CHAPTER XV.
ELECTRIC BELLS AND BUZZERS.
213. Electric Buzzer. Fig. 100. A buzzer is, in construction, very similar to an electric bell; in fact, you will have a buzzer by removing the bell from any ordinary electric bell. They are used in places where the loud sound of a bell would be objectionable. As the buzzer is easier to make than a bell, we shall discuss it first.
214. The arrangement of the parts, (Fig. 100), is very much like that of the sounder of [App. 121], Fig. 95. The armature is, in this case, a vibrating one and acts on the same principle as the automatic interrupter on [App. 100], which you should study. ([See § 148].) The general dimensions may be taken from [App. 121]. The base, B, in this case is about 1 in. wide. D also is made 1 in. wide. H is 1 × 1 × ½ in., and is nailed to A. Through its center is a hole for the regulating screw-eye, I. The end of I presses against F. The exact position of H will have to be determined after the magnets are in place. The armature, L, should be about ⅛ or 3⁄16 in. above the poles. They are not allowed to strike the poles, as a screw, E, regulates that. ([See § 203]). Y and Z are two binding-posts, like [App. 46]. To these are connected the battery wires. The strip of tin or copper, which forms Y, is cut like a letter T there being three holes in it, one near the end of each arm. The screw-eye, 2, and the screw, 3, are put through the horizontal part of the T, and the regulating-screw, I, passes through the hole in the vertical part which springs up against I, thus forming an electrical connection between Y and I. The magnets are made and fastened as in [App. 89].
215. Connections. The inside ends of the magnet coils, ([§ 123]), are fastened between a screw-head and a copper bur, S. One outside end goes to Z, and the other under the screw, G, which holds F to D.
Fig. 100.