Page:Popular Science Monthly Volume 91.djvu/163

 �q Amateur - Electrician

��^And Wireless Operator

��Applying Insulation to Splices Made in Electric Wires

TO comply with the rules of the American Institute of Electrical Engineers, it is necessary to apply a rubber coating over a soldered joint in a wire. One of the best methods of doing this is to lay on the rubber over the splice before it begins to cool from the soldering operation. The thickness of the coating depends on the amount of voltage carried in the line. Cover the rub.ber insulation immediately with friction tape, drawing it tight, while putting on a sufficient number of layers to stand the wear.

To make a neat covering, cut the friction tape into narrow strips, less than */£ in. wide, and a smoother joint will be the result after the wrapping. If this is done neatly and drawn tight enough there will be a noticeable bulge in the joint. This can be easily wrapped with a cord — silk if the case calls for it — then given a coat of shellac. If the proper color cord or silk is selected a joint that cannot be easily detected results.

��A Simple and Easily Made Electric Battery Motor

A SIMPLE and easily made motor that will run at high speed with two or three cells of dry battery, or on an alternat- ing current with a transformer, is shown in the illustration. While this motor can be made in any size that will appeal to the experimenter, only one dimensioned draw- ing is given. Procure two hexagon-head bolts, A, 2Y2 in. long and \i in. in diameter under the head, also some thin hard fiber tubing l /i in. inside diameter to slip over the bolts. Cut two pieces B, each 2 in. long, and fit on heads or washers, C, about J/g in. in diameter, leaving J4 in. of the tubing projecting at the threaded end. This forms the spools for the magnets.

��Wind the spools with No. 22 or No. 24 magnet wire in the usual manner having the inside as well as the outside ends come out at the back end of the magnet.

The soft iron standard D is about 3 in. high. V2 m - wide and 3^8 i n - thick and bent L-shaped at the lower end to form a foot by which it is screwed to the base. In the standard are drilled three holes. Two of these are of the same size to allow the ends of the bolts or magnet core to enter and project on the outside for the nuts, which hold the back ends of the coils in position. The third hole is located centrally between

���Universal motor that will run on a battery current or reduced alternating current

the other two to accommodate the shaft. The same number of holes and in the same position must be drilled in the brass yoke for supporting the front ends of the magnets and the front bearing. This brass yoke may be a flat strip about ^ in. wide and of a length to cover the front ends of the coils. When the bolts are put through the magnets the protruding ends of the fiber tube will butt up against the back standard and all parts will be held securely in place.

The armature poles F consist of soft iron buttons about Y* in. in diameter and }/i in. thick, connected by a strip of brass % in. wide, having a hub # in the center for

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