File:OldBuzzer.png

Simple Electro-mechanical Buzzer

Image from page 688 of "St. Nicholas [serial]" (1873) Identifier: stnicholasserial322dodg Title: St. Nicholas [serial] Year: 1873 (1870s) Authors: Dodge, Mary Mapes, 1830-1905 Subjects: Children's literature Publisher: [New York : Scribner & Co.] Contributing Library: Information and Library Science Library, University of North Carolina at Chapel Hill Digitizing Sponsor: University of North Carolina at Chapel Hill

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Text Appearing Before Image: On the base, near the armature-block a binding-post is made fast. The current passes in through the wire A, goes through the coils and around to the screw B, then through the armature to the block and out through the wire C. In its circuit the bolts are magnetized and they draw the armature, but the instant they do so the loose spring-brass end is pulled away from the screw at B and the circuit is broken,— the bolts cease to be magnetized then and the armature flies back as the spring-brass neck at D makes it do so. The loose brass-end then, on touching the screw-point, conducts the current through the coils again with the continual vibrating action as long as the electric current is passing in at A and out at C. The greater the volume of current the greater the number of vibrations, and to properly regulate the contact, the set-screw B must be adjusted at the right point. hole in the middle of it, an upholsterers brass-headed tack is driven for the under side of the

Text Appearing After Image: Paste pieces of heavy paper over the heads of the bolts to overcome residual magnetism. An electric bell is made the same as a buzzer, but, continuing on from the end of the armature, a wire or rod is mounted with a ball or clapper at the end, which strikes the bell as the current causes the armature to vibrate.