US2395390A

US2395390A - Phonograph

Info

Publication number: US2395390A
Application number: US433877A
Authority: US
Inventors: John J Antalek
Original assignee: VIRGIL HAMILTON
Current assignee: VIRGIL HAMILTON
Priority date: 1942-03-09
Filing date: 1942-03-09
Publication date: 1946-02-26
Anticipated expiration: 1963-02-26

Description

Patented Feb. 26, 1946 UNITED' STATES PATENT oFFlcE PHONOGRAPH John J. Antalek, Chicago, Ill., assignor to Virgil Hamilton, doing business as Hamilton Associated Industries, Chicago, Ill.

Application March s, 1942, serial No. 433,877

z claims. (ci. 17o-10011) This invention relates to a phonographor radio phonograph, and more particularly to the reproducing or amplifier circuits of a phonograph, radio phonograph, or public address system.

It is an object of my invention to provide irnproved circuits for the reproduction of sound from phonograph records or the like.

A further object of the invention is to provide phonograph record pick-up amplifying circuits having a high signal to noise ratio and improved frequency response.

A more specific object of the invention is to Y provide improved pick-up, reproducing, and amplifying circuits for phonograph record players which shall obtain greater fidelity and quality in the reproduction of the phonograph signals.

A further and important object of the inven.. tion is to provide phonographic and reproducing circuits wherein the phonographic pick-up circircuit condenser 34 and the grid resistor 30 is grounded as at 40, andthereby connected to the plate circuit of the oscillator. The selector switch 24 cooperates with the switch contact 22 and a like contact 42 connected to the primary 46 of the usual antenna coupling-transformer 48, the secondary 50 of this transformer being tunable by y the condenser 52, which is connected in shunt to the secondary and connected by a wire 54 to the iirst radio receiver tube 56, 'which may comprise a radio frequency amplifying tube, a' convertor or mixer tube or a detector tube.

The primary 46 is grounded as at 58 and the corresponding end of the secondary is grounded as at 60. The tube 56 may comprise a plate electrode 62, a screen grid electrode 64, a control grid 66, and a cathode 68. The plate `electrode 62 is connected with a wire lll to the usual radio frequency or intermediate frequency output circuits 12 of the radio receiver, and in shunt thereto by a wire 14 through a resistor 16 to a positive plate supply terminal 18, the negative side of the y plate -supply being, of course, grounded. The

screen grid electrode is connected by the wire 80 to the usual positive screen grid supply terminal 82. The control grid is connected to the wire 54.

'The cathode 68 is connected to the cathode resistor 84, shunted by the by-pass condenser 86 and grounded as vat 88.

When the selector switch 24 is in position engaging contact 42, the radio receiver, of which the tube 56 constitutes the first tube, operates in phonograph circuit embodying the invention; and

Figure 2 is a. schematic diagram of another form of phonograph circuit embodying the invention.

In Figure 1 the phonograph circuit comprises an oscillator tube 2 having a plate electrode 4, a control grid electrode 6, and a cathode 8. The plate is connected by the wires I0 and I2 to the positive plate supply terminal lI`4 through the resistor I6, the negative sideof the plate supply source being grounded. The plate is also connected through the wire l0, the wire i8, and the blocking condenser 2 0 to the contact. 22 of s. selector swltch 24. The control grid 6 is connected by the wire 26'to'a-grid condenser 28 and a grid resistor or leak 30, this condenser and resistor being connected in 'shunt to the' oscillator tank circuit comprising an inductance coil 32 and a condenser 34, which may comprise a variable impedance phonographic pick-up. The cathode! `is connected by wire 36 to an intermediate point of the oscillator coil 32. Thc wire 38 connecting the lower end 'of the oscillator coil to the tank the usual manner to receive and reproduce radio signals. With this switch 24 in position engaging contact 22, the radio receiver is disconnected from the antenna and thus made ineffective to receive or reproduce radio signals, but is connected to the phonographic circuit. vWith the switch in this position, the antenna transformer 48 is tuned by the condenser 52 to a frequency within approximately plus and minus eight kilocycles of the unmodulated signal carrier supplied by the oscillator, of which the tube 2 vforms a` part. Variations in the impedance of the pick-up, due

to the lateral undulations of the record groove.

effect a frequency modulation of the carrier or the signal supplied by the oscillator. This frequency modulated signal is transmitted as an amplitudel modulated signal by the tuned antenna coupling to the input circuit of the tube 56, which amplifles or converts the 'signal and passes it to the R. F. or I. F. output circuit 12 of the receiver. It will be understood that the remaining usual circuits of the radio receiver ampliiiesgthe modulated signal supplied to the output circuit 12, and/or convert it into I. F. amplitude modulated signal which is then detected, amplied and supplied to the reproducer or loud speaker.

In the case of a tuned radio frequency receiver, the'tube'56 may constitute a radio frequency amplifier feeding into the usual circuits, Where the phonographically modulated signal is detected, amplified, and supplied to the reproducer or loud speaker. In the case of a 'superheterodyne receiver, the tube 56 or the electrodes thereof may also constitute a part of the convertor or mixer section, by which the modulated Vsignal or radio frequency is converted into va modulated intermediate frequency signal, and' thereafter ampliiied and converted into audio frevcondenser being connected in series with the resistor in this shunt circuit so as' to vary the effective impedance and the resultant frequency of the oscillator circuit in accordance with the undulations of the record groove. Where an impedance pick-up is employed, it may be connected so as to form all, or a part, of the tankcircuit inductance 92.

In the circuit shown in Figure 2, an oscillator tube or tube section 90 is connected to a detector tube or section 92 by' a doubly tuned transformer coupling 94. The oscillator tube or section ,90 comprises4 a plate 96, a control grid 98, and a cathode |00. The cathode is connected by the wire |,02 to an intermediate point of the adjustable tank circuit inductance coil |04. The control grid is connected by a wire |06 to one side pacity type pick-up ||2 grounded as at H4. It

will, of course, be evident that the phonographic pick-up may be of a resistance or inductance type so connected as to eifect a frequency modulation of the carrier or unmodulated signal supplied by the oscillator. Where a resistor or inductance type of pick-up is employed, the capacity necessary for the tank circuit of the oscillator may be provided by a condenser connected-in the saine manner as the pick-up capacity 2; withthis condenser, in the case of a resistor pickup,"being shunted by the pick-up and an auxiliary condenser connected in/series with the pick-up resistor. In the case of the inductance type pickup, the pick-up may form apart or all of the tank circuit coil |04.

The plate electrode 96 is connected by a wire ||6`to one side of the primary winding ||9 of. the transformer coupling v94,'the-other side vof ,the primary being connected'by a wire |20 to the positive plate supply terminal |22. The pri- .mary ||8 is tunable by a condenser |24 in shunt therewith,

'I'he detector tube or section 92.,may comprise-a plate ,electrode |26, -a control grid |28, and a` cathode |30. The Icontrol grid is connected through grid condenser |32 and bywire |34 to one side of the secondary winding |36 of the aseaseo' transformer coupling 94. @The other side of the secondary winding f 36 is grounded by the wire |38. The secondary winding is shunted by tuning condenser I 4ll.l The cathode I 30 is connected to the ungrounded end of the cathode biasing resistor |42 which is shunted by the usual bypass condenser |44 and groundedvas at |46. The control grid is connected to the grounded end of the biasing resistor through the grid resistor o r leak |48. l

The plate electrode |26 is connected by a wire |50 to the ungrounded side of an R. F. by-pass condenser |52; to the positive plate supply terminal |54 through a resistor |56; and to audio output circuit |58 through blocking condenser |60. I'he audio output circuit |58 may comprise any usual audio amplifier or audio amplifying section of a radio receiver orpublic address system, by which the audio signals in the output circuit of the detector tube or section 92 are amplined and supplied to the usualreproducer or loud speaker.

'I'he oscillator and

detector sections

90 and 92 graphic pick-up along the steep slope of the selectivity curve ofthe doubly tuned transformer coupling 94. Accordingly, this coupling impresses on the input circuit of the. detector tube a radio frequency amplitude modulated signal, and this signal is detected by the-detector tube'or section and supplied to the audio output circuit. r It is thought that the inventionand numerous of its attendant advantages will be understood from the foregoing description, and it is'obvious that numerous changes may be made in the form,

construction and arrangement 'of the several parts without departing from the spirit or scope ant advantages, the formshherein described being preferred embodiments for thepurpose of illustratingthe invention.

Having thus described my invention, what claim as new and desire to secure by Letters Patent is:

1. In a radio phonograph, a radio receiver comprising aiirstir'adio frequencyamplifier, and a tuned antenna coupling in the input of said ampllfler, a phonographic circuit adapted to be connected to said antenna coupling circuit, saidl phonographic circuit comprising an impedance varying record pick-up, an oscillator having plate, grid, and cathode electrodes, means for connecting said antenna coupling circuit'in the plate-tocathode circuit of said tube.' and a tank circuit connected to all of said electrodes forgenerating radio frequency oscillations, said tank circuit having inductive and capacitive branches, one of said branches including said pick-up to tune said oscillator and vary the frequency of oscillations-in said antenna coupling circuit, said tuned antenna tuning said circuit to a frequencywithin the side bands of the modulated oscillations supplied to of the invention or sacrificing any of its attendcoupling circuit including a, tuning element fox" said antenna ccuplins circuit by said Phcn0 i l0 graphic circuit.

coil connected tuali ofsaid electrodes,r said ca-v pacity Avarying pick-up being connected in shunt to said coil to tune said phonographic circuit and vary the` frequency of the oscillations supplied to said antenna coupling circuit, said tuned antenna coupling circuit including a tuning element for tuning said circuit t0 a frequency within the side bands of the modulated oscillations supplied to said antenna coupling circuit by said phono- I i JOHN J.