PLL_FOR_RTTY

Published:2009/7/15 2:17:00 Author:Jessie | From:SeekIC

Complete phase-locked loop uses all four sections of LM3900 quad linear opamp. Variable capacitor is set to give center frequency of 2.2 kHz for VCO. Once in lock, loop will maintain lock over range of 1.55 to 2.9 kHz, to cover tones normally used in RTTY. Additional keying circuit for TTY selector magnets and more filtering of output completes setup for driving printer, C1 is 2N706, with 33K resistor in base circuit.-C. Sondgeroth, More PLL Magic, 73 Magazine, Aug. 1976, p 56-59.



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