| 摘要 |
<p>PURPOSE:To simplify a circuit controlling hunting so as to lock a PLL circuit for driving a rotary head motor. CONSTITUTION:At the time of transferring to a searching mode, a tape T is fast-forwarded or rewound at a high speed. At the point of time switched to the searching mode, a switch SW1 is changed over to the voltage Va of a control voltage generating circuit 6. Thereby, a current is made to flow through the motor and the number of the revolution of the motor M is increased. Immediately after the motor M starts operation, the switch SW1 is turned OFF and the current to motor is interrupted. Simultaneously, a SW2 is turned ON and a resistor R is connected with the motor in parallel. Thus, the motor M is braked and the number of the revolution reduced rapidly. By the increase/decrease of the number of the revolution of the motor, the number of the revolution of a rotary drum 1 is changed, the frequency (f) of a read signal by magnetic heads H1 and H2 is varied and then, the frequency to lock the PLL circuit 2 is searched.</p> |
