BINDING-POSTS AND CONNECTORS.
_57. Binding-Posts_ are used to make connections between two pieces of
apparatus, between two or more wires, between a wire and any apparatus,
etc., etc. They are used simply for convenience, so that the wires can
be quickly fastened or unfastened to the apparatus. There are many ways
of making them at home. The following forms will be found useful and
practical. Although some that are given are really connectors instead of
binding-posts, we shall give them the general name of binding-posts.
APPARATUS 40.
_58. Binding-Post._ About the simplest form is a screw, or a nail with a
flat head. The bare wire may be placed under the head of the screw or
nail before forcing it entirely into the wood. This will keep the end of
the wire in place, and another wire may be joined electrically to the
first by merely touching it to the screw-head, or by placing it under
the screw-head.
APPARATUS 41.
_59. Binding-Post._ Fig. 26. This consists of a screw and a copper
washer or "bur." The screw is a "round-headed brass" one, 5/8 in. long,
number 5 or 7. The copper burs are No. 8, and fit nicely around the
screws. By using 2 burs instead of 1, several wires may be easily joined
together at one point. Scrape the covering from the ends of the wires,
and place them between the burs.
[Illustration: Fig. 26.]
APPARATUS 42.
_60. Binding-Post._ Fig. 27. A coiled spring serves very well as a
connector. One end should be fastened to the apparatus, as shown, by
clamping it under a screw-head. The other end of the coil should be
pulled out a little, away from the other turns, so that you can stretch
the spring in order to put the bare ends of wires between the turns. Any
number of wires placed between these turns will be pinched and
electrically connected. The coil should be about 1/2 in. long and less
than 1/2 in. in diameter. You can make a coil by tightly wrapping stiff
iron wire around a pencil. The steel wire springs taken from old
window-shades are excellent for this purpose. They may be cut into
lengths with tinner's shears.
APPARATUS 43.
_61. Binding-Post._ Fig. 28. Two copper or tin strips fastened at one
end by a screw, the upper strip being bent a little at one end, make a
connector that is useful for some purposes, where you want to make and
break the connection frequently. The bare end of the wire which belongs
to the apparatus is fastened under the screw-head. The outside wire, or
wires, to be connected are pushed between the strips of metal. Another
way is to fasten the outside wire to a strip of metal about 1/2 in.
wide, and then push this between the strips shown in the figure. The
strips shown should be about 3/4 in. wide and 1-1/4 in. long.
[Illustration: Fig. 27.]
[Illustration: Fig. 28.]
[Illustration: Fig. 29.]
APPARATUS 44.
_62. Binding-Post._ Fig. 29. A combination made between App. 42 and 43
does well. Fasten a metal strip, 3/4 in. x 1-1/4 in., to the apparatus
by means of a screw. The apparatus wire should be fastened under the
screw-head. A short length of spring may be pushed upon the upright part
of the strip, as shown. Into this you can quickly fasten the outside
wires.
APPARATUS 45.
_63. Binding-Post._ Fig. 30. This makes a very simple and practical
binding-post for home-made apparatus. It consists of a screw-eye,
preferably of brass. The circle or eye should be about 3/8 or 1/2 in. in
diameter. The thread on such a screw-eye will be about 1/2 in. long. Two
copper burs are used to pinch the wires.
APPARATUS 46.
_64. Binding-Post._ Fig. 31. This consists of a screw, screw-eye, bur
and a metal strip, 3/4 x 1-1/4 in. The apparatus wire should be fastened
under the screw-head. Any outside wires which are to be joined to the
apparatus should be clamped under the bur by turning the screw-eye. A
small hole should be made in the wood before putting in the screw-eye.
(See App. 25.) Do not turn the screw-eye too hard, or you will spoil the
thread made in the wood.
[Illustration: Fig. 30.]
[Illustration: Fig. 31.]
[Illustration: Fig. 32.]
APPARATUS 47.
_65. Binding-Post._ Fig. 32. The size of the bolt used in this form of
binding-post will depend somewhat upon the thickness of the base of the
apparatus. In general, a 3/4 or 7/8 in. base should be used where screws
or screw-eyes are necessary. With this kind (Fig. 32) a thin base can
be used. The head is shown counter-sunk into the bottom of the base.
This is not necessary, provided at least 3 heads are placed far enough
apart to form legs for the apparatus to stand on. Strips of wood may be
nailed upon the underside of the base to make room for the heads in case
they are not used as legs. The wires should be pinched between the nut
and the copper bur shown. If the bolt is too large for a bur, an iron
washer may be used. A washer may be made of tin, or two nuts may be
used.
APPARATUS 48.
_66. Binding-Post._ Fig. 33. This is a suggestion for a combination of
App. 44 and 47. It is useful in school apparatus. Wires may be
permanently fastened on the right, under the nut, and a spring, as in
App. 44, may be slipped on the metal strip at the left, which is held
under the head of the bolt.
[Illustration: Fig. 33.]
APPARATUS 49.
_67. Mercury Connector._ A cup of mercury may be used as a connector.
Make a small hole about 1/4 in. in diameter and depth, in a piece of
wood, and place 2 or 3 drops of mercury in this. The ends of wires
dipped in this will be electrically connected.
APPARATUS 50.
[Illustration: Fig. 34.]
_68. Connector._ Fig. 34. This shows how a wire may be fastened to one
end of a short strip of tin. At the other end of the strip a slot is
cut. This may straddle the body of a screw, or when left plain may be
used to slip between the two metal strips shown in App. 43.
APPARATUS 51.
_69. Binding-Post._ Fig. 35. The ends of two or more wires may be
quickly joined electrically by placing them between the nuts of a short
bolt. By using 3 nuts the bolt will more easily connect a large number
of wires.
[Illustration: Fig. 35.]
_Make Additional Notes and Sketches Here._