| 摘要 |
PURPOSE:To ensure a good automatic control of the recording bias, etc., by detecting the reproducing level of a control signal with high accuracy and without having any effect of the level change of a reproduced signal due to the dropout of a magnetic tape, etc. CONSTITUTION:The 1st monostable multivibrator 22 detects the fall of a pulse and supplies a stabilized pulse of a prescribed width to the base of a transistor TRQ1 via a circuit EX1. The TRQ1 is kept on for a prescribed period and resets a peak holding circuit 13. A comparison is carried out to decide whether the reproducing level of the control signal of a high frequency is coincident with that of the control signal of a low frequency. If the coincidence is obtained, the end of an automatic control is decided for the recording bias. Then the automatic control proceeds to the recording sensitivity. In such a way, the recording bias, etc. can be set automatically and satisfactorily. |
