Improved Telephone Transmitter.
Year: 1892

page_text: Date of Application, 5th May, 1892
Complete Specification Left, 21st Sept., 1892-Accepted, 19th Nov., 1892
PROVISIONAL SPECIFICATION.
Improved Telephone Transmitter.
RICHARD WHITEHEAD, 7 Well Road, Heeley, Sheffield, Manufacturer of Blind
Roller Fittings, ALFRED DOXEY, 7 Well Road, Heeley, Sheffield Electrical
Engineer, do hereby declare the nature of this invention to be as follows:-
This invention relates to the construction of a telephone transmitter, consisting
essentially of the following.
A ring of carbon or other suitable material, is suspended by its inner edge resting
on two carbon or other suitable supports, or electrodes. Each electrode being
attached to the center of a separate diaphragm. The two diaphragms are then
placed parallel to each other, & separated by a ring of suitable thickness, forming a
case, which encloses ring & electrodes, & permitting access of sound waves to the
ontside of each diaphragm only. One or more carbon rings may be used, the same.
having their inner surface rounded or beveled. The electrodes may be square, or
of such other shape as that each shall present two points of support to the carbon
ring. This device preventing undue vibration at the points of contact.
Dated this 4th day of Mov 1892
ALFRED DOXEY.
RICHARD WHITEHEAD.
COMPLETE SPECIFICATION.
Improved Telephone Transmitter.
RICHARD WHITEHEAD, 7 Well Road, Heeley, Sheffield, Manufacturer of Blind
Roller Fittings, ALFRED DOXEY, 7, Well Road, Heeley, Sheffield, 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:―
Improved telephone transmitter.
In practice, telephone transmitters exhibit certain defects. Foremost amongst
which is undue vibration at the microphone contacts, giving rise to jarring sounds.
Several means have been devised to obviate these defects, usually by the application
of some additional mechanism for damping the pencils or contacts.
The present invention has for its object, the construction of a transmitter in
which the shape or form of the microphone contacts themselves, are such that do
not permit of undue vibration, thereby dispensing with additional contrivances.

page_text: edge of the carbon ring resting upon points a & a¹ on 'either side the ring, preventing
undue vibration as claimed.
ATTACHMENT TO DIAPHRAGMS.
Two circular diaphragms of wood or other suitable material, are mounted parallel
to each other by being placed one on either side of a separating ring, constructed of
some nonconducting material shaped to the required breadth & thickness. Thus
forming an hermetically closed case. Fig. 4. showing a single diaphragm d. with-
separating ring S.
inside the case described an electrode E. is attached to the center of each
diaphragm, forming the support to a carbon ring placed midway between the
electrodes. See sectional drawing Fig. 5. which shows the transmitter complete.
d & d¹ being the two diaphragms, S. nonconducting separating ring, E & E' carbon
electrodes each attached to its own diaphragm by means of small screw & nut f.
& R. carbon ring, supported by two electrodes, E. E'.
OUTER CASE.
The whole is then enclosed within a metal case M. with mouthpiece P. The
case & mouthpiece are threaded t. to k. & provided with flanges V. with the object
of its ready attachment to wood cases of varying thickness, by screwing or.
unscrewing mouthpiece P.
The microphone proper rests on three elevated terminals of brass, at the back of
case M. two of which, & are insulated from the body of the case by ivory
bushings n & n. Screws o & of passing through the two diaphragms & separating
ring, are threaded into insulated terminals, 1 && in addition to securing the
diaphragms in position, make electrical connection between terminals & carbon
electrodes, by means of a narrow strip of copper foil, .. Fig. 4. passing along each
diaphragm from electrode E, to head of screw o.
Provision is also made that sound waves entering the mouthpiece P. Fig. 5. &
striking diaphragm d', have also access to diaphragm d, along the air chamber Z.
Thereby producing an increased effect upon the enclosed microphone.
Having now particularly described & ascertained the nature of my said inven-
tion, & in what manner the same is to be performed, I declare that what I
claim is―
NATURE OF CLAIM.
I. The invention claims as a combination, a carbon ring or rings mounted between
electrodes as described, the same enclosed between two diaphragms, forming an
hermetically closed case, & the means adopted for mounting the same within an
outer metal case with air chamber, permitting access of sound waves to both
diaphragms.
TI
RICHARD WHITEHEAD.
ALFRED DOXEY.