| 摘要 |
<p>PURPOSE:To switch quickly the operation to a constant speed reproduction mode, by comparing the voltage obtained by giving the wave detection to the output of a tape under a high-speed reproduction mode with three different types of reference voltage to actuate an FF and to give the driving control to a plunger and at the same time by reducing the discharging time constant. CONSTITUTION:A capacitor C is charged after giving the high pass saturated amplification 21 and wave detection 22 to the output of a tape under a high- speed reproduction mode. A constant current source voltage VCC is divided, and the reference voltages V11-V13 are fed to comparators 31-33. In the case of the signal existing part of a tape, the output voltage VD is higher than the V11. Thus an FF25 is preset to deliver Q'. When th tape is at its non-signal part with a reduction of the VD, the comparator 32 delivers level 0. Then a negative logical AND circuit 28' delivers an output to control a plunger driver 29. Thus a splunger 30 is actuated to switch the operation to a constant speed mode. When the VD drops further, the comparator 33 delivers an output to clear the FF. While the output of the driver 29 turns on a TRQ31 to promote the discharging of the capacitor C. Thus the non-signal part is assuredly detected at an interval of music, and the program searching is possible in an assured way.</p> |
