A practical working set of such instruments can be very easily constructed, and with little expense, by following the sketches and instructions given here.
The magnets for the sounder may either be constructed by the intending telegraph operator or secured from some old electrical instrument such as a magneto-bell. In the latter case, the hardest part of the work will be avoided.
If they are to be home-made, the following suggestions may prove of value in carrying out their construction.
Fig. 135.—A Complete Telegraph Set, consisting of a Keyboard and a Sounder.
The cores are made from one-quarter-inch stove-bolts with the heads cut off. The magnet heads are cut out of hard-wood fiber, one-eighth of an inch thick and one inch in diameter. They should fit tightly and be held in place with glue. They are separated so as to form a winding space between of seven-eighths of an inch. The magnets should be wound full of No. 25 B. & S. gauge cotton-covered wire.
Fig. 136.—Details of the Telegraph Set shown in Figure 135.
The yoke is made of enough strips of sheet-iron, one-half inch wide and two inches long, to form a pile one-quarter of an inch thick. Two one-quarter-inch holes are bored in the opposite ends of the yoke, one and one-half inches apart. The lower ends of the magnet cores are passed through these holes. The ends should project one-half of an inch beyond the yoke.
They are passed through two holes in a base-board three-quarters of an inch thick. The holes are countersunk from the lower side, so that a nut can be screwed on the lower end of each and the magnets held tightly in an upright position. The remaining parts of the instrument are very easily made, and are so clearly shown by the drawing that it is hardly necessary to say more than a few words in explanation.