| 摘要 |
PURPOSE: An apparatus and a method for automatically controlling incoming volume are provided to make the incoming volume automatically adjusted according to a level of a received external sound, by installing an operational amplifier and a signal conversion part at a microphone output terminal of a cellular phone. CONSTITUTION: A microphone(21) receives and outputs an external sound of the cellular phone. An operational amplifier(22) amplifies a signal output from the microphone(21). A signal conversion part(23) converts the signal amplified by the operational amplifier(22) to a digital signal. A microcomputer(24) compares a level of the digital signal applied from the signal conversion part(23) with that of a reference signal, and then generates a mode change signal that enables a proper incoming mode to be decided. A mode change part(25) controls the incoming volume and changes a current mode to a vibration mode or an LED blinking mode, in response to the mode change signal applied from the microcomputer(24).
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