GB884832A - Improvements in or relating to telephone subscriber's line circuits - Google Patents
Improvements in or relating to telephone subscriber's line circuitsInfo
- Publication number
- GB884832A GB884832A GB3637458A GB3637458A GB884832A GB 884832 A GB884832 A GB 884832A GB 3637458 A GB3637458 A GB 3637458A GB 3637458 A GB3637458 A GB 3637458A GB 884832 A GB884832 A GB 884832A
- Authority
- GB
- United Kingdom
- Prior art keywords
- lamp
- current
- subscriber
- telephone subscriber
- resistor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M3/00—Automatic or semi-automatic exchanges
- H04M3/22—Arrangements for supervision, monitoring or testing
- H04M3/2272—Subscriber line supervision circuits, e.g. call detection circuits
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Devices For Supply Of Signal Current (AREA)
- Interface Circuits In Exchanges (AREA)
Abstract
884,832. Automatic exchange systems. GENERAL ELECTRIC CO. Ltd. Feb. 12, 1960 [Nov. 12, 1958], No. 36374/58. Class 40 (4). [Also in Group XL (b)] A circuit for terminating a telephone subscriber's line comprises a lamp 10 at the exchange, Fig. 1, which is lighted when the subscriber lifts his handset, and a photocell 12 which causes a current to flow in resistor 14 when the cell is illuminated. A Zener diode 11 limits the current in the lamp 10 so that the light output is independent of subscriber line current. A diode 16 ensures that the voltage across resistor 14 does not exceed 5 volts. The lamp 10 and cell 12 are formed as one unit, Fig. 2, the photo-conductive element 23 and electrodes 20, 21 being against the lamp bulb 22. The whole is encased in an opaque resin. The circuit is stated to be of particular use in electronic exchanges of the type described in Specification 856,732.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB3637458A GB884832A (en) | 1958-11-12 | 1958-11-12 | Improvements in or relating to telephone subscriber's line circuits |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB3637458A GB884832A (en) | 1958-11-12 | 1958-11-12 | Improvements in or relating to telephone subscriber's line circuits |
Publications (1)
Publication Number | Publication Date |
---|---|
GB884832A true GB884832A (en) | 1961-12-20 |
Family
ID=10387562
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB3637458A Expired GB884832A (en) | 1958-11-12 | 1958-11-12 | Improvements in or relating to telephone subscriber's line circuits |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB884832A (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3783198A (en) * | 1971-03-18 | 1974-01-01 | Gte Automatic Electric Lab Inc | Battery reversal detection |
US3819866A (en) * | 1972-12-18 | 1974-06-25 | Bell Telephone Labor Inc | Light coupled loop current detector |
US3944752A (en) * | 1974-11-01 | 1976-03-16 | Porta Systems Corporation | Telephone line status indicator |
US3971898A (en) * | 1974-04-09 | 1976-07-27 | Iwatsu Electric Co., Ltd. | Visual indicating control circuit in key telephone system |
-
1958
- 1958-11-12 GB GB3637458A patent/GB884832A/en not_active Expired
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3783198A (en) * | 1971-03-18 | 1974-01-01 | Gte Automatic Electric Lab Inc | Battery reversal detection |
US3819866A (en) * | 1972-12-18 | 1974-06-25 | Bell Telephone Labor Inc | Light coupled loop current detector |
US3971898A (en) * | 1974-04-09 | 1976-07-27 | Iwatsu Electric Co., Ltd. | Visual indicating control circuit in key telephone system |
US3944752A (en) * | 1974-11-01 | 1976-03-16 | Porta Systems Corporation | Telephone line status indicator |
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