JPS55143822A - Automatic frequency control unit - Google Patents

Automatic frequency control unit

Info

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
Application number
JP5210779A
Other languages
Japanese (ja)
Other versions
JPS5923645B2 (en
Inventor
Masakazu Teraoka
Akihisa Wada
Masakazu Aya
Yasuo Shioyama
Tadaaki Nishiguchi
Kenji Katayama
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Priority to JP54052107A priority Critical patent/JPS5923645B2/en
Publication of JPS55143822A publication Critical patent/JPS55143822A/en
Publication of JPS5923645B2 publication Critical patent/JPS5923645B2/en
Expired legal-status Critical Current

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

  • Television Receiver Circuits (AREA)
  • Channel Selection Circuits, Automatic Tuning Circuits (AREA)
  • Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (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.
JP54052107A 1979-04-26 1979-04-26 automatic frequency control device Expired JPS5923645B2 (en)

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)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57208775A (en) * 1981-06-18 1982-12-21 Pioneer Electronic Corp Afc circuit for tv tuner

Cited By (1)

* Cited by examiner, † Cited by third party
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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