sa - bo circuit null of magnetic te - pu

摘要

PURPOSE:To improve noise removal effect by adding a pulse corresponding to the travel speed of the magnetic tape as a clock to a digital monostable multivibrator which widens the pulse width of a magnetic tape control signal and removes noise. CONSTITUTION:If the reproduction control CTL signal A of the magnetic tape 1 is converted into a high level at t1, the output C of an OR gate 19 becomes the high level, and a frequency-divider 16 starts counting the pulse B. At that time, the output E of the frequency-divider 16 is converted into a low level, and the noise of the reproduction CTL signal is removed. If the output of the frequency-divider 16 reaches the set value of a preset 17 at t4, the output E is again converted into the high level and waits for the next CTL signal. With deciding noise removal periods t2-t4 by the pulse corresponding to the travel speed of the tape, noise removal effect which is not influenced by the tape speed can be obtained.