Evening star., 1896-12-05
A BOYS INGENUITY
How He Succeeded in Making a
Toy Dynamo.
1t LESS THAN A DOLLARS EXPENSE
Only Few Pieces of Iron, Wood.
Wire, Etc, Needed.
SOME OF THE RES ULT s

In actual cash young John Hartley's toy
Hyramo cost less than a dollar 1t was
worth good deal MORE than that to John
he hCwever. for he made il, himself. and it
had for him certain and lasting value in
the form of that knowledge which is born
only of experience. When he first thought
about the undertaking, il seemed almost
too dlfficUIt for him TO try, and II Is doubt
ful whether he would ever have made
beginning even had he not been fortunate
enough to be acquainted with young man
who knows all about the full size dynamos
that run trolley cars and electric lights and
stationary motors III manufactures and
else :, here.
The first thing of Importance learned by
the boy about dynamo was that the
parts OF g perfectly practical machine for
the making of electric current need
be very few. These parts are all shown
in the pictures accompanying this article;
they are, first, the magnet; second, the
armatUre and shaft; third, the .'exciters;''
fourth, the brushes end fifth, the pull
ley"
All these things can he made out of few
small pieces of frCn and sheet copper, a
common spool which silk has been
wound flor the pulley and a half pound
of No. ~ copper wire. Besides there must,
OF course. be certain framing, not included
in the working parts of the dynamo, but
necessary 10 hold them together. The form
adopted by young Hartley under his
friends advice is clearly shown in the pic
ture- His magnet was of the horseshoe
form-the form used in all the earlier
dynamos Of large pattern. though il has
been discarded of late by some of the most
prominent and successful dynamo builders
fer other forms and combinations more
compact and perhaps more effective, but
not 50 simple, and not so available in
making such d machine as John had in
mind
John did not find it easy to buy a mag
net of just the size and form he wanted,
and so he got from blacksmith a piece
of steel twelve inches long. two inches
wide and a quarter Of an inch thick. pay
ing only few cents for it by weight.
w h=n the blacksmith understood what the
boy wanted of the metal he laughed and
bent ii to the required form, and then
hardened il for frieIdship.' he said When
this vas done. John took the steel to the
power house of the trolley line whose cars
run through the street his house is on, and
got the superintendent to magnetic it by
passing strong current through 1t from
the big dynamo. The bent piece of steel
was then q permanent magnet, one end
being the positive north pole and the
other the negative or south pole"
Making the Frame.
The space between the poles of the mag
net was ~ inches, and John cut out two
pieces of wood a shade larger than 2E
inches one way, 2 inches the other way
and a quarter of an inch thick. Then he
whitfield out two strips of wood, inches
long by 1 inch wide. Through one of these
strips he cut two oblong holes, each about
quarter of an inch long and about a quarter
of an inch apart. These were to serve as
arms to hold the front bearing of the
armature shaft to be mentioned later.
Then two strips of wood "a inches long
by inch wide were made quarter
frf.h afp hole do fI<.
center of each piece. one being fastened to
the two large pieces to serve as the
rear bearing for the armature shaft, and
the other to the ends of the two 1-inch
arms Just mentioned. When the six pieces
of wood wers properly fastened together
with screws. they formed the frame of the
dynamo. and presented the appearance
shown in the picture. The two large pieces
were exactly q. inches apart and the space
inclosed by the frame and the top and bot
tom of the magnet exactly square.
Acting on his friends instructions, John
had been extremely careful to have this
just right.
The next step to be taken was one of the
most important of all. 1t was the making
and winding of the armature. The shape
OF the core and shaft of the armature is
shown In one of the cuts. The core proper
was an inch long and about rs of an inch
in diameter The shaft longer. and
either end was passed through holes in the
frcnt and back pieces of the frame. which
served as bearings: the front piece of
course, had TO be removed in order to put
the shaft in position and then screwed i'm
place again John was puzzled a long time
about getting the peculiar shaped piece of
iron needed for the armature core and
shaft, but his blacksmith friend finally
came 20 his aid.
SILK and Wire.
Before he put the armature in its place
he had to wind II with silk or cotton-cov-
cred wire. He chose the silk covering.
though it cost a little more. because it is
better and the difference In price was not
enough TO count much on so small guam
NY NJ II ~ T@ ~"~ wv