Improvements in and connected with Magneto Generators.
Year: 1899

page_text: [Communicated from abroad by ACTIEN-GESELLSCHAFT MIX & GENEST, Electrical
Engineers, 67, Bülow Strasse, Berlin, W., in the Empire of Germany.]
Improvements in and connected with Magneto Generators.
I, HERMANN OPPENHEIMER, Electrical Engineer, of 55, Redcross Street, Bar-
bican, London, E.C., in the County of Middlesex, do hereby declare the nature
of this invention to be as follows:
It is a well known fact that induction takes place in parallel running telephone
lines when magneto generators are used for ringing up purposes, thereby causing
disturbing sounds in the neighbouring lines, especially on trunk lines.
To overcome this difficulty, large batteries are preferably used for ringing pur-
poses, but these latter require too much attention, and the expenses of the up-keep
are too heavy, so that magneto generators, which will avoid the disadvantages
mentioned above, would be of great service for long distance telephony.
The present invention aims at preventing inductive or stray currents interfer-
ing with other lines when magneto generators are used for ringing up sub-
scribers, and the desired effect is obtained my making the armature or the magnet
(or both) notched, coombed, or castellated.
The general construction of the magneto generator does not vary in the present
case with the exception that the armature on that side which faces the magnets
is notched in one place, and the magnets which face the armature are notched
in two places. In consequence of this arrangement, i.e. when armature and
magnets are constructed notched, coombed, or castellated, in the manner as
explained above the irregularities in the current waves produced by generators
having solid armatures (and which irregularities are the main cause of induction
taking place) are almost entirely avoided.
Various tests made with such notched, coombed, or castellated generators have
prooved that no induction takes place, even on long distances lines, although
they run in close proximity to each other.
Dated this 10th day
1030
HERMANN OPPENHEIMER.
COMPLETE SPECIFICATION.

page_text: of this invention and in what manner the same is to be performed, to be parti-
cularly described and ascertained in and by the following statement:―
It is a well known fact that induction takes place in parallel running telephone
lines when magneto generators are used for ringing up purposes, thereby causing
disturbing sounds in the neighbouring lines, especially trunk lines.
To overcome this difficulty, large batteries are preferably used for ringing pur-
poses, but these latter require too much attention, and the expenses of the up-keep
are too heavy, so that magneto generators, which will avoid the disadvantages
mentioned above, would be of great service for long distance telephony.
The present invention aims at preventing inductive or stray currents interfer-
ing with other lines when magneto generators are used for ringing-up sub-
scribers, and the desired effect is obtained my making the armature or the magnet
(or both) notched, coombed, or castellated."
1 -
r
On accompanying drawing I shew in Fig. 1, a vertical section of such gene-
rator, in Fig. 3 a section of that part, indicated by the line of Fig. 1, and
in Fig. 2 a plan of the armature.
The general construction of the magneto generator does not vary in the pre-
sent case from those generally in use, with the exception that the armature a
on that side which faces the magnets is notched at the point b and the magnets c
which face the armature are notched in two places d. In consequence. of, this
arrangement, i.e. when armature and magnets are constructed notched, coombed,
or castellated, in the manner as explained, the irregularities in the current
waves produced by generators having solid armature (which irregularities are
the main cause of the disturbances, and of induction taking place in neighbour-
ing lines) are almost entirely avoided.
Various tests made with such notched, coombed, or castellated generators have
proved that no induction takes place, even on long distance lines, although
they run in close proximity to each other.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
The construction and arrangement and use of generators for telephonic ring-
ing up purposes, the armature and magnets of which have either one or more
notches, coombs, or castellations, in the manner and for the purpose fully
described
Dated this 9th day of March 1900.