PLL_TOUCH_TONE_DECODER

Published:2009/7/14 20:45:00 Author:May | From:SeekIC

Seven 567 PLLs sense presence of selected tones from common 100-200 VBMS input line, while 8885 NOR gates perform necessary decoding logic to generate decimal outputs. Circuit takes advantage of good frequency selectivity provided by lock-and-capture ranges of PLLs, as required for discriminating against many tones.-E. Murthi, Monolithic Phase-Locked Loops-Analogs Do All the Work of Digitals, and Much More, EDN Magazine, Sept. 5, 1977, p 59-64.



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