The Experimenter for April, 1925 length of one inch. Four fibre plugs three eighths inch thick and of a diameter to fit the tubes snug come next. Drill holes in the exact center of each plug so that the brass Next bend the brass rods will screw in. rods in the shape of a "U" so that each rod will fit the holes in the plugs when they are placed in adjacent tubes. Get two short pieces brass rod about one inch long and of a diameter to fit the brass balls; thread one end of each rod to fit tight in the brass balls. These short pieces are to be welded one to the exact center of each U-shaped rod. Get six brass nuts to fit the bent brass rods, co: two of them in half, making eight nuts in all.. Now assemble the terminals by placing a half nut on each leg of the bent rods, next put on the fibre plugs, then a brass washer one inch in diameter, then a full nut; turn up the last nut until it is flush with the end of the rod, then turn clown the half nut until it is good and tight, put on the brass balls, and place in the tubes, first coating the edge of the plugs with good. strung glue or thick shellac. Press the plugs down firmly upon the paper discs so that a Wire good electrical contact is obtained. the plugs in while crying so that the pressure is not released which would result in a weak battery. Next mount the clock works. The movement used was that of a discarded electrically wound, sixty beat movement. Everything not necessary in the actual gear train was removed, including the main spring; the pendulum was also discarded. The small brackets, which originally held the clock to the back board, are to be bent ttp. An oak board one inch thick, (our inches wide, twenty inches long is firmly glued to the back of the baseboard and farther secured with two long brass screws; two cleats of oak are then fastened to this backboard with glue, one at the top, the other six inches below. These cleats form the support for two brass rods of a diameter to fit the clock brackets and in turn pass through the cleats in which hules are drilled for the purpose; these holes must be parallel and. straight, therefore it is best to drill the cleats after glueing. The brass rods are first threaded one end just the enough to accommodate a brass nut other is threaded to s length of four inches. In all, the length of the rods will be about ;
\
,play
large as possitle. resting on a wooden box. which should not stand high. A boat with a piece of iron or steel on its bottom floats on water filling the copper pan. The phonograph could be operated by a motor and the magnet could be an electromagnet. Tile latter s mounted on a wooden be as
BOAT W/TH
BOTTOM MAGNET
$50
.
TÉEL
5/ 4/4OW DAN
IN PRIZES
A special prize contest for Junior Electricians and Electrical Experimenters
will
be
held
each
month.
There will be three monthly prizes as
follows: First Prize Second Prize Third Prize Total This department
$25.00 in gold $15.00 in gold $10.00 in gold $50.00 in gold
desires particularly to publish new and original ideas on how to make things electrical, new electrical wrinkles and ideas that arc of benefit to the user of electricity, be he a householder, business man, or in
factory. There are dozens of valuable little stunts and ideas that we young men run across every month, and we mean to publish these for the benefit of all electrical experimenters. This prize contest is open to everyone. All prizes will be paid upon publication. If two contestants submit the same idea, both will receive the same a
prize. Address, Editor. Electrical Wrinkle Contest, in care of this publication. Contest closes on the 15th of each month of issue.
than necessary. The one used by the writer, as cut to finished length, is six and a quarter incites long. The extra three incites allow for regulating. Attached to the lower end
CThird Prize Window Attraction
attractive and effective window disis illustrated here. It consists of a ccpper pan, which should
A L
411 nine inches. The holes drilled through the cleats must be spaced to agree with the distance between the clock brackets, and in such position that the pendulum will hang exactly in the center of the baseboard of the battery stand. This will govern the width of the cleats to be used. The thin brass rod secured to the escapement must be removed and a thin one sixteenth fibre rod substituted in its stead which is held in place with sealing wax. Have the fibre rod about three inches longer
Under a copper pan containing water a magnet is rotated by a phonograph mechanism; a boat with an iron plate or keel floats on the water and goes round and round in a circle following the magnet. Be sure not to use an iron vessel to hold the water.
the fibre rod by means of a small rubber band. The fibre rod runs through a hole drilled through the brass ball. Assemble the brass rods and clock movement through the cleats as shown; eight brass nuts are used for this purpose. Now to start and adjust. It may be necessary to turn the movement upside down, as in the case of the movement used. First make a couple of clamps of oak, one for each side of the battery piles; drill holes in each end to take a quarter -inch bolt; also drill a quarter -inch hole in each corner of the baseboard. Four of these bolts are required about four and a half inches long. The size of the pieces of wood for the clamps is one inclt square by eight inches long. The alternate attraction and repulsion of the little brass ball furnishes the motive power for the clock. Place the small brass hall about five incites from the escapement lever. Now lower the clock movement, by means of the brass nuts on the rods fastened to the upright piece, so that the small brass ball just about hits the center of the large brass balls fastened to the batteries. Now start the pendulum swinging. It must he remembered that the brass balls must always hang at exactly the same distances from the pendulum balls. The slightest difference will affect the proper regulating of the clock. Place the damps in position to hold down the battery piles, moving the entire battery (butlt sides an equal distance always) back and forth and by sliding the pendulum ball up and down upon the fibre rod until the clock is regulated within ten seconds error in twenty-four hours This requires a world of patience, but it is worth the trouble. If it runs slow, slide tite battery piles closer to the center, clamping them down each time with the same amount of pressure, sliding the brass ball upon the pendulum roll and lowering the clock movement down. If too fast, reverse the operation. As accuracy is acquired. cut off a little of the extra length from the pendulum rod. This will make a slight difference each time, but is easily corrected. An error of more than five seconds in twenty-four hours is easily corrected with a little patience.
Honorable mention Testing Cell
arm. svhich is attached to the phonograph disc. The magnet is thus revolved slowly in a good sized circle. attracting a steel or tin strip attached to the bottom of tite boat. The boat thus actuated sails around slowly on the water. making an effective advertisement, especially if the boat is painted in
water, or vinegar, s produced.
a
much stronger current
A head set acts to give the characteristic sound if the circuit is not broken.
Tt 5 T PO/NT!
bright colors. The advertisement may be painted on the sails or on the sides. The impression given by the beat is quite mysterious. inasmuch as the propelling apparatus is hidden in the box.
ATĂœST cell costing next to nothing and which will produce a current strong enough to test coils. circuits, condensers, etc.. can be easily made as shown in the diagram. The strip of zinc is about an inch shorter than the carbon and half as wide as the circumference of the carbon. The blotting paper is a little larger than the zinc. These arc held on the carbon with string.
BOX
of the fibre rod is a small brass ball three eighths of an inch in diameter and held on
Right: An interesting battery whose electrolyte to supplied by the moisture of the hand. It gives a very minute current, enough to affect a head set. and is quite practical for testing for breaks in circuits.
It
only necessary to grip the cell in one hand. which will cause it to generate a c.o.rent. at the same time serving as a handle for one of the test points. By standing it in a glass of water, salt
ZINC 3TRING
TEST P0bV75
SLOTTING GAPER
PRY CELL CARBON
is
tnUTCR, 5.4 LT WATER OR V/NCGAQ