| 摘要 |
PURPOSE:To decrease the number of terminals of a tone control circuit and to attain the improvement of an attenuation effect at high frequencies by providing two multiplier circuits whose output value is changed in response to a reception level. CONSTITUTION:An adder circuit 28 of the tone control circuit 21 receives a sound signal at a terminal 22 from an input terminal 29, an output of an amplifier circuit 31 is given at an input terminal 30 and a multiplier circuit 32 multiplies the sound signal at the terminal 22 with a value corresponding to a reception level at a terminal 27. Further, an output terminal 33 of the circuit 28 is connected to a terminal 23 via a resistor 34, a capacitor 35 is connected between the terminal 23 and an amplifier 25 and an output of a connecting point 23 and the value corresponding to the reception level at the terminal 27 are inputted to a multiplier 36. An output of the circuit 36 is subtracted from the output of the circuit 32 by a subtraction circuit 37 and the difference is given to the amplifier circuit 31. Furthermore, the multiplication coefficient of the circuit 32 is zero at the minimum reception level and 1 at the maximum level. |
