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http://hackaday.com/2010/03/09/tube-clock-database
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http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1258726587
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http://www.dutchtronix.com/Arduino-ClockShield.htm
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http://www.cathodecorner.com/scra/index.html
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http://www.piccoder.co.uk/content/view/55
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http://www.dutchtronix.com/ScopeClock.htm
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http://web.jfet.org/inGrid
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http://members.iinet.net.au/~andronis
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http://www.instructables.com/ex/i/280...BB22B071029BC6B001143E7E506/?ALLSTEPS