US2173497A - Level-maintenance for television amplifiers - Google Patents

Level-maintenance for television amplifiers Download PDF

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Publication number
US2173497A
US2173497A US94130A US9413036A US2173497A US 2173497 A US2173497 A US 2173497A US 94130 A US94130 A US 94130A US 9413036 A US9413036 A US 9413036A US 2173497 A US2173497 A US 2173497A
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United States
Prior art keywords
potential
bias
grid
level
diode
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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
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US94130A
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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 Opta GmbH
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Loewe Opta GmbH
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.)
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Publication date
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Publication of US2173497A publication Critical patent/US2173497A/en
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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
    • H04N5/16—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level
    • H04N5/165—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level to maintain the black level constant

Definitions

  • Fig. 1 shows one form of my invention applied to the output circuit of an amplifier.
  • Fig. 2 shows the defect in the amplitude oscilloram and the correction desired.
  • FIG. 3 to 6 illustrate alternative forms of my invention.
  • Fig. 1 in accordance with the invention the bias passes from the battery 3 by Way of the leak resistance 4 to the connecting lead 5, which is traversed by the total of bias and alternating potential.
  • the valve 6 is the final tube of the image amplifier, and is coupled by condenser l 35 with the preliminary stage it.
  • the bias is impressed at the grid of tube 6 by a battery 8 through resistance II.
  • Fig. 2 there is shown the curve a which an amplitude oscillogram should have in the case of a level-maintaining means acting in ideal fashion.
  • the potential of the battery 3 is plotted as a certain positive value with the same 50 figure in relation to the earth potential zero.
  • the negative synchronisation impulses 8 should always reach with their peaks the line 3. If there is a load 2 present, its leakage current causes a discharge of the condenser 9, the elec- 55 trade of which connected with 2 thus suffers a 1936, Serial No. 94,130.
  • Fig. 3 illustrates the first method. If there is passed to the consuming apparatus 2 by way of a condenser 9 merely a fraction of the oscillation potential, which has been adjusted at a tapping l2 of the anode resistance of the final valve 6, and if the diode I0 is coupled by way of a condenser l3 with the full oscillation potential of the final stage, the diode produces in idle no-load- Work at the leak resistance 4 a potential which is equal and opposite to the negative peak value of the oscillations amplitude. If the diode is now connected by way of the resistance It with the modulation lead 5 and by way of the lead I with the bias 3, the said slip in amplitude by reason of the load at 2 is compensated by the over-excitation of ID. 40
  • Fig. 4 The second method is explained in Fig. 4. It avoids the waste of oscillation amplitude involved by the method above described.
  • Fig. 4 there is connected in series to the diode an auxiliary battery I5, by means of which the initiation of the electronic current in It! is advanced. By adjustment of IS the slip in amplitude may be exactly compensated.
  • the circuit is naturally also capable of being used in the case of mains connections.
  • the third method of solving the problem which is to be particularly recommended consists in removing the diode l0 entirely from all loaded circuits and disposing the same in the grid circuits of the power amplifier.
  • Two schemes of this kind are shown in Figs. 5 and 6.
  • Fig. 5 there is shown a preliminary amplifier tube It, which is coupled by way of a condenser I in R,C connection with the grid of the final tube 6.
  • the valve 6 must be provided with a special insulated potential source is for grid and anode. Since the sign of an oscillation, which is negative in the anode circuit, is positive in the grid circuit, the polarity of the diode I! must also be changed, and it is connected by the anode with the control grid of 6, and in parallel to its leak resistance H.
  • the tube Hi operates without error in this form, even without over-excitation or auxiliary bias, so long as the tube is not traversed by grid currents. This must be ensured by means of a sufiiciently large grid bias H3.
  • the cathode of the tube 6 is earthed by way of a condenser ill.
  • Fig. 6' shows a circuit in which the bias necessary for maintaining a constant level is also taken from the grid circuit of the amplifier 6, but in which this bias itself is not conjointly amplified in the tube 6 but is employed in direct fashion.
  • the circuit therefore, possesses certain disadvantages as compared with Fig. 5.
  • the diode I9 is connected but in series with condensers 22 and 20, and accordingly loads the grid circuit of 6 but to very little extent.
  • the anode of 6 is connected to the consuming apparatus 2 by Way of a condenser 9 and lead 5.
  • the regulating bias is received by this consuming apparatus from a condenser 20 through the medium of a leak resistance 2 I.
  • the condenser 20 is positively charged by the tube NJ, as it is connected with its cathode.
  • the anode of the tube is connected by way of a condenser 22 with the anode of the preliminary valve IS.
  • the bias is only equal to the maximum out put potential of 6 when the amplification of E is equal to 1:1, as the excitation of H3 takes place only with the grid alternating potential of 6.
  • the tube l 6 is bridged by a leakage 23, whilst the desired bias 3 is supplied by way of a resistance 24.
  • the condenser 2Q has been charged to a positive bias, which is equal to the maximum positive potential of the grid of 6, all flow of current to the condenser 22 ceases, and a loading of I5 by the regulating elements no longer takes place.
  • a possible slip may be compensated also in this case by the use of over-excitation or auxiliary potential.
  • the devices set forth in the above which are employed here for maintaining the negative peak values at a constant level, may also be employed without difiiculty for maintaining constant peak values of positive sign merely by changing the polarity of the two-electrode tube it. This may be necessary in all transmission methods in which modulation is performed in reversed fashion, i. e., with increasing aerial current upon decreasing light intensity.
  • Fig. 5 there is shown a reversepolarity connection of this kind rendered necessary by the fact that the reversed polarity has required to be considered within an amplifying stage.
  • a television apparatus comprising an amplifier tube the grid of which is supplied with the mixed image and synchronisation signals and the alternating anode potential of which is conducted to the input of a consuming apparatus, a device for maintaining constant the potential level or" input independently of the consumption of said apparatus, said device consisting of a diode shunting the grid leak of said amplifier tube thus ducing a bias equal to the amplitude of said al-..rnating potential.
  • a television apparatus comprising an amplifier tube the grid of which is supplied with the mixed image and synchronisation signals and the alternating anode potential of which is conducted.
  • a device for maintaining constant the potential level of said input independently of the consumption of said apparatus consisting of a diode which is connected on one side via a condenser to said grid and via a resistance and a bias source to earth, and on the other side viaa resistance to said input and via acondenser to earth, and which is shunted by a high resistance, said amplifier having an amplification factor of about 1 so that the bias produced by said anode is equal to the amplitude of said alternating potential.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)
US94130A 1935-08-05 1936-08-04 Level-maintenance for television amplifiers Expired - Lifetime US2173497A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE202120X 1935-08-05

Publications (1)

Publication Number Publication Date
US2173497A true US2173497A (en) 1939-09-19

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ID=5769887

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US94130A Expired - Lifetime US2173497A (en) 1935-08-05 1936-08-04 Level-maintenance for television amplifiers

Country Status (6)

Country Link
US (1) US2173497A (xx)
BE (1) BE416843A (xx)
CH (1) CH202120A (xx)
FR (1) FR808993A (xx)
GB (1) GB468905A (xx)
NL (1) NL48531C (xx)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2418480A (en) * 1944-05-24 1947-04-08 Arthur C Prichard Asymmetrically conducting network
US2468087A (en) * 1943-01-29 1949-04-26 Int Standard Electric Corp Thermionic valve circuits
US2471246A (en) * 1944-05-25 1949-05-24 Rca Corp Electronic apparatus
US2543797A (en) * 1942-05-23 1951-03-06 Irving H Page Radio amplifier circuits
US2599287A (en) * 1950-05-23 1952-06-03 Gen Electric Wide frequency range power-factor meter
US2911464A (en) * 1955-11-16 1959-11-03 Muirhead & Co Ltd Facsimile telegraph systems
US3396236A (en) * 1965-06-07 1968-08-06 Fairchild Camera Instr Co Automatic black-level control circuit

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL159242B (nl) * 1950-02-25 Felten & Guilleaume Carlswerk Elektrische verdeelinrichting.

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2543797A (en) * 1942-05-23 1951-03-06 Irving H Page Radio amplifier circuits
US2468087A (en) * 1943-01-29 1949-04-26 Int Standard Electric Corp Thermionic valve circuits
US2418480A (en) * 1944-05-24 1947-04-08 Arthur C Prichard Asymmetrically conducting network
US2471246A (en) * 1944-05-25 1949-05-24 Rca Corp Electronic apparatus
US2599287A (en) * 1950-05-23 1952-06-03 Gen Electric Wide frequency range power-factor meter
US2911464A (en) * 1955-11-16 1959-11-03 Muirhead & Co Ltd Facsimile telegraph systems
US3396236A (en) * 1965-06-07 1968-08-06 Fairchild Camera Instr Co Automatic black-level control circuit

Also Published As

Publication number Publication date
GB468905A (en) 1937-07-15
NL48531C (xx)
BE416843A (xx)
FR808993A (fr) 1937-02-19
CH202120A (de) 1938-12-31

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