US2379617A - Combined radio and phonograph system - Google Patents

Description

y 1945- J. w. WHITE ETAL 2,379,617

COMBINED RAD-IO AND PHONQGR[KPH SYSTEM Filed Jul 24, 1942 POWER I /27 RADIO SUPPLY RECEIVER AMPLIFIER OUTPUT g 7 32 D E s PHONOGRAPH i PICKUP VVVV III

INVENTORS JULES W WHITE 'ATTQRNEY A Patented July 3, 1945 oomnman mnro AND rnonocmrn SYSTEM Jules W. White and Louis A. G. ter Veen, Marion,- Ind., assignors to Farnsworth Television and ltadio Corporation, a corporation of Delaware Application July 24, 1942, Serial No; 452,226 6 Claims. (Ci. 179-10011) This inventionrelates generally to combined radio receivers and phonographs and more particularly to a switching circuit for connecting either a radio receiver or a phonograph pickup device to a sound reproducing loud speaker.

Combined radio receivers and phonographs are customarily provided with a number of circuit components consisting of a radio-frequency amplifying circuit and an audio-frequency amplifying circuit, a. phonograph pickup, a power supply and a sound reproducing loud speaker. There is also provided a switching means for connecting either the radio-frequency amplifier or the phonograph pickup to the audio-frequency amplifier thereby providing a means for selecting either a radio program or a program recorded on a recording medium. Previous radio-phonograph combinations do notprovide the high quality re-v production of recorded speech and music corresponding tothe present high quality of recording, for the reason that interference and-back ground noise signals which are normally received in a radio receiver make it imperative that the volume level and volume range of the audio-frequency amplifier be limited to prevent undue ampliflcation of such interference and background noise signals. By so limiting the volume range and level in the audio frequency amplifier, it is impossible to provide the greater undistorted output which is needed for reproducing a recorded program.

In previous radio-phonograph combinations, no provision has been madefor cutting oil the flow of power to the radio frequency portion of the combination during record playing time. Therefore, the life of this portion of the combination is considerably lessened, as a portion of its energized time is wasted while the phonograph is being utilized. Furthermore, there is always an unnecessary drain on the power supply during the use oi the phonograph which reduces the power available to the audio-frequency circuit to thereby reduce the available volume range and level which is needed during the use of the phonograph. v

i The principal object of this invention is to improve, in a radio-phonograph combination, the quality of reproduction of recorded programs.

in a radio-phonograph combination, increased volume range and level during reproduction of recorded programs.

Still another object of this invention is to prov vide,-in a radio-phonograph combination, means for providing a greater undistorted output during the reproduction of recorded programs than is possible during the reception of radio programs. A further object of this invention is to increase the life of the radio receiver in a radio-phonograph combination.

A still further object of this invention is to provide, in a radio-phonograph combination, a means I for increasing the amount of power availableto Another object of this invention 'is'to provide.

the audio-frequency amplifier during the reproduction of recorded programs,

In accordance with the present invention there is provided a. radio-phonograph combination consisting of a radio-receiver, a phonograph pickup, an audio-frequency amplifier, a sound reproducing loud speaker and a. power supply for the combination. There is also provided'a switching device and circuits whereby either the radio receiver or the phonograph pickup may be connected to the audio-frequency amplifier. Switching means is also provided for connecting the power supply to the radio receiver only when it is connected to the audio-frequency amplifier and disconnecting the power supply from the radio receiver when the phonograph is in use. A switch is also provided for changing the bias in one stage of the audio-frequency amplifier to increase its volume range and level during use of the phonograph. The power supply may thus be disconnected from the radio receiver and the amplifier circuit altered in such a way that it will draw more power to thereby have increased volume range and level during periods in which recorded programs are reproduced. v

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims. a

In the accompanying drawing: Fig. 1 is a circuit diagram of a combined radio and phonograph together with the novel switching circuit provided by this invention. Fig. 2 illustrates the switching circuit-shown in Fig. l but in a different operating phase.

Referring now more particularly to Fig. l of the drawing, the combined radio receiver and phonograph lliustrated therein comprise a radio receiver I, a phonograph pickup device 2, audio-frequency amplifier 3, a sound reproducing loud speaker 4 a power supply 5 and a switch 6. The radio-frequency amplifier output of radio receiver I is connected to switch 6 by means of conductor 1, and in switch 6 there is provided -a switch contact 8 in electrical connection :with the ductive contacts adapted to connect either the radio receiver I or pickup 2 to input conductor ll conductor I. Another contact id of switch 6 is connected to the first amplifier tube l2 of amplifier 3. Phonograph pickup 2 is connected to switch contact I3 by conductor 14. Switch 8 includes a rotor having arcuate electrically con- H, is and i3, contact the phonograph of amplifier 3.

There is provided for connecting the power supply 5 to the radio receiver I, conductor 2|, switching contacts 22 and 23, and conductor which is in turn connected to the radio receiver for energizing the vacuum tube circuits therein. Power supply 5 is also connected to amplifier 3 by means of conductors 21 and 28, together with plate resistor '30. Conductor 2! also energizes the anode of amplifier tube It through the coil 32 of loud speaker 4. V

The volume range and level of amplifier 3 is altered by means of a shunt resistor 34 which is grounded and connected through conductor 36, contacts I9, 33 and 39 and conductor 40 across the resistor 4| in the cathode circuit of tube I6. There is provided the usual biasing resistors 43, 44 and 45 for properly energizing tubes l2 and ii of amplifier When the combined radio receiver and phonograph is operated to reproduce recorded programs, switch 6 is rotated into the position illustrated in Fig. 1. Phoncgraph pickup 2 is thus connected to the input of amplifier 3 through conductor l4, contacts l3, l8 and Ill and conductor ll. At the same time resistor 34 is connected in shunt to resistor 4| through conductor 36, contacts 38, I9 and 39 and conductor 40. Since contacts 8 and 22 are open when switch 6 is in this position, there is no circuit between power supply 5 and receiver l and there is also no circuit between the amplifier output of receiver l and the input of amplifier 3. Therefore, the tubes of radio receiver I receive no energy since there can be no reproduction of radio programs at this time and the entire power output of power supply 5 is impressed on the audioamplifier 3. In addition, resistor 34 is connected across resistor 4] which increases the voltage on the cathode circuit of tube [6, thereby changing the class of operation of amplifier 3 and increasing its output to provide greater volume range and level.

Radio programs are reproduced by rotating the switch 3 in a clockwise direction to the position illustrated in Fig. 2 of the drawing, thereby electrically connecting contacts 22 and 23 and also contacts 8 and I0. Power supply 5 is thereby connected to the radio receiver I through conductors 2| and 25 and contacts I1, 22 and 23. The amplifier output of radio receiver l is connected to amplifier 3 through conductor 1, contacts 3, I0 and I3 and conductor H. The phonograph pickup is disconnected from amplifier 3 at contact [3 and the shunt including resistor 34 is also open at contacts 33 and 39. Power having been applied to radio receiver I, its output is amplified in audio-frequency amplifier 3 and reproduced in loud speaker 4. Inasmuch as the power supply to the amplifier 3 has been reduced, the volume range and level is reduced to such a value that there cannot be undue distortion resulting from interference and background noises which may be received by radio receiver I.

I8 being nents of the radio-phonograph combination, it will be obvious to those skilled in the art that any type of switch arrangementmay be utilized for connecting and disconnecting the illustrated circuits. It is not intended that this invention shall be limited to the specificaudio-frequency amplifier circuit illustrated in the drawing nor shall the invention be limited to the specific type of phonograph pickup and sound reproducing loud speaker.

F While there has been described what is at present considered the preferred embodiment of the invention, it will'be obvious tothose skilled in the art that various changes and modifications may be made therein the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. In combination, a first signal channel, a second signal channel, amplifier means for amplifying signals from either of said channels, a source of power connected to said amplifier means switch means for connecting said power source and said amplifier means to said first signal channel or said second signal channel to said amplifier, and means controlled by said switch for changing the output level of said amplifier means.

2. In combination, a first signal channel comprising an amplifier, a second signal channel, amplifier means for amplifying signals from either of said channels, a source of power connected to said amplifier means, and switch means for simultaneously connecting said source to said first channel amplifier and said amplifier means to said first signal channel or for simultaneously disconnecting said power source from said first channel amplifier and connecting said second signal channel 'to said amplifier means.

3. In combination, a radio channel, a phono graph pickup device, amplifier means for amplitying signals from said channel or said pickup device, a source of power connected to said amplifier means, and rotatable switch means includin a first group of contacts connected to said power source and said radio channel, a second group of contacts including a first contact connected to said amplifier means, a second contact connected to said radio channel and a third contact connected to said pickup device and a rotor including conductive portions adjacent each group of said contacts in such angular relation to one another that in one position of said rotor said first group of contacts connect the power source to said radio channel and the first and second contacts of said second group of contacts connect said radio channel and said amplifier means whereas in another position of said rotor said first group of contacts are opened to impress the full power output of said source of power on said amplifier means and the second and third contacts of said second group of contacts connect said phonograph pickup and said amplifier means.

4. In combination, a radio channel, a phonegraph pickup device, amplifier means for ampli tying signals from said channel or said pickup device including in one stage thereof a permanently connected biasing resistor and a second biasing resistor adapted to be connected in shunt therewith, and rotatable switch means including a first group of contacts connected to said permaular type of switch ha been disclosed for connecting and disconnecting the various componently connected biasing resistor and said second biasing resistor, and a second group of contacts including a first contact connected to said without departing from amplifier means, a second contact connected to said radio channel and a third contact connected to said pickup device and a rotor including con- .ductive portions adjacent each groupof said conpermanently connected biasing resistor to increase the volume range and level of said amplifier means, and the second and third contacts of said second group of contacts are closed to connect said phonograph pickup and said amplifier means.

5. In combination, a radio channel, a phonograph pickup device, amplifier means for amplifying signals from said channel or said pickup device includin in one stage thereof a permanently connected biasing resistor and a second biasing resistor adapted to be connected in shunt therewith, a sourc of power connected to said amplifier means, and rotatable "switch means including a first group of contacts connected to said power source and said radio channel, a second group of contacts connected to said permanently connected biasing resistor and said second biasing resistor, a third group of contacts including a first contact connected to said amplifier means, a second contact connected to said radio channel and a third contact connected to said pickup device and a rotor including conductive portions adjacent each group of said contacts in such angular relation to one another that, in one position of said rotor said first group of contacts are closed to connect said power source to said radio channel, said second group of contacts are open, and the first and second contacts of said third group of contacts are closed to connect said radio channel and said amplifier means whereas in another position of said rotor, said first group of contacts are opened, said second group of contacts are closed to connect said second biasing resistor in shunt with said permanently connected biasing resistor to increase the volume range and level of said amplifier means, and the second and third contacts of said third group of contacts are closed to connect said phonograph pickup and said amplifier means.

6. In combination, a first signal channel comprising an amplifier, a second signal channel. amplifier means for amplifying signals from either of said channels, said amplifier means including a biasing means, energizing means connected to said amplifier means, first switch means for simultaneously connecting said energizing means to said first channel amplifier and said amplifier means to said first signal channel or for simul taneously disconnecting said energizing means from said first channel amplifier and connecting said second signal channel to said amplifier means and means operative simultaneously with said first switch means for adjusting said biasing means when. said first switch means is operated.

' JULES w. WHITE.

LOUIS A. G. TER VEEN;

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