| 摘要 |
PROBLEM TO BE SOLVED: To detect an abnormality of a telephone line without burdening the telephone line and without using an external power supply. SOLUTION: This telephone line abnormality detector 1 is constituted so as to detect the abnormality of the telephone line 2 by providing a first resistor 12 serially connected to the telephone line 2, a capacitor 13 to be charged by voltage of the telephone line via the first resistor 12, a second resistor 14, a photocoupler 16 and a transistor 17 to be connected in parallel with the capacitor 13 and a voltage monitoring part 15 which monitors voltage of the capacitor 13, charging the capacitor 13 via the first resistor 12 by the voltage from the telephone line 2, monitoring the charged voltage of the capacitor 13 by the voltage monitoring part 15, turning the transistor 17 on when the charged voltage reaches predetermined voltage or more, passing power charged to the capacitor 13, supplying current to an emission part 16A of the photocoupler 16 via the second resistor 14 and outputting a pulse signal on the side insulated with the telephone line 2. COPYRIGHT: (C)2007,JPO&INPIT |
