| 摘要 |
<p>PURPOSE:To stop reproduction automatically at [0000] by using a differentiation circuit in the constitution where a counter switch is provided only to the 4th digit of the counter to detect the count value [0000] of the counter at reproduction. CONSTITUTION:When the reproduction is progressed and a count of the counter reaches [9000], a counter switch 5 is set, a potential at a point (a) falls to a Low level, which is kept until the count reaches [0000], and when the level reaches [0000], the potential at the point (a) changes again to a High level. A differentiation pulse as shown in the figure appears at a point (b) at the change from High to Low or Low to High. Since a transistor (TR) 71 in this case in an NPN TR, the TR71 is not conducted by a negative differentiating pulse and conducted momentarily only with a positive differentiation pulse. Then a TR72 is cut off momentarily during the period of the differentiation pulse, and only a discrimination signal representing [0000] of the count is outputted to the collector to stop automatically the reproduction.</p> |
