| 摘要 |
PURPOSE:To emit alarm sound at a large volume during daytime and at a small volume during nighttime, by changing the volume of alarm sound corresponding to the counting of the time counter. CONSTITUTION:A counter 2 counts the time, and also outputs a time signal Sc which is necessary for a buzzer control circuit 8 to change the volume of the alarm sound. The alarm time is set by the manipulation of an external operation member 11 by way of an external operation control circuit 12. The buzzer control circuit 8 prepares a volume changeover signal of the alarm sound from the time signal Sc, and a buzzer driving signal Sg changed over by said signal is led into a buzzer driving circuit 9. By changing the duty of the alarm driving signal Sg differently for the daytime and the nighttime, a buzzer 10 is driven at a large volume during daytime and at a smoll volume during nighttime to sound an alarm. |
