| 摘要 |
PURPOSE:To set the optimum ALC level, by adjusting the offset voltage of a comparator circuit which compares the output signal level of an amplifier in accordance with a working supply voltage. CONSTITUTION:The output signal level of a sound recording amplifier 8 is compared at a comparator circuit 13. The reference voltage of the comparator circuit 13 is given from a reference voltage generating circuit 16. The offset voltage of the comparator circuit 13 is determined by values of a variable resistor 17 and resistance 24. Therefore, when the value of the resistance 24 is set at a prescribed value and the value of the variable resistor 17 is set in accordance with the working supply voltage, the offset voltage of the comparator circuit 13 can be changed and, as a result, the ALC level can be changed. Accordingly, the optimum ALC level corresponding to the working supply voltage can be set. |
