UC-NRLF
SB
77M
HOW TO INSTALL
Electric Bells, Annunciators,
and Alarms.
INCLUDING
Batteries, Wires and Wiring, Circuits, Pushes, Bells,
Burglar Alarms, High and Low Water Alarms,
Fire Alarms, Thermostats, Annunciators,
and the Location and Remedying
of Troubles.
BY
NORMAN H. SCHNEIDER,
Author of "The Study of Electricity for Beginners," "Care and
Handling of Electric Plants," etc., etc.
SECOND EDiTIONH ENLARGED
NEW YORK
SPON & CHAMBERLAIN, 123 LIBERTY STREET
LONDON
E. & F. N. SPON, Limited, 57 HAYMARKET, S.W.
1913
[No. 4]
S3
Copyright 1904
Copyright 1913
By SPON & CHAMBERLAIN
The Camelot Press, 16-18 Oak St., New York
PREFACE
Among all the applications of electricity to
domestic or commercial uses, few are as wide-
spread as the electric bell. Practically every build-
ing used for a dwelling, storage or manufacture
requires an electric bell, annunciator or alarm
system.
This book was written to explain in practical
language how an electric bell system operates and
how it is installed; its success shown by its large
sale has resulted in this new edition which brings
the subject up to date.
Many new diagrams of annunciator and burglar
alarm systems have been added, together with de-
scriptions and illustrations of wiring elevators for
electric bells, wiring for door openers, the use of
transformers for furnishing suitable ringing cur-
rent from electric light circuits; and high voltage
bells intended to be used on other than the cus-
tomary low voltage battery circuits.
The author expresses his acknowledgment to the
Western Electric Company for diagrams of door
opener circuits in connection with their interphone
systems, to Edwards and Company of New York
for diagrams of fire alarms, burglar alarms and
annunciators, and to the Westinghouse Company
for illustrations of bell-ringing transformers.
267494
CONTENTS
INTRODUCTION
PAGE
Introduction. The principle of an electric bell. ix
CHAPTER I
The Leclanche cell — Polarization — Setting up — The .
dry cell — The gravity cell — Connecting up cells . 1
CHAPTER II
The single stroke bell— The shunt bell— The differen-
tial bell — The continuous ring bell — The water-
proof bell — Forms of gongs — The buzzer — Long
distance bells — The relay — The push — Three point
or double contact push — Floor push — Door pull
— Indicating push 9
CHAPTER III
Bell wires — Joints — Running wires — How to put up a
door bell — Combinations of bells, pushes and bat-
teries— Faults in bells, faults in wiring — How to
locate and remedy faults 23
Vl CONTENTS
CHAPTER IV
PAGE
Fire alarms — Thermostats — Metallic thermostats — Mer-
cury thermostat— How to connect thermostats-
Water level indicators — Burglar alarms — Open and
closed circuit alarms — Window, door and shade
springs — Alarm matting — Yale lock alarm — Doo
trip alarm 40
CHAPTER V
The annunciator drop — The needle or arrow drop—
The pendulum drop — Wiring up annunciators —
Return or fire call systems — Double wire system —
Western Electric single wire system .... 55
CHAPTER VI
Three-wire return call system— Installing elevator an-
nunciators— Burglar alarm annunciators — Clock
alarm circuit — Bells for high voltages — Bell-ringing
transformers — Combination bell, door opener and
telephone circuits — Fire alarm circuit — interior fire
alarm system — Fire alarm system for considerable
areas 64
LIST OF ILLUSTRATIONS
FIG. PACK
1 Electric bell, push, and battery x
2 Leclanche cell 1
3 Dry cell 4
4 Gravity cell . . 5
5 Vibrating bell 10
6 Single stroke bell 10
7 Shunt or short circuit bell 10
8 Continuous ring bell 13
9 Waterproof bell 14
10 Dome gong 15
11 Tea gong 15
12 Cow gong 15
13 Sleigh bell gong .15
14 Spiral gong 15
15 Relay and circuit 16
16 Door push 19
17 Pear push . 19
18 Door push 19
19 Wall push 19
20 Floor push 20
21 Door pull attachment 22
22 Wire joint first operation . . 25
23 Wire joint second operation 25
24 Wire joint insulating 25
25 Section of house showing wiring ..... 29
26 Bell with ground return 30
27 Pushes in multiple 31
viii
PIG.
LIST OF ILLUSTRATIONS
PAGE
28 Bells in series 31
29 Bells in multiple 31
30 Two bells and two pushes .... 32
31 Two bells and two pushes 32
32 Two bells, two pushes and one battery .... 33
33 Double contact push 33
34 Grounded bell 34
35 Tongue test of wiring 38
36. Knife test of wiring 38
37 Knife test of wiring 39
38 Metallic thermostat 40
39 Mercury thermostat 41
40 Mercury thermostat circuit 42
41 Water level alarm 44
42 Lever water level alarm 45
43 High or low water level alarm 45
44 Window spring for burglar alarm 47
45 Burglar alarm— closed circuit 47
46 Special bell connection for burglar alarm ... 48
47 Special bell connection for burglar alarm ... 49
48 Burglar alarm and relay 50
49 Window-shade contact spring 51
50 House wired for burglar alarm 52
51 Door trip alarm 53
52 Annunciator drop 55
53 Needle drop 56
54 Needle drop indicating 56
55 Pendulum drop 57
56 Annunciator drop circuit 58
57 Simple annunciator circuit k 59
58 Annunciator and fire call circuit 60
59 Single-wire room and fire call ... 61
LIST OF ILLUSTRATIONS
.Fie. PAGE
60 Three-wire return call circuit 65
61 Elevator bells and annunciator circuit 67
62 Burglar alarm annunciator circuit 69
63 Clock alarm circuit 71
64 Bell-ringing transformer 73
65 Bell-ringing transformer with three secondary
voltages 73
66 Western Electric interphone system 75
67 Western Electric interphone system for more ex-
tensive service 77
68 Fire alarm circuit 79
69 Interior fire alarm circuit 81
70 Fire alarm circuit for considerable areas 82
INTRODUCTION
An electric bell depends for its action on the
fact that a piece of iron wound with insulated
wire becomes a magnet and will attract another
piece of iron just so long as an electric current is
allowed to travel through the wire.
The instant the current ceases, the magnetism
also ceases, and the attracted piece of iron (termed
the armature) is no longer held in contact.
The general construction of an electric bell
is shown in Fig. 1. MM are coils of insulated
wire wound on soft iron cores. A is a soft iron
armature mounted on a flat spring so that it is
normally kept a slight distance away from the
soft iron cores. 5* is a brass screw with a plat-
inum tip touching a platinum disc on a spring
attached to the armature.
When the push button P is pressed down, its
two brass springs touch each other, the current
from the battery cell B then flows through the
wire W ', through the push P, through the
coils M M, along A to the platinum disc, out
INTRODUCTION
FIG. 1
INTRODUCTION
at Sf which touches this disc, and back to the
battery.
The instant this is done the current causes the
iron cores to become magnets, they attract A,
which then breaks contact at S. The spring
mounting of A causes it to jump back to its
first position, ^ then touches the platinum disc
again, the current flows as before, and the arma-
ture is again attracted only to break contact
with 5* and fly back.
This continual making and breaking of the
circuit keeps up as long as the push is pressed, a
ball mounted on A by means of a rod strikes
against the gong G causing a continuous ringing
of the bell. The wires leading between the bell,
battery cell and push must all be insulated, that
is, covered with cotton, rubber, etc., which pre-
vents the leakage of current should t\vo wires
cross each other. Copper wire is mostly used for
circuits indoors, the details of the kind and size
of wire will be given later on.
The main parts of an electric bell circuit are
then — the battery to supply the electric current;
the circuit, or wires, to carry this current ; a push,
or circuit breaker, to control the current flow;
and a bell to utilize the current.
CHAPTER I
The Battery
The Battery Cell. The battery cell most used
in electric bell work is the Leclanche, or some
modification of it.
The Leclanche battery cell is shown in Fig. 2,
FIG. 2
where 7 is a glass jar, Z a rod of zinc, and P a jar
of porous earthenware containing a carbon rod
surrounded by powdered carbon and peroxide of
manganese.
£L2CTKIC BELLS AND ALARMS
In setting up this cell about four ounces of
sal ammoniac (chloride of ammonia) are put into
the jar and enough water added to come about
half way up the jar.
The porous jar P and the zinc Z are then
inserted, and the cell is ready for use in a few
minutes after the liquid has soaked through the
earthenware into the carbon-manganese mixture.
Water is often poured into the porous jar through
holes in its top to hasten this wetting.
Wires are clamped by nuts or set-screws to the
negative terminal on the zinc or the positive ter-
minal on the carbon, it generally not being of
consequence which terminal is attached to either
wire of the circuit.
A battery cell could be constructed without the
manganese, using simply a plate of carbon and
a rod of zinc, but hydrogen gas would be gen-
erated on the carbon plate when the cell was work-
ing and would stop the current flowing.
This is called polarization, and peroxide of man-
ganese is a de-polarizer, because it combines with
this hydrogen gas almost as fast as it is generated,
and prevents, to a great extent, the polarization.
But it does not stop it entirely, as will be seen
if the Leclanche cell is kept working above its
capacity. Then the hydrogen is generated too
fast for the manganese to destroy it, and the cell
THE BATTERY 3
ceases to work. In this case a rest will often
restore the cell to its former power.
Cells which have been almost unable to make
a bell give even a single tap have been found
good again when allowed to remain at rest over
night.
In setting up a battery cell no liquid should be
splashed on the brass terminals or corrosion will
take place. Every metal surface where connec-
tion is made to allow electric current to pass must
be clean and bright, and all screws, or nuts, hold-
ing wires must be screwed up tight so that the
wires are firmly clamped.
Loose or dirty connections are the cause of
probably eight out of every ten troubles affecting
bells and batteries.
When the fluid in a Leclanche cell becomes
milky, more sal ammoniac must be added. Or,
better still, throw out the old solution, wash the
porous jar thoroughly in clean water, scrape the
zinc bright, and half fill the cell with fresh solu-
tion.
The zinc wearing away rapidly or becoming
covered with crystals, and a strong smell of am-
monia, show generally that the cell is being worked
too hard, or that the current is leaking where it
should not.
A zinc rod in a cell working the average door
4 ELECTRIC BELLS AND ALARMS
beli should last for six months, the porous jar for
a year.
The Dry Cell. The Leclanche cell being a
cell with much free liquid is liable to dry up if
not watched. The dry cell (Fig. 3) is a modern
[NORRIE'S
DRY
ATTERI I
FIG. 3
form of the Leclanche where the liquid is held by
an absorbent material, such as blotting paper, or
plaster.
A typical dry cell* is shown in the figure. An
*For full description of this class of battery see No. 3
Book on "Dry Batteries."
THE BATTERY
outside case of zinc is lined with blotting paper
dampened with chloride of zinc and sal ammoniac.
A carbon rod is then inserted in the centre and
packed around with carbon dust and peroxide of
manganese. The latter mixture is also somewhat
dampened.
Molten wax, or a suitable composition, is then
poured on top of the contents of the cell to seal it
up and prevent the evaporation of the fluid. A
FIG. 4
terminal on the carbon rod and another on the
zinc case complete the cell.
The voltage of both the Leclanehe and the dry
cell is about 1.45, when it goes below this it in-
dicates that the cell is worked out.
The two cells described are known as open-
circuit cells and are only intended for intermittent
working.
When a current is needed for a long period at
a time a closed circuit cell should be used, such as
the gravity Daniell cell.
6 ELECTRIC BELLS AND ALARMS
The Gravity Daniell Cell. The gravity cell,
Fig. 4, has a zinc block Z suspended from the
side of the jar and a number of copper leaves C
standing on edge at the bottom. A quantity of
bluestone (sulphate of copper) is poured over the
copper leaves and the jar filled with water.
During the working of this cell, copper is de-
posited on the copper plate, and sulphate of zinc
formed at the zinc. To hasten the action a small
quantity of zinc sulphate can be added to the
solution when setting up the cell.
The name of this cell comes from the fact that
the ...copper solution being heavier remains at the
bottom of the jar. If the cell is not worked
enough, all the solution will become blue and the
zinc will blacken. If very dirty from this cause,
remove the zinc, scrape and wash it thoroughly.
Throw out all the solution, add new sulphate and
water and replacing the zinc, then put the cell
on short circuit by connecting the copper and
zinc together- for a few hours.
E. M. F. The e. m. f. of a gravity cell is within
a fraction of one volt, its current nearly one-half
ampere.
Warmth makes it give a greater current; on
no account let a gravity cell freeze.
THE BATTERY 7
Resistance of a Cell. The fluids in a cell do
not conduct electricity as well as copper does ; they
offer more resistance and thus reduce the current
output.
The internal resistance of a cell may be low-
ered by using large zinc plates curled around the
porous pot.
The Samson cell has a large zinc plate bent in
the form of a cylinder, the carbon-manganese
combination standing in the centre of it.
The dry cell also has a large zinc, the internal
resistance being thus much lowered, the current
output is increased. This is by reason of Ohm's
law, which teaches that to increase the current
flow, either the voltage of the battery must be in-
creased, or the resistance decreased.
But increased current means lessened life ; there
is only just so much energy in a cell mainly de-
pendent on the quantity of chemicals.
Grouping of Cells. Cells may be grouped in a
battery to get increased voltage, or increased am-
perage. When connected for the former, they
are in series, the carbon of one is connected to the
zinc of the next, and so on.
If all the carbons are connected together and all
the zincs, they are in multiple, and will give the
8 ELECTRIC BELLS AND ALARMS
same voltage as of one cell but the combined am-
perage of all.
In ordinary bell work the series is the general
connection, the higher the resistance of the cir-
cuit, or the longer the wires, the more voltage is
required.
CHAPTER II
Bells and Pushes
Electric Bells. The two main types of house
bells are the iron box and the skeleton.
The iron box has a cast-iron frame, or base, and
a cast- or stamped-iron cover over the mechanism.
The skeleton bell has an iron frame but no
cover, and is generally better finished and more
expensive than the iron box bells.
For fire alarm purposes, mechanical bells or
gongs are made, in which a clockwork mechan-
ism causes the hammer to strike the gong upon
being released by electromagnetism.
Marine or waterproof bells have an iron cover
fitting tight over a rubber gasket; they are for
marine, or mining, work.
Polarized, or magneto, bells are used in tele-
phone work, and are rarely operated by a battery,
but have a miniature dynamo generator operated
by hand, or power, to supply the actuating cur-
rent.
Most bells are classed for size by the diameter
of the gong, a four-inch bell being one with a
gong four inches in diameter; a six-inch bell one
with a six-inch gong, and so on.
10 ELECTRIC BELLS AND ALARMS
According to the use for which they are in-
tended, bells may be vibrating, as before described,
single-stroke, shunt or short-circuiting, differen-
tial, continuous-ringing, or adapted for circuits of
high voltage.
The Single-stroke Bell. The bell before de-
scribed, and again shown in Fig. 5, is a vibrating,
or trembling, bell. It is often desired to have the
hammer give only one stroke for each pressure of
the push, as in signaling with a code of taps; in
this case a single-stroke bell is used. The circuit
FIG. 5 FIG. 6 FIG. 7
from the binding posts is then directly through
the magnet coils without any break at the contact
screw, as in Fig. 6.
In adjusting such a bell to give a clear sound,
press the armature up against the iron magnet
cores and then bend back the hammer until it just
clears the gong. The spring of the hammer wire
will carry the hammer sufficiently forward to hit
the gong. The tone will be clearer than if the
hammer dampered the gong by pressing against
it when the armature was nearest the core.
BELLS AND PUSHES 11
By bringing out a third connection, a vibrating
bell may be made both single stroke and vibrating.
The Shunt Bell. There is a form of bell,
Fig. 7, known as the shunt, or short circuit bell,
which is often used when two or more are to be
connected in series, as will be seen in the descrip-
tion of circuits. In this bell the circuit through
the magnets is not broken at the contact screw,
but the forward movement of the armature short
circuits the coils.
As the short, or shunt, circuit is very much
lower in resistance than the wire on the magnet
coils, the main current flows around the latter and
they do not become energized. The sparking at
the shunting contact screw is much less than it
would be at the ordinary breaking contact screw,
and the platinum points last longer.
The Differential Bell. Sparking at the break-
ing contacts of an electric bell is detrimental to
the platinum points, and many remedies have been
devised to overcome it.
Sparking is due to the self Induction of one
turn of the wire coil acting on its neighbor, and
this property is utilized in the gas engine,.. QL^as,-
lighting spark coil, where a fat spark is needed to
ignite gas.
12 ELECTRIC BELLS AND ALARMS
The differential bell has two windings in oppo-
site directions. The action of one would be to
produce an N-pole at one end and an S-pole at
the other. But the second coil produces poles just
the opposite, as the polarity of a magnet depends
on the direction in which the current flows around
it.
Where the current flows around the first wind-
ing the armature is attracted and its spring con-
tact meets the contact screw and allows the cur-
rent to divide, part flowing through the first coil,
the other flowing in the reverse direction in the
opposite way. One coil would tend to produce
an N-pole where the other coil produced an S-pole,
and these opposite poles would so neutralize each
other that there would be no magnetism.
The armature would therefore be pulled back
by its spring when both coils were thrown into
circuit. In so doing it would cut out one coil
and the same series of operations would recom-
mence.
As a spark is normally produced where mag-
netism is lost by a break of circuit,* no spark ap-
pears, as magnetism is produced by a break of
circuit in this case.
*For a full explanation of self-induction see No. i of
this series.
BELLS AND PUSHES
13
Continuous-ring Bell. In some classes of bell
work, such as burglar alarms, it is desired that the
bell when once started shall continue to ring until
stopped by the person called. In this case a con-
tinuous-ringing bell is needed, such as in Fig. 8.
When the push P is pressed, the current flows
FIG. 8
in the usual way through contact screw L, arma-
ture spring A, magnet coils M M, battery B, back
to P, and the bell rings. But on the first forward
movement of the armature it releases the spring
contact S, which flies forward and makes contact
at U. The circuit is now from B, through M M,
14
ELECTRIC BELLS AND ALARMS
to A, thence through L and S, to U and back
to B.
The bell will continue to ring until the spring
contact ^ is moved back and caught by the pro-
jection on the armature A.
A continuous-ring attachment is also made and
sold in most electrical supply stores, which is com-
plete in itself and can be applied to any bell.
FIG. 9
I
Waterproof Bells. In Fig. 9 is an example of
a waterproof bell where the mechanism is almost
all entirely encased in a waterproof brass case.
The circuit is made and broken inside the case,
but the magnet cores project through it and act
on a second armature placed outside. This sec-
ond armature carries the hammer which strikes
the gong and is governed in speed by the contact-
breaking armature inside.
BELLS AND PUSHES
15
Forms of Bell Gongs. In order to provide a
variety of sounds, bells are provided with gongs
of various shapes.
Fig. 10 shows the ordinary form of gong.
FIG. 10
FIG. 11
FIG. 12
FIG. 13
Fig. 11, a tea gong; Fig. 12, a cow gong; and
Fig. 13, a sleigh bell.
A coil of steel wire is also used, as in Fig. 14,
which on being struck by the hammer gives a
pleasant but not loud tone.
FIG. 14
The Buzzer. The buzzer is the mechanism of
a vibrating bell less the hammer and gong. As
the armature vibrates it makes a buzzing noise
which does not carry as far as the sound from
a struck gong. It is used chiefly for a desk call
16
ELECTRIC BELLS AND ALARMS
and in telephone exchange work, or any place
where general attention is not desired to the signal.
Operating Bells at a Distance. When it is
desired to ring a bell situated at a considerable
distance from the push, the resistance of the line
becomes objectionable.
FIG. 15
On lines of 500 feet, No. 18 copper wire and
upwards, the battery necessary would be very
large, two small batteries and a relay would prove
more satisfactory.
In Fig. 15 the circuit of a simple form of relay
is given. An adjustable contact screw C is placed
where an extension 5 of the armature A can strike
BELLS AND PUSHES 17
it. This extension is provided with a platinum
contact. The connections are as in the figure.
When the push P is depressed, the current from
the main battery M energizes the electromagnet E,
and the armature A being attracted, contacts 5*
and C meet. These contacts close the second cir-
cuit containing the bell .9 and the local battery L.
The relay resembles a second push near the
bell, but controlled by current from a distance
instead of being depressed by hand. Its advan-
tage consists in it needing but a very weak cur-
rent to move the armature A, which is held back
by a light spring, or by gravity.
The relay may then be set near the bell and
the wires from the push may be of a very great
length. Battery L, which actually rings the bell,
will thus only have to work through a few feet
of wire.
Reducing Resistance of a Bell. Sometimes
it is desired to reduce the resistance the bell coils
offer to the current, the bell then working over a
very short line with few cells of battery. Or
the bell coils may have been wound with fine
wire for large battery voltage and a long line.
The bell coils may be put in multiple, the cur-
rent then dividing and one-half going through
each spool.
18 ELECTRIC BELLS AND ALARMS
Untwist the joint between the spools near the
yoke or iron bar to which the spools are attached.
Join one of these ends to the wire at the armature
end of the other spool and the second untwisted
end to the armature end wire of its neighboring
spool. Use short pieces of insulated wire for
these extra connections.
The current now instead of having to go
through one spool and then the other, can branch
through both at once.
The resistance to the current of one spool is
half the resistance of two, the current through one
spool will therefore be twice that through the
two spools as at first connected. And as there are
two paths for it, each one-half the first resistance,
the total will be only one-fourth the resistance
of the ordinary series arrangement.
The same size battery will therefore send four
times, the current through the spools in multiple
than when they are in series.
It is to be noted that the wire on one spool is
wound in the reverse direction to that on the
other. The reason will be apparent if the two
spools and yoke are considered as merely one
spool bent in a U or horseshoe form.
If both spools were wound in the same direc-
tion they would be in opposite directions when the
U were straightened out, and would cause like
BELLS AND PUSHES
19
poles at the same ends. These poles would neu-
tralize one another, so that there would be no
magnetic attraction.
This can be readily proved by joining together
the two yoke ends and the two armature ends of
the spool wires. Then pass the current through
these two joined connections.
0
0
FIG. 16
FIG. 17
FIG, 18
FIG, 19
The Push Button. Push buttons, or pushes,
are made in a variety of forms, with metal, wood,
hard rubber, or porcelain bases.
Fig. 16 has a metal base, and is suitable for
a front door.
Fig. 17 is a wooden pear push, and is attached at
the end of a cord which has the two conductors
braided in it, each, however, having its own in-
sulation.
Fig. 18 is a plate push for an outside door.
20
ELECTRIC BELLS AND ALARMS
Fig. 19 is either of metal, wood, or porcelain,
and is the shape most commonly used.
A three-point push has three contact springs.
One is movable by means of the button, one is
below the movable spring, and the third is above
it.
When the push button is not being depressed,
FIG. 20
the movable spring makes contact with the upper
spring. But when the button is depressed, these
two springs part, and the movable spring makes
contact with the lower one.
This style of push is used for special bell and
annunciator work, as will be described later.
The form of combination floor and table push in
Fig. 20 is the most solidly constructed device of
its kind. The lower part is set in a hole bored
in the flooring, the metal flange keeping it in
place and preventing its slipping through.
BFLLS AND PUSHES 21
The floor push attachment works as follows:
The central metal rod is divided into two parts
B D, by an insulating piece of hard rubber. When
depressed against the action of the spiral spring
by the foot, the upper part B connects together the
contact springs A C, closing the circuit of bell
and battery. These contact springs are insulated
from each other by a hard rubber block R.
From the table push a cord containing two in-
sulated wires leads to the two parts of the rod
at B and D. When the push centre is pressed
down, the push springs come together and practi-
cally short circuit B and D, which completes the
circuit of bell and battery. At any time the centre
rod may be removed, leaving a surface almost
flush with the carpet, or floor, over which furni-
ture may be moved without injury to the mechan-
ism of the push.
For a floor push alone a shorter form of the
centre rod is also sometimes furnished which is
not divided by insulation. The -spiral spring
keeps it clear of the lower contact A but enables
it to always make connection with the upper con-
tact B. Pressing this rod down will also short
circuit the bell and battery so that the signal is
given.
A door pull attachment, like Fig. 21, is made
so that the ordinary form of lever pull bell may
22 ELECTRIC BELLS AND ALARMS
be changed into an electric bell. Being screwed
up near the door pull, a wire is run from the lat-
ter and fastened to lever L. When the pull is
drawn out the lever L turns on a pivot and a
projection presses the insulated spring S against
the metal base B. The circuit of the bell and
battery being thus closed, the bell rings.
FIG. 21
Indicating Push Button. A push button is
made which contains in the base a small electro-
magnet in series with the line. An armature on
a spring is fixed near the magnet poles. When
the push is depressed, the current travels through
this electromagnet, and as the circuit is made
and broken at the distant bell, it is also interrupted
in the electromagnet. The armature vibrates in
unison with the bell and thus gives an audible
indication that the bell is ringing.
CHAPTER III
Wiring, Circuits and Troubles
The Wire. The size of the copper wire used
in bell work is No. 16, or No. 18, B and S gauge,
and sometimes smaller, such as No. 20 to 22.
But smaller wire than No. 18 has too much re-
sistance, and would necessitate a larger battery
power, even if its mechanical strength were not
too low. The insulating coverings are cotton satu-
rated with paraffin wax or compounds.
The covered wires are variously known as an-
nunciator, office, or weatherproof wire, these terms
being mostly for distinction of the coverings and
not for the use to which the wire would be put.
Annunciator wire has two layers of cotton
merely wrapped around the copper and then satu-
rated with paraffin.
Office wire has the two cotton layers braided,
the inside one being filled with a moisture-repel-
ling compound.
Both office and annunciator wires have their
outside coverings filled with paraffin and highly
polished.
From the ease with which annunciator wire is
24
ELECTRIC BELLS AND ALARMS
stripped of its cotton covering, the braided office
wire is to be preferred. These coverings are made
in a variety of colors.
Weatherproof covered wire is mostly used for
electric light work, but the sizes given above are
good for bell work, although their larger outside
diameter makes them harder to conceal.
The approximate number of feet to the pound
of office and annunciator wire is given in the
table.
Office Wire.
Annunciator Wire.
No.
Feet per Ib.
No.
Feet per Ib.
12
35
18
180
14
55
20
225
16
95
18
135
Joints. Upon the care with which a joint is
made much depends, a loose or poorly made joint
will offer much resistance to the current.
The correct way to start a joint in annunciator,
or office, wire is shown in Fig. 22. About three
inches of each wire to be joined is bared of its
insulation and scraped bright. The ends are then
WIRING, CIRCUITS AND TROUBLES 25
bent at right angles to each other, hooked together
and one end firmly twisted around the other, as
shown in Fig. 23. Any projecting pieces are cut
off, and the joints should then be soldered to pre-
vent corrosion.
FIG. 22
FIG. 23
i i i
]//////
FIG. 24
Adhesive tape ("friction tape") is wrapped
around the joint, Fig. 24, and pressed firmly to-
gether so that there is no chance of its unravelling.
The tape wrapping should extend across the joint
and on to about a half inch of the insulation
around each wire.
26 ' ELECTRIC BELLS AND ALARMS
Running the Wires. To detail all the opera-
tions of installing a complex system of bell, alarm
and annunciator wires would be impossible from
the reasons that conditions vary and space is lim-
ited. General directions will then only be given
to enable the inexperienced to run such wires as
may be needed in ordinary domestic work and to
guard against the most common causes of failure.
Wires may be run in tin tubes to prevent the
depredations of rats and mice, or they may be run
with simply their own covering for protection ; it
is presumed the latter is undertaken.
In a case where the building is of frame and
in course of erection the task is much simplified.
Having first decided upon the plan, number of
bells, pushes, etc. and their location, proceed to
run the wires first in order that the pushes, bells,
etc. may not be injured.
But where the house is already occupied, as in
the majority of cases likely to be met with by the
reader, the bell and battery may be set first.
Take the case of an ordinary door bell with the
push at the front door, the bell in the kitchen and
the battery in the cellar. If possible get the wire
on two spools; it will simplify matters if both
wires are of different colors. Starting at the push,
have a foot of each wire for connection and slack,
and fasten each wire lightly to the woodwork with
WIRING, CIRCUITS AND TROUBLES 27
staples, or double-pointed tacks, never putting two
wires under one staple nor driving in a staple so
it cuts the insulation. Some cases will require a
staple about every foot, on straight runs some-
times every three feet.
In many cases the wires can be partly con-
cealed in the angle between a moulding and the
wall, or even in a groove of the moulding itself.
When running along a skirting, the wires may
often be pushed Out of sight between it and the
floor. Do not attempt to draw the wires too
tight or the changes of the weather may break the
wires when the woodwork shrinks or swells.
The wires will be, one from the push to the
bell, one from the push to the battery, and one
from the bell to the battery. So it is probable
that the second wire can be run right through a
small hole bored in the flooring under the push,
but inside the front door. In this case it will
be perhaps easier if the spool be left in the cellar
and the end of the wire be pushed up from below
and stapled to the woodwork near the push, leav-
ing the cellar work to the last. Only one wire
will be run then direct to the bell upstairs and
it can be better concealed than two.
If necessary it may be drawn under a carpet
and not stapled, or it can often be forced into the
crack between two boards. But if not, run it
28 ELECTRIC BELLS AND ALARMS
along the skirting, following the walls until it
reaches below the bell. It is often better to go
entirely around a room than to cross below a
door.
If a door must be crossed the wire may either
run up one side of the frame and down the other
or laid beneath the carpet on the sill. The former
is preferable, but takes more wire.
In many houses the bell wire as well as the bat-
tery wire may be run across the cellar beams
(Fig. 25), in which case bore a second hole for it
near the push; do not draw it through the same
hole as the push to battery wire. And, of course,
here work upwards with the spool in the cellar.
Having reached the bell location, run the third
wire down into the cellar to the battery. Now
connect up the push, baring an inch or so of each
wire, push them through the holes provided in
the push base, screw down the push base and
clamp the wires under the washers through which
the connection screws run. Do this neatly, be sure
the ends of the wires do not stick out, cut off
what is left free of the bared ends. Then con-
nect the battery to the wire from the push and the
wire from the bell. The last thing is to scrape
and fasten the bell wires to the bell binding posts.
Do this so that they cannot come loose and that
they make good contact.
30
ELECTRIC BELLS AND ALARMS
The bell should now ring properly when the
push is pressed.
To sum up, one wire leads from one spring
of the push to the bell, one wire from the other
spring of the push to the battery, and another wire
from the remaining binding post on the bell to the
remaining binding post on the battery. It is im-
material whether the zinc terminal or the carbon
terminal go to the bell or push.
Combinations of Bells and Pushes. One of
the wires in a bell circuit may be replaced by
the ground (Fig. 26). Connection may be made
to a gas or water pipe or to a metal plate buried
deep in damp earth. Any wire fastened to such a
FIG. 26
plate must be thoroughly soldered to it or a voltaic
action will be set up, which will eat it away at the
poiat of contact.
When one bell is to be rung from two or
more points the pushes are to be connected in
WIRING, CIRCUITS AND TROUBLES
31
multiple (Fig. 27) as if they were in series; all
would have to be closed to complete the circuit.
If two bells are to be operated from one push
FIG. 27
they may be in series (Fig. 28), but in this case
one of them must be arranged for single stroke.
FIG. 28
If both were vibrating bells the armature of one
would not vibrate in unison with the other arma-
FIG. 29
ture and the result would be irregular contact
breaking and intermittent ringing.
A preferable connection for two or more bells
32
ELECTRIC BELLS AND ALARMS
and one push is Fig. 29, where the bells are in
multiple. This requires more current than the
series method.
FIG. 30
To ring two bells from either one of two points,
the arrangement in Fig 30 will answer. It re-
quires only two wires or one wire and ground
return, but two batteries. As both bells are in
FIG. 31
multiple both will ring, the one nearest the push
being depressed ringing the loudest. This is a dis-
advantage. If the series arrangement in Fig. 31
WIRING, CIRCUITS AND TROUBLES
33
be selected, one bell must be arranged for single
stroke. Both bells will ring with equal power.
In Fig. 32 only the distant bell rings, the cir-
FIG. 32
cuit having only one battery but three wires, or
two wires and ground return.
A plan where two batteries are needed but only
two wires, or one wire and ground is in Fig. 33.
Double contact or three-point pushes are necessary
FIG. 33
here, making one contact when depressed and a
second one when not being touched.
In this figure only the distant bell rings.
34
ELECTRIC BELLS AND ALARMS
Faults in Bells. On examining many electric
bells it will be noted that only one binding post
is insulated from the frame when the latter is
FIG. 34
of. iron (Fig. 34). As the armature spring vS is in
electrical connection with the frame F by reason
of its metal screws and support, the circuit may
run from the insulated post U to the magnet coils,
thence through the insulated contact screw C
through the armature spring (when it is making
contact) and through the frame to the uninsulated
post 7.
This saves labor, wire and complication, but if
the insulation of the post U, the wires W V , or the
contact screw C be injured, the current may take
a short path back to the frame.
If C were thus grounded, the bell would act as
a single-stroke bell.
If U were grounded, the bell would not ring
WIRING, CIRCUITS AND TROUBLES 35
at all, as that would be a short circuit on the bat-
tery between / and U and the latter would also
result if the bare wire were touching the frame
at F.
If the bare wire touched the frame beyond M M,
that is, along W , it would be a single-stroke bell,
as if C were grounded.
As any one of these faults is likely to occur,
they should be looked for when the bell acts im-
perfectly, or not at all.
A very common fault in a bell is when its arma-
ture sticks to the cores and thus does not make
contact with the contact screw. This may be from,
a weak spring or because of the loss of the pieces
of brass inserted in the ends of the cores to keep
the armature away from actual contact. A piece
of a postage stamp stuck over the core end will
often help out in the latter case.
A high screeching noise from the armature vi-
brating too rapidly but with too little play, may
be from excessive battery power or the contact
screw being too far forward. The former will
generally be detected by the violent sparking as
well as the rapid vibration.
In very cheap bells the platinum contacts may
be replaced by German silver or some other metal.
Platinum is necessary because the sparking
would soon corrode other metals, but it is very
36 ELECTRIC BELLS AND ALARMS
expensive. To test for platinum put a tiny drop
of nitric acid on the suspected metal. If bubbles
or smoke appear it is not platinum. After apply-
ing this test in any case however, carefully wash
off and remove all traces of the acid, as it will cor-
rode the metal into which the platinum is riveted.
Dirty contacts will decrease the current in the
bell coils and it will not work well, if at all.
Loose contact screws and wires also give
trouble. The adjusting of the contact screw is of
the utmost importance, and should never be at-
tempted unless it is clearly necessary.
Faults in Line. In looking for a fault in a
bell circuit make sure the battery is working; if
only one or two cells, put the ends of two wires
attached to the terminals on the tongue : a metallic
taste will indicate current.
Then see that the circuit wires are firmly
clamped in the terminals and no dirt or corrosion
on the connections.
Next examine the push button and see that the
wire connections at the springs are perfect.
If there is no movement of the bell at all when
the push is pressed in, take a pocket knife or
screw driver, and touch the blade across the push
springs. If there is current flowing sparks will
be seen when the blade breaks contact between
WIRING, CIRCUITS AND TROUBLES 37
the springs. If there are no sparks, detach the
wires from the bell and twist the bare ends to-
gether. Then try again for sparks — they may
now be very minute. The tongue test is good here.
If current is detected, examine the bell for the
defects first mentioned.
But if no current is found at the push now the
wires are broken somewhere.
First short circuit the push springs by insert-
ing a knife blade or piece of wire so as to touch
both of them. Then touch the two wires at the
bell, one to each side wire coming from the mag-
net coils. If current is up to the bell and the coils
are all right, a single stroke should result.
Replace the wires in the binding posts, clean
the platinum on both contact screw and armature
spring and try the adjustment. Troubles in the
bell will be mostly similar to those before men-
tioned.
If no current has been obtained at either bell
or push, and the battery is in good working order,
the line must be tested for a cross or break.
If the wires are touching each other (Fig. 35)
at some bare spot S between the bell and the bat-
tery, it will be shown by the metallic taste upon
detaching one wire from the battery and laying
it on the tongue T, together with another wire W
from the disconnected terminal of the battery. The
38
ELECTRIC BELLS AND ALARMS
current will travel from the battery to the cross
at S, then back along the second circuit wire to
the tongue and through the short wire to the
battery.
-^v
FIG. 35
If no current is obtained in this way it is prob-
able that the wire is broken.
a
1
\ 1
C K K
, D \ \
m
\ \ \
FIG. 36
The easiest way to find this is to take a bell
to the battery and connect it between the circuit
wires and the battery (Fig. 36).
Then with a sharp knife carefully cut away a
WIRING, CIRCUITS AND TROUBLES
39
little piece of the insulation from each wire beyond
the bell and battery and short circuit the bared
spots with the knife blade K. Keep working
towards the push. The bell will ring each time
p)
C K K
n
— i
3H
\ ° \ \
FIG. 37
at K K until the break D is passed, at C it will
not. It becomes an easy matter then to locate
it.
If the bell and push are far apart, as in Fig. 37,
a break between the push and the bell may be
found as shown. With the knife blade K at differ-
ent points the bell will ring, but after passing the
break D it will not ring.
Such simple tests as are here given can be car-
ried out by any one, but far better results will be
obtained if the reason for each is first learned.
This can be readily done by a careful study of
the diagrams and text.
CHAPTER IV
Alarms
Fire Alarms. Thermostats, heat alarms and
fire alarms are all practically the same, the term
thermostat being applied principally to the appa-
ratus which closes the electrical circuit.
e XA
(
2>
VA s
R
00
-
0
L (
9
FIG.
Thermostats act on the principle that heat causes
expansion whether of substances, liquids, or gases.
The degree in which different substances ex-
pand varies for the same increase in temperature.
This fact is used in a common form of thermo-
stat shown in Fig. 38. A strip of wood or hard
rubber R has a strip of thin sheet metal S riveted
to it. This compound strip is held at one end by
ALARMS
41
a lug L screwed fast to a baseboard. Upon an
•increase of temperature the hard rubber expands
more than the metal strip and the compound strip
bends towards the adjustable contact screw A.
Upon touching the latter, the circuit through the
bell B, battery C and the metal strip 5" is com-
pleted, and the bell rings. A contact screw can
be arranged at the other side of S R, which will
FIG. 39
give warning of a decrease in temperature, as the
rubber contracts more than the metal strip.
In some thermostats of this character two metals
having different coefficients of expansion, such as
steel and brass, are used instead of metal and hard
rubber.
Thermostats of this nature are much used in
incubators, and they can readily be combined with
electric apparatus to open or close hot-air valves,
42
ELECTRIC BELLS AND ALARMS
dampers, etc., and thus regulate the supply of
hot air, hot water, or gas.
A thermostat much used in fire alarm work has
a thin metal chamber which is air tight. An in-
crease of temperature causes the air to expand,
which swells out the walls of the chamber and
closes an electric circuit.
o
B
0
D-
€>
0
i
i
0
l~
FIG. 40
The mercurial thermostat shown in Fig. 39 has
a glass tube T and bulb containing mercury. Into
each end is sealed a platinum wire P P. Upon
the temperature rising to a predetermined degree,
the expanded mercury completes the circuit be-
tween P P and the battery C and bell B are put
in operation.
Fig. 40 is the open circuit system most used by
ALARMS 43
the fire alarm companies, only one circuit of six
thermostats being illustrated.
It will be seen that if any thermostat closes the
circuit between the outer and inner wires of the
ring A B, current will flow through the corre-
sponding drop of the annunciator and will attract
the armature A of the relay. This will cause the
bell to ring. As the relay is connected to the an-
nunciator as before shown for the annunciator bell,
it offers a common path for any drop to the bat-
tery. Thus the bell will ring for any circuit, but
the individual drop only will fall. In a simpler
circuit the relay may be dispensed with and a
vibrating bell only used.
Thermostats may be operated on open or closed
circuits, that is, they may give the alarm by clos-
ing a circuit and ringing a bell, or by opening one
and releasing a contact spring as in the burglar
alarm system to be described later.
Water Level Alarms. Where it is desired to
signal the rising or falling of water in a tank
above or below a given point, a water level in-
dicator as in Fig. 41 may be used.
A hollow ball H. is mounted on the end of a
rod which slides vertically in guides, not shown.
Adjustable stops 6* S press against a spring
arm R, pressing it up or down, according as the
44
ELECTRIC BELLS AND ALARMS
water level is rising or falling. If rising, R makes
contact with the adjustable screw A, if falling,
with D, in both cases completing the electrical cir-
cuit of the battery C and bell B.
FIG. 41
Another and simpler form is shown in Fig. 42,
where the ball H is mounted on the end of a
lever L pivoted at P, its rise or fall completing
the circuit of B and C as before.
ALARMS
45
Where it is desired to give a different signal for
the rise and the fall of level, two bells B and E
(Fig. 43) may be used connected as shown. The
rising of the ball will ring bell B, and its fall,
bell E.
46 ELECTRIC BELLS AND ALARMS
In both forms of indicator, a means must be
provided that an undue rise may not bend the
lever. This may be accomplished by using contact
springs instead of contact screws; it is, however,
then harder to adjust the indicator to fine differ-
ences of level.
In all cases the contacts must be faced with
platinum to prevent corrosion.
Burglar Alarms. A burglar alarm is a device
for indicating the opening of a door or window,
by the ringing of a bell or operation of an annunci-
ator. The contact apparatus at the points to be
protected may either open an electrical circuit or
close one, in the latter case being mere modifica-
tions of push buttons. The simplest form is the
latter or open-circuit method.
The spring contact to be inserted in the door
jamb or window frame is so constructed that
while under pressure the contacts are kept apart
and the circuit is open. "But when the door or
window is opened, the pressure is released and
a spring forces the contacts together.
Fig. 44 is an open-circuit window spring fitted
in the window frame so that when the window
is closed the spring lug 5* is pressed inwards,
breaking contact with the base B.
If the window is raised, the lug flies to the
ALARMS
position shown by the dotted lines, and making
contact with B, completes the circuit through bell
and battery. These springs are fitted in the side
©HE
FIG. 44
of the window frame in a vertical position and
are entirely concealed when the window is shut.
In the closed-circuit system the reverse hap-
pens. The pressure of the closed door or win-
FIG. 45
dow keeps the contacts together and its opening
enables them to spring apart.
In Fig. 45 is a diagram of a closed-circuit
burglar alarm, C a cell of gravity battery, R a
ELECTRIC BELLS AND ALARMS
relay, F the fixed contact and M the movable con-
tact of the spring, ^ a stud projecting through
the base of the spring and pushed in by the closed
door.
When the door is closed, S being pushed in,
--p^f
]
r^f"
j
G
c
FIG. 46
the circuit of C, R, F and M is closed. The
magnets of the relay hold the armature arm A
forward against a hard rubber contact. But when
S is released, the relay circuit is opened, 7? loses
its power and A flies back, making contact, and
throwing in circuit bell B and battery L.
ALARMS
49
A form of bell and relay combined is shown in
Fig. 46. Here the armature A is held against the
magnets while the circuit through the spring F
and battery G is closed. But on opening this cir-
cuit the armature flies back and makes contact
with an adjustable contact screw S putting in
circuit a local battery C. The bell is now practi-
FIG. 47
cally a vibrating bell; on a closed circuit it rings
until the circuit is again closed or the battery runs
down.
A different connection of the same scheme is
Fig. 47, where only one battery is used. This
must be a gravity battery or some other closed-
circuit battery. The circuit can be easily traced
in the figure and needs no special description.
50
ELECTRIC BELLS AND ALARMS
Both of the latter schemes are inferior to one
using a separate relay. If the circuit at the spring
were quickly closed again the bell would either
stop ringing, or be so hampered as to ring very
weakly.
FIG. 48
A relay made as in Fig. 48 has no spring sup-
port to the armature A, which falls down by grav-
ity. The adjustable contact C is screwed far back,
so that the armature must fall a considerable dis-
tance away from the electromagnets before it
makes contact. This ensures that the armature
will not be attracted and the bell stopped from
ringing by a re-closing of the circuit at the door
or window spring.
A shade spring (Fig. 49), is made for either
ALARMS
51
open or closed circuits. In operation, the shade is
pulled down and its string or ring hooked on
to H. This draws H up a trifle against a spiral
spring and its lower end makes contact with an
insulated spring .S closing the circuit. If the
shade is disturbed, the spiral spring on the lower
part of H is released and it causes a break of
contact with S in the direction of the arrow.
When made for open circuit, S is bent so that
FIG. 49
while under tension no contact is made, but re-
lease of tension causes the contact.
Fig. 50 gives the wiring of two windows and
a door on the closed-circuit system. It will be
seen that the contact springs are all in series,
opening a window or the door will thus break
the circuit.
When setting the alarm at night by connecting
up the batteries, relay and bell, should any one
of these springs be open the relay armature will
not hold, and the bell rings.
ALARMS
53
In this figure the relay is replaced by an electro-
magnet holding up a drop shutter by magnetic
attraction. Upon the circuit opening, this shutter
falls, exposing a number painted on it. At the
same time it hits a spring contact placed below
it and closes the bell and local battery circuit.
Door Trip Alarm. A swinging contact door
trip can be attached over a door to ring a bell
when the door is opened.
FIG. 51
In Fig. 51 the door trip is screwed over the
door so that the lowest arm A is struck by the
door. When the door is opened, in the direction
of the arrow, the arm A is thrust forwards, and in
its turn moves the contact arm C, completing the
bell and battery circuit. But when the door is
being closed, A swinging in the reverse direction
does not move C and no alarm is given.
54 ELECTRIC BELLS AND ALARMS
Miscellaneous Alarms. The Applegate elec-
trical matting is composed of wooden slats with
springs so arranged that the weight of any person
stepping on it will close a circuit and ring a bell.
It is intended to be put under the ordinary door
mat or under stair and room carpeting.
The Yale lock switch is a Yale lock and switch
combined. Upon any key but the right one being
inserted, a circuit is closed and an alarm bell is
rung.
CHAPTER V
Annunciators
The Annunciator. The mechanism of an an-
nunciator consists of electromagnets which allow
shutters to drop or needles to move on the cir-
cuits being closed. A bell is also rung in most
cases to call attention to the annunciator. The
number of the circuit is marked on the shutter,
FIG. 62
or near the needle, either shutter or needle being
replaced by a reset device, which may be mechan-
ical or electrical.
Annunciator drops are made in a variety of
forms. Fig. 52 illustrates the principle under-
lying nearly all of them.
When current flows through the magnet coils
My the armature A is attracted, and being pivoted
at P, the lever hook H rises and allows the
56
ELECTRIC BELLS AND ALARMS
weighted shutter S to fall and display a number
painted on its inside surface.
The needle drop in Fig. 53 is one that has met
with great favor and works as follows : the soft
iron core of the magnet C has a hole drilled
through it, in which turns the shaft S. An arrow
or needle is attached at the front end over the
FIG. 53
FIG. 54
face of the annunciator. A notched arm B is
fixed on the rear end of the shaft and is held in
a horizontal position by the end of armature A.
When the current flows around C, armature A
turns on its pivot towards the core of C, as in
Fig. 54, unlocking J5, which falls and thereby
partly rotates shaft S and the arrow.
When it is desired to reset the arrow and arm,
ANNUNCIATORS
57
a button is pressed upwards, which Taises a rod
carrying an arm R. This latter arm in turn
raises B to its former position, the heavy end
of A falls, and its pointed end locks B.
Pendulum, or swinging, signals are used in an-
nunciator work, where there is a liability that the
FIG. 55
ordinary drop shutter would not be reset. They,
however, only give a visible signal for a few sec-
onds, and are therefore liable to be overlooked.
In Fig. 55 a pivoted arm carrying a soft iron
armature A and a thin plate B having a number
on it is free to swing in front of an electromag-
net M .
58
ELECTRIC BELLS AND ALARMS
When the current flows in the electromagnet
the armature is attracted, and upon the circuit
being broken at the push, the armature is released
and the arm swings to and fro.
The drops of an annunciator are wired up as
in Fig. 56.
One end of each coil is attached to a common
FIG.
return wire C, the other end going to the push P.
When P is depressed, the circuit of any drop is
through M along C through bell, battery and up
common battery wire W back to other contact
of push P. Depressing any push does not there-
fore affect any other drop but the one controlled
by it.
ANNUNCIATORS
59
Wiring up an Annunciator. A diagram of
the connections for an annunciator with a separate
bell is given in Fig, 57. Where the bell is con-
tained in the case a terminal will be generally
found for connection.
The figure shows a wire running from the bat-
tery to one side of each push button. This is the
common return, or battery wire, and saves instal-
L
— i i i-
! 1 I
\\
FIG. 57
ling two wires from each push. It should be
larger, however, than the rest of the wires, gener-
ally about No. 16 B. & S.
All the wires for an annunciator should be run
before connecting up. There are different methods
of sorting out the wires at the annunciator. One
way is to connect the wires (except of course
common or battery return wires) to the drops in
any order. Then an assistant travels from push
to push and presses each button, noting the
60
ELECTRIC BELLS AND ALARMS
room numbers and the order in which they were
visited.
As each drop falls, its number and order is
noted.
Comparing this with the list made by the assis-
tant will show the correct changes to make.
FIG. 58
For instance, suppose pushes 1, 2, 3, 4, 5 and 6
were pressed in that order, and drops 3, 4, 5, 1,
2 and 6 fell in that order. Then the wires at
the annunciator would be changed as follows :
From 3 to 1, 4 to 2, 5 to 3, 1 to 4, and 2 to 5 ;
6 would already be in its right place.
Another way is to commence by /twisting to-
ANNUNCIATORS 61
gether say the wires at No. 1 push. Then go to
the annunciator and touch each of the push wires
to No. 1 drop until it falls. Then connect it,
untwist the wires at No. 1, push and connect it
up. Proceed to No. 2 and so on until all the
pushes have been connected in turn.
In some cases it is desired to answer back to
the person calling, or to be able to call any person
from the annunciator.
A circuit like Fig. 58 answers the purpose of
both annunciator call and return, or fire, call.
This requires two wires from each room to the
annunciator and a common return wire. By trac-
ing out the circuit it will be seen that when a
room push is pressed, the annunciator needle and
bell indicate. And when one of the pushes near
the annunciator is pressed, the corresponding
room bell rings. The former circuit is from the
push, along the common return wire, through
bell and annunciator back to the push.
The fire call is from push up line to bell through
bell along common return and through battery to
the push.
The Western Electric single-wire system
(Fig. 59) uses three-point pushes, two batteries
and two return wares. Battery A is for the annun-
ciator circuit and battery F for the fire, or return,
call.
62 ELECTRIC BELLS AND ALARMS
FIG. 69
ANNUNCIATORS 63
In each room the top contact and push spring
contact are normally together.
If one of the pushes below the annunciator is
pressed, battery F is thrown in series with the
bell in the room.
But when the room push is pressed its bell is
cut out and the circuit becomes like an ordinary
annunciator circuit.
« i r.
CHAPTER VI
Annunciators and Alarms
Three Wire Return Call System. A three
wire return call annunciator system is shown in
Fig. 60.
There are two battery wires installed, from
which taps are taken off and led to each room
or push button.
Three way or return call push buttons are
used as shown at points marked B.
In the diagram, the bells are marked A, the
drops in the annunciator D, the annunciator bell
C and the return call buttons in the annunciator
E. The batteries are as shown at F. The heavy
black outline encloses the annunciator mechanism
and connections which are drawn diagrammatically
for the sake of clearness.
Three stations only are shown on the sketch,
but the annunciators which are manufactured by
Edwards and Co., Inc., of New York, are made
in all standard sizes.
Installing Elevator Annunciators. The install-
ing of electric bells and annunciators in elevators
does not present any special problems, although
the apparatus used must be selected with a view to
64
Q
J
mm
FIG. 60
66 ANNUNCIATORS AND ALARMS
its being suitable to withstand the shocks incident
to elevator service.
In general the wires leading from the push but-
tons on the different floors to the bell or an-
nunciator in the elevator, are flexible and made up
into a cable. One end of this cable is attached to
the underside of the elevator car, the other end
being fixed usually to the elevator wall, at a point
midway between the top and bottom of the shaft.
In Fig. 61 is shown a diagram of the general
circuit used, details of course differing in each
installation.
One point to be taken care of in elevator work
is the attachment of the cables. The continual
movement tends to break the wires at the two ends
if good flexible cable is not used and the installa-
tion done in a workmanlike manner.
Elevator cable is a standard article and may be
procured through any electrical supply store.
That most commonly used consists of the requisite
number of copper conductors each composed of
16 strands No. 30 B. and S. gauge soft and un-
tinned copper wire. These flexible conductors are
insulated with two reverse wrappings of cotton and
one braid of cotton. The insulated conductors
are cabled together with a steel supporting strand
where extra tensile strength is required, as in the
case of extra long cables. The number of con-
ductors generally ranges from 3 to 20 inclusive.
The wires leading from the push buttons to the
cable should be preferably rubber covered and
PUSH BUTTON
4TH FLOOR
3RD FLOOR
2ND FLOOR
1ST FLOOR
68 ANNUNCIATORS AND ALARMS
braided. Only where economy at the outset is de-
sired may ordinary annunciator or office wires be
employed.
A connection block carrying binding posts is
used at each point where the cable connects to the
push button wires or to the annunciator. This may
be home-made or purchased ready made, as desired.
Burglar Alarm Annunciators. Although almost
any annunciator may be used for open circuit
burglar alarm work, they usually do not contain
certain devices which are desirable in burglar alarm
work.
In Fig. 62 is shown a diagram of a burglar alarm
annunciator, the view being schematic of the back
board.
The references are as follows: A is the main
alarm bell situated wherever desired and connected
to the binding posts BB. The battery connection
leading directly to the battery K is marked C
and that leading to the contact spring is marked
D. The cut-off switch E cuts off the battery while
F is the constant ring switch. G is the upper bar
and H the lower bar, while the letters // denote
the indicating drops. The door and window springs
are lettered S. At L is a switch which may be
used to disconnect the entire burglar alarm sys-
tem. Where it is desired to disconnect only a sec-
tion at a time, the switch corresponding to the
section is turned off the upper bar G and on to the
lower bar H.
FIG. 62
70 ANNUNCIATORS AND ALARMS
Clock Alarm Circuit. A diagram of the wiring
and connections on the back board of all clock
alarms is illustrated in Fig. 63. This diagram
embodies the principles of the last described circuit,
but includes the circuit of a clock-operated alarm.
Bells for High Voltages. The use of electric
bells on lighting circuits is becoming quite general,
as it obviates the necessity of using batteries, and
thereby simplifies both installation and maintenance.
There is no fundamental objection to operating
make and break bells on electric light circuits. Pro-
viding the voltage and amperage are the same,
there is little difference between the current from
a direct-current dynamo and that from a battery.
But owing to the higher voltages of the lighting cir-
cuit over that generally employed from batteries,
the bell coils must be wound to high resistances to
keep down the current strength. There are also
other slight changes to assist in suppressing spark-
ing, as have been already treated on.
Where the circuit is not over 220 volts, the bells
are wound with fine wire and have also self-con-
tained resistance coils. For 500 volts and over, a
resistance lamp is connected in with the bell which
in this case is wound for a 150-volt circuit.
These bells up to 6-inch and inclusive will operate
on circuits of either direct or alternating current.
Above this size it is necessary to use specially
constructed bells on alternating current circuits.
Most large hotels and office buildings having
FIG. 63
72 ANNUNCIATORS AND ALARMS
direct current lighting service are using it for ring-
ing bells and similar work to the total exclusion
of batteries.
Where the number of units to be operated justi-
fies it, motor generators are operated in connection
with the lighting mains to produce a low voltage
most suitable for the bells. The connections in
this case are no different to those when batteries
are employed.
Bell-ringing Transformers. The best system
for operating bells and annunciators from alternat-
ing current circuits is undoubtedly that employing
small specially constructed transformers to reduce
the voltage. These transformers are being used
universally for hotel and office work where alternat-
ing current is available. They are simple, being
merely one or more coils of well insulated wire
wound on soft iron cores and having connections
for both the lighting circuit and the bell circuit.
As a general rule the coils are divided as to their
number of turns or according to the ratio of trans-
formation desired. For example, if the circuit
were 110 volts and 10 volts was required for the
bell circuit, the total number of turns in the trans-
former would be connected, l%i to the lighting cir-
cuit and l/ii to the bell circuit.
The bell-ringing transformers on the market are
made in several styles. One small style, Fig. 64,
for single residences, is for use on 110 volts and
produces a bell voltage or secondary voltage as it
ANNUNCIATORS AND ALARMS
73
FIG. 64
FIG. 65
BELL-RINGING TRANSFORMERS.
74 ANNUNCIATORS AND ALARMS
is termed, of 6 volts. Another size, Fig. 65, of this
transformer has three secondary voltages 6, 12 and
18, each of which can be used by connecting to the
right binding posts.
It is to be noted that where the lighting service
voltage or primary voltage varies from the above,
the secondary voltage delivered to the bell circuit
will vary in like proportion. It should also be noted
that a careless reversing of the connections, that
is connecting the secondary leads to the light-
ing circuits, instead of the primary leads would
cause a like high voltage at the other terminals of
the transformer, raising it in due proportion in-
stead of lowering it. Thus such carelessness would
produce a voltage of 2,400 volts instead of 6 if a
transformer intended to deliver 6 volts from a 120-
volt circuit was wrongly connected.
The results might very well then be dangerous.
All transformers are properly marked, however,
and such an error only occurs through ignorance or
carelessness.
The installation of these bell-ringing transformers
is simplicity itself; they require no care after in-
stallation and have met with the approval of the
National Board of Fire Underwriters.
Combination Circuits. Circuits intended pri-
marily for electric bells or annunciators in houses
and apartments may often be also made to serve
for other electrical devices such as door openers,
house telephones, etc. This subsidiary apparatus
76 ANNUNCIATORS AND ALARMS
may be installed with a little additional wiring or
perhaps will not need any other wires, as when
both the devices are not used at once.
Electrical door openers are great conveniences
and are practically indispensable where the outside
door is on another level to the location of the
dweller or where two or more families occupy the
same house. The device is simple, consisting of an
electrically released spring-plate against which the
lock bolt is normally 'held and a door opening spring.
When the door opener button is pressed, the
spring plate is released, releasing the lock bolt by
the same action. The door spring then forces the
door open enough to clear the opener plate, which
flies back into position when the button is released.
These door openers are made in several forms
for -door frames, such as those on thin doors, iron
gates, for surface or rim locks, for thick doors,
sliding doors and any other regular type of door.
The push button is the same as used for electric
be'lls and may be located wherever desired. The
pushes are wired in multiple as shown in Figs. 66
and 67, which are two circuits of a type of the
Western Electric interphone, a -system of house
telephones supplied for houses and buildings of
every size. Fig. 66 shows a circuit which provides
telephone service between the vestibule and the
apartments, the door opener wiring bein^ clearly
indicated. In Fig. 67 the circuit provides a more
extensive service, enabling the janitor, the apart-
ments and the tradesmen to intercommunicate in
78 ANNUNCIATORS AND ALARMS
the most desirable system. The door opener wiring
is also deafly shown.
The convenience of having telephone .connection
in the house or hotel and its advantages over speak-
ing tubes are 'too well known to need extended
comment. Where electric bells have already been
installed it is quite feasible now to use the same
wires for telephones also.
Telephone sets especially designed for this serv-
ice are manufactured by the Western Electric Com-
pany in their interphone series. They are simple
and compact, and may be installed by anyone who
can put up an electric bell.
Fire Alarm Circuits. A fire alarm circuit suit-
able for factories, private plants or groups of
buildings is shown in Fig. 68. It is a series system,
with closed circuit, the gongs sounding whenever
the circuit is opened whether by the contact breaker
in the boxes or by the accidental breaking of a wire.
This insures that it remains in good working order,
as when any part of the circuit is opened, a warn-
ing tap is sounded on every bell or gong.
The boxes have contact breakers which send a
separate number of impulses for each box, thus an-
nouncing the box number on each gong. The boxes
and gongs may be located anywhere, as the system
is perfectly flexible.
The reference letters in the diagram are as fol-
lows: C indicates the gongs which are preferably
of the electro-mechanical type, a coiled spring pro-
FIG. 68
80 ANNUNCIATORS AND ALARMS
viding force for the blow, electricity being merely
used to release and retain the hammer or striker.
The alarm boxes are marked BB and the battery
which is of the closed circuit type is marked D.
Interior Fire Alarm System. Another system
suitable more particularly for indoor operation is
illustrated ki Fi£. 69. Here the alarm is given by
breaking the glass front of an alarm box and re-
leasing or pressing an electrical contact.
The box sounded indicates by causing a drop to
fall on an annunciator and at the same time rings
an alarm bell. The latter are generally provided
with constant ring attachments, which keep the
bell sounding until shut off.
The annunciator shown in the diagram has
switches for controlling each individual bell circuit,
and also for control of the entire system.
There is no practical limit to the number of sta-
tions in this system, it being determined by the size
of the annunciator used or by other obvious factors.
The reference letters on the diagram are as fol-
lows : A, alarm bells which may be located where-
ever desired. B, break-glass alarm boxes also lo-
cated at convenient points. C, annunciator drops,
D, 'switches on annunciator which control each in-
dividual bell circuit, enabling any circuit to be cut
out, cut in or tested without disturbing any other
circuit. £ is a general alarm switch, causing all
bells to ring at once when it is operated.
The battery F varies with the number of bells and
FIRE ALARM SYSTEMS
81
boxes and the length of line, from three cells up-
wards. A cut-out switch H is added to cut out
the entire system by opening the battery wire.
o
o
LJJ
==-t
FIG. 69
The annunciator bell is at /, an auxiliary bell being
added in multiple with it when necessary.
FIG. 70
FIRE ALARM SYSTEMS 83
Fire Alarm System for Considerable Areas.
Where the area is more extensive and the number
of stations considerable, the system illustrated in
Fig. 70 is very suitable. It consists of the requisite
number of break-glass boxes, bells and a more
elaborate annunciator system. In general details it
resembles the last system, but uses a relay to send
out the current for ringing the alarm bells.
When a box operates, the current impulses sent
on the line act on the relay instead of directly on
the bells. Each stroke of the relay closes a local
circuit which includes the bells and the battery.
This system does away .with large batteries and
is very enconomical of wire.. The current needed
for the relay is very small, whereas in a direct sys-
tem of any size, the current and voltage to ring a
number of bells located at wide intervals would be
prohibitive.
The reference letters are as follows: AA are
the alarm bells, BB the break-glass alarm boxes,
C is the annunciator be'll, D is the relay which re-
mains closed when an alarm comes in keeping the
bells constantly ringing until shut off. £ is a re-
sistance coil and F is the battery.
A system cut-out switch G and // switches on
the annunciator for controlling individual circuits
are also provided. HH are the annunciator drops
and K is a constant-ring switch which can also be
used for a general alarm to ring all the bells at
once.
LEARN TO DO THINGS
Model Library Series
OF COPYRIGHTED BOOKS
1 . The Study of Electricity for Beginners.
2. Dry Batteries, How to Make them.
it 3. Electrical Circuits and Diagrams, Part 1.
4. Electric Bells, Annunciators and Alarms.
5. Modern Primary Batteries.
6. Experimenting with Induction Coils.
if 7. Electric Gas Igniting Apparatus.
it 8. Small Accumulators, How to Make and Use
9. Model Steam Engine Design.
* 10. Practical Electrics.
1 1. Inventions, How to Protect and Sell them.
12. Woodwork Joints, How to Make and Use.
it 13. The Fireman's Guide to the Care of Boilers
* 14. The Slide Valve Simply Explained.
it 15. The Magneto Telephone.
^-16. The Corliss Engine and Its Management.
* 17. Making Wireless Outfits.
18. Wireless Telephone Construction.
* 19. The Wimshurst Machine, How to Make It.
20. Simple Experiments in Static Electricity.
2 1 . Small Electrical Measuring Instruments.
22. Electrical Circuits and Diagrams, Part 2.
^23. Induction Coils, How to Make Them.
24. Model Vaudeville Theatres,
it 25. Alternating Currents, Simply Explained.
it 26. How to Build a 20 foot Bi-plane Glider.
^27. A B C of the Steam Engine.
it 28. Simple Soldering, Hard and Soft.
it 29. Telegraphy for Beginners.
30. Low Voltage Lighting with Storage Batteries
33. House Wiring for Electric Light.
34. Magnets and Magnetism.
it 36. Small Windmills and How to Make Them,
Injectors, Their Construction and Use. Keppy.
Refrigeration and Ice Making. Wakeman.
37. Collin's Wireless Plans, Part 1.
38. Collin's Wireless Plans, Part 2.
In paper covers Price 25c each postpaid.
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Dubelle's Famous Formulas.
KNOWN AS
Non Plus Ultra Soda Fountain Requisites of Modern Times
By 1±. Mr DUBEUrE.
A practical Receipt Book foi fjruggists, Chemists, Confectioners and Venders
of Soda Wtter.
S/NOPSIS OF CONTENTS.
INTRODUCTION. — Notes on natural fruit juices and improved me-
thods for their preparation, Selecting the fruit. Washing and
pressing the fruit. Treating the juice. Natural fruit syrups and
mode of preparation. Simple or stock syrups.
FORMULAS.
FRUIT SYRUPS. — Blackberry, black current, black raspberry, ca-
tawba, cherry, concord grape, cranberry, lime, peach, pineapple,
plum, quince, raspberry, red current, red orange, scuppernong grape,
strawberry, wild grape. NEW IMPROVED ARTIFICIAL FRUIT SYRUPS —
Apple, apricot, banana, bitter orange, blackberry, black current,
cherry, citron, curacoa, grape, groseille, lemon, lime, mandarin, mul
berry, nectarine, peach, pear, pineapple, plum, quince, raspberry,
red current, strawberry, sweet orange, targerine, vanilla. FANCY
SODA FOUNTAIN SYRUPS. — Ambrosia, capillaire, coca-ldna, coca van-
illa, coca-vino, excelsior, imperial, kola ox a, kola-kina, kola-vamlla,
kola-vino, nectar, noyean, orgeat, sherbe', syrup of roses, syrup of
violets. ARTIFICIAL FRUIT ESSENCES. — Apple, apricot, banana, berg-
amot. blackberry, black cherry, black currant, blueberry, citron,
cranberry, gooseberry, grape, lemon, lime fruit, melon, nectarine,
orange, peach, pear, pineapple, plum, quince, raspberry, red currant,
strawberry. CONCENTRATED FRUIT PHOSPHATES. Acid solution of
phosphate, strawberry, tangerine, wild cherry. — 29 different formulas.
NEW MALT PHOSPHATES — 36. FOREIGN AND DOMESTIC WINE PHOS-
PHATES—9. CREAM-FRUIT LACTARTS — 28. SOLUBLE FLAVORING EX-
TRACTS AND ESSENCES — 14. NEW MODERN PUNCHES -18. MILK
PUNCHES — 17. FRUIT PUNCHES— 32. FRUIT MEADS — 18. NEW FRU.T
CHAMPAGNES — 17. NEW EGG PHOSPHATES — 14. FRUIT JUICE SHAKES
— 24 EGG PHOSPHATE SHAKES. HOT EGG PHOSPHATE SHAKES.
WINE BITTER SHAKES— 12. SOLUBLE WINE BITTERS EXTRACTS — 12
NKW ITALIAN I/EMONADES — 18. ICE CREAM SODAS— 39. NON.POISON-
ous COLORS. FOAM PREPARATIONS. MISCELLANEOI s FORMULAS— 26.
LATEST NOVELTIES IN SODA FOUNTAIN MIXTURES— 7. TONICS. —Beef.
iron and cinchona; hypophosphite ; beef and coca ; beef, wine and
iron ; beef, wine, iron and cinchona ; coca and calisaya. LACTARTS.
— Imperial tea ; mocha coffee ; nectar; Persian sherbert. PUNCHES.
EXTRACTS. — Columbia root beer ; ginger tonic ; soluble hop ale
LEMONADES. — French ; Vienna. Egg nogg. Hop ale. Hot torn. Malt
wine. Sherry cobbler. Saratoga milk shake. Pancretin and wine.
Kola-coco cordial/ Iron malt phosphate. Pepsin, wine andiron, etc
157 Pages, Nearly 500 Formulas. 12mo, Clotfc, $1.00
A NEW AMERICAN BOOK ON INDUSTRIAL ALCOHOL
A PRACTICAL HANDBOOK ON THE
Distillation of Alcohol
FROM FARM PRODUCTS AND
DE=NATURINQ ALCOHOL.
By F. B. WRIGHT*
Including the Free Alcohol Law and its Amendment, the Govern-
ment regulations -therefore and a number of U. S. government
authorized de-naturing formulas.
In the preparation of this, the second edition, the author has
followed his original plan of writing a plain practical handbook on
the manufacture of alcohol and de-naturing for industrial pur-
poses. This industry is bound to grow to enormous proportions
as it has in Germany where over 100,000,000 gallons were manu-
factured last year principally in small farm distilleries. This work
is not intended as a scientific treatise but as a help to farmers
and others wishing to go into this industry on a moderate scale.
The original matter has been carefully revised. Some of the
chapters rewritten and a very considerable amount of new informa-
tion added. The total number of illustrations brought up to 60
including a number of plates giving the layout of distilleries.
Contents of Chapters.
1, Alcohol, its various forms and sources. 2, The preparation
of mashes and Fermentation. 3, Simple Distilling Apparatus. 4,
Modern Distilling Apparatus. 5, Rectification. 6, Malting. 7
Alcohol from Potatoes. 8, Alcohol from Grain, Corn, Wheat, Rice
and other Cereals. 9, Alcohol from Beets. 10, Alcohol from Molasses
and Sugar Cane. 11, Alcoholometry. 12, Distilling Plants. Their
general arrangement and equipment. 13, De-natured Alcohol and
U.S. Authorized De-naturing Formulae. 14, De-naturing Regu-
lations in the United States. Index.
281 pages, 60 illustrations and plates, 12mo., cloth, $1.00.|
I
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