COUNTER_DRIVE_FOR_WWVB

Published:2009/7/6 2:09:00 Author:May | From:SeekIC

Uses LM311 as true zero-crossing detector for 60-kHz carrier of NBS standard-frequency station at Boulder, Colorado. Resulting square wave is fed to chain of 7490 dividers whose outputs are selected by S2 to serve as gate for frequency counter.T1 is 24-V 500-mA power transformer, and T2 is 40-kHz cupcore slugtuned RF transformer as used in many TV remote controls. Primary inductance (7.5-46 mH) of T2 is tapped at 0.5 mH;secondary is 20 pH. Article also gives circuit of preamp that can be built into 60-kHz loop antenna to build up signal strength to 0.4 V as re quired for input to processor.-H. Isenring, WWVB Signal Processor, Ham Radio, March 1976, p 28-34.



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