US1816227A - Radio receiving apparatus - Google Patents

Description

July 28, 1931. B. B. MINNIUM I RADIO RECEIVING APPARATUS Filed Nov. 25, 1927 Q; 4 A H25 v O I Q Q: Q g R m f- A m Q C\ Qf U H 1 TOD/13. MUULl/LL/TL Patented July 28 1931 f fumreo A COREGRAFION 6i DELL ir-LAKE M V d g I I g v v more nEcEIvING'nrrABA rUs I hiiplfcatidnfil'ed November 25,1927. east Ni 23 5,5 2 1.

-This invention relates to radiore'ceiv ing sets of thekin'd in which, for one reason or another, there'is ordina'fiily some liability of a burn or ripple voltageiti the amplifier out- "Generall stated, the 'object of the invention is to provide improved construct-ion and 'eireuit rrangement whereby the said hum or'ripple veitage is prevented, or at least it) greatly redueemevenwhen alternating cur, rent is employed for heating or energizing the filament of the am lifier, thus improving the receiving qualities of a receiving set of thiskind. v l v It is elso'anebiiect' to provide certain details' a'rid features of im rovement and com binatieiis tending'to increase the general efficiency and the desirabilityef-aradio receiving set of this particular ClltlftICl'ilK id To these and other useful ends, the invention consists in the matters hereinafter set forth and claimed, and shown in the accompan'y'iiig drawings, in which the single diagraiiiiliustrates aradio receiving set involv- 456 the principles cf the invention.

, As thus illustrated, the invention comrises: an ordi ary aerial 1', which is connected to ground 2 through the primary ot an ordinary induction or repeating coil. The secondary 4 of said induction coil and the adjustable condenser 5 are connected in,

parallel or in shunt of each other, at the points v by a conductor 8 to the grid 9 of the first vacuum tube or amplifier, while the junction point 7 isconnected by the conductors 10 and Y 11 to the ground 2, as shown. The conductor 10 is also connected through the conductor 12 with the negative pole of the battery 13, While the positive pole of this battery is connected by the conductor 1 L with the intermediate point 15 on the resistance 16, as shown. The filament 17 of said tube or amplifier has its terminals connected to the opposite ends of the secondary 18 of the transformer or induction coil 19, and a resistance 20 is connected in bridge across the filamentcircuit, as shown. The conductor 12 islconnected through aresistance 21 with the ustable point 22 on the resistance 20,

' c'nnected to the filament. I

tlft-e tube or amplifier is connected a can:

6 and 7, and the point 6 is connected (anode Y potential whereby negative pole-o 'i the battery i3 is I The plate 23 of (motor 24 with the junction petites, where v by said plate connected to one terminal of 26, and with oneteriniiial at the res'istaiice I the inim-ye? of th second induction or repeating coil, The lowe terminals resistance 96 and rimary winding] 27 are connected together by a conductor 28, as shown; The resistances 16 a r'1d'i26 are "con:- nected togetherin any suitable manner, for example, bya slide having" movable contacts 2 9' and 30 for engaging said resistances, re spec-tively. The input circuit of the second stage of amplification includes secondary 31,as'shown; I V V V I It will also he seen that th diagram, which is illustrative of oneiorin of the invention,

includes a primary32 for the transformer 19, to which is connected a plug???" that can be inscrtedin any electrical base or receptacle which has connection with a source of alt er In this way, the

nating current sup-plyf tra sformer coils rs and 32 are adapted to of the g co=o'pe'r'ate to su ply alternating current to, v

the filament 17 of the first stageei amplifiertion; willbe seen that another secondary' 34 is also included in the transformer 19, sothat the filaments of second stage of amplification is also heated ot energized by'a-lternatingcurrent.

In e-i'dii ar rec" iv'n sets of this kiiiLtlie control of gain (or volume) is usually by varying the filament (cathode) or plate In the use "of tubes or amplifiers i'n which the filament or electron -'emitting element is heatedbyaIternating cur- -i"-eiit, normaro ei-atirig values of plate and filament voltage must be maintained in order tepi-ev'eiit hufn or rip le vdltager'iiithe ain'- plifiei, output. The eireii i't shown and described,jttiiichis illustrati; f *irieformbf the" iii-ve'n't'bn, sei vesstohpidth e plate voltage v I rent) constant, but vitriestheaiiiqunt sip-late (and therefore the plate energy flowing through the tran former or 1 iridtictieii'ceil' primar 2"? te which' it is con-- nected. If rim ry- 27 ig retttiv ly in met,-

is may be omitted.

WVhen the resistance of the primary coil 27 is high, the fixed point 15 must be placed near the lower end of the resistance 16, and the resistance of this coil 16 must be so proportioned as to always maintain a fixed value of resistance between this fixed point 15 and the plate 23 of the tube or amplifier.

It is obvious that the invention may be employed in connection with any output primary alone, or in connection with two or more output primaries, as may be desired. But Whether the invention is employed in one form or another, the adjustment of the con tact points 29 and 30 (or the contact 30 alone if the resistance 16 is not necessary) can be employed to eliminate any hum or ripple voltage in the amplifier output, while at the same time varying the volume. In other words, the object of the invention is to provide means for easily and satisfactorily varying or changing the volume without producing objectionable hum or ripple voltage.

It will be seen that the zero point on resistance 16 is reached when the movable points 29 and 30 are moved downward until point 29 is opposite point 15 on the resistance. Thus, while one resistance is increasing, the other resistance is decreasing, so to speak, by adjustment of the points 29 and 30 in either direction, in any range of adjustment above the fixed point 15, connected with the source of plate potential. In other words, each reslstance varies reversely to the other, for as one increases, the other diminishes, and vice versa, according to the direction in which the points 29 and 30 are adjusted. The point 15 can be attached wherever necessary on the 'coil 17, depending upon the resistance of the primary 27 of the transformer.

Without disclaiming anything, and without prejudice to any novelty disclosed, what I claim as my invention is:

1. In a radio receiving set, an amplifier output induction coil primary having a re sistance in shunt thereof, and having the source of plate potential connected to a variable point between the ends of said resistance, including a variable resistance be tween said source and said first mentioned re sistance.

2. In a radio receiving set, an amplifier output induction coil primary having a resistance in shunt thereof, and having the source of plate potential connected to a va riable point between the ends of said resistance, including a variable resistance between said source and said first mentioned resistance, there being a variable point for engaging said variable resistance between the ends thereof, and said variable points being adjustable in unison.

3. In a radio receiving set, an amplifier output induction coil primary having a resistance in shunt thereof, and having the source of platepotential connected to a variable point between the ends of said resistance, including a variable resistance between said source and said first mentioned resistance, there being a variable point for engaging said variable resistance between the ends thereof, and said variable points being adjustable in unison, said variable points and said resistances being so relatively arranged that as more of one resistance is included in the plate circuit, less of the other resistance is included therein, and vice versa, by the adjustment of said points in unison in one direction, or in the opposite direction.

4. In a radio receiving set, an amplifier output induction coil primary having a resistance in shunt thereof, and having the source of plate potential connected to a Variable point between the ends of said resistance, including a variable resistance between said source and said first mentioned resistance,with means whereby one resistance varies reversely to the other.

5. In a radio receiving set, an amplifier output induction coil primary having a variable resistance in shunt thereof, so that the coil and more or less of said resistance are in multiple in the plate circuit, and a variable resistance in series with said resistance in the plate circuit.

6. A structure as specified in claim 5, having means whereby each resistance is necessarily variable in unison with the other, but reversely thereto.

7. A structure as specified in claim 5, said source being connected to an intermediate point on said last mentioned resistance.

8. A structure as specified in claim 5 having means whereby any portion of said resistance which at any time is not in shunt of said Jrimary is in series therewith in the plate circuit.

Specification signed this 22nd day of November, 1927.

BYRON B. MINNIUM.

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