| 摘要 |
An audio-visual communicating system which comprises an illuminated sign containing printed information and including a plurality of recorded messages on a recording device, and which recording device is selectively activated by one or more detectors each monitoring a specific condition whereby an audio message corresponding to the sensed circuit is sounded. The system includes a circuit containing a primary source of electrical power and a secondary source of electrical power, the latter being in the form of a rechargeable battery and a charging circuit for maintaining a charge on the battery. The arrangement is such that the system is rendered operative whether or not there has been a failure of the primary power source.
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