| 摘要 |
PROBLEM TO BE SOLVED: To reduce the power consumption of equipment which has a voice output device. SOLUTION: A voice signal level detecting circuit 5 always detects the level of the voice signal outputted from a voice preamplifier 2 and a microcomputer 7 controls a power supply circuit 6 according to the level of the voice signal detected by the voice signal level detecting circuit 5 to vary a source voltage supplied to a voice power amplifier 3. |
