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The Clapper is a sound-activated electrical switch, [1] sold since 1984 by San Francisco, California based Joseph Enterprises, Inc. Joseph Pedott marketed the clapper with the slogan "Clap On! Clap Off! The Clapper!". [2] The Clapper plugs into a U.S.-type electrical outlet, and allows control of up to two devices plugged into the Clapper. [3]
The original iron clapper made about 12 million strokes during the 479 years of its history. [2] During the 19th century, it broke and underwent repairs in 1859, 1865, and 1876. [7] After it broke again on 25 December 2000, it was replaced by a new one – paid for and cast by Kraków metallurgic companies – on 14 April 2001. [1]
[6] [7] [8] Quizlet's blog, written mostly by Andrew in the earlier days of the company, claims it had reached 50,000 registered users in 252 days online. [9] In the following two years, Quizlet reached its 1,000,000th registered user. [10] Until 2011, Quizlet shared staff and financial resources with the Collectors Weekly website. [11]
Vibrating "hammer" interrupters were invented by Johann Philipp Wagner (1839) and Christian Ernst Neeff (1847), and was developed into a buzzer by Froment (1847). [ 5 ] [ 6 ] John Mirand around 1850 added a clapper and gong to make the standard electric bell [ 5 ] [ 6 ] for use as a telegraph sounder .
The bell will eventually stop when the dry piles have distributed their charges equally if the clapper does not wear out first. [5] [6] The Bell has produced approximately 10 billion rings since 1840 and holds the Guinness World Record as "the world's most durable battery [delivering] ceaseless tintinnabulation". [2]
Clapper-bells made of pottery have been found in several archaeological sites. [7] The pottery bells later developed into metal bells. In West Asia, the first bells appear in 1000 BC. [6] The earliest metal bells, with one found in the Taosi site and four in the Erlitou site, are dated to about 2000 BC. [8]
Cowbell made in wood from Indonesia. The bell and clapper are commonly crafted from iron, bronze, brass, copper, or wood. The collar used to hold the bell is traditionally made with leather and wood fibers. The craftsmanship of cow bells varies by geographic location and culture. Most cow bells are made of thin, flat pieces of plated sheet metal.
Tesla, for example, invented a coherer in which the tube rotated continually along its axis. In later practical receivers the decoherer was a clapper similar to an electric bell, operated by an electromagnet powered by the coherer current itself. When the radio wave turned on the coherer, the DC current from the battery flowed through the ...