The magnets are clamped down to the bell-base by means of a hard-wood strip having a screw passed through it between the magnets into the base.
Fig. 119.—Details of the Magnet Spools, and Yoke for an Electric Bell.
The armature of the bell is shown in Figure 120. It is made of a piece of iron having a steel spring riveted to it, as illustrated. The armature is fastened to a small block mounted on the lower left-hand corner of the base.
Fig. 120.—Details of the Armature, and Contact Screw.
A second block with a contact-point made from an ordinary brass screw by filing the end into the shape shown in the illustration, is mounted on the base so that it is opposite the end of the contact-spring fastened to the armature. The gong may be secured from an old bell or alarm clock. It is mounted on the upper part of the base in such a position that the hammer will strike it on its lower edge.
The instrument is connected as shown in Figure 121. One terminal of the magnets is connected to the contact-screw. The other end is connected to the binding-post. A second binding-post is connected to the armature.
Fig. 121.—The Completed Bell.