An Electric Bell.
Year: 1892

page_text: Date of Application, 9th Aug., 1892
Complete Specification Left, 22nd Apr., 1893-Accepted, 27th May, 1893
PROVISIONAL SPECIFICATION.
An Electric Bell.
GEORGE DAVIS 46 Brookbank Road Lewisham, S.E. London Electrician do
hereby declare the nature of this invention to be as follows:-
An electric bell intended for use in houses or places supplied with electricity by
public electric supply companies or in places where the current is generated by a
private plant or in any place where the electric current is in use at a mean pressure
of 100 volts. It is worked directly by the energy so supplied or generated and is
connected on to the mains in the same way as an incandescent lamp would be.
Thus the necessity of using a special cell or battery of cells to work it is done
away with.
An electric bell consisting of:
1° A solenoid wound with a large number of convolutions of fine copper wire or
German silver or platinoid wire & forming a shunt of a resistance safely pro-
portionate to the electro-motive force of the circuit to which it is connected.
2° An electro-magnet lying free in the core of the solenoid.
3° A contact maker and breaker composed of two platinum contacts one being
fitted on a fixed terminal, the other being fitted on,
4° A fixed spring holding the electro-magnet in the required position (i.e. making
contact) when at rest.
'
5° A brass knob fixed on the other end of the electro-magnet & serving as
hammer to
6° A bell gong which surmounts the whole of the apparatus above described.
When therefore current is switched on, the solenoid draws up the electro magnet
causing the brass knob at the end of it to strike against the gong. This action
however breaks the circuit and the electro-magnet falls back to its original position,
re-establishes the circuit, is drawn up & strikes the gong again and so on until the
current is switched off. The bell is thus of the type called "trembler" bell but I
can by suppressing this contact maker and breaker, make the bell of that type
called a "
single stroke" bell.
Dated this 9th day of August 1892
COMPLETE SPECIFICATION.
An Electric Bell.
I GEORGE DAVIS Electrician of 46 Brookbank Road Lewisham, S.E. 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 :-
An electric bell intended for use in houses or places supplied with electricity by
public electric supply companies or in places where the current is generated by a
private plant or in any place where the electric current is in use at a mean pressure
of 100 volts. It is worked directly by the energy so supplied or generated and is
connected on to the mains in the same way as an incandescent lamp would be.
Thus the necessity of a special cell or battery of cells to work it is done away
with.
The accompanying drawing is only an illustration of the principle of this bell as
various types may be made as will be shewn further on.
Fig. 1 is a plan view and Fig. 2. a side elevation of an electric bell constructed
TD011

page_text: according to my invention and consisting of the following parts mounted on a
base W made of some insulating material such as wood, porcelain &c.
(1) A solenoid S wound with a large number of convolutions of fine copper wire
and forming a shunt of a resistance safely proportionate to the electro-motive force
of the circuit to which it is connected. The last layer of the solenoid is wound
with German silver wire to increase the resistance.
(2) An electro magnet E, made of soft round iron, lying free in the core of the
solenoid.
(3) A contact maker and breaker composed of two platinum contacts one being
fitted on a fixed terminal C, the other C being fitted to
(4) A fixed spring P. which holds the electro-magnet in the required position
(ie. making contact) when at rest.
(5) A brass knob or attachment K fitted in the top end of the electro-magnet
and serving as hammer to
(6) A bell gong G which surmounts the whole of the apparatus above described
and is held in place by a metal support B.
T and T are the connecting terminals for the leads. T³ is also a connecting
terminal to which the spring is fixed.
The dotted line in Fig. 2 shews the run of the solenoid connections.
MODE OF WORKING.
When therefore current is switched on the solenoid S draws up the electro-
magnet E causing the brass knob K at the top end of E to strike against the gong.
This action however breaks the circuit and the electro-magnet falls back to its
original position, re-establishes the circuit, is drawn up and strikes the gong again
and so on until the current is turned off. The bell so arranged is of the type
called "trembler" bell.
The volume of sound emitted by the bell, may be increased by fixing the make
and break device to K on the top side of the solenoid so that E becomes the
hammer and strikes on the bottom of the gong with a stroke rendered heavier by
its own falling weight.
By suppressing the make and break device and the brass knob or attachment K
the bell becomes a "single stroke" bell, the mode of working being that when
current is turned on the electro-magnet E is drawn up by the solenoid and is held
up until current is turned off when it falls down striking the gong once.
Having now fully 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 :-
An electric bell constructed as above described in which an electro-magnet
operated by a solenoid in the core of which it lies, acts as bell hammer, with a
brass knob or attachment in "trembler" bells and without knob or attachment in
single stroke bell.
Dated this 21st day April 1893.
F. G. CASSELL,
Of Cassell & Co.,
22, Glasshouse Street, Regent Street, London, Agent for the Applicant.