On-hook/off-hook detector circuit
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United States of America Patent
Stats
-
Aug 4, 1981
Grant Date -
N/A
app pub date -
Oct 25, 1979
filing date -
Oct 25, 1979
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
An on-hook/off-hook detection circuit comprises a light-emitting device 54 connected across the tip T and ring R leads of a subscriber's telephone set 50 and between current source 56 and ground 57. A photo-transistor 60 is optically coupled to the light-emitting device 54 for signaling a line scanner 53. When the subscriber's telephone set 50 goes off-hook, a short circuit comprising tip T, telephone set 50 and ring lead R causes light-emitting device 54 to become non-conducting while the light-emitting device 54 is conducting when subscriber's telephone set 50 is on-hook.
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Family
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Cited Art Landscape
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