How Two Boys Made Their Own Electrical Apparatus.
by Thomas M. (Thomas Matthew) St. John.
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 ill.u.s.trations 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-cla.s.s connections between the wire and rods. (See -- 3.)
[Ill.u.s.tration: Fig. 1.]
APPARATUS 2.
[Ill.u.s.tration: 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 1 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 1 1/2 in. The carbon and zinc rods, C and Z, are 4 in. long 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.
[Ill.u.s.tration: 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 -- 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 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 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.
[Ill.u.s.tration: 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 1 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 -- 3.)
APPARATUS 5.
[Ill.u.s.tration: 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 1 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.
[Ill.u.s.tration: 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 1/2 in. They are screwed to the cross-piece, which is 4-1/2 1 7/8 in. Do not let the screws touch each other. The wires are fastened under the screw-heads.
APPARATUS 7.
[Ill.u.s.tration: 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 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 2 in. The narrow strip, or leader, A, is 5 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.