50_MHz_WITH_1_Hz_RESOLUTION

Published:2009/7/6 1:33:00 Author:May | From:SeekIC

Combination of CMOS and TTL devices reduces chip count for digital frequency counter that provides 1-Hz resolution from below20 Hz to above 50 MHz. Use of 10:1 prescaler, also given in article, extends range to above 300 MHz with 10-Hz resolution. Uses Intersil 7208 CMOS seven-decade counter that includes multiplexor, decoder, drivers, and other controls for Fairchild FND.503 8-digit display. High-stability 5.24288-MHz crystal oscillator and frequency divider provide 1-s gate required for counting, outputs for synchronizing multiplexer, and short pulses for latching and resetting counters. Resolution can be decreased by factor of 10 by connecting pin 11 of 7207A to VCC, which is regulated 5 V.-H. E. Harris, Simplifying the Digital Frequency Counter, Ham Radio, Feb. 1978, p 22-25.



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