A New or Improved Device for Varying the Resistance in Telephone Circuits.
Year: 1891

page_text: Date of Application, 17th Nov., 1891
Complete Specification Left, 16th Sept., 1892-Accepted, 12th Nov., 1892
PROVISIONAL SPECIFICATION.
A New or Improved Device for Varying the Resistance in Telephone
Circuits.
1, ERHARD LUDWIG MAYER, of 11 Billiter Square, London, E.C., Engineer,
do hereby declare the nature of this invention to be as follows:-
.
My invention relates to what are frequently termed tension regulators but which
are more correctly termed resistance variers.
In resistance variers as usually constructed the action depends upon variations in
the amount of pressure or in the extent of contact surface between their essential
elements, the said variations depending upon the movement of the diaphragm. My
present invention differs therefrom in its action and construction. Instead of causing
the resistance of the circuit to vary by altering the amount of pressure or the extent
of contact surface between the elements constituting the resistance varier, I cause
the resistance to vary by altering the length of one of the elements of the resistance
varier included in the circuit. In other words vary the resistance by interposing
a greater or less length of carbon rod (when such is employed) in the circuit so
that the current will have a greater or less length of carbon rod to traverse and so
meet with a greater or less resistance to its passage.
In carrying my invention into effect I employ a carbon rod (or its equivalent)
which I lay upon two conducting blocks in the same manner as a board is laid upon
two trestles. One of these blocks I attach to the diaphragm in the usual well known
manner and the other I attach to the back of the instrument case or other convenient
fixed part.
The action of my invention is as follows. As the diaphragm vibrates under the
influence of the sound waves actuating it the block attached to the diaphragm is
pushed more or less far under the carbon rod and towards or from the other block,
so that the length of the carbon rod between the two blocks is altered, and the
resistance of the circuit, which includes the part of the carbon rod between the two
blocks, thereby varied.
1
1
1001
ERHARD LUDWIG MAYER,
Per J. G. Lorrain, M. Inst. E.E., M. Inst. M.E.,
Norfolk House, Norfolk Street, London, W.C., Patent Agent.
COMPLETE SPECIFICATION.
A New or Improved Device for Varying the Resistance in Telephone
Circuits.
I, ERHARD LUDWIG MAYER, of 11 Billiter Square, in the City of London
Engineer, do hereby declare the nature of this invention and in what manner the
same to be performed to be particularly described and ascertained in and by the
following statement :-
My invention relates to what are frequently termed tension regulators but which
are more correctly termed resistance .variers.
In resistance variers as usually constructed the action depends upon variations in
the amount of pressure or in the extent of contact surface between their essential
elements, the said variations depending upon the movement of the diaphragm. My
present invention differs therefrom in its action and construction. Instead of causing
the resistance of the circuit to vary by altering the amount of pressure or the extent
Prins Qd11

page_text: of contact surface between the elements. constituting the resistance varier, I cause
the resistance to vary by altering the length of one of the elements of the resistance
varier included in the circuit. In other words 1 vary. the resistance by interposing
a greater or less length of carbon rod (when such is employed) in the circuit so
that the current will have a greater or less length of carbon rod to traverse and so
meet with a greater or less resistance to its passage.
In carrying my invention into effect I employ a carbon rod (or its equivalent)
which I lay upon two conducting blocks in the same manner as a board is laid upon
two, trestles. One of these. blocks I attach to the diaphragmn in the usual well known
manner and the other I attach to the back of the instrument case or other convenient
fixed part.
"
The action of my invention is as follows. As the diaphragm vibrates under the
influence of the sound waves actuating it the block attached to the diaphragm is
pushed more or less far under the carbon rod and towards or from the other block,
so that the length of the carbon rod between the two blocks is altered, and the
resistance of the circuit, which includes the part of the carbon rod between the two
blocks, thereby varied.
Having now described my invention in general terms, I shall proceed to show
how it can be practised or carried into effect, and for that purpose I shall proceed
to describe it more in detail and with reference. to the accompanying sheet of
drawings.
When
Figure illustrates my invention diagrammatically. A is the diaphragm.
B. B are respectively the front and back conducting blocks upon which rests the
carbon rod or block C. When spoken against, the diaphragm moves alternately
inwards and outwards in accordance with the sound waves impinging upon it.
the diaphragm moves inwards, say to the position shown by the dotted line a the
front contact piece B will move backward to the position shown in dotted lines b; and
when the diaphragm moves outward, say to the position shown by the dotted line a',
the support B will be moved to the position shown in dotted lines 1. It will thus
be seen that as the block B moves backwards, a smaller length of C will be included
in the electric circuit, and the resistance of the said circuit will therefore be
diminished whilst as it moves forwards a greater length of C will be included in
the said circuit and the resistance of the circuit be thereby increased, the same
effect being produced as in an ordinary microphone or resistance varier whose action.
depends upon variation of pressure or of surface contact.
For the purpose of illustration, I have greatly exaggerated in the, diagram the
amount of movement which takes place.
Figures 2 and 3 illustrate a practical form of my invention. A is the diaphragm
as before, and B the front support. B' is the back support and C, the piece corre-
sponding with the rod C shown in Figure 1, and which I shall hereinafter term the
free piece. This free piece is further illustrated in Figures 4 and 5. It consists
of a block of carbon shaped as shown with a knife edge c which rests upon the front
support, and an ebonite pin cl to be mentioned hereinafter.
The front support B has its upper surface tapered to a knife edge, the said knife
edge running in a direction at right angles to the plane of the diaphragm. The
rear support B' consists in this case of two separate carbon rods placed about one
eighth of an inch from one another: These two rods constituting the rear support
are tapered on their upper surface to knife edges, which edges lie in the samen
direction as that of the front support B. The free piece C.rests upon the two
supports Band B' as shown in Figure 2, the knife edge c resting upon and being at
right angles to the knife edge of B, whilst the pinse lies between the two rods
constituting the rear support B' and retains the free piece, Cin position.. As, the..
diaphragm moves, the front support B.moves to a greater or less extent, under the
knife edge of C, and so varies the resistance as described with, reference-to
Figure 1:
Figures 6 and 7 illustrate another practical form of my invention, and Figure 8
is an end view of the free piece C employed in this. form.In this case the..free.

page_text: piece consists of a short length of carbon rod such as is used in electric arc lamps,
filed away at each end to leave the bearing arms cc. These arms are filed to a
knife edge running in the direction of the geometrical axis of the cylindrical part
from which they spring.
In this form of my invention the front and rear supports are of the same shape
and have knife edges lying in a direction parallel to the plane of the diaphragm so
that when C is placed in position upon the supports B and B', as shown in Figure 6,
the knife edges of C are at right angles to the knife edges of the supports on which
they rest.
The action of this form of my apparatus will be readily understood from what
has preceded.
The parts shown in Figures 2 to 8 are full size.
The two practical forms of my invention which have described and illustrated
constitute the best means of carrying my invention into effect with which I am
acquainted at this date.
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 new or improved device for varying the resistance in telephone circuits
which consists in the combination of a diaphragm, two conducting supports and a
free piece substantially as herein before set forth.
2. The arrangement and combination of parts substantially as set forth with
reference to Figures 2 and 3.
3. The arrangement and combination of parts substantially as set forth with
reference to Figures 6 and 7.
4. The specific form of free piece shown in Figures 2, 3, 4, and 5.
5. The specific form of free piece shown in Figures 6 and 7 and 8.
J. G. LORRAIN, M. Inst. E.E., M. Inst. M.E.,
Norfolk House, Norfolk Street, Strand, London, W.C.,
Chartered Patent Agent.