| 摘要 |
A drum servo circuit for a magnetic recording and/or reproducing apparatus uses a 30 Hz or 60 Hz oscillator circuit (counter), and a trapezoidal wave signal (or a sampling pulse signal) is produced by selectively using threshold values set in the oscillator circuit depending on the play mode, so as to eliminate the need to externally couple a plurality of variable resistors to a monostable multivibrator. A drum motor which drives a rotary drum is controlled responsive to a phase error signal which is obtained by comparing the phase of the trapezoidal wave signal (or the sampling pulse signal) and the phase of a rotation detection signal which is obtained by detecting the rotation of the drum motor.
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