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HOW TWO BOYS MADE THEIR OWN ELECTRICAL APPARATUS
by
THOMAS M. ST. JOHN, Met. E.
* * * * *
HOW TWO BOYS MADE THEIR OWN ELECTRICAL APPARATUS
By THOMAS M. ST. JOHN, Met. E.
EIGHTH EDITION Price, postpaid, $1.00
This book contains 141 pages, 125 illustrations, and directions for
making 152 pieces of apparatus. Size, 5x7-1/2; red cloth.
CONTENTS: Chapter I. Cells and Batteries.--II. Battery Fluids and
Solutions.--III. Miscellaneous Apparatus and Methods of
Construction.--IV. Switches and Cut-Outs.--V. Binding-Posts and
Connectors.--VI. Permanent Magnets.--VII. Magnetic Needles and
Compasses.--VIII. Yokes and Armatures.--IX. Electro-Magnets.--X.
Wire-Winding Apparatus.--XI. Induction Coils and Their
Attachments.--XII. Contact Breakers and Current Interrupters.--XIII.
Current Detectors and Galvanometers.--XIV. Telegraph Keys and
Sounders.--XV. Electric Bells and Buzzers.--XVI. Commutators and Current
Reversers.--XVII. Resistance Coils.--XVIII. Apparatus for Static
Electricity.--XIX. Electric Motors.--XX. Odds and Ends.--XXI. Tools and
Materials.
"The author of this book is a teacher and writer of great
ingenuity, and we imagine that the effect of such a book as this
falling into juvenile hands must be highly stimulating and
beneficial. It is full of explicit details and instructions in
regard to a great variety of apparatus, and the materials required
are all within the compass of very modest pocket-money. Moreover,
it is systematic and entirely without rhetorical frills, so that
the student can go right along without being diverted from good
helpful work that will lead him to build useful apparatus and make
him understand what he is about. The drawings are plain and
excellent. We heartily commend the book."--Electrical Engineer.
"Those who visited the electrical exhibition last May cannot have
failed to notice on the south gallery a very interesting exhibit,
consisting, as it did, of electrical apparatus made by boys. The
various devices there shown, comprising electro-magnets, telegraph
keys and sounders, resistance coils, etc., were turned out by boys
following the instructions given in the book with the above title,
which is unquestionably one of the most practical little works yet
written that treat of similar subjects, for, with but a limited
amount of mechanical knowledge, and by closely following the
instructions given, almost any electrical device may be made at
very small expense. That such a book fills a long-felt want may be
inferred from the number of inquiries we are constantly receiving
from persons desiring to make their own induction coils and other
apparatus."--Electricity.
"At the electrical show in New York last May one of the most
interesting exhibits was that of simple electrical apparatus made
by the boys in one of the private schools in the city. This
apparatus, made by boys of thirteen to fifteen years of age, was
from designs by the author of this clever little book, and it was
remarkable to see what an ingenious use had been made of old tin
tomato-cans, cracker-boxes, bolts, screws, wire, and wood. With
these simple materials telegraph instruments, coils, buzzers,
current detectors, motors, switches, armatures, and an almost
endless variety of apparatus were made. In his book Mr. St. John
has given directions in simple language for making and using these
devices, and has illustrated these directions with admirable
diagrams and cuts. The little volume is unique, and will prove
exceedingly helpful to those of our young readers who are fortunate
enough to possess themselves of a copy. For schools where a course
of elementary science is taught, no better text-book in the first
steps in electricity is obtainable."--The Great Round World.
Exhibit of Experimental Electrical Apparatus
AT THE ELECTRICAL SHOW, MADISON SQUARE GARDEN, NEW YORK.
While only 40 pieces of simple apparatus were shown in this exhibit, it
gave visitors something of an idea of what young boys can do if given
proper designs.
[Illustration:
"HOW TWO BOYS MADE THEIR OWN ELECTRICAL APPARATUS"
Gives Proper Designs--Designs for over 150 Things.]
BY THE SAME AUTHOR--(LIST R)
LIST NO. LIST PRICE
R1--FUN WITH MAGNETISM. A book and complete outfit of apparatus for
sixty-one experiments. Weight 4 ounces. Price $0.35
R2--FUN WITH ELECTRICITY. A book and complete outfit of apparatus for
sixty experiments. Weight 1 pound. Price $0.65
R3--FUN WITH PUZZLES. A book and complete outfit for four hundred
puzzles with key to them. One pound. Price $0.35
R4--FUN WITH SOAP-BUBBLES. A book and complete outfit of apparatus for
fancy bubbles and films. One pound. Price $0.35
R5--FUN WITH SHADOWS. A book and complete outfit of apparatus for shadow
pictures, pantomimes, etc. One pound. Price $0.35
R6--FUN WITH PHOTOGRAPHY. A book and complete outfit of apparatus for
amateur work. One pound. Price $0.65
R7--FUN WITH CHEMISTRY. A book and complete outfit of apparatus for
forty-one experiments. One pound. Price $0.65
R41--ELECTRIC SHOOTING GAME. Absolutely harmless; fascinating. Paper
bullets shot by electricity. One pound. Price $0.35
R42--ELECTRIC AIR-SHIPS AND OTHER GAMES. Great fun. Get into the game;
be an aviator at home; for two players. One pound. Price $0.35
R43--ELECTRIC FORTUNE-TELLER tells a lot. Mysteriously electric. Comic
and otherwise. In preparation. One pound. Price $0.35
R51--HOW TWO BOYS MADE THEIR OWN ELECTRICAL APPARATUS. A book containing
complete directions for making many kinds of electrical apparatus.
Seventh edition; 141 pages; cloth. Price $1.00
R52--THE STUDY OF ELEMENTARY ELECTRICITY AND MAGNETISM BY EXPERIMENT. A
text-book for students and others. Systematic course for home or school.
220 pages; 200 experiments; cloth; fourth edition. Price $1.25
This book with 105 pieces of apparatus complete, by express $6.25
R53--THINGS A BOY SHOULD KNOW ABOUT ELECTRICITY explains in simple
language things a boy wants to know, things he should know. Seventh
edition. 180 pages; cloth. Price $1.00
R54--REAL ELECTRIC TOY-MAKING FOR BOYS contains complete directions for
making and using many electrical toys. Over 100 original drawings,
diagrams and plates. Second edition; 140 pages, cloth. Price $1.00
R55--WIRELESS TELEGRAPHY FOR AMATEURS AND STUDENTS contains theoretical
and practical information, together with directions for performing
numerous experiments on wireless with simple home-made apparatus. Third
and enlarged edition in preparation. Price $1.00
R56--ELECTRICAL HANDICRAFT contains complete directions for making and
using nearly 150 pieces of electrical apparatus, including various
devices and outfits for experimental purposes. New ideas and inexpensive
supplies. Cloth; 252 pages; 250 drawings. Second edition. Price $1.00
R57C--THE STUDY OF ELECTRIC MOTORS BY EXPERIMENT contains sixty
experiments that bear directly upon the construction, operation and
explanation of electric motors, together with much helpful information
upon the apparatus required. Over 100 pages; paper cover. Price $0.35
R58--THINGS A BOY SHOULD KNOW ABOUT WIRELESS contains much practical and
some theoretical information on the operation and explanation of
wireless outfits, together with numerous wiring-diagrams. Third edition;
126 pages; cloth. Price $1.00
Ask your Bookseller, Toy-dealer or Electrical Store for our Books,
Games, Toys and Electrical Apparatus.
Write for Catalogue.
THOMAS M. ST. JOHN, Cascade Ranch, East Windham, N.Y.
* * * * *
HOW TWO BOYS MADE THEIR OWN ELECTRICAL APPARATUS
Containing Complete Directions for Making All Kinds of Simple
Apparatus for the Study of Elementary Electricity
by
THOMAS M. ST. JOHN, Met. E.
Author of "Fun With Magnetism," "Fun With Electricity,"
"The Study of Elementary Electricity and Magnetism
by Experiment," "Things A Boy Should Know
About Electricity," etc.
Eighth Edition
Thomas M. St. John
Cascade Ranch
East Windham New York
Copyright, 1898,
by Thomas M. St. John
How Two Boys Made Their Own Electrical Apparatus.
TABLE OF CONTENTS.
CHAPTER. PAGE.
I. Cells and Batteries, 5
II. Battery Fluids and Solutions, 15
III. Miscellaneous Apparatus and Methods of Construction, 20
IV. Switches and Cut-Outs, 28
V. Binding-Posts and Connectors, 32
VI. Permanent Magnets, 37
VII. Magnetic Needles and Compasses, 40
VIII. Yokes and Armatures, 45
IX. Electro-Magnets, 51
X. Wire-Winding Apparatus, 60
XI. Induction Coils and Their Attachments, 64
XII. Contact Breakers and Current Interrupters, 75
XIII. Current Detectors and Galvanometers, 78
XIV. Telegraph Keys and Sounders, 92
XV. Electric Bells and Buzzers, 104
XVI. Commutators and Current Reversers, 110
XVII. Resistance Coils, 114
XVIII. Apparatus for Static Electricity, 117
XIX. Electric Motors, 122
XX. Odds and Ends, 133
XXI. Tools and Materials, 137-141
A WORD TO BOYS.
The author is well aware that the average boy has but few tools, and he
has kept this fact constantly in mind. It is a very easy matter for a
skilled mechanic to make, with proper tools, very fine-looking pieces of
apparatus. It is not easy to make good apparatus with few tools and a
limited amount of skill, unless you follow simple methods.
By following the methods given, any boy of average ability can make the
apparatus herein described.
Most of the illustrations have been made directly from apparatus
constructed by young boys.
It is impossible to describe the different pieces of apparatus in any
special or logical order. It is taken for granted that you have some
book of simple experiments and explanations to serve as a guide for the
order, and to give you an idea of just the apparatus needed for the
special experiments.
It would be foolish to start in and make all the apparatus described,
without being able to intelligently use it in your experiments. Take up
a systematic course of simple experiments, and make your own apparatus,
as needed.
Before making any particular piece of apparatus, read what is said about
the other pieces of the same general nature. This will often be a great
help, and it may suggest improvements that you would like to have.
In case your apparatus does not work as expected, read the directions
again, and see if you have followed them. Wrong connections, poor
connections, short circuits, broken wire, etc., will make trouble. With
a little patience and care you will be able to locate and correct any
troubles that may come up in such simple apparatus.
THOMAS M. ST. JOHN.
How Two Boys Made Their Own Electrical Apparatus
CHAPTER I.
CELLS AND BATTERIES.
APPARATUS 1.
_1. Carbon-Zinc Cell._ Fig. 1. If you have some rubber bands you can
quickly make a cell out of rods of zinc and carbon. The rods are kept
apart by putting a band, B, around each end of both rods. The bare wires
are pinched under the upper bands. The whole is then bound together by
means of the bands, A, and placed in a tumbler of fluid, as given in
App. 15. This method does not make first-class connections between the
wire and rods. (See Sec. 3.)
[Illustration: Fig. 1.]
APPARATUS 2.
[Illustration: Fig. 2.]
_2. Carbon-Zinc Cell._ Fig. 2. In case you want to make your cell out of
carbon and zinc rods, and do not have any means of making holes for them
in the wood, as in App. 3 and 4, you will find this method useful. Cut
grooves, G, into one side of the wood, A, which should be about 4-1/2 x
1 x 1/2 in. The grooves should be quite deep, and so placed that the
rods will be about 1/4 in. apart. A strip of tin, T, 1/2 in. wide,
should be bent around each rod. The screw, S, put through the two
thicknesses of tin will hold the rod in place. Another screw, X, acts as
a binding-post. The zinc rod only is shown in Fig. 2. The carbon rod is
arranged in the same way. Use the fluid of App. 15.
3. Note. When the bichromate solution of App. 15 is used for cells, the
strong current is given, among other reasons, because the zinc is
rapidly eaten up. This action goes on even when the circuit is broken,
so always remove and wash the zinc as soon as you have finished.
APPARATUS 3.
_4. Carbon-Zinc Cell._ Fig. 3. The wooden cross-piece, A, is 4-1/2 x 1 x
1/2 in. The carbon and zinc rods, C and Z, are 4 in. long x 1/2 in. in
diameter. The holes are bored, if you have a brace and bit, so that they
are 3/4 in. apart, center to center. This makes the rods 1/4 in. apart.
To make connections between the rods and outside wires, cut a shallow
slot at the front side of each hole, so that you can put a narrow strip
of tin or copper, B, in the hole by the side of each rod. Setscrews, S,
screwed in the side of A, will hold the rods in place, and at the same
time press the strips, B, against them. Connections can easily be made
between wire and B by using a spring binding-post, D, or by fastening
the wire direct to the strips, as shown in App. 4.
[Illustration: Fig. 3.]
Use the battery fluid given in App. 15, and use a tumbler for the
battery jar. This cell will run small, well-made motors, induction
coils, etc. (See Sec. 3.)
APPARATUS 4.
_5. Carbon-Zinc Cell._ Fig. 4. The general construction of this cell is
the same as that of App. 3. There are 2 carbons, C, each 4 x 1/2 in. The
holes for these are bored in A 1-1/4 in. apart, center to center. The
zinc rod, Z, is a regular battery zinc, 6 x 3/8 in., and has a
binding-post, Y, of its own. The rods, C, are held in A, and connections
are made as explained in App. 3.
[Illustration: Fig. 4.]
The wire, X, is fastened direct to the strips, B, as shown. When ready
to use this cell, be sure that the wire connecting the carbons does not
touch Z. (Why?) The other wire is connected to Y. The wooden piece is
4-1/2 x 1 x 1/2 in. Use the battery fluid of App. 15 in a tumbler. This
cell will run small motors, and is good for induction coils, etc. (See
Sec. 3.)
APPARATUS 5.
[Illustration: Fig. 5.]
_6. Experimental Cell._ Fig. 5. Cut a strip each of copper, C, and zinc,
Z. (See list of materials.) They should be about 2 in. wide and 4 in.
long. Punch a hole through each, one side of the center, for screws, E.
The wooden cross-piece, A, should be 4-1/2 x 1 x 7/8 in. The
battery-plates, or elements, should be screwed to this, taking care that
the screws, E, do not touch each other. If the holes are made in the
position shown in Fig. 5, the screws can be arranged some distance
apart.
The wires leading from the cell may be fastened under the screws with
copper burs, or spring binding-posts (App. 42) can be slipped on the top
of the plates.
The solution to be used will depend upon what the cell is to do. For
simple experiments use the dilute acid (App. 14). If for small motors,
use the formula given in App. 15. The zinc should be well amalgamated.
(App. 20.)
APPARATUS 6.
[Illustration: Fig. 6.]
_7. Experimental Cell._ Fig. 6. In some experiments a comparison is made
between cells with large plates and cells with small ones. This form
will be convenient to use where narrow plates are desired. Those shown
are 4 x 1/2 in. They are screwed to the cross-piece, which is 4-1/2 x 1
x 7/8 in. Do not let the screws touch each other. The wires are fastened
under the screw-heads.
APPARATUS 7.
[Illustration: Fig. 7.]
_8. Experimental Two-fluid Cell._ Fig. 7. This cell has a zinc strip, Z,
and copper cylinder, C, for the "elements." The porous cup, P C, is
fully described in App. 11. Z is 5 x 1 in., and should be well
amalgamated (App. 20). (Study reasons for amalgamation.) A zinc rod,
like that shown in Fig. 4, may be used instead of the strip. The copper
cylinder, C, nearly surrounds P C, and is made from a piece of thin
sheet-copper, 6 x 2 in. The narrow strip, or leader, A, is 5 x 1/2 in.
To fasten it to C, punch two small holes in C and A, put short lengths
of stout copper wire through the holes, and hammer them down so that
they will act as rivets, R. C can be hung centrally in the tumbler by
bending A as shown. Y and X are spring binding-posts (App. 42). The
battery wires can be fastened directly to Z and A, as suggested in Fig.
4.
9. Setting up the Cell. Arrange as in Fig. 7, but remove Z from P C.
Pour some of the acid solution of App. 14 into P C until it stands about
2-1/2 in. deep, and at once pour the copper solution of App. 16 in the
tumbler, on the outside of P C, until it stands at the same height as
the liquid in P C. As soon as the liquids have soaked into P C, you can
put Z in place, when the cell will be ready for use. Remove and wash Z,
when you have finished, and if you wish to use this cell occasionally,
remove the liquids and wash P C thoroughly in water. When dry it will be
as good as new. The acid rapidly acts upon Z, so it is better to remove
Z if you wish to leave the experimenting even for a few minutes only.
Put a few crystals of copper sulphate (blue vitriol) in the tumbler
under the copper, to keep the copper solution saturated. (See text-book
for the chemical action in this two-fluid cell.)
APPARATUS 8.
_10. Two-fluid Battery._ Fig. 8. When two or more cells are joined
together the combination is called a battery. Fig. 8 shows two
experimental cells joined in series. (Study methods of joining cells.)
For convenience, and to keep them from being easily overturned, a frame
has been made for them. The base, B, is 8 x 4 x 7/8 in. To the back of
this is nailed the upright board, A, 8 x 4-1/2 x 1/2 in. On the top of A
are 3 binding-posts, 1, 2, 3, which consist of metal strips 1-1/4 x 1/2
in. At the lower ends are screws which are connected with the cells, as
shown. Spring binders can be easily slipped on and off the upper ends of
the strips, so that one or two cells can be used at will. Bent strips,
C, are nailed to B, to hold the tumblers firmly in place. This framework
is not necessary, of course, to the proper working of the battery, but
with it you are much less liable to upset the cells.
[Illustration: Fig. 8.]
APPARATUS 9.
_11. Gravity Cell._ Fig. 9. In the two-fluid cell of App. 7 the fluids
were kept apart by the porous cup. The gravity cell is really a
two-fluid cell in which the two liquids are kept separate by the joint
action of the current and the force of gravity. This cell is used for
telegraph lines and for other closed-circuit work.
12. Construction. The zinc and copper, Z and C, Fig. 9, can be purchased
about as cheaply as you can make them. There are many forms of the
zincs, the one shown being called the crow-foot shape. The copper may be
star-shaped, or as shown. If you wish to make C, use thin sheet-copper.
Brush copper, 1-3/4 in. wide, is excellent for the purpose. Use a piece
12 or 15 in. long, and fasten to one end of it a copper wire, W, which
must be covered with paraffined paper, or with rubber or glass tubing,
where it passes up through the zinc sulphate solution and near Z. The
glass jar, J, may be made from a large glass bottle. (See index for
battery jars.)
13. To Set Up the Cell. (A) Place C upon the bottom of J, with W in the
position shown. (B) Put in enough copper sulphate crystals to cover the
bottom of J, but do not try to entirely cover C. At the start 1/2 lb.
will be enough. (C) Pour in clean water until J is half full. (D) In
another vessel dissolve 1 or 2 oz. of zinc sulphate in enough water to
complete filling, J. (E) Hang Z in place (Fig. 9). Z must never touch C.
They should be about 3 in. apart. A wire is attached to Z by the screw,
S, and the hole, H. (F) Pour the zinc sulphate solution into J until it
is within an inch of the top. It should cover Z.
[Illustration: Fig. 9.]
(G) Connect the wires leading from Z and C to your sounder and key. (See
diagram.) The cell will be weak at first, and it may not be able to run
your sounder. If this is the case, "short-circuit" it by allowing the
current to run around and around through the sounder and key, the switch
being closed. You may also "short-circuit" the cell by joining the two
wires together. This will, in a few hours, make the dividing line
between the blue and white quite distinct, when the cell will be
stronger. If you have a short line only, the battery may be
short-circuited through your sounder or other coils of wire for 5 or 6
hours a day, without working it too much. It may be necessary to draw
off some of the clear zinc sulphate, replacing it with clear water, if
the blue line gets too low. Add water occasionally to make up for
evaporation.
14. Regulating. The two solutions are kept apart by gravity, as the
copper sulphate is heavier than the zinc sulphate. The dividing line
between the blue and white solutions is fairly clear when the battery
works well, and it should be about half way between C and Z, or about at
J, Fig. 9. Never allow the blue to get as high as Z, as this indicates
that the cell is not worked enough. The dividing line can be lowered by
allowing it to run a buzzer or bell for a few hours, or by simply
short-circuiting it. If the blue gets much below J it indicates that you
are working the cell too hard, or that you need more copper sulphate.
The harder the cell works, the more zinc sulphate is formed, and the
lower the dividing line becomes.
15. Gravity Batteries of two more cells are needed when used on
telegraph lines. You will need 1 cell to each sounder; that is, for a
short line in the house with two sounders, use 2 cells. If you use a few
hundred feet of wire running to a friend's house, use 3 cells. They must
be joined in series; that is, the copper of one to the zinc of the
other. (See diagram of complete telegraph line.) Do not use ground
connections for short lines and home-made sounders; use a return wire.
Do not use different kinds of cells upon the same line.
APPARATUS 10.
_16. Storage Battery._ To show the principle of storage batteries it is
only necessary to use two plates of lead dipped in the battery fluid of
App. 14. The cell may be made as in App. 5, Fig. 5, the only difference
being that both plates are of sheet-lead. It will be an advantage to
make the plates rough by hammering against them a coarse file. (See
explanations and experiments with this form of cell in text-book.)
APPARATUS 11.
[Illustration: Fig. 10]
_17. Porous Cups for Two-fluid Cells._ Fig. 10. Very good porous cups
can be made from ordinary blotting-papers, the average ones measuring
9-1/2 x 4 in. White ones should be used, so that you will not be
bothered with the color coming out. Soak the edge along one end of the
blotter in paraffine (Index) for about 1/4 in. When this is cold, roll
the blotter into the form of a cylinder that is a little over 1 in.
inside diameter, and have the paraffined end on the outside. This will
make 2 thicknesses of paper all around, and a little to spare. Rub a hot
nail over the paraffine to melt it, and stick the end to the cylinder.
By putting on a little more paraffine along the edge where the end laps
over, a good solid cylinder can be made. The cylinder should be
strengthened still more by dipping each end into melted paraffine for
about 1/8 in. The dark stripes around the ends and down the front of the
cylinder (Fig. 10) are to represent the paraffine. Cut out a bottom
about 1/4 in. larger all around than the cylinder. This may be
paraffined to make it stiff. It should be fastened to the cylinder with
paraffine. Paraffine is not acted upon or softened by water or acid, as
is the case with glue.
APPARATUS 12.
_18. Porous Cups for Two-fluid Cells._ Instead of the blotters of App.
11, you can use short lengths of mailing-tubes, which are used to
protect pictures, etc., when sent by mail. If you find that the
particular tube tends to unwind when soaked, you can use a little
paraffine along the edges of the spiral, as suggested in App. 11.
Bottoms can be made for the cups as before.
APPARATUS 13.
_19. Porous Cups for Two-fluid Cells._ Ordinary unglazed earthen
flower-pots make good cups. The hole in the bottom should be closed with
a cork, or by fastening a piece of pasteboard over the hole with
paraffine. The pasteboard may be fastened to the under side of the
bottom more easily than to the upper side.
20. Note. It is a good idea to soak the top edge of porous cups for
about 1/4 in. in paraffine to keep the solutions from crawling up by
capillary attraction. If the solutions constantly evaporate from the
soaked tops of the cups, they not only waste but they get the whole
thing covered with crystals.