| 摘要 |
PROBLEM TO BE SOLVED: To alarm by an easy and inexpensive circuit constitution that a switching part of a door or the like is illegally opened. SOLUTION: When the opening state of switching part of a door is maintained longer than the specified time, a signal outputted from a detection circuit 3 is latched to a latch circuit 4. An alarm is raised by making the output of this latch circuit 4 operate a singing driving circuit 5 and sound a speaker 6 and a singing state of the speaker 5 is maintained, even if the switching part of the door is closed again, by making the latch circuit 4 hold the output signal. |
