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Title:
SUBSCRIBER SUPERVISORY CIRCUIT
Document Type and Number:
Japanese Patent JPS5527748
Kind Code:
A
Abstract:

PURPOSE: To secure a miniature subscriber supervisory circuit featuring the low power consumption and high reliability by constituting the originating register trunk circuit with the operational amplifier, the photo coupling element and others.

CONSTITUTION: The output of dial tone signal line 204 is converted into two signals featuring the equal absolute value and different polarities via voltage follower 203 and inversional amplifier 210 to be transmitted to the subscriber between terminals 200 and 205. Voltage -24V of power source 211 is turned to -48V through resistances 207 and 208. At the feeding time to the subscriber, photo detectors 213 and 216 are turned on by LED 212 and 215 with the zero-output. At the feed breaking time, the photo detector is turned off, and 5V emerges via resistances 214 and 217. Furthermore, the misdecision is prevented via AND circuit 219, and the information obtained at terminal 218 is sent to CPU. In such way the subscriber supervisory is carried out, and as a result the device can be formed into an IC with low power consumption, high reliability and long life time.


Inventors:
NAGASHIMA KUNIO
Application Number:
JP10074078A
Publication Date:
February 28, 1980
Filing Date:
August 17, 1978
Export Citation:
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Assignee:
NIPPON ELECTRIC CO
International Classes:
H04Q1/32; H04M3/22; H04Q3/72; (IPC1-7): H04Q3/72
Domestic Patent References:
JPS54107609A1979-08-23



 
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