large New England wire mill, are used to spool up very fine copper wire as fast as it is drawn. In preparing this little book, the author has endeavored to give the instructions for the different operations as clearly and concisely as possible, without regard to literary excellence. The illustrations, particularly those showing the actual operations in progress, will be of great help to the amateur and student in the construction of such a machine. ARTHUR J. WEED. NEW YORK, April, 1910. Long and short yoke pieces-Building up the field- Hard fiber-Drilling and turning core-Fitting to brass ring-Locating positions of screw holes-Drilling and Chucking the casting—Drilling, boring and reaming— Arrangement of coils-Size and number of turns of wire-Holding the armature-Winding coils-Mark- CHAPTER I FIFTY-WATT DYNAMO This little machine, when properly constructed, is exceedingly efficient and will be found very useful to the experimenter. When finished and connected up in "shunt" it is equally applicable as a motor or a generator and can be used in either capacity without any change in wiring or connections. The output when driven as a generator, at a speed of three to four thousand revolutions per minute, is ten to thirteen volts and about five amperes. This gives sufficient current to light six miniature 6 c.p. lamps. When used as a motor and connected with five cells of storage battery it will develop one-twelfth horse-power. This is sufficient to drive a small lathe or a sewing machine on any and all ordinary work. The field and armature are built up of punchings of electric steel which, being much more permeable to the magnetic current than cast iron, require a smaller bulk. The weight of the entire machine when completed will be about five and one-quarter pounds. This is a machine the punchings, castings and material for which can be purchased in the rough. |