The transformer is now ready for mounting. The usual method of mounting a step-down transformer is to place it in an iron box or case. This is of course the best way because the windings and core are then protected. The experimenter who wishes to go to the trouble of building an iron box for his transformer will find it worth the time. For the benefit of those however who may wish to mount the transformer on a switchboard or as part of some apparatus, the scheme shown in Figure 63 is suggested. The base consists simply of a rectangular piece of hardwood which has been given a coat of shellac. [Illustration: FIG. 63.—The Step-down Transformer mounted on a Wooden Base.] The transformer core rests on two wooden strips marked "S" and "S" in the illustration. It is clamped to the base by two strips, "T" and "T," held in position by round head wood screws at each end. The terminals of the primary winding are led to the two binding posts, marked "P" "P." The secondary terminals are connected to three binding posts, marked 1, 2 and 3. The 110 volt A. C is connected to the primary posts P P by means of a flexible wire and plug which can be screwed into the nearest lamp socket. The low voltage is secured from the binding posts 1, 2 and 3. · Binding Posts 1 and 2 will give 2 volts · Binding Posts 2 and 3 will give 8 volts · Binding Posts 1 and 3 will give 12 volts [Illustration: FIG. 64.—A detailed Drawing showing how the Sides of the Case are formed by bending a long strip of Sheet Iron at four points.] The drawings in Figures 64, 65 and 66 will be of assistance to those who wish to enclose the transformer in an iron case instead of mounting it on a board. The case is made of sheet iron. The sides are composed of a strip of sheet iron fifteen and seven-eighths inches long and two and three-quarters inches wide. The strip should be bent at four points so as to form a rectangular box, the sides of which are four and three-sixteenth inches long and the front and back, three and nine-sixteenths. The ends of the strip should overlap about three-eighths of an inch and be riveted or soldered. The bottom may be fastened to the sides with a couple of rivets or by soldering at one or two points. The bottom and top of the case should both be the same. They are made from a rectangular shaped piece of sheet iron four and seven-eighths inches long and four and one-quarter inches wide. A notch five-sixteenths of an inch square is cut out of each corner and the sides and ends then folded down along the dotted lines as indicated in Figure 65. [Illustration: FIG. 65.—Details of the Top and Bottom of the Case.]