The dynamo will be found to operate as a very powerful little motor, but on account of having only a two pole armature, it must be started when the current is turned on by giving the shaft a twist.
The dynamo may be driven by a small water motor or from the driving wheel of a sewing machine. It may be used as a generator for lighting lamps, ringing bells, electroplating, etc.
CHAPTER XIII. AN ELECTRIC BATTERY MOTOR.
AN electric motor has two essential parts. These are a field magnet for furnishing a strong magnetic field and a revolving armature.
It is an easy matter to make a strong electric motor suitable to operate on batteries by the exercise of a little careful workmanship.
The field frame and armature of the motor shown in Figure 133 are laminated, that is, built up of separate sheets of iron. They may be made out of sheet tin or ordinary stove pipe iron. The cheapest and simplest method of securing good flat material is to get some old scrap from a tinner’s or plumbing shop.
*The Details of the Field* are shown in Figure 134. The exact shape and dimensions can be understood by reference to the illustration. Lay out one lamination very carefully as a pattern. Cut it out and smooth up the edges, making certain that it is perfectly true to size and shape. Then use it as a template to lay out the other laminations by placing it on the metal and scribing a line around the edges with a sharp pointed needle. Enough laminations should be cut out to make a pile five-eighths of an inch high when tightly pressed together.
[Illustration: FIG. 133.—The completed Electric Motor.]
*The Armature* is made in exactly the same manner as the field frame, that is, by cutting out a pattern according to the shape and dimensions shown in Figure 136 and using it as a template to lay out the other laminations. Enough should be cut to make a pile five-eighths of an inch high when tightly squeezed together.
[Illustration: FIG. 134.—Details of the Field Frame.]