System for indicating that an object has been placed in a closed chamber such as a letterbox, and chamber, such as a letterbox, equipped with such a system

摘要

The invention relates particularly to a system capable of detecting and indicating that an object such as mail has been placed in a letterbox, said system comprising an infrared emitting-receiving cell (6) pointing towards the inside front wall (7) of said box on which is a reflective surface (8) at this level. The default signal triggered by the introduction of an object which breaks the infrared beam as it falls through it, which signal is amplified by the amplifier (9), closes the secondary circuit of the self-energised relay (11) whose secondary comprises the indicating means (12). The primary of said relay comprises the push button (13) which when operated opens the primary circuit of said relay (11), thereby restoring the system to its initial monitoring condition. The invention is advantageously used for monitoring letterboxes external to the dwelling that they serve. <IMAGE>