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Heat watch

Japanese electronics company Seiko has launched a wristwatch powered by body beat. The watch, which went on sale in Japan from December 15, 1998, exploits the temperature difference between the surroundings and the wearer's arm. According to the designers of the watch, it starts to generate electri- city as soon as it is put on and con- tinues to operate and keep perfect time in its "sleep mode" when taken off. The generator uses the principle of the Seebeck effect, in which a temperature difference between a pair of junctions of dissimilar conductors generates a current.

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