| 摘要 |
PURPOSE:To compensate an increase in a flux, which is caused by the wear of a video head and to obtain long term's stable sound reproduction level by giving to a video recording current a reduced current characteristic which decreases as the time expires. CONSTITUTION:A video signal Vi given to an amplifier 11 through an attenuator 10, and a head current IH available from branching an output current is given to the video head 13 through a rotary transformer 12. It is detected by a transformer 14, converted into the DC detecting signal ¦V1¦ by a circuit 15 and led to a subtractor 17. On the other hand, the head voltage VH of a transformer 12 is led to a circuit 16, converted into a signal ¦VH¦ and led to the subtractor 17, which gives an output corresponding to a difference DELTAV between both signals as a control signal VC to the control input of the attenuator 10. Thus the increase in the flux, which is caused by the wear of the video head, is compensated by the reduced current characteristic, and accordingly a drop in the sound reproduction level can be prevented.
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