Fig. 94.—Binding-Post removed from the Carbon of a Dry Cell.
Several very simple home-made switches are illustrated in Figure 95.
Fig. 95.—Simple Switches. A, Single-Point Switch. B, Two-Point Switch. C, Three-Point Switch. D, Five-Point Switch. E, Lever with End Rolled up to form Handle. F, Lever with Handle made from part of a Spool.
The first one shown (A) has one contact, formed by driving a brass-headed tack through a small strip of copper or brass.
The movable arm is a strip of copper or brass, rolled up to form a handle at one end. The other end is pivoted with a brass screw. The brass screw passes through a small strip of copper or brass having a binding-post mounted on the end. A small copper washer should be placed between the movable arm and the copper strip to make the switch work more easily.
A somewhat similar switch is shown by B in the same illustration, only in this case a handle made from half of a spool is used, instead of rolling up the end of the arm.
The other illustrations show how the same method of construction may be applied to make switches having more than one "point" or contact.
No dimensions have been given for constructing these switches, because it is doubtless easier for the young experimenter to use materials which he may have at hand, and construct a switch of his own proportions. Only one suggestion is necessary, and that is to bevel the under edges of the arm with a file, so that it will slip over the head of the brass tack more easily.