GB928091A - Loud-speaking telephone systems, particularly for use in mines - Google Patents
Loud-speaking telephone systems, particularly for use in minesInfo
- Publication number
- GB928091A GB928091A GB3470959A GB3470959A GB928091A GB 928091 A GB928091 A GB 928091A GB 3470959 A GB3470959 A GB 3470959A GB 3470959 A GB3470959 A GB 3470959A GB 928091 A GB928091 A GB 928091A
- Authority
- GB
- United Kingdom
- Prior art keywords
- mines
- loud
- telephone systems
- handset
- oct
- 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
- H04M9/00—Arrangements for interconnection not involving centralised switching
- H04M9/001—Two-way communication systems between a limited number of parties
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Interconnected Communication Systems, Intercoms, And Interphones (AREA)
Abstract
928,091. Two-station systems. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Oct. 25, 1960 [Oct. 13, 1959], No. 34709/59. Class 40 (4). In a system particularly for use in mines having two stations connected by a 2-wire line 6, there is provided at each station a loudspeaker 5 used primarily for calling, this and the earpiece 3 of the handset being connected normally to the output of the local amplifier 4. Upon removal of the handset from the hook 7 the loud-speaker 5 is disconnected and D.C. is applied to relay 16 at both stations to energize the amplifiers, which may be of the transistor type. The circuit may be modified to avoid side-tone.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB3470959A GB928091A (en) | 1959-10-13 | 1959-10-13 | Loud-speaking telephone systems, particularly for use in mines |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB3470959A GB928091A (en) | 1959-10-13 | 1959-10-13 | Loud-speaking telephone systems, particularly for use in mines |
Publications (1)
Publication Number | Publication Date |
---|---|
GB928091A true GB928091A (en) | 1963-06-06 |
Family
ID=10369000
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB3470959A Expired GB928091A (en) | 1959-10-13 | 1959-10-13 | Loud-speaking telephone systems, particularly for use in mines |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB928091A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4064366A (en) * | 1976-01-15 | 1977-12-20 | Winster Engineering Group Limited | Intrinsically safe telephone systems |
US4214127A (en) * | 1977-05-18 | 1980-07-22 | S.I.L.E.C.-Division Signalisation Industrielle | Intrinsically safe telephone network |
-
1959
- 1959-10-13 GB GB3470959A patent/GB928091A/en not_active Expired
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4064366A (en) * | 1976-01-15 | 1977-12-20 | Winster Engineering Group Limited | Intrinsically safe telephone systems |
US4214127A (en) * | 1977-05-18 | 1980-07-22 | S.I.L.E.C.-Division Signalisation Industrielle | Intrinsically safe telephone network |
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