Improvements in Electric Alarm Apparatus.
Year: 1898

page_text: Date of Application, 7th Apr., 1898-Accepted, 7th May, 1898
COMPLETE SPECIFICATION.
Improvements in Electric Alarm Apparatus.
I, HEINRICH WIGAND, of 1, Bahnhofstrasse, Monsheim, Hessen, in the Empire of
Germany, Postmaster, 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 :-
This invention relates to electric-alarm apparatus and has for its object to provide
apparatus which will not only indicate the opening of a door but will give notice in case
of the cutting of the conducting wires which lead to such door and thus give timely
warning of an intended burglary. The invention lies in the arrangement of apparatus
which I will now describe in reference to the accompanying drawing. Fig. 1 is a
diagrammatical view of an apparatus constructed according to this invention and
showing the arrangement of electric circuit. Figs. 2 and 3 are longitudinal sections of
the switch.
By my preferred construction the apparatus is so arranged that it can act only when
the metal switch-plates c c and d d' respectively are in electrical contact one with the
other, and this is effected by the turning of a round plug or stem t which may
conveniently be arranged beneath or adjacent to metallic tongue pieces q. The said
plug is flattened at diametrically opposite sides as shown in Figs. 2 and 3 and according
as the tongues bear against the flat or the round surfaces of the plug, the circuit
through the plates c c and d d¹ will either be closed or open.
If the circuit be closed an electric current flows from the pole a of the battery
through the conductor 1 to the screws of the door contact C', where the conductors 1
and 2 are in metallic connection. The current passes from the screw 8 through the
conductor 2 to the screw a of contacts C2 and C³, and again through conductor 2 to
the switch plates c c¹, binding screws e and n, coils A A, binding screws lk, and
through the conductor 3 back to the battery by its pole b.
The iron cores of the coils A A are thus rendered magnetic and so attract the
armature v and thus interrupt the contact between the spring f and the contact pin z.
The conductor 2 at the screws x is insulated from the door contacts, and obviously any
number of doors can be included in the circuit.
On any one of these doors being opened the contact springy with contact u comes
against the metal plate m and a current is caused to flow from the pole a of the
battery though the conductor 1 to the screws s of the contact C', or contacts C2 C3, thence
through the spring y of such door, contact u, metal plate m and screw i, then
through the binding screw g, metallic strip o, iron fraine R', coil B B, frame R²,
spring w, and through the contact screw r which is insulated from K2, and finally
through the conductor 3, binding screws k back to the battery by its pole b.
This current causes the alarm to sound and give notice that the door has been
opened in the same manner as is now done by ordinary safety alarms.
If a burglar succeeds in cutting one of the conducting wires he renders the ordinary
contrivance as hitherto constructed useless by preventing it acting.
By combining the herein described arrangement with an ordinary burglar alarm

page_text: the signal is given also on the wire being cut. To this end, that circuit to which
belong the coils A A becomes at once interrupted in case the wires 2,2 are cut and in
consequence of this the armature v is released. The spring f then comes against the
contact pin and causes the alarm to sound. This action is as follows:-A current
passes from the pole of the battery through the conductor 3 to the binding
screws and thence through the contact pin 7, spring w, frame R², coils BB,
frame R', spring f of the armature v, insulated pin 2, metal sprip p to the binding
screw h, and thence through the conductor 4, plates d d¹ back to the battery by its
pole a.
It is thus shown that the alarm is equally effective whether the doors be opened or
the wires 2 cut.
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. An electric alarm apparatus arranged substantially as above described, wherein
an ordinary alarm bell W is connected to door contacts C¹, C2, C3 and so on, in such
a manner as to act either on the door being opened or on the conductors 2 being cut,
said conductors serving normally for attracting an armature v of an electromagnet,
while the releasing of this armature through the cutting of the wire switches the alarm
into circuit.
•
2. A switch for use in combination with the apparatus above referred to and claimed
in Claim 1, in which contact is established or broken, between two metal plates d d'
or c c¹, by means of a plug t provided with flat faces diametrically opposite each other,
and arranged and adapted to open or close the circuit by raising or lowering tongue
pieces 99, substantially as hereinbefore described.
3. My improved electric alarm apparatus constructed, combined and arranged
substantially as described in reference to the accompanying drawings.
3
1
1000
J. C. CHAPMAN, C.P.A.,
Associate Agent for the Applicant, 70, Chancery Lane, London, W.C.