| 摘要 |
PURPOSE:To prevent the excessive reduction of the battery voltage of an automobile, by automatically turning off the power source of a car telephone equipment if the battery voltage of the automobile is reduced to a prescribed voltage or lower because of incoming when a driver leaves the automobile after setting automatic answering telephone functions. CONSTITUTION:A voltage monitor circuit 16 monitors the voltage of a battery 3 while an automatic answering telephone equipment 12 is operated, and a power switch 17 is turned on when the voltage of the battery is higher than a prescribed voltage, and the power switch is turned off when it is reduced to the prescribed voltage or lower. At each time of incoming, the current flows from the battery 3 of the automobile to each part of the car telephone equipment through the power switch 17 and a power supply part 11. When the voltage of the battery 3 of the automobile is reduced to the prescribed voltage, the voltage monitor circuit 16 detects this reduction to turn off the power switch 17. Thus, power supply from the power supply part 11 to the car telephone equipment is stopped. |
