JPS55143822A - Automatic frequency control unit - Google Patents
Automatic frequency control unitInfo
- Publication number
- JPS55143822A JPS55143822A JP5210779A JP5210779A JPS55143822A JP S55143822 A JPS55143822 A JP S55143822A JP 5210779 A JP5210779 A JP 5210779A JP 5210779 A JP5210779 A JP 5210779A JP S55143822 A JPS55143822 A JP S55143822A
- Authority
- JP
- Japan
- Prior art keywords
- frequency
- voltage
- channel selection
- power
- local oscillation
- 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.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J7/00—Automatic frequency control; Automatic scanning over a band of frequencies
- H03J7/02—Automatic frequency control
- H03J7/04—Automatic frequency control where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
- H03J7/08—Automatic frequency control where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant using varactors, i.e. voltage variable reactive diodes
Landscapes
- Channel Selection Circuits, Automatic Tuning Circuits (AREA)
- Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
- Television Receiver Circuits (AREA)
Abstract
PURPOSE:To prevent malfunctions when the first local oscillation frequency shifts upward, by fixing temporarily the second local oscillation frequency to a frequency lower than the reference tuning state at a power on time and a channel selection operation time. CONSTITUTION:The +B voltage of constant-voltage circuit 14 is divided by resistances 15 and 16 to obtain value VL lower than the AFC reference voltage (the AFC control voltage in a normal tuning state). FET 11a of switching circuit 11 is turned on by pulss from a power on detecting circuit and a channel selection detecting circuit to apply voltage VL to the varactor diode of the second local oscillator 7, and the capacity is increased more than the reference state (the normal tuning state) to obtain frequency fL lower than the reference frequency. This frequency fL is fixed temporarily, so that malfunctions are prevented when the first local oscillation frequency shifts from a low frequency to a high frequency at a power on time and a channel selection operation time in the separate carrier-system TV receiver.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP54052107A JPS5923645B2 (en) | 1979-04-26 | 1979-04-26 | automatic frequency control device |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP54052107A JPS5923645B2 (en) | 1979-04-26 | 1979-04-26 | automatic frequency control device |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS55143822A true JPS55143822A (en) | 1980-11-10 |
JPS5923645B2 JPS5923645B2 (en) | 1984-06-04 |
Family
ID=12905627
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP54052107A Expired JPS5923645B2 (en) | 1979-04-26 | 1979-04-26 | automatic frequency control device |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS5923645B2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57208775A (en) * | 1981-06-18 | 1982-12-21 | Pioneer Electronic Corp | Afc circuit for tv tuner |
-
1979
- 1979-04-26 JP JP54052107A patent/JPS5923645B2/en not_active Expired
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57208775A (en) * | 1981-06-18 | 1982-12-21 | Pioneer Electronic Corp | Afc circuit for tv tuner |
Also Published As
Publication number | Publication date |
---|---|
JPS5923645B2 (en) | 1984-06-04 |
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