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The E-Sylum: Volume 12, Number 15, April 12, 2009, Article 20

DETECTING COUNTERFEIT COINS BY THEIR SOUND

Speaking of detecting fake coins, Richard Giedroyc has a nice article (available now on the NumisMaster web site) about a new method of detecting counterfeit coins by their sound. That's an age-old method of course, but this invention listens with technology rather than old-fashioned flesh-and-blood ears. -Editor
It has been pointed out in the "Around the World" column in the past that with coins increasingly replacing low denomination bank notes in circulation there has been a renewed interest in counterfeiting circulating coinage worldwide. The call to arms now includes recruiting Mototsugu Suzuki, a Japanese scientist with a doctorate in applied physics from Osaka University, who has recently developed a new counterfeit coin detection method for the Yomiuri Metropolitan Police Department.

Suzuki's method sounds relatively simple, no pun intended. Slide a coin down a brass-plated chute. A computer analyzes the sound the coin makes as it slides, determining if the coin is genuine or not from the noise the coin generates. This relatively quick method is increasingly replacing labor intensive methods the Japanese police had to use, either using a microscope or subjecting coins to fluorescent X-rays, which could take up to three to five minutes per coin.

There is already talk about applying this technology to vending machines, where according to the Feb. 26 Daily Yomiuri or Yomiuri Shimbun newspaper in Japan, a 30 millimeter brass composition chute allowing for oscillation provided by an accompanying high-performance microphone would allow computer analysis of each coin vended.

Suzuki told the Japanese newspaper he is aware of different frequencies between each coin denomination and of the difference in frequencies between genuine and fake coins. He was particularly focused on the hardness and density of each coin.

Suzuki is quoted in the newspaper article as saying, "I hit upon the idea of making the device from my image of a coin clinking when it is put into a piggy bank."

I'm not sure I'd want my MS-67 1909-S VDB cent sliding down a chute to determine its authenticity, but this does seem like a technology applicable to vending and coin counting machines. -Editor


To read the complete article, see: Sound Determines if Coins are Sound (www.numismaster.com/ta/numis/Article.jsp?ad=article&ArticleId=6543)

THE BOOK BAZARRE

DAVID SKLOW - FINE NUMISMATIC BOOKS Sale #7 closes June 13th 2009. Consignments include: The Library of Myron Xenos U.S. Copper Literature {also} The Estate Library of a New England Bibliophile {also} The Personal Library of a Former Numismatic Literature Dealer. numismaticbooks@aol.com PH: (719) 302-5686, FAX: (719) 302-4933. Visit our web site: www.finenumismaticbooks.com.





Wayne Homren, Editor

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