A New or Improved Method of Telephonic Transmission, and Apparatus therefor.
Year: 1891

page_text: Date of Application, 6th Jan., 1891
Complete Specification Left, 6th Nov., 1891-Accepted, 12th Dec., 1891
PROVISIONAL SPECIFICATION.
A New or Improved Method of Telephonic Transmission, and
Apparatus therefor.
I, ERHARD LUDWIG MAYER, of 11 Billiter Square, London, in the County of
Middlesex, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to a new or improved method of and apparatus for
telephonic transmission by means of which I succeed in obtaining an increased
undulatory effect in the current transmitted to the line.
In carrying out my invention I employ a microphonic transmitter of any
convenient type and I connect this up in circuit in any of the usual well known
ways. In addition however to the devices usually employed with the transmitter
I employ a device which for convenience I shall term a reinforcer, its function
being to reinforce, as it were, the microphonic effects otherwise produced. I
shall explain the nature of this reinforcer by briefly describing one form of the
same, it being understood that the said form is merely a type or example of many
This form consists of an electro-magnet
forms which the reinforcer may assume.
An armature is so
the winding of which forms part of the transmitter circuit.
arranged with respect to this electro-magnet that in its movements to and from
the same it causes a variation of pressure in a microphone contact or tension
regulator in the circuit of a separate battery from that of the transmitter. This
The said
second circuit I shall for distinction term the reinforcing circuit.
One way
reinforcing circuit is connected to the line in any convenient manner.
which I have ascertained by experiment to give good results is by employing an
induction coil with two primary windings and one secondary winding. Of the two
primary windings I insert one in the reinforcer circuit and the other in the
transmitter circuit. The secondary winding I insert in the line circuit in the
usual way.
The action of my invention is as follows. The variations in the current traversing
the transmitter circuit as is well understood will cause corresponding variations in
the attraction which the electro-magnet exercises upon the armature and therefore
cause corresponding variations in the pressure exerted upon the tension regulator
in the reinforcer circuit. Such variations of pressure will by the usual microphonic
It will
action cause variations in the current traversing the reinforcer circuit.
thus be seen that a double set of current variations or undulations will be
transmitted to the line and an increased effect obtained.
Dated this 6th day of January 1891.
J. G. LORRAIN, M.I.E.E., M.I.M.E.,
Norfolk House, Norfolk Street, London, W.C., Applicant's Patent Agent.
COMPLETE SPECIFICATION.
A New or Improved Method of Telephonic Transmission, and
Apparatus therefor
I, ERHARD LUDWIG MAYER, of 11 Billiter Square, London, in the County of
Middlesex, 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 :-
improved method of and apparatus for

page_text: telephonic transmission by means of which I succeed in obtaining an increased
undulatory effect in the current transmitted to the line.
In carrying out my invention I employ a microphonic transmitter of any convenient
type and I connect this up in circuit in any of the usual well known ways. In
addition however to the devices usually employed with the transmitter I employ a
device which for convenience I shall term a "reinforcer," its function being to
reinforce as it were the microphonic effects otherwise produced. I shall explain
the nature of this reinforcer by briefly describing one form of the same it being
understood that the said form is merely a type or example of many forms which
the reinforcer may assume. This form consists of an electromagnet the winding
of which forms part of the transmitter circuit. An armature is so arranged with
respect to this electromagnet that in its movement to and from the same it causes
a variation of pressure in a microphone contact or tension regulator in the circuit
of a separate battery from that of the transmitter. This second circuit I shall for
distinction term the reinforcing circuit. The said reinforcing circuit is connected
to the line in any convenient manner. One way which I have ascertained by
experiment to give good results is by employing an induction coil with two primary
windings and one secondary winding. Of the two primary windings I insert one
in the reinforcer circuit and the other in the transmitter circuit. The secondary
winding I insert in the line circuit in the usual way.
This form of my invention I illustrate in the accompanying drawing. I is an
induction coil which differs from that usually employed in telephone transmitters
only in that it has two primary windings instead of one. C is the core formed as
is usual of a bundle of soft iron wires. P is the primary coil consisting of two
windings pl and p². I generally form the primary coil by winding on two primary
wires simultaneously so that they lie side by side throughout. S is the secondary
coil. ss are the ends of the secondary wire passing to line L and earth E in the
usual manner. In the circuit of the first primary winding p' of the primary coil P
is the transmitter T, and also the transmitter battery T B and the electromagnet A
of the reinforcer R. In the circuit of the second primary winding p³ of the primary
coil P is the microphone contact or tension regulator M of the reinforcer R and
also the reinforcer battery R B. The transmitter T may be any ordinary microphone
transmitter. The reinforcer R consists of a microphonic contact or tension
regulator M and an electromagnet A with its armature a, A being in the circuit
(called the transmitter circuit) of the first primary winding p' and M being in the
circuit (called the reinforcer circuit) of the second primary winding p². The parts
constituting the reinforcer are so arranged that when A attracts its armature a the
microphone contact is compressed. In the figure I have illustrated M as consisting
of a microphone of the form described in the Complete Specification filed in
pursuance of my application for Letters Patent dated the 6th day of January 1891
and numbered 284 but any ordinary form of microphone or tension regulator will
answer my purpose. For the reinforcer battery, cells of such number and size
should be employed as would be necessary to work a similar microphone as a
transmitter. I have hereinbefore spoken of two separate batteries but it will be
obvious that a single battery may be employed common to both the transmitter and
the reinforcer circuits.
The action of my invention is as follows. The variations in the current traversing
the transmitter circuit as is well understood will cause corresponding variations
in the attraction which the electromagnet exercises upon the armature and there-
fore cause corresponding variations in the pressure exerted upon the tension
regulator in the reinforcer circuit. Such variations of pressure will by the usual
microphonic action cause variations in the current traversing the reinforcer circuit.
Thus the movement of the armature a will cause increase and decrease of pressure
on the tension regulator of the reinforcer just as the movement of the transmitter
diaphragm will cause increase and decrease of pressure on the tension regulator of
the transmitter, so that a set of undulations will traverse p² similar to the set of
undulations traversing p', and these two sets of undulations will be coincident.
It

page_text: will thus be seen that a double set of current variations or undulations will be
transmitted to the line and an increased effect be obtained.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is.
1. The new or improved method of telephonic transmission substantially as set
forth.
2. The new or improved apparatus for telephonic transmission consisting of the
combination of a transmitter, a reinforcer, an induction coil with double primary
winding, and a battery (or other source of electrical energy) substantially as and
for the purpose set forth.
Dated this 5th day of November 1891
J. G. LORRAIN, M. Inst. E.E., M. Inst. M.E.,
Norfolk House, Norfolk Street, London, W.C., Applicant's Patent Agent.