Improvements in and relating to Portable Electric Burglar Alarms and Bells, and Apparatus to be Used in Connection therewith.
Year: 1886

page_text: Improvements in and relating to Portable Electric Burglar
Alarms and Bells, and Apparatus to be Used in Connection
therewith.
LOUIS CHARLES DETTMER of 19 Poland Street in the county of Middlesex
Electrician do hereby declare, the nature of this invention to be as follows:-
According to one part of my Invention I provide Electric Burglar Alarms &
Bells designed to ring with a small current of Electricity for this purpose I con-
struct the said Electric Bells with an Electro magnet of U pattern. to one pole of
which a straight armature is pivetted, the said armature being pivetted between
two springs, that is to say one on each side in such a manner that the armature
vibrates between the free pole of the electro magnet & a set screw fitted in a metal
cock placed behind the armature, in such a position as to regulate the swing of the
armature & also to break the current of Electricity. To the end of the armature is
fixed a hammer projecting through the wooden case in such a manner as to strike on
the inside of a bell as the armature recedes from the magnet the said bell being
supported on pillar screwed to the case.
According to another part of my invention, I provide a suitable alarm contact,
constructed in such a manner as to be applicable, in a temporary manner, to either
doors, windows, safes, traps, and so forth; the said contact being preferably con-
structed of two springs of metal, fixed at one end of each by means of screws, or
other suitable fastenings, to a peice of insulating material of sufficient thickness
to insure the screws not making contact, electrically, bettween the springs; to the
end of the shorter spring is rivetted a short spring extending to within a short
distance from the insulator, in such a position that when the short spring is pulled
away from the longer one, this third spring makes a connection between the two
main springs; so that if a thread is attached to the end of the short spring and
the other end to a book or staple fixed at the opposite side of a passage, or room,
with sufficient tension to keep the springs apart, on pulling or cutting the thread
a contact is formed and the alarm bell started.
Also, that the rivet holding the two short springs together, is drilled and a set
screw run through, in order to provide an adjustment for the proper setting of the
small spring. To the end of the long spring is fixed a peice of metal considerably
thicker than the spring, on to which is fixed on the side nearest the short springs,
a short pillar of metal, long enough to lift the long spring away from the others

page_text: when the contact is applied to a door, or window, so that on the door, or window,
being opened the long spring falls back into its natural position and makes
contact; to the extreme end of the peice of metal fixed to the long sping, is
pivotted a metal trigger in such a manner that, in case of the contact being fixed
above a door, the said door can be closed without disturbing the springs, but on
opening the door, the trigger is caught by the top of the door and pushes the long
spring, against the others making a contact.
The mode of fixing the contact is as follows a hole is drilled through the
insulator and both springs so that a screw or other fastenings may be passed
through and driven into the frame of the door, window, or, other opening; the
entire contact with the affixing screw is arranged to fit in a suitable case which has
a push peice or plunger fitted through one side so situated as to engage the shorter
spring and, on being pressed, to act as an invalid's press when not required as an
alarm.
According to another part of my invention I provide a wooden case, of suitable
dimensions, to contain the operative mechanism of the bell, and also a battery of
any description, to furnish a current of electricity, to operate the bell; the case is
provided with a handle to carry the same, which handle can stand upright or lay
flat, connected by a bell crank lever to the handle, is a plunger which descends into
the case and rubs against two discs of metal, one of which is in electrical connec
tion with the carbon pole of the battery, and is placed in such a position that,
when the handle stands up, the plunger rests only on the lower disc, which is
connected to the bell by means of a drop lever, and when the handle lays down
the plunger is against both discs and puts them in electrical contact, thus acting
as an automatic switch; the drop lever is a peice of metal in the form of a strip,
pivotted at one end and provided with a catch engaging with a stud on the
armature so that when the armature is attracted the lever falls on to a plate or
disc of metal, which also is part of the switch described, the course of the current
being, when the alarm and switch is set, as follows, starting from the positive pole
of the battery through the connecting wire to the contact, then back by the other
connecting wire to the electromagnet of bell and from that to the armature from
the armature to the break screw, thence to the negative pole of the battery; the
motion of the armature causes the lever to drop, and then the current runs from
the positive pole to the first disc through the plunger to the second disc then by
the lever to the electromagnet and armature to the negative pole.
The drop lever is replaced by means of a projection issuing through the case and
ending in a thumb peice.

page_text: The spring H rests normally on a projection of platina fixed in the metal-cock J
which forms one of the terminals of the vitrating arrangement, the course of the
electricity being from the carbon or positive pole of the battery to the contact by
way of the line wire and thence to the frame D and through the spring H to the
electromagnet E leaving which it returns to the zinc or negative pole of the
battery B To the end of the armature is attached by a short wire a hammer G¹
which projects from the case and strikes on the inside edge of the bell C.
"
The continous ringing arrangement I prefer to form as shown in figures 2. 3.
6. 7. 8 & 9 where K is a frame of metal carrying a drop lever K¹ which is held
up normally by a spring K³ of the form shown in Figures 2 & 8. The free end
of the lever K¹ projecting over the wire carrying the hammer G₁ in such a position
that on the hammer striking the bell C the said wire strikes the lever K¹ releaseing
it from the spring K³ causing it to fall. The lever K¹ is replaced by a lever K¹
pivoted also on the frame K the free end of lever K projecting through the
case A to form a finger peice the opposite end being curved upward, the spring K³
is supported by a cock on frame K. and continued downward to form a counter
spring for lever K. On pressing down the outer end of lever K it lifts lever K¹
into the position shown in Figure 2 and 8 where it is held by the spring K³.
The combined switch and handle I prefer to form as shown in Figures 2. 3. 6
and 7 where L is a handle of U pattern pivoted to the frame L' by means of
2 lugs or projections L³, to one foot of lever L is pivoted a connecting peice L'
which engages by means of a pin with a lever M said lever M being pivoted to a
ock of metal M¹ secured to the case A by a screw M³ In Figures 6 and 7 the
adle L and lever M are shown in the "off" position. In Figures 1. 2 and 3
'the handle L and lever M are shown in the on or continous ringing position.
On the said lever K¹ is a projection of platinum K' which rests, when the lever K¹
is dropped, on a similar projection of platinum M³ fitted in the end of lever M.
The frame K is electrically connected with frame D and lever M is electrically
connected with the positive pole of the battery. The action is as follows, the finger
lever K2 is depressed raising lever K¹ and handle L is also depressed raising
lever M in the position shown in Figures 2 and 3 on the bell being sounded the
said wire carrying hammer G₁ causes lever K¹ to fall and rest by means of the
projection K On projection M³ thus establishing a connection between frame K
and lever M thereby causing the electricity to flow directly into the frame D and
electro-magnet E of bell keeping the bell ringing continously until stopped by
1st lever K being depressed raising K¹ into normal position or 2ndly handle L being
raised lowering lever M out of contact with K' the projection on K¹. According
to another part of my invention I provide a contact to be used in connection with
the said bell and apparatus the said contact being so constructed as to be applicable
to windows, doors opening inwardly or outwardly desks, trapdoors or any other
opening closed by a removable shutter, also as a silk thread, staircase or passage
contact. I prefer to form the said contact as shown in Figures 10, 11, 12 and 14
in which o is a peice of insulating material to either side of which are secured, by
means of 2 plates of metal a a, 2 springs b, and c, spring c being half the length of
spring b. A spring g. is secured to the outer end of spring c by means of a rivet,
said rivet being drilled and tapped to take a screw, d, to the head of which, after
the fashion of a watchbow is attached a ring of metal e, spring, g, being fixed in
such a manner that the free end of it which is capped with platinum almost
touches a peice of platinum soldered to the inner surface of spring b. a peice of
platinum is soldered on to the surface of spring 6 opposite the end of screw d
said screw d being provided at its end with a projection of platinum.
To the extremity of spring b is affixed a peice of metal h to which is rivetted
a projection of metal j and the extremity of peice h is slotted, and a trigger k is
pivoted between the lugs thus formed the block of insulating material o is peirced
by two holes at right angles to each other said holes of sufficient diameter to
admit the body of screw m shown in Figure 13, the said screw m being provided
with a bend n of insulating material the metal plates a a are provided with a

page_text: spike in each and are electrically connected each one to one end of a flexible
wire u.
The cover for the said contact is shown in figure 14 where N N are two
halves of a turned peice of wood or other suitable material hollowed out on the
inside to contain the said contact, one side N of said cover is pierced to admit of
a push peice s and bushed at the outer end of the hole with a turned peice t. To
the large end of half N' of said cover is fitted a turned peice of metal p through the
centre of which screw m passes engaging at its screwed end with a projection on
half N. To the opposite inner end of half N is secured an eye r, shown in
elevation at Figure 15-and to the inner end of N¹ is secured a hook q also shown
at q in Figure 15.
Referring to Figure 14, on the push peice s being pressed it causes the spring b
to make contact with screw d thus completing the electrical circuit through flexible
wire the other ends of which are connected one with the positive pole of
battery B Figures 2 and 3 and the other with the frame D of bell."
The manner of using the said contact is as follows on application to a door
opening inwardly the screw d is withdrawn a short distance from spring b the
contact being then screwed to the top jamb of the door in such a position that the
trigger k is caught by the top of the door on the said door being opened thus
completing the electrical circuit, and in the case of a door opening outwardly the
screw d is advanced until the point touches the spring b the contact being then
screwed to the side jamb of the door in such a manner that the projection; presses
against the face of the door so that the spring b is pressed away from the screw d.
On the door being opened the spring 6 falls by its elasticity into electrical contact
with screw d thus completing the electrical circuit. In the application of the
contact to a window, the contact is screwed to the top of the inside sash with the
projection j resting on the bottom bar of outside sash so that on opening the
window the spring b makes contact with screw d thus completing the electrical
circuit. In the application of the contact to a staircase or passage the contact
is screwed to the skirting with the spring c away from the wall; the screw dis
advanced until it touches the spring 6 and a silk thread is attached to ring e the
said thread being stretched across to the opposite side of staircase or passage and
secured to a nail or hook driven thereinto; on the thread being pulled, spring g is
moved over into contact with spring b, or, on the said thread being cut, spring c
falls, bringing screw d into contact with spring b, thus, in both cases, completing
the electrical circuit..
Having now particularly 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
First. The combination of an electric bell and contact of my improved form
substantially and for the purposes set forth.
Second. An electric bell provided with the peculiar arrangement of electro-
magnetic apparatus whereby one pole of an electromagnet, wound with one coil,
will attract, the other pole, substantially as set forth.
Third. The continuous ringing arrangement substantially as described in
Figures 2. 3. 6. 7. 8 and 9. for the purposes and substantially as set forth.
Fourth. The contact and cover substantially as described in Figures 10, 11, 12,
13, 14, and 15, for the purposes and substantially as set forth.
Dated this 28th day of August 1886.