| 摘要 |
<p>A cheap and simple alarm mechanism for use in apartment blocks designed to operate in conjunction with a door lock and consists of a detection circuit (17) controlled by a detection mechanism which is sensitive to the position of the bolt of the lock and can set off the alarm. The detection mechanism is a connection placed on a circuit to which is connected the feed circuit of the alarm. The complete alarm mechanism can be fitted inside the same casing (15) as the door lock-Being battery-operated, it does not need to be connected to the electricity supply and is therefore more difficult to neutralise. The batteries can also be placed inside the case.</p> |
