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imported>Robert W King (even though the article is in fact a draft, we nominate it based on it's quality not its status; hence the section below "New draft of the week.") |
imported>Robert W King (I was wrong and didn't read the instructions...) |
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=== | === Draft of the Week <font size=1>[ [[CZ:Article of the Week|about]] ]</font> === | ||
[[Image:Tapping_coherer.jpg|thumb|left|200px|Classic "tapping" form of a glass tube "filings coherer".]]A '''[[coherer]]''' is a type of [[radio]] detector, popular in the earliest days of radio development, beginning around 1890. Coherer receivers, used in conjunction with [[spark-gap]] transmitters, were the first devices to make radio communication practical. However, although hailed at the time as a "marvelous electric eye", their relative insensitivity and unreliability led to their replacement by more sophisticated detectors, so the device that helped create a communications revolution disappeared from commercial use by around 1905. | [[Image:Tapping_coherer.jpg|thumb|left|200px|Classic "tapping" form of a glass tube "filings coherer".]]A '''[[coherer]]''' is a type of [[radio]] detector, popular in the earliest days of radio development, beginning around 1890. Coherer receivers, used in conjunction with [[spark-gap]] transmitters, were the first devices to make radio communication practical. However, although hailed at the time as a "marvelous electric eye", their relative insensitivity and unreliability led to their replacement by more sophisticated detectors, so the device that helped create a communications revolution disappeared from commercial use by around 1905. | ||
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Draft of the Week [ about ]A coherer is a type of radio detector, popular in the earliest days of radio development, beginning around 1890. Coherer receivers, used in conjunction with spark-gap transmitters, were the first devices to make radio communication practical. However, although hailed at the time as a "marvelous electric eye", their relative insensitivity and unreliability led to their replacement by more sophisticated detectors, so the device that helped create a communications revolution disappeared from commercial use by around 1905.The defining characteristic of a coherer detector is a "light-contact" segment that is normally a poor electrical conductor, but which undergoes a sudden change in conductivity — usually a marked increase — in response to increased voltage, including that induced by a received radio signal. A limitation of coherers is that they cannot be used for full audio reception of radio signals, and are limited to receiving simple on-off transmissions, such as the telegraphic dots-and-dashes of Morse code produced by the intermittent keying of a transmitter. [more...] New Draft of the Week [ about ] (CC) Photo: Franklin Bynum Whale meat is considered a delicacy in Japan. Here, the meat has been sliced into a strip of 'whale bacon'. Whale meat refers to the edible flesh of various species of whale. It can be prepared and eaten in various ways, and for example forms one part of traditional Japanese cuisine (鯨肉 gei niku 'whale meat'). Servings also appear on menus in Norway and Iceland, where whales are also hunted, and also some Aboriginal communities take whales for their meat. In recent years, however, concerns have been raised about the levels of pollutants in samples of whale meat,[1] and many people around the world object to the hunting and eating of whales and dolphins. In turn, pro-whaling representatives have argued that eating whale meat is more environmentally friendly than consuming meat raised from cattle. [more...] | ||||
- ↑ New Scientist: 'Extreme mercury levels revealed in whalemeat'. 6th June 2002.