| 摘要 |
The invention relates to an automated electronic device for antiterrorist protection against blackmail, corruption and unauthorized calls on a private line. According to the invention, the device uses the direct and alternating current voltages from the exchange line in order to control the optical and the acoustical alarm conditions and to register the same. The device comprises an electronic unit (A) for taking over the audio signal from the exchange line, an electronic unit (B) for signalling acoustically and optically the operating or resting condition of the exchange line, and an electronic unit (C) for furnishing a supply voltage of 220 v/ 50Hz from the network or from batteries of 4.5 v.
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