The Electrical experimenter

May, 1917 THE ELECTRICAL EXPERIMENTER 37
nets and armature on 4 columns consisting
of six Jx incli tibre washers, the wliole being
mounted upon a suitable baseboard of 9
inches by 6 inches oak ( I'ig. 3). The piece
L is of I J inch brass -j^ inch long and is
threaded at both ends so as to receive the
adjusting screw of spring T at one end
and a screw that holds L to the base at the
other end. One-and-one-half inch stovebolts,
y, hold the frame of the sounder to
the base. The machine screws to hold the
magnets must be 2 inches long in order to
go thru the base, the washers, the yoke of
the magnets and finally screw into the magnets
themselves.
Then sliape a hook of l4 or 3/32 inch
stock, as shown in Fig. 2. .\ fret saw may
be used to cut it out with, but any one at
all handy with a tile can shape the hook
quite as well.
Xow remove the armature of the sounder
by pressing the uprights outwards. Urill
and tap a hole for an i^/32 screw '4 inch
from the end of the armature shaft (Fig.
7). Slip an 8/32 machine screw into the
upper hole of the hook and screw it into
the armature, so that the hook swings easily
but has very little play. Lock the bolt on
the other side of the armature by a nut M.
The armature now looks as in F'ig. 7.
The commutator is made from a small
wooden cylinder having a hole bored thru
it longitudinally. Brass segments are
screwed round it, in a manner to be described.
The author found considerable
difficulty in securing a cylinder of suitable
size, but he finally used one of the small
wooden rollers on which the paper for adding
machines is wound. Such a cylinder is
3-j,s inches long, ys inch in diameter and has
a 7/16 incli hole thru it, and will answer
very well for the purpose.
Cut a piece of 1/64 inch brass as shown in
Fig. 4 and drill small holes near the corners
as indicated. The brass is attaclied to the
cylinder by' small I4 inch brass screws. Screw
one segment of brass down on the cylinder
near one end, then bend the brass
around the cylinder and screw the second
segment on. -V reference to E and G of
Fig. 1 will serve to make this clear. Before
screwing the last segment down, drill
a small hole diametrically thru the roller
to meet the central hole, and pass a thin
wire thru it, so that the wire is underneath
the last segment. The other end of the
wire should come out thru the last hole in
the cylinder. It will now be evident that
there is an electrical connection from the
protruding wire to every commutator segment.
The shaft for the commutator is made of
Wiring Scheme for the "Eiectricai Paradox"
Which Enabies the iVIanlpulator to Successsiveiy
and Indlviduaily Light and Extinguish
Any One of Three Lamps, by Simply
Operating the Main Switch Three Times.
7/16 inch steel or brass, 4^ inches long.
The details for it are shown at A (Fig.
5). Force the shaft into the hole in the
cylinder so that it projects the sarne distance
from either end. While putting the
shaft in, the wire that comes thru the hole
will be caught between the shaft and the inside
wall of the cylinder, so that an electrical
circuit is established from the shaft to
all the segments of the commutator. The
brushes 1 (Fig. \) that bear against the
segments are of \'> inch wide spring brass.
Three of these are needed, 3 inches long.
They are supported on the two oak blocks
H 11, 3!i( inches long, by \'/2 inches wide
and Yz inch thick. One of the oak blocks
must have three small
holes thru it so that
the holes are vertical
as the blocks stand on
end. The outer two
holes are 9/16 inch
from the end, and the
inner one is in the center.
These holes are
for the wires which
connect the brushes to
the binding posts.
Drill Ys inch holes in
the brass strips as
shown ( Fig. 1 ) but do
not fasten them to the
oak blocks until later.
Procure a ratchet
wheel R (Fig. 3) V/s
inches in diameter, and
Js inch thick, also two
cog wheels, J and K
(Fig. 1), K being 1^4
inches long and having
48 teeth, and J having
12 teeth. The larger
cog and the ratchet
should each have a Y
inch hole thru their
centers, the smaller
cog a 3/16 inch hole.
Then turn a shaft B,
the details of which
are given in Figure 5.
The end bearings for
the two shafts are
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made of i/i2 inch or '/i inch wrought iron.
They may be shaped as shown at X (Fig.
3) or V (Fig. \). Bearing X has a Yi inch
hole drilled 13/16 inch up, and Y has a Yi
inch hole drilled 1 1/16 inches up from the
bottom. The center bearing D (Fig. 1)
must be wider than the other two since it
supports both shafts. The details for its
construction are shown in F'ig. 6. The
holes should be laid out very carefully and
accurately, as upon them depends the proper
meshing of the two cogs, and consequently
the smooth operation of the contrivance.
The uprights U and Y are made of y%
inch brass or steel. They are threaded at
the lower end so as to be held down to the
base by nuts. U should be about 2'.. inches
high and Y, 2 inches. Three-eighths inch
from the top of Y, drill and tap a hole
diametrically- thru it, to receive an 8/32
spring adjusting screw. On U solder a
cross-piece which has an adjusting screw
and lock nut X in it. Place U so that
when it is screwed down, X' will touch the
center of the armature shaft. Y is directly
in front of the ratchet, but far enough
away so as not to interfere with the ratchet's
operation.
The parts are now ready for assembling.
First put the armature shaft back into its
supports. Then place the small bearing .X
in such a position that when the ratchet is
put on the shaft and the shaft into the
bearing the hook will engage a tooth of the
ratchet. (Be careful to have the direction
of pitch of the ratchet just as shown in Fig.
3 and not the reverse way.) When the position
of hearing and of the ratchet have
been determined, solder the latter to shaft
B in the required position, and also solder
cog K to B. about 1/16 inch from the end
of the shoulder. Bearing X may now be
screwed down.
Pass the long shoulder of shaft A, i.e., the
left end (Fig. 5), thru the upper hole of
bearing D. Then force the small cog J on
to this long shoulder far enough so that
there is very little play, but not so far as
to cause the cog to bind on the bearing.
Xow place the cog wheel end of shaft B
into the lower hole of D, and if the work
has been done correctly, the cogs will mesh
with each other. Then slip bearing Y on
to the other end of the commutator shaft.
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Commufator shaft
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B-
Rafchet ihaft
f/g 5
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L-.
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holes drilled^
each s/i^
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Detail Worsting Drawings of Parts Necessary in Constructing the
"Eiectricai Paradox."
-After a little experimenting to place the
bearings in such a position as to make the
parts turn with as little friction as possible,
screw bearing D and Y down (after shaft
B is in position of course). Before screwing
Y down, drill a small hole thru the
base directly beneath it ar ' pass a thin wire
thru this hole so that the bearing will press
on the wire. Connect the other end of the
wire underneath the base to a binding post.
It will now be noticed that contact is established
from the binding post to bearing
Y, from Y to the shaft A, and from there
to the commutator segments E E E.
Place the oak blocks parallel to the commutator,
at equal distances on either side
of it and 3 inches apart. Drill 3 small holes
thru the base at places to correspond with
the 3 holes in one of the blocks. Then
fasten the blocks down to the base with
screws. (It must be clearly understood
that the screws DO XOT go thru these
holes, but thru other holes which may be
bored for the purpose.) Pass a wire
thru each of the holes in the base
and thru the block, so that they project
from the top. Xow screw the brushes down
on the blocks (this time the screws go
thru the holes in the block). Connect the
three wires from the under side of. the
base to three binding posts. Contact is
now established from each binding post to
each brush and to that commutator segment
which happens to be touching that brush
at the moment. Connect one of the wires
from the magnet to a binding post and the
other wire splices on to tlie wire coming
from bearing Y. (Refer to Fig. 8.) Put
a light brass spring S thru the hole in C
and hook it over the spring adjusting screw
in Y, so that it can be adjusted to any tension.
The spring T is of fairlv heavy steel,
since it is its tension that really drives the
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