TELEFAX_PHASING

Published:2009/7/7 4:17:00 Author:May | From:SeekIC

Simple coincidence circuit provides reliable synchronization of Telefax machine in which 2500-Hz signal is generated by photoelectric scanning of paper placed on revolving drum. Circuit uses 7402 quad twoinput NOR gate. If alternate connection enclosed in dashed line is not used, connect pin 8 to ground at pin 7. Q1 is S0014 silicon or equivalent. If relay contacts will handle motor voltage and current, they can be connected directly across points of test switch on machine, with switch left open for phasing circuit to work.-W. C. Smith, A Logic Circuit for Phasing the Telefax, QST, Nov. 1978, p 33-34.



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