| 摘要 |
PURPOSE:To realize the optimum recording for each magnetic tape, by providing a means which enlarges the changing step of the recording bias level with interlocking to a tape selector switch and a limiter ciruit which switches the attenuating quantity of the DC level of a reproduced signal. CONSTITUTION:A processor 11 drives selectively oscillators 17 and 18, records a controlling signal via a recording head 16 and compares the DC level of the controlling signal reproduced by a reproducing head 22 by a voltage comparator 31 to perform an automatic control of the optimum recording bias. When a switch S is connected to a terminal C with interlocking to a tape selector, transistors (TR) Q2 and Q8 are turned on with TRs Q3, Q4 and Q7 turned off respectively. Thus the changing step is increased for the output of a bias oscillating circuit 15. At the same time, the DC level of the reproduced signal delivered from a rectifying circuit 28 is attenuated by a limiter circuit 30 and applied to the comparator 31. Thus the changing width is equivalently increased to the recording bias level which can be detected by the processor. As a result, an automatic controlling range can be increased for such a kind of tape that has a small change of its reproducing level. |
