Nikola Tesla Books
INDUCTION COIL OUTFITS Booden head in either end of cylinder Length of cardboard cylinder to be about twice its diameter End of cylinder 57 Use only glue and wooden pegs in assembling oylinder Fig. 1.-Cardboard cylinder and wooden heads for secondary of oscillation transformer in order that he may play with the sparks for the entertainment of his friends and himself. The resonator can be built by any worker who has made a tuning coil. A cardboard cylinder from 2 to 4 in. in diameter and twice its diameter in length may be fitted with the usual wooden heads and given a coat of shellac. When the latter is quite dry, the cylinder may be mounted between centers in a simple winding rig such as is shown in the illustration. The cylinder, turned away from the operator by hand, is then to be wound full of double cotton covered wire which may be of any size between 34 and 28 B. & S. gauge. The completed secondary is then to be coated with several applications of shellac, each layer being permitted to dry thoroughly before the next is applied. When the final coat is hard, the secondary may be mounted upon a simple wooden base by means of screws passing up from beneath and into the lower wooden head. The lower end of the winding is carried down through the base to a terminal which will be âground.â The upper end of the winding terminates in a rod carrying a brass ball at its tip. This ball and rod may be taken from the clapper of an old electric bell, or, the ball may be a large leaden shot of the variety known as "buck shot."
