| 摘要 |
The door phone produces an announcement sound when a sensor (1) detects a visitor at a door and generates a buzz sound when the visitor responds to the announcement sound. The door phone comprises (a) a sensor(1) to detect the visitor; (b) an alarm circuit including a buzzer and LED; (c) a voice processing circuit (8) including a microprocessor (5), a D/A converter, and a ROM which is selected by the combination of the voice detector (15) and the voice output circuit(18).
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