Figure 60 shows how the core should look when it is assembled. It should form a rectangle three and three-quarters inches long and two and five-eighths inches wide.
The method of piling up the *laminations*, as the pieces forming the core are called, is illustrated in Figure 59. One of the strips B is placed against the open end of A. The next set of strips is arranged in the same manner except that the position is reversed so that the strip B is at the opposite end of the pile. This method is continued, reversing each alternate set of strips until the pile is complete as shown in Figure 60. After the core has been assembled, examine it carefully and make certain that none of the strips are of the wrong size so that some protrude farther than others.
The next step in the work is to make the windings, The windings are each made on a cardboard tube having an inside diameter of about 1 1/16 inches. The tubes may be made by rolling a strip of wrapping paper around a piece of broom handle or some other round object of the proper size. The edges of the tube should be glued so that it cannot unroll.
[Illustration: FIG. 60.—Assembly of the Core.]
The *secondary winding* is an inch and nine-sixteenths long and one and thirteen-sixteenths of an inch in diameter.
It is composed of 120 turns of No. 17 B. S. gauge single cotton covered wire wound in six layers.
A tap is led out at the end of the second layer.
The *primary* is one and nine-sixteenths inches in diameter and one and one-sixteenth long. It is composed of 1040 turns of wire wound in 13 layers.
[Illustration: FIG. 61.—Details of the Primary and Secondary Windings.]
[Illustration: FIG. 62.—Showing the Core completely assembled with the Primary and Secondary in position. P, P are the Primary Terminals. 1, 2 and 3 are the Secondary Terminals.]