| 摘要 |
PURPOSE:To prevent noise such as pop noise from being reproduced from a speaker by completing charging of a bias cut-off capacitor until when the speaker starts reproduction of an audio signal after power application. CONSTITUTION:When a switch 32 is turned off, no potential is caused between the anode and cathode of a diode 54. Thus, a capacitor 53 is charged through resistors 51 and 52, the charging voltage is fed to a transistor (TR)45 via a resistor 55 to turn on the TR45. When the device operation is started with the switch 32 turned on, since the cathode potential is lowered in comparison with the anode potential of the diode 54, the power supply through the resistor 51 is interrupted and the charged electric charge in the capacitor 53 is discharged through the resistor 52, a circuit through the diode 54 and a circuit through the resistor 55 and the TR45 and the potential is lowered. A bias cut-off capacitor 17 is charged by a current flowing to the TR45 in this process. |
