GB1084023A - Improvements relating to regulating arrangements - Google Patents
Improvements relating to regulating arrangementsInfo
- Publication number
- GB1084023A GB1084023A GB2189365A GB2189365A GB1084023A GB 1084023 A GB1084023 A GB 1084023A GB 2189365 A GB2189365 A GB 2189365A GB 2189365 A GB2189365 A GB 2189365A GB 1084023 A GB1084023 A GB 1084023A
- Authority
- GB
- United Kingdom
- Prior art keywords
- line
- feedback
- amplifier
- gain
- 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
- H04M1/738—Interface circuits for coupling substations to external telephone lines
- H04M1/76—Compensating for differences in line impedance
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Networks Using Active Elements (AREA)
Abstract
1,084,023. Automatic volume control; telephone sets. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. March 23, 1966 [May 24, 1965], No. 21893/65. Headings H4K and H4R. In a telephone set having a transistor amplifier for the outgoing signals the gain of the amplifier is controlled according to the line current in order to compensate for the attenuation of the line to which the set is connected, and the gain controlling circuit is arranged to maintain the impedance presented by the set to the line substantially constant. In Fig. 1 the line current flows through the non-linear resistor NLR which has a positive resistance coefficient and so provides gain control of the microphone amplifier transistor TR2 by variation of the current negative feedback of this transistor. The current feedback tends to lower the output impedance of this stage, and so voltage negative feedback is provided by the varistor V1, which has a negative resistance coefficient, the voltage feedback tending to increase the output impedance of the amplifier, so that the overall effect of the two feedback paths is to maintain the output impedance substantially constant, while both feedback paths co-operate in increasing the gain of the amplifier with fall in line current so providing compensation for the attenuation of the line to which the set is connected. In a modification, Fig. 2 (not shown), the impedance presented by the set to the line is lowered by increasing the current flow through TR2 by reducing the base bias resistor (R4 and R5), the resistor being split into two parts and decoupled for A.C. to prevent voltage feedback over this path. This arrangement provides greater control of gain by NLR and so the varistor V1 (Via) is not connected to the emitter of TR1 but directly across the line terminals to provide impedance compensation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB2189365A GB1084023A (en) | 1965-05-24 | 1965-05-24 | Improvements relating to regulating arrangements |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB2189365A GB1084023A (en) | 1965-05-24 | 1965-05-24 | Improvements relating to regulating arrangements |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1084023A true GB1084023A (en) | 1967-09-20 |
Family
ID=10170565
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB2189365A Expired GB1084023A (en) | 1965-05-24 | 1965-05-24 | Improvements relating to regulating arrangements |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB1084023A (en) |
-
1965
- 1965-05-24 GB GB2189365A patent/GB1084023A/en not_active Expired
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