US2226746A - Low-frequency amplifier - Google Patents

Low-frequency amplifier Download PDF

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Publication number
US2226746A
US2226746A US84437A US8443736A US2226746A US 2226746 A US2226746 A US 2226746A US 84437 A US84437 A US 84437A US 8443736 A US8443736 A US 8443736A US 2226746 A US2226746 A US 2226746A
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US
United States
Prior art keywords
potential
anode
grid
voltage
characteristic
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
US84437A
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English (en)
Inventor
Schulze-Herringen Erich
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.)
Alcatel Lucent Deutschland AG
C Lorenz AG
Original Assignee
Standard Elektrik Lorenz AG
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
Priority to NL46317D priority Critical patent/NL46317C/xx
Priority to DESCH108372D priority patent/DE677548C/de
Priority to DESCH104131D priority patent/DE730227C/de
Priority to DESCH104738D priority patent/DE732782C/de
Priority to GB12962/35A priority patent/GB444050A/en
Priority to US19469A priority patent/US2137629A/en
Priority to FR789537D priority patent/FR789537A/fr
Priority claimed from US19469A external-priority patent/US2137629A/en
Application filed by Standard Elektrik Lorenz AG filed Critical Standard Elektrik Lorenz AG
Priority to US84437A priority patent/US2226746A/en
Application granted granted Critical
Publication of US2226746A publication Critical patent/US2226746A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/22—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with tubes only
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C1/00—Amplitude modulation
    • H03C1/62—Modulators in which amplitude of carrier component in output is dependent upon strength of modulating signal, e.g. no carrier output when no modulating signal is present
    • 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
    • H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H03F1/04—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation 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
    • H03F3/26—Push-pull amplifiers; Phase-splitters therefor
    • H03F3/28—Push-pull amplifiers; Phase-splitters therefor with tubes only

Definitions

  • the main feature of the invention is that in push-pull low frequency amplifiers of the class B type the direct current potential of the ano-de and the biasing potential of the grid are varied in the rhythm of the average amplitude variations of the voice frequencies, the variation of the anode potential being preferably such that a complete voltage utilization shall be attained.
  • voltage utilization is meant the ratio between the anode alternating voltage and theanode direct voltage and, in accordance with the present invention, by virtue of the alternating control voltage, the linear portion of the tube characteristic is completely utilized.
  • FIGs. 1 to 4 are diagrams relating to the operation of arrangementsconstructed in accordance with the invention.
  • Fig. 5 is a diagrammatic representation of such an arrangement.
  • the ideal characteristic of a push-pull low frequency amplifier in class ⁇ B connection has the shape-represented in Fig. 1.
  • the slope of this characteristic is a straight line, as will be seen from Fig-2.
  • the energy conditions may be considered as follows:
  • the operating potential i. e., momentary plate voltage Ua
  • the threshold potential i. e., the Voltage at which a slope occurs in the anode current-anode voltage characteristic
  • ⁇ as the characteristic curves worked upon must all run parallel with each other.
  • Fig. 3 an example of amplitude variations is shown which are produced for instance by speech and correspond to the curve of the continuous anode ⁇ voltage with an at rest Value 0.3.
  • the continuous grid potential is regulated in such a manner that in case the voice frequency input potential is half the value between zero and maximum, the working point is located at the zero point of the characteristic for half the continuous anode potential. If voice alternating potential is supplied then with an increasing anode potential, the grid potential is increased towards the negative side by a negative increment DAUa whenever the anode potential is increased by a positive increment AUa.
  • This word ist is a familiar German term meaning the throughgrip of theplate of the electron tube on the electrons between the grids and the cathode which may be eX- pressed as the reciprocal of the amplification factor. If Ug is small then Ust depends very much upon DUa and thus upon the continuous anode voltage Us.
  • the DU@- compensation is accomplished in a nonlinear form to compensate for the curvature of the characteristic at its lower end, in order to diminish the distortion of loudness ratios and sound caused by the characteristic curvature.
  • the grid bias since because of the curvature of the characteristic, signals of low amplitude are not linearly amplified, the grid bias must be made less negative at a greater rate with' respect to the decrease in anode potential than on the linear portion of the characteristic .when the slope is diminishing, as shown in the drawing. This insures that the points at which the average amplitude is a minimum the signal will still be amplified properly.
  • each control amplitude of the voice frequency has a different working point on the curved portion of the characteristic.
  • This mode of eliminating distortions has the advantage that the elimination can be effected in the classB amplifier itself or that owing to such special circuit arrangement a substantial distortion cannot occur.
  • the correction of distortion of voice frequencies in such a B-amplifier may be eected by a non-linear displacement of the working point by means of the grid without altering the continuous anode voltage.
  • the push-pull tubes are designated R.
  • the voice frequencies are in a well known manner conveyed over ⁇ the transformer vT1 and on the grid side directly to the push-pull tubes R and are also conducted through an amplifier V to the push-pull arrangement, the amplifier V belonging to the novel control arrangement by which the grid voltage as well as the anode voltage are influenced.
  • N is a non-linear amplifier which, according to the foregoing, serves for compensating the curvature of the characteristics.
  • a rectifier G1 Connected to the output of the non-linear amplifier is a rectifier G1, which through a smoothing means Ai, such as a filter circuit, acts to control In the output of V another recticontrolled.
  • the anode voltage is intended to derive the anode voltage from the alternating current network by means of a grid control rectifier GL.
  • the grid of GL is controlled by the rectifier ⁇ G2.
  • the controlled anode voltage is then fed over a smoothing linkAz to the anode circuit of the push-pull arrangement.
  • the method of controlling a push-pull low frequency amplier in class B connection having a grid controlled anode potential supply source which comprises, using the average amplitude variations of the low frequencies to vary the direct current potential ofthe anodes of the amplifier in the same sense as the direction of average amplitude varies by controlling the grid voltage of said grid controlled anode supply source, simultaneously varying the grid biasing potential of both tubes in a sense opposite to the change in said anode potential to increase the average efficiency of said amplifier and maintain distortion at a substantial minimum and further controlling said grid biasing potential to compensate for curvature in the amplifier characteristic by effecting a non-linear displacement of the working point.
  • An arrangement for controlling a low frequency push-pull class B amplifier employing vacuum tubes having cathodes, grids and anodes for amplifying low frequency variable amplitude waves ycomprising an anode supply rectifier, means responsive to the average amplitude variations of the low frequencies controlling said rectier to control the ⁇ direct current potential on the ⁇ anodes, means responsive to said ampliresponsive to average amplitude variations of the 10W frequencies for controlling the output of said rectifier directly as the variation of said average amplitude, other means responsive to said amplitude variations for simultaneously varying the bias potential of said grids in a ⁇ sense opposite to said plate potential variation and amplifying means for controlling said other f means to produce a non-linear variation of said grid bias to compensate for curvature of said vacuum tube characteristic.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)
  • Transmitters (AREA)
US84437A 1934-05-02 1936-06-10 Low-frequency amplifier Expired - Lifetime US2226746A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
NL46317D NL46317C (enrdf_load_html_response) 1934-05-02
DESCH104131D DE730227C (de) 1934-05-02 1934-05-03 Verfahren zur Verbesserung des Wirkungsgrades von fremderregten modulierten Sendern
DESCH108372D DE677548C (de) 1934-05-02 1934-05-03 Verfahren zur Steuerung von Hochfrequenzsendern
DESCH104738D DE732782C (de) 1934-05-02 1934-07-21 Verfahren zur Vermeidung von Dynamik- und Klangverzerrungen bei Gegentakt-Niederfrequenzverstaerkeren in B-Schaltung
GB12962/35A GB444050A (en) 1934-05-02 1935-05-01 Improvements in or relating to thermionic valve amplifiers
US19469A US2137629A (en) 1934-05-02 1935-05-02 Method of controlling high frequency transmitters
FR789537D FR789537A (fr) 1934-05-02 1935-05-02 Procédé de réglage des émetteurs à haute fréquence et ses applications
US84437A US2226746A (en) 1934-05-02 1936-06-10 Low-frequency amplifier

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE444050X 1934-05-02
US19469A US2137629A (en) 1934-05-02 1935-05-02 Method of controlling high frequency transmitters
US84437A US2226746A (en) 1934-05-02 1936-06-10 Low-frequency amplifier

Publications (1)

Publication Number Publication Date
US2226746A true US2226746A (en) 1940-12-31

Family

ID=32073683

Family Applications (1)

Application Number Title Priority Date Filing Date
US84437A Expired - Lifetime US2226746A (en) 1934-05-02 1936-06-10 Low-frequency amplifier

Country Status (4)

Country Link
US (1) US2226746A (enrdf_load_html_response)
FR (1) FR789537A (enrdf_load_html_response)
GB (1) GB444050A (enrdf_load_html_response)
NL (1) NL46317C (enrdf_load_html_response)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2598221A (en) * 1947-11-08 1952-05-27 Bell Telephone Labor Inc Power amplifier circuit
US2721907A (en) * 1949-01-22 1955-10-25 Charles T Jacobs Electric-oscillation amplifiers
US2918630A (en) * 1955-02-25 1959-12-22 Jr Martin V Kiebert Power amplifier and method of operation

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH664655A5 (de) * 1980-12-12 1988-03-15 Patelhold Patentverwertung Verfahren und verstaerkerschaltung zum verstaerken elektrischer signale, insbesondere nf-modulationssignale eines rundfunksenders.
US4462004A (en) * 1982-03-18 1984-07-24 At&T Bell Laboratories Dynamic class-4 FET amplifier
FR2655790B1 (fr) * 1989-12-08 1992-01-24 Thomson Tubes Electroniques Tube a grille a rendement ameliore.

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2598221A (en) * 1947-11-08 1952-05-27 Bell Telephone Labor Inc Power amplifier circuit
US2721907A (en) * 1949-01-22 1955-10-25 Charles T Jacobs Electric-oscillation amplifiers
US2918630A (en) * 1955-02-25 1959-12-22 Jr Martin V Kiebert Power amplifier and method of operation

Also Published As

Publication number Publication date
FR789537A (fr) 1935-10-30
GB444050A (en) 1936-03-12
NL46317C (enrdf_load_html_response)

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