US1768182A - Thermionic valve circuits - Google Patents

Thermionic valve circuits Download PDF

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Publication number
US1768182A
US1768182A US99944A US9994426A US1768182A US 1768182 A US1768182 A US 1768182A US 99944 A US99944 A US 99944A US 9994426 A US9994426 A US 9994426A US 1768182 A US1768182 A US 1768182A
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Prior art keywords
inductance
capacity
grid
winding
circuit
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US99944A
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English (en)
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Willans Peter William
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    • 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
    • H03F1/08—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements
    • H03F1/14—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements by use of neutralising means
    • H03F1/16—Modifications of amplifiers to reduce detrimental influences of internal impedances of amplifying elements by use of neutralising means in discharge-tube amplifiers

Definitions

  • This invention relates to, and has for its object the provision of improvements in, thermionic valve circuits; More particularly the invention relates to thermionic valve circuits in which means have been provided for neutralizing the capacity coupling between the grid and plate circuits of the valve. Means for this purpose have beenheretofore proposed comprising what is essentially a transformer and a capacitative device, the
  • transformer having one of its windings connected between the plate and the filament system. of the valve and the other winding connected between the grid and the filament system of said valve and the capacitative'device being connected in series with either of'said windings.
  • coeflicient of coupling between the transformer windings shall be unity and that the number of turns of the former and latter windings shall bear the same ratio to one another as the capacity to be neutralized bears to the capacity of said capacitative device, or in other words that the ratio of the turns shall be-in the inverse ratio of the associated capacities.
  • the object of the present invention is the provision of improved means for neutralizing the capacity coupling of a thermionic valve and the invention consists broadly in the arrangement according to which the capacitative device in an arrangement such as the above constitutes the major part of the effective capacity across an inductance to which the valve is connected.
  • the capacity of this device will be not less than .00005 micro farads.
  • said inductance is the plate circuit inductance
  • the said capacitative device may in some cases be constituted by the variable capacity condenser by which the aforesaid inductance is adapted to be tuned but in this case the mutual inductance between the transformer winding must be variable.
  • other condenser of smaller capacity may be connected across said inductance for tuning purposes.
  • the tuning is effected" by a variation in value of the aforesaid mutual inductance with or without the small additional condensers.
  • the essential feature is that the said capacitative device constituted as above stated the major part of the effective capacity across said inductance.
  • the transformer winding other than that in series with which the capacitative device is connected preferably constitutes either the grid circuit inductance or the plate circuit inductance according as whether the capacitativedevice is connected, as above described, across the plate circuit inductance or across the grid circuit inductance. It will therefore be seen that in one simple embodiment the invention simply. consists in connecting, in series with either the anode or grid circuit condenser of an ordinary receiving set, a coil which is magnetically coupled to the grid or anode circuit inductance.
  • L and L are the transformer windings, A is the capacitative device and I is the inductance across which said capacitative device is connected. In each case L is thewinding in series with which the capacity A is connected.
  • Figure 1 illustrates a simple case in which If desired anthe winding L constitutes the grid circuit inductance and the inductance I the plate circuit inductance.
  • the condenser A and winding I are connected in series between the plate and filament i. e. across the inductance I and high tension battery II. T.
  • the condenser A preferably con stitutes the entire capacity across the inductance I but a second condenser B of less capacity may be connected across said in;- ductance I'for the purpose of tuning.
  • Figure 2 illustrates a simple case in which the winding L constitutes the plate circuit inductance and the inductance I the grid circuit inductance.
  • the condens 3 A and the winding L are connected in series as shown between the grid and the side of the high tension battery H. T. which is remote from the filament.
  • the condenser A may be the entire capacity across the coil I or a second condenser B of smaller capacity may be pro-- vided.
  • Figure 3 illustrates a case in which the winding L constitutes the grid circuit inductance and the inductance I the secondary of the plate circuit transformer.
  • the series connection of the winding L and the condenserA between the plate and the filament is inductive instead of. direct. .Thus the winding L and the condenser A are connected, as shown, together with the inductance I in a closed circuit extending from and returning to the filament the said inductance I being coupled to the primary I of the plate circuit transformer.
  • the condenser B across the inductance I in this case it will have the eifect of throwing capacity across the inductance I according to well known transformer theory. If how" ever we reckon the total effective capacity across the inductance I, the condenser A constitutes the major part of this effective capacity.
  • either the inductance coil I or theneutralizing transformer windings L or I1 may be connected indirectly to the appropriate electrodes through the medium of a condenser.
  • Figure 4 is shown an example of' an arrangement wherein the windingL is connectcd'to the grid through the medium of a condenser C.
  • the inductance coil I constitutes the plate circuit inductance
  • the winding I is connected in the plate circuit of a preceding valve
  • the winding I1 and neutralizing condenser A is connected preferably has an impedance which is small (for the frequencies being received) in comparison with that of said condenser A.
  • I impedance which is small (for the frequencies being received) in comparison with that of said condenser A.
  • the condensers and/ or inductances may be vari-' able.
  • I may tune the inductance I by varying the capacity of the condenser A and at the same time varying the mutual inductance between the windings L and L
  • the anode circuit is tuned by variation of its'inductance.
  • no tuning adjustments are required as the amplifier operates on a fixed band of wave, length.
  • the neutralizing coupling may be efi'ecte-d by a plug-in coil assembly comprising both the grid circuit inductance and the neutralizing inductance.
  • the fixed coupling' is suitable in this case for any range of wave-lengths for which the grid circuit inductance is suitable, the coil assembly beinginterchanged when necessary for another with correctly proportioned windlngs.
  • this coupling device may consist of a single coil wit-h a suitable tapping point.
  • the invention may be combined with other forms of retroactive coupling in order to obtain greatersensitivity.
  • I may apply any form of retro-- active coupling to the anode circuit for the purpose of reducing its damping, the neutralizing coupling enable this effect tobe obtained without the aerial circuit damping being reduced.
  • the load on the anode circuit due to the internal resistance of the valve may thus be counteracted without the tem becoming self oscillatory. This'res'ults in greatly enhanced sensitivity and selectivity.
  • the transformer in the drawings is shown as having two windings connected in se ies. It may thus convenientlyconsist of a single tapped coil. Alternatively the two windings may be quite separate. For example one may be connected to the filament and the other to the high tension positive.
  • the invention may be applied to a receiver in which there are a number of stages of amplification connected in cascade.
  • Two examples of three stage amplifiers having capacity coupling neutralization in accordance with the invention are illustrated in Figures 5 and 6.
  • the three stage amplifier illustrated in Figure 5 is on the basis of Figure 1; that is to say the inductances I are on the plate circuits and the windings L of the transformers are in the grid circuits.
  • the parts L L A, I and C are related there to and function with respect thereto in subvalve from the left but that the inductance I, which constitutes the plate circuit inductance of said second valve, functions in re spect of said thlrd valve in the same capaclty as does the transformer winding L in respect of the second valve.
  • the drawing is deemed sufiiciently explicit.
  • the amplifier illustrated in Figure 6 is on the basis of Figure 2; that is to say the inductances I are in the grid circuits and the windings L are in the plate circuits.
  • the transformer winding L is connected through the high tension battery H, T. across the plate and filament.
  • the condenser A and transformer winding L are connected in series through a condenser C and the high tension battery H. T. across the grid and filament.
  • the inductance I is connected in parallel with said con- 3: denser A and winding L i. e. is connected across the grid filament through the condenser C and high tension battery H. T.
  • Apparatus for neutralizing capacity coupling between the grid and plate circuits of a thermionic valve comprising a transformer, a capacitative device and an inductance, said transformer having one of its windings connected between the plate and the filament system and the other winding between the grid and the filament system,
  • said capacitative device being connected in series with one of said windings and, together with said one winding, across said inductance, said capacitative device moreover having a capacity of the order of ten or more times the capacity between the plate and grid of the thermionic valve and constituting, with said inductance and said latter winding, a resonant oscillatory circuit, tuned to the required frequency of which it is the dominating capacity.
  • Apparatus for neutralizing capacity coupling between the grid and plate circuit of a thermionic valve comprising a transformer, a capacitative device and an inductance, said transformer having one of its windings connected between the plate and the filament system and the other winding between the grid and the filament system, said capacitative device being connected in series with one of said windings and, together with said winding, across said inductance, said capacitative device moreover having a capacity of the order of ten or more times the capacity between the plate and grid of the thermionic valve and constituting the variable capacity condenser by which said inductance is adapted to be tunedto a variety of frequencies.
  • Apparatus for neutralizing capacity coupling between the grid and plate circuits of a thermionic valve comprised in a multi stage amplifier, comprising a transformer a capacitative device and an inductance, said transformer having one of its windings connected between the plate and the filament system and the other between the grid and the filament system the former of said wind ings being also in circuit with an adjacent valve, said capacitative device being connected in series with one of said windings and,
  • said capacitative device moreover having a capacity of the order of ten or more times the capacity between the plate and grid of the thermionic valve and constitut- In witness whereof I atfix my signature.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Coils Or Transformers For Communication (AREA)
  • Amplifiers (AREA)
US99944A 1925-04-07 1926-04-05 Thermionic valve circuits Expired - Lifetime US1768182A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9289/25A GB253277A (en) 1925-04-07 1925-04-07 Improvements in, or relating to, thermionic valve circuits

Publications (1)

Publication Number Publication Date
US1768182A true US1768182A (en) 1930-06-24

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Application Number Title Priority Date Filing Date
US99944A Expired - Lifetime US1768182A (en) 1925-04-07 1926-04-05 Thermionic valve circuits

Country Status (4)

Country Link
US (1) US1768182A (enrdf_load_stackoverflow)
BE (1) BE333742A (enrdf_load_stackoverflow)
FR (1) FR617708A (enrdf_load_stackoverflow)
GB (1) GB253277A (enrdf_load_stackoverflow)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE977332C (de) * 1952-06-22 1965-12-16 Telefunken Patent Hochfrequenzvorstufe in Zwischenbasis-Schaltung eines Empfaengers fuer ultrakurze Wellen

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Publication number Publication date
GB253277A (en) 1926-06-17
FR617708A (fr) 1927-02-24
BE333742A (enrdf_load_stackoverflow)

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