| 摘要 |
PURPOSE:To realize an automatic stopping device of a tape recorder which is capable of reducing the cost with simple constitution, by detecting the change of a current waveform as a rotary pulse and resetting a tape recorder mechanism to the stop mode when no ratary pulse exists. CONSTITUTION:A gate circuit 127 is put between a differential amplifying part 122 in a rotary pulse detecting circuit 12 and a monostable multivibrator 123. At the same time, a monostable multivibrator 128 is newly added to control the gate period of the circuit 127. In such constituion, if the pulse period becomes long when some fault arises in the terminal part of a tape, for instance the winding of the tape, etc., the circuit 127 does not allow the pulse to pass since the gate period is set at a value which is about 1.5-fold length as long as the period of the rotary pulse in the normal time. Thus the detection is carried out at the detecting part 12 without any rotary pulse to ensure automatic stopping action. As a result, the state of rotation can be assuredly detected for a reel turntable. |
