| 摘要 |
PURPOSE:To make a scale of a circuit small, and to convert it to an IC by switching successively reproducing signals of al tracks by a switching means, and thereafter, executing an automatic adjustment of a gain of the reproducing signal at every track by one attenuator, an analog-to-digital converter, and adder and subtracter, etc. CONSTITUTION:Signals of an (n) track portion reproduced from a magnetic head group 1 are amplified by an amplifier group 2, respectively, switched and outputted successively by being synchronized with a clock from an input terminal 3 in a multiplexer 4, and converted to a digital signal by an A/D converter 6 through an attenuator 5. In case when it has exceeded the first reference value, a comparator 10 supplies a subtrahend '1' to an adder and subtracter 8, a value which has subtracted '1' from a gain constant which a shift register 9 has outputted is outputted, and it is supplied to the attenuator 5. On the other hand, in case when said signal is smaller than the first reference value and larger than the second reference value, a value which has added '1' to a constant by the adder and subtracter 8 is outputted and supplied to the attenuator 5. On this way, the digital signal from the A/D converter 6 is adjusted automatically by the attenuator 5 so that it goes in between the first and the second reference values. |
