| 摘要 |
<p>A security alarm apparatus which informs that someone trespassed by opening a door during the resident's absence. This apparatus comprises a sequential circuit which is enabled by mode selection by the resident at his going out, and the sequential circuit which stores the door opening and closing produces an output signal upon second door opening, and the timer circuit is operated by the output signal of the sequential circuit and at the time-up to generate alarms. The sequential circuit can be cleared or disabled when the resident comes home and production of an alarm is then prevented.</p> |
