END_OF_TAPE_DETECTOR

Published:2009/7/6 6:13:00 Author:May | From:SeekIC

Self-compensating sensor automatically compares short-term light variations produced by beginning and end markers on digital magnetic recording tape against long-term variations of ambient light, to improve reliability of sensing marker when there are reflections from blank tape. Low-pass filter R3-C1, having time constant about 5 times expected 10-ms incoming pulse width, stores long-term light level without reacting to short signal pulse. Low-pass filter R4-C2, having 1/20 time constant of incoming pulse width, reduces spurious noise without deteriorating incoming pulses.-C. A, Herbst, Optical Tape-Marker Detector, EEE Magazine, March 1971, p 79.



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