected together at both stations by branch conductors 11
in which are introduced the resistances (rheostats) R or electromagnets, whose
resistance can be considerably less. The extent of the resistances R is determined by
experiment, and by this simple means telephonic communication of the most perfect
kind desirable is rendered possible over any distances and with conductors of any
metal, such as iron copper &c.
The same effect is also produced with condensers if such be used in place of
the resistances R in the branch conductors Il¹.
The electrical capacity of the condensers must be determined in every case by
experiment. We have found that with an iron line wire of over 600 kilometres, this
capacity must be from one to 1 microfarads.
In such cases where the length of the conductors between the stations reaches the
limit at which the branch line must have only a very slight resistance, so that a
further reduction of this resistance cannot be effected without a weakening of the
transmitted speech, we have found that this difficulty can be overcome by the
introduction of a discharging conductor Fig. 2, between the line wire L and
the return conductor L'. This discharging conductor is provided with an ordinary
make-and-break contact lever k, which, after every word transmitted is pressed so as
to close the discharging conductor, and is left free, so as to break contact again, on
pronouncing the following word.
By this means it is rendered possible to speak over lines of unlimited length and of
any conducting medium.
The speech is somewhat slow, but with a certain amount of practice, the momentary
interruptions are scarcely perceptible.
It will be evident that the action of the discharging conductor could also be made
automatic.
For this purpose it only requires a continuously rotating ratchet wheel a, Fig. 3,
acting upon a contact spring b, forming part of the discharging line 11, to be arranged
in such manner as to press the spring b intermittently against the contact screw c,
forming the other part of the line, so as to close the line and effect the discharge, the
spring having the tendency to break the contact. The wheel a can be driven by
clockwork or by an electromotor, the speed of which is made to vary according to the
length of the line; the greater this length is, the greater must be the speed. The

page_text: direction of the current of the microphone battery must change not less than twice
per minute during speaking. The momentary short circuiting of the circuit has no
prejudicial effect on the speech.
Both the branch lines as also the discharging line have for their object, to
free the circuit from those electrical charges which accumulate therein in consequence
of the passage of alternating telephonic currents. These charges are, according to
experience, the greater, the longer the circuit and the greater its self-induction
coefficient are
For the complete discharge of long lines it will be advisable to provide branch
conductors not only at the stations, but also along the line itself, the number of such
conductors being the greater, the longer the line is.
Dated this 16th day of January 1890.
ABEL & IMRAY,
Agents for the Applicants.
COMPLETE SPECIFICATION.
Improved Means for Preventing Disturbing Action in Long
Telephonic Circuits.
We, EUGENE GWOSDEFF, Nobleman, and HEINRICH BUNGE, Civil Engineer, both
of Konnogwandeiski Boulevard, No. 20 St. Petersburg in the Russian Empire, 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:-
In all existing telephone installations, it is considered essential to have as perfect as
possible an insulation of the line wire and circuit generally.
Experience has proved however that notwithstanding the best possible insulation,
the telephonic communication over long distances can only be carried on up to
certain not very wide limits (about 250 kilometres); with greater .length of line,
the disturbing action induced is so considerable that no means heretofore proposed
have been able to render telephonic communication intelligible.
According to the present invention the disturbing influences of iron wire conductors
upon the transmission of speech are prevented by the following means.
If between the two telephonic stations A and B Fig. 1 of the drawings accom-
panying my Provisional Specification which are connected by the line wire Land
return conductor L¹, the communication is rendered impossible on account of the
stations being too far apart, the conductors L and L' are connected together at both
stations by branch conductors in which are introduced the resistances (rheostats) R
or electromagnets, whose resistance can be considerably less. The extent of the
resistances R is determined by experiment, and by this simple means telephonic
communication of the most perfect kind desirable is rendered possible over any
distances and with conductors of any metal, such as iron, copper, &c. &c.
The same effect is also produced with condensers if such be used in place of the
resistances R in the branch conductors P.
The electrical capacity of the condensers must be determined in every case by
experiment. We have found that with an iron line wire of over 600 kilometres, this
capacity must be from one to 1 microfarads.
In such cases where the length of the conductors between the stations reaches the
limit at which the branch line must have only a very slight resistance, so that a
further reduction of this resistance cannot be effected without a weakening of the
transmitted speech, we have found that this difficulty can be overcome by the
introduction of a discharging conductor 11 Fig. 2 between the line wire L and
the return conductor L¹.
This discharging conductor 11 is provided with an ordinary make and break
contact lever k, which after every word transmitted is pressed so as to close the
discharging conductor, and is left free, so as to break contact again on pronouncing
the following word.

page_text: By this means it is rendered possible to speak over lines, of unlimited length and of
any conducting medium.
The speech is somewhat slow, but with a certain amount of practice, the momentary
interruptions are scarcely perceptible.
It will be evident that the action of the discharging conductor could also be made
automatic.
For this purpose it only requires a continuously rotating ratchet wheel a Fig. 3
acting upon a contact spring & forming part of the discharging line 11, to be arranged
in such manner as to press the spring b intermittently against the contact screw c,
forming the other part of the line so as to close the line and effect the discharge, the
spring having the tendency to break the contact.
The wheel a can be driven by clockwork or by an electro motor, the speed of which
is made to vary according to the length of the line; the greater this length is, the
greater must be the speed. As the line wire becomes charged with statical electricity
which interferes with the distinctness of transmission, it requires to be discharged
from time to time, and this we effect by reversing the direction of the current of the
microphone battery at certain intervals of time. These changes must not be of too
frequent occurrence, as they might also interfere with the distinctness of the speech,
and we have found that if the change is effected about twice every minute, it is
sufficient to prevent accumulation in the line wire, while the momentary short
circuiting at such comparatively long intervals will have no prejudicial, effect on the
speech.
Both the branch line as also the discharging line "have for their object to
free the circuit from those electrical charges which accumulate therein in consequence
of the passage of alternating telephonic currents. These charges are, according to
experience, the greater, the longer the circuit, and the greater its self-induction
coefficient are.
For the complete discharge of long lines it will be advisable to provide branch
conductors not only at the stations, but also along the line itself, the number of such
conductors being the greater, the longer the line is.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
:-
1. The herein described means for preventing disturbing action in telephonic
circuits, consisting in the use of branch conductors between the line wire and return
conductor or generally between the outward and return terminal screws of telephonic
circuits, in which branch conductors are introduced either resistances, electro magnets
or condensers.
.
2. The use, in long telephonic lines, of discharge conductors between line wire and
return conductor, in combination with contact closers or devices for automatic inter-
mittent making and breaking of the communication with the discharge conductor,
substantially as described.
Dated this 3rd day of October 1890.
ABEL & IMRAY,
Agents for the Applicants.