[Illustration: FIG. 102.—Regulator Tube.]
*The Vibrator Parts* are illustrated in Figures 101 and 106.
The vibrator spring is a piece of thin steel or phosphor bronze, one-quarter of an inch wide and one and three-sixteenths inches long. A soft iron armature, five-sixteenths of an inch in diameter and one-eighth of an inch thick is fastened to one end of the spring. A five-thirty-seconds inch hole is drilled in the other end and it is then mounted in the "vibrator posts". This consists of a small brass pillar, one-quarter of an inch in diameter and five-eighths of an inch long. The lower end is drilled, and tapped to receive a 4-36 screw which fastens it to the base. A saw slot one-quarter of an inch deep is made in the top to receive the vibrator spring.
The post which holds the adjustment screw is identical with that which supports the vibrator spring, except that a threaded hole is drilled through the saw slot, fifteen-thirty-seconds of an inch from the bottom, through which the screw passes. The end of the adjustment screw, which may be an ordinary knurled thumbscrew from a binding post, should be fitted with a "contact" point. The best contact point is a piece of platinum, but a small piece of silver can be made to serve the purpose very well.
[Illustration: FIG. 103.—The Base with Location of Holes.]
[Illustration: FIG. 104.—Top View of Finished Coil.]
The vibrator spring should also be fitted with a similar contact point.
[Illustration: FIG. 105.—Side View of Completed Coil.]
The medical coil is very easy to connect. Run the inside primary terminal to the binding post on the rear left hand corner of the base. Connect the other terminal to the vibrator post. A wire should be led from the adjustment screw post to the binding post mounted on the forward left hand corner of the base.
[Illustration: FIG. 106.—Vibrator Parts.]