GB704228A - Improvements in or relating to circuit-arrangements for use in automatic signalling systems - Google Patents
Improvements in or relating to circuit-arrangements for use in automatic signalling systemsInfo
- Publication number
- GB704228A GB704228A GB8820/52A GB882052A GB704228A GB 704228 A GB704228 A GB 704228A GB 8820/52 A GB8820/52 A GB 8820/52A GB 882052 A GB882052 A GB 882052A GB 704228 A GB704228 A GB 704228A
- Authority
- GB
- United Kingdom
- Prior art keywords
- leg
- loop
- cathode
- changes
- current
- 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
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/26—Devices for calling a subscriber
- H04M1/515—Devices for calling a subscriber by generating or selecting signals other than trains of pulses of similar shape, or signals other than currents of one or more different frequencies, e.g. generation of dc signals of alternating polarity, coded pulses or impedance dialling
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Devices For Supply Of Signal Current (AREA)
- Interface Circuits In Exchanges (AREA)
Abstract
704,228. Automatic exchange systems. PHILIPS ELECTRICAL INDUSTRIES, Ltd. April 7, 1952 [April 10, 1951], No. 8820/52. Class 40 (4) [Also in Group XXXVIII] In a system, e.g. for signalling digital information from a subscriber to a telephone exchange in which signals are transmitted to a receiver over a line loop by changing the value of the resistance inserted at the distant end of the loop, one leg a of the loop is connected to battery at the receiving end and the other leg b is connected to the cathode of a valve B1 the control electrode of which is fed with such a potential that the cathode remains substantially at earth potential irrespective of the value of the resistance inserted in the loop. This arrangement minimizes the errors due to leakage to earth in the line loop. Thus the current through the leak resistance of the leg b unlike that of the leg a passes through the signal receiver and may produce an erroneous operation therein. By maintaining the cathode of B1 at earth potential no current through the leakage resistance Rb of the leg b is permitted. The valve B 1 behaves as an earthed impedance equal to the reciprocal of its mutual conductance which is small compared with the values of the signalling resistors Rk1 ... Rk10 so that changes in current due to changes in these resistors produce only a small change in its cathode potential. This small change is however further reduced by the use of a negative feed backcircuit incorporating the valve B 2 . Changes in signalling current produce corresponding changes in voltage across the anode resistor R 1 which are detected by a known signal detector OI.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL704228X | 1951-04-10 |
Publications (1)
Publication Number | Publication Date |
---|---|
GB704228A true GB704228A (en) | 1954-02-17 |
Family
ID=19812023
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB8820/52A Expired GB704228A (en) | 1951-04-10 | 1952-04-07 | Improvements in or relating to circuit-arrangements for use in automatic signalling systems |
Country Status (2)
Country | Link |
---|---|
DE (1) | DE918512C (en) |
GB (1) | GB704228A (en) |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL73400C (en) * | 1948-02-05 |
-
1952
- 1952-04-06 DE DEN5337A patent/DE918512C/en not_active Expired
- 1952-04-07 GB GB8820/52A patent/GB704228A/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
DE918512C (en) | 1954-09-27 |
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