GB785031A - Improvements in or relating to radio-receiving circuits comprising means for automatic gain control - Google Patents
Improvements in or relating to radio-receiving circuits comprising means for automatic gain controlInfo
- Publication number
- GB785031A GB785031A GB20384/54A GB2038454A GB785031A GB 785031 A GB785031 A GB 785031A GB 20384/54 A GB20384/54 A GB 20384/54A GB 2038454 A GB2038454 A GB 2038454A GB 785031 A GB785031 A GB 785031A
- Authority
- GB
- United Kingdom
- Prior art keywords
- diode
- anode
- cathode
- valve
- potential
- 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
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
- H03G3/20—Automatic control
- H03G3/22—Automatic control in amplifiers having discharge tubes
Abstract
785,031. Automatic gain control; muting; limiters. PHILIPS ELECTRICAL INDUSTRIES, Ltd. July 12, 1954 [July 10 1953], No. 20384/54. Class 40 (5). Automatic gain control. Intermediatefrequency signals are fed from the primary 3 of the I.F. transformer 3, 4, to an A.G.C. diode 9. The diode 9 is shunted with a load resistor 10 and its cathode is connected to a potentiometer, comprising resistor 12 and gas-discharge tube 23, across the H.T. supply. The A.G.C. voltage is applied to earlier stages in the receiver via high-value resistors 13, 14 and resistor 16, delay being provided by a diode 15 the anode of which is connected to the join of resistors 14, 16. A negative bias is applied to the cathode of the diode 15; it constitutes the initial bias for the gain-controlled stages and may be obtained by rectification from the A.C. heater supply. The delay voltage, substantially that across gas-discharge tube 23, is made large, as is also the gain of the preceding I.F. amplifier 2, the signal detector 5 being tapped well down the secondary 4 of the I.F. transformer 3, 4. In this way a load 6 of relatively low impedance may be used. Muting and noise limiting. Rectified audio signal from the load 6 is applied via a blocking condenser 17 to the cathode of a diode 7, the anode of which is connected to one of the output terminals 8 via a further blocking condenser. The cathode of the diode 7 is connected to a potentiometer comprising resistors 19, 20 across the H.T. supply; its anode is connected to a further potentiometer comprising resistor 21 and the anode-cathode path of a valve 18, across the H.T. supply. The grid of the valve 18 is connected, via a series resistor 24, to the join of resistors 13, 14. In the absence of a signal, a positive potential is applied to the grid of the valve 18, grid current occurs and the anode potential is low, thereby rendering diode 7 non-conductive. When the potential on the A.G.C. line becomes sufficiently negative, the valve 18 is cut off, the anode potential rising and rendering the diode 7 conductive. A condenser 22 in shunt with the valve 18 prevents the anode potential of the diode 7 following the cathode potential on positively-going noise impulses, which are thereby limited.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL785031X | 1953-07-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB785031A true GB785031A (en) | 1957-10-23 |
Family
ID=19832252
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB20384/54A Expired GB785031A (en) | 1953-07-10 | 1954-07-12 | Improvements in or relating to radio-receiving circuits comprising means for automatic gain control |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB785031A (en) |
-
1954
- 1954-07-12 GB GB20384/54A patent/GB785031A/en not_active Expired
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