GB907419A - Automatic frequency tuning circuit for an oscillator - Google Patents

Automatic frequency tuning circuit for an oscillator

Info

Publication number
GB907419A
GB907419A GB3278360A GB3278360A GB907419A GB 907419 A GB907419 A GB 907419A GB 3278360 A GB3278360 A GB 3278360A GB 3278360 A GB3278360 A GB 3278360A GB 907419 A GB907419 A GB 907419A
Authority
GB
United Kingdom
Prior art keywords
oscillator
valve
resistance
cathode
rectifier
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
Application number
GB3278360A
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.)
STC PLC
Original Assignee
Standard Telephone and Cables PLC
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 Standard Telephone and Cables PLC filed Critical Standard Telephone and Cables PLC
Publication of GB907419A publication Critical patent/GB907419A/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
    • H03J7/045—Modification of automatic frequency control sensitivity or linearising automatic frequency control operation; Modification of the working range

Landscapes

  • Channel Selection Circuits, Automatic Tuning Circuits (AREA)
  • Superheterodyne Receivers (AREA)

Abstract

907,419. Automatic frequency control systems. STANDARD TELEPHONES & CABLES Ltd. Sept. 23, 1960 [Sept. 28, 1959], No. 32783/60. Class 40 (5). A receiver local oscillator 14 is automatically tuned by a frequency discriminator with output applied through a cathode follower 1 to vary the effective resistance of a rectifier 33 in series with the tuning capacitor 34 of the oscillator 14. Further, the cathode follower output is connected through a voltage dependent resistance 43 to the junction of a resistance 44 and thermionic valve 48 series-connected with a voltage source V<SP>11</SP> so that, on switching on the receiver, the rectifier 33 is rendered conductive by the source V<SP>11</SP> and the oscillator is prevented from producing a higher (inaccurate) frequency until the valves 1, 48, 14, warm up. Thereupon the voltage on rectifier 33 is supplied by the cathode follower 1 and, since the valve 48 is then also conductive, the potential across voltage dependent resistance 43 decreases to increase its resistance and isolate circuit 43, 44, 48 to prevent it loading the oscillator circuit. As shown, valve 1 is a television I.F. amplifier, the discriminator being tuned to the video carrier I.F. with its D.C. output applied between the grid and cathode through filters 28-31. The valve 48 may have its grid and cathode connected, to act as a diode, and preferably is contained in the same envelope as valve 1. The oscillator 14 is part of the channel selector.
GB3278360A 1959-09-28 1960-09-23 Automatic frequency tuning circuit for an oscillator Expired GB907419A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
BE39247 1959-09-28

Publications (1)

Publication Number Publication Date
GB907419A true GB907419A (en) 1962-10-03

Family

ID=3840163

Family Applications (1)

Application Number Title Priority Date Filing Date
GB3278360A Expired GB907419A (en) 1959-09-28 1960-09-23 Automatic frequency tuning circuit for an oscillator

Country Status (1)

Country Link
GB (1) GB907419A (en)

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