US2226995A - Television amplifier - Google Patents

Television amplifier Download PDF

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Publication number
US2226995A
US2226995A US19816A US1981635A US2226995A US 2226995 A US2226995 A US 2226995A US 19816 A US19816 A US 19816A US 1981635 A US1981635 A US 1981635A US 2226995 A US2226995 A US 2226995A
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United States
Prior art keywords
resistance
anode
potential
amplifier
tube
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 - Lifetime
Application number
US19816A
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English (en)
Inventor
Schlesinger Kurt
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.)
LOEWE RADIO Inc
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LOEWE RADIO Inc
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 LOEWE RADIO Inc filed Critical LOEWE RADIO Inc
Application granted granted Critical
Publication of US2226995A publication Critical patent/US2226995A/en
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/14—Picture signal circuitry for video frequency region
    • H04N5/148—Video amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/32—Modifications of amplifiers to reduce non-linear distortion
    • H03F1/33—Modifications of amplifiers to reduce non-linear distortion in discharge-tube amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/34—DC amplifiers in which all stages are DC-coupled
    • H03F3/36—DC amplifiers in which all stages are DC-coupled with tubes only

Definitions

  • the invention relates to the construction of an amplifier with condenser resistance coupling which does not possess the disadvantages of the previously known photo-cell amplifiers of this kind for television transmitters, viz., the so-called fog formation. To explain the physical occurrences it is necessary to deal briefly with the formation of the fog.
  • the subject matter of the invention is an amplifier which, whilst avoiding the carrier current method permits of the production and reproduc- 1 tion of images completely free of reverberatory effects.
  • Fig. 1 is the diagram of an ordinary resistance capacity couple-d connection.
  • Fig. 2 is an equivalent circuit diagram of the coupling stage according to Fig. 1.
  • Fig. 3 shows a potential curve to be transinitted
  • Fig. 4 shows an exemplary embodiment of the amplifier circuit according to the invention.
  • Figure 5 shows a modification of the present invention.
  • Fig. 1 there is shown a normal tube member 5 5 of a resistance capacity coupled amplifier with the usual battery blocking and the resistance coupling.
  • a normal tube member 5 5 of a resistance capacity coupled amplifier with the usual battery blocking and the resistance coupling.
  • I is the amplifier tube, in practice usually a screen grid tube, 2 the anode resistance 1%,.3 the repeating condenser C of the next stage, 4' the grid leak resistance Rg of the latter, '5 the anode battery decoupling condenser Ca, and 6 the decoupling resistance Rb.
  • amplifier tube I is replaced in the -30 known fashion by a generator i and a resistance 8 in series with the generator. There is shown the bridging condenser 3 and the grid leak resistance 4, and there is to be observed the potential at the terminal 9 when the potential curve 35 shown in Fig. 3 reaches the input terminal Hi.
  • the grid and anode circuitsof the individual stages are so construct.- ed and dimensioned that the magnitude of N remains below a definite limiting value (e. g. be-
  • Equation 1 It is evident from Equation 1 that even very short signals of the duration T will cause an echo effect if they are repeated frequently.
  • Suitable values for Hg and C are therefore 0.5 megohm and 2 microfarads or 1 megohm and 1 microfarad or 0.1 megohm and microfarads. It has been found however that in practice it is not necessary to have such a large time constant and that a time constant of 0.1 second is suflicient in most cases.
  • Suitable values for R; and C in this case are l megohm and 0.1 microfarad.
  • a selection of suitable dimensions for the elements in the grid and anode circuits should be made in the manner already described in all the stages of the amplifier since if only one stage is treated in this manner the production of the fog formation may still occur in other stages.
  • the circuit elements of the gridand anode circuits of the several stages are in practice dimensioned in such manner that the value of N amounts to 0.1 to 0.01. It is advantageous that for the last stages of the arrangement the value of N amounts to nearly 0.1 whilst for the preceding stages there are used practically smaller values of N amounting to 0.02 to 0.01.
  • This may be accomplished, for example, by the provision of means for reducing to zero the alternating potentials which are linked up with the anode block during operations and cause the residual charges resulting in the interference.
  • a special push-pull tube which supplies a potential equal in amplitude to the anode potential but of reversed phase.
  • phase reversal tube I which operates on an anode resistance 2' preferably equal to the resistance 2, and the anode circuit potential of which is raised to the same amplitude as the anode circuit potential of the main tube by coupling the grid circuit with a corresponding tapping of the anode resistance 2 of the main tube, so that the same supplies a reflectory-reverse potential of the same amplitude.
  • the elements 4 and 6 are biasing resistances. Further the anode of the phase-reversing tube is connected via condenser 3 to a separate output terminal. This separate terminal may be used as well as-that terminal adjacent to condenser 3 of the main amplifier l as output ter minal. Either the one or the othermay be used as output terminal. This enables to tap either positive or negative amplitudes of the image-contents signals which is most advantageous for television.
  • the charging fault of the anode block may also be eliminated without the use of special push-pull reversing tubes by making the alternating potentials zero during operations at the anode block by means of a neutralizing branch.
  • Fig. 5 shows a corresponding circuit diagram. There are shown three tubes of a resistance amplifier. The last thereof, which possesses the most powerful anode potentials, is guarded against fog formation by a glow lamp l I.
  • a neutralising connection system comprising the resistances 2
  • a potential of equal amount and reversed phase such as obtained by the same from the anode circuit of the appertaining amplifier stage.
  • the tapping at the anode resistance 2 must correspond with the amplification ratio of the appertaining stage, and the series resistance 2
  • the former is, for example, 0.1 megohm, and the latter approximately 5,000 ohms. It is possible by means of a galvanic neutralisation of this nature to affect the fog formation quite considerably, and with correct adjustment of the condensers even to overcome the same entirely.
  • the transmission element 3, 4 (according to Equation 1) is, with the insertion of a suitable value of 1; dimensioned for example,
  • An amplifying device for television picture signals wherein the picture signals constitute voltage variations occurring within a frequency band from at least one megacycle to substantiallyzero comprising a first electron tube having a cathode, a control electrode and an anode, means for impressing the picture signals upon said control electrode, means including a series connected load impedance and decoupling resistance for maintaining said anode positive with respect to said cathode, a condenser connected between a point of fixed potential and the junction of the load impedance and decoupling resistance, a second electron tube having a cathode, a control electrode and an anode, means for coupling the control electrode of said second tube to an intermediate point on the load impedance of said first tube, a load impedance for said second tube connected between the anode of said second tube and the junction of said first-named ⁇ load impedance and decoupling resistance whereby amplified picture signals of the same intensity and opposite phase relationship are present at the anode of each tube and whereby the total anodic current present

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Amplifiers (AREA)
  • Picture Signal Circuits (AREA)
US19816A 1934-05-09 1935-05-04 Television amplifier Expired - Lifetime US2226995A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2226995X 1934-05-09

Publications (1)

Publication Number Publication Date
US2226995A true US2226995A (en) 1940-12-31

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Family Applications (1)

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US19816A Expired - Lifetime US2226995A (en) 1934-05-09 1935-05-04 Television amplifier

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US (1) US2226995A (enrdf_load_stackoverflow)
NL (1) NL45412C (enrdf_load_stackoverflow)

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NL45412C (enrdf_load_stackoverflow)

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