Improvements in and connected with Telephones.
Year: 1895

page_text: Date of Application, 4th Jan., 1895
Complete Specification Left, 25th Sept., 1895-Accepted, 2nd Nov., 1895
PROVISIONAL SPECIFICATION.
Improvements in and connected with Telephones.
I, HERMANN OPPENHEIMER of 55 Redcross Street London E.C. Electrical
Engineer, do hereby declare the nature of this invention to be as follows:-
The distance between the poles of the magnet and the diaphragm in the well-
known Bell telephone receiver was hitherto adjusted by means of paper rings laid
between the diaphragm and magnet. In order however to be able to regulate the
proper distance between diaphragm and magnet, while listening, I have constructed
the magnet in such a manner that a screw S (Fig. 2) the head of which rests in
the ebonite case of the receiver will either when screwing home bring the magnet
closer to the diaphragm, or when loosening the screw, remove the magnet from the
diaphragm thus obtaining a proper degree of adjustment.
It is however essential that the shanks of the horse-shoe magnets M. should not
be fixed to the ebonite case H. For guiding the magnet in the proper manner, I
use a metal part, similar in shape to an ordinary spectacle frame F. In order
however to be able to make such guides uniform and at the same time to avoid
vibration of the shanks of the horse-shoe magnet, I attach to said spectacles F,
2 tempered arms, which not only embrace the shanks of the magnet from without
(Fig. 2 5) but also force their angular ends between the vibrating shanks.
The terminals generally used for connecting conducting cord to the receiver,
I do away with entirely, and replace them by 2 metal bushes let into the ebonite
disc D. of the receiver, whereby the possibility of short circuit, by the metal parts
of the tags accidentally touching each other, is avoided.
I fasten metal tags to such bushes by means of 2 screws s. 1. & s. 2. which are let
into the receiver at right angles to the metal bushes k. 1. & k. 2. thus gripping the
metal tags, at the same time retaining the bushes in their proper position in the
ebonite case of the receiver.
Dated this 3rd day of January 1895.
I, HERMANN OPPENHEIMER of 55 Redcross Street, Barbican, London, E.C.
Electrical Engineer, 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 :-
The distance between the poles P of the magnet and the diaphragm in the well-
known Bell telephone receiver was hitherto adjusted by means of paper rings laid
between the diaphragm and magnet. In order however to be able to regulate the
proper distance between diaphragm and magnet, while listening, I have constructed
the magnet in such a manner that a screw S, (Fig. 2) shewn in the drawing filed
with my Provisional Specification of 4th January 1895, the head of which rests in
the ebonite case of the receiver will either when screwing home bring the magnet

page_text: closer to the diaphragm, or when loosening the screw, remove the magnet from the
diaphragm, thus obtaining a proper degree of adjustment.
It is however essential that the shanks of the horse-shoe magnets M should not
be fixed to the cbonite case H. For guiding the magnet in the proper manner,
I use a metal part, similar in shape to an ordinary spectacle frame . In order
however to be able to make such guides uniforin, and at the same time to avoid
vibration of the shanks of the horse-shoe magnet, 1 attach to said spectacles F,
two tempered arms f.. which not only embrace the shanks of the magnet from
without (Fig. 2 & 5) but also force their angular ends between the vibrating
shanks.
The terminals generally used for connecting conducting cord to the receiver,
I do away with entirely, and replace them by two metal bushes k. 1. k. 2. let into
the cbonite disc D of the receiver, whereby the possibility of short circuit, by the
metal parts of the tags accidentally touching each other, is avoided.
1 fasten metal tags to such bushes by means of two screws s. 1. and s. 2. which
are let into the receiver at right angles to the metal bushes k. 1. & k. 2. thus
gripping the metal tags, at the same time retaining the bushes in their proper
position U in the ebonite case of the receiver.
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 -
:-
1.. The construction and fixing of a guide frame to the shanks of the horse shoe
magnet in receivers in the manner and for the purpose substantially as described
and set forth.
2. The replacing of terminals on receivers. by letting metal bushes into the
ebonite disc of receivers, which bushes are retained in their proper position by
screws let in at right angles, and which latter also serve to grip the metal tags of
the connecting cords, substantially as described, and for the purpose as set forth.
Dated this 24th day of September 1895.
HERMANN OPPENHEIMER.