US2680786A - Electric phonograph - Google Patents

Description

June 8, 1954 I N. L. CHALFIN 2,680,786

ELECTRIC PHONOGRAPH Filed May 24. 1950 Fl G. 3.

" INVENTOR.

ATTORNEY Patented June 8, 1954 ELECTRIC PHONO GRAPH Norman L. Chalfin,

thirty per cent to New York, N. Y., assignor of Irving Seidman, New York,

Application May 24, 1950, Serial No. 163,934

2 Claims.

of the apparatus, to encounter a delayed period of time, .between the starting of the motor and the full operation of the vacuum tubes. This delay is due to the fact that the indirectly heated cathodes of the tubes normally used require time to heat up and reach an operating temperature.

It is the purpose of this invention to provide an apparatus wherein the circuits and parts are so arranged and electrically connected that the tubes are instantly heated to the desired operating temperature. In other words, the starting of the motor and the heating of the tubes to the required operating temperature are substantially simultaneous with the turning on of the current supply.

The best embodiment of the invention has been chosen for illustrative purposes, but this embodiment should be viewed as being illustrative only and not as limiting because obviously the invention is capable of other embodiments having revised details of construction, so long as they fall within the ambit of the appended claims.

The invention itself, however, both as to its organization and its method of operation, will best be understood from the following description of a specific embodiment when read in connection with the accompanying drawing, in which:

Fig. l is a diagram showing a circuit hook up with a radio-phonograph self acting switch and quick heating phonograph amplifier.

Fig. 2 is a circuit diagram showing a phonograph unit employing quick heating vacuum tubes.

Fig. 3 is a circuit diagram showing a carbon pick up in the circuit, and

Fig. 4 shows in diagram, an amplifier with a double button carbon microphone.

An example of the application of this invention is illustrated in Fig. 1 which shows a phonograph pick up preamplifier which can be attached to existing radio equipment or built into radio phonograph combinations. The preamplifier is so constructed that when the motor start- (Cl. I'm-400.4)

ing switch of a phonograph record changing or single record playing equipment is closed, the preamplifier is instantly ready for operation and simultaneously switches the preamplifier output into electrical connection with a radio unit.

Referring in detail to the parts, and particularly to Fig. 1, numeral designates a normally closed switch which is held in its open position by the weight of a pick up mechanism i2 engageable with a record disk upon a turntable (not shown). A motor i3 is connected between a power line it and the normally closed switch The primary coil I5 of a transformer 16 has connection with the power line I1: and the line H, through the switch I when same is closed. A switch H3 is provided in the line it as alternative to switch The secondary coil |9 of the transformer it leads through the line 26 to a ground connection which is the negative side of the D. C. line. The positive branch of the D. C. is obtained through chemical rectifier 26 and supplies D. C. power to the plates and filaments of preamplifier 2|. The negative or ground return of the D. C. is made through the series connected filaments of tubes 39 and 3| to ground terminal connection 22. Ground terminal connection 22 is common with ground terminal connection 45. A line 2t connects the pick up unit with the preamplifier 2|. The ground terminal of pickup i2 is connected to ground terminal 22 through lead 23. A relay 2 is connected, in series with the filaments of tubes 30 and 3|. A line 28 leads from the output circuit of a radio (not shown) and line it to a power amplifier (not shown). The amplifier tubes 39 and 3| heat very quickly (in less than three seconds). This type of tube is generally known as the filamentary cathode type and is con structed with filaments that will heat almost instantaneously, to a temperature, surficiently high to emit electrons, thus rendering the tube fully operative when a record is started revolving.

The operation of the system will best b understood when read in conjunction with the diagram shown in Fig. 1. With the switch is (if used) and the pick up switch closed, power is simultaneously transmitted to the motor 3 of the sound record playing apparatus and the primary coil l5 of the power isolation transformer l6 inducing a like voltage in the secondary coil L9. The secondary voltage is applied to the chemical type rectifier 2t and filter system which delivers D. C. along lin 25 for both plate and filaments of the tubes 3i! and 3|. The relay 24' and a voltage dropping resistance 32 is disposed in the filament circuit 27. When the power is applied, the filaments of the tubes and 3|, which are of the instant heating filamentary types, are suplied with the proper voltage. The current, which the filaments draw energizes the relay 24. The said relay, in its deenergized condition normally has its contacts and 31 closed. When energized, however, contact 49 is drawn over to close contact point 42 and open the contact at M. Attached to contact 40 is the input of the power amplifier, while attached to contact 41 is the audio output circuit of the radio detector.

The output of the phonograph pick up preamplifier 43 is attached to the contact point 42 through capacitor 44. The return circuits of both preamplifier and radio are through the shield grounds 45 which are bonded together. The preamplifier input 45 connects with the pick up unit 12 through the line 24.

The diagram illustrated in Fig. 2 shows an instant heating phonograph record playing system particularly suited for a childs use. The action of lifting the phonograph pick up arm (2 allows switch contact H to close, thus energizing rectifier 23, supplying D. C. plate and filament power to the amplifier tube T. The tube T being of the filamentary type is immediately ready to reproduce the energy picked up from the sound record by the pick up unit.

A third example of the application of this invention is illustrated in Fig. 3 wherein sound record reproduction is accomplished without vacuum tubes. A bridge circuit is employed to cancel out the D. (3. component in the high impedance voice coil of a speaker unit 5!. The bridge comprises buttons 52 and 53 of the double button carbon pick up as one pair of arms and the resistance arms 54 and 55 as the other pair. when current through a circuit comprising button A, resistance 54 and voice coil 50 in one direction equals the current flow through resistance 54, button B and voice coil 50 in the opposite direction, the net current in the voice coil 59 will be Zero. The application of the invention to this circuit is the switch on system and chemical rectifier combination in which lifting the arm from a rest, places the apparatus in instant operation. A like result may be accomplished with the use of batteries B-B' as an alternative source of power, as shown in Fig. 4.

In the Fig. 4 instance, however, the switch 55 must be of the double pole single throw type. The batteries B-B are of equal potential and are connected in series. The junction of the two batteries is connected to the central (common) connection of the double button pick up unit.

If the pick up unit D. B. P. should be a double carbon button microphone instead of a phonograph pick up, a public address system is possible in which the instantaneous operational readiness is available, actuated by a double pole normally open-press to-use type of switch.

I claim:

1. In an electric phonograph record player preamplifier system, the combination of: a multistage, direct-heater vacuum-tube amplifier. the tubes of said amplifier being coupled in cascade relation, the heaters or" said amplifier tubes being connected in a series circuit; a relay, having a coil and at least single-pole-double-throw contact terminals, said contact terminals being connected between the output circuit of said amplifier and a utilization circuit for transferring said output circuit to said utilization circuit, in place of some other circuit, that may be connected to said utilization circuit through said relay contacts, when said relay is energized; the said relay coil being connected in series with said heater circuit; a semi-conductor rectifier supply for energizing said amplifier tubes and said heater circult; a motor and turntable means; a normallyopenonpressure switch coupled between a source or electrical power and said motor and said rectifier supply 1 or applying said power to said motor and said rectifier supply when said pressure on said switch is relieved; and a phonograph pickup arm assembly electrically coupled to the input of said amplifier and engageable with said pressure switch whereby movement of said pickup arm into its record playing position relieves said pressure on said switch to energize said motor and said amplifier and said filament circuit to render said amplifier operative and to energize said relay.

2. In an electric phonograph record player, the combination of: a vacum tube amplifier, said amplifier being capable of substantially instantaneous energization upon application of power thereto; an instantaneously energizable rectifier means coupled to said amplifier means for energizing said amplifier means; electric motor and turntable means; pressure switch means for conmeeting said rectifier means and said motor means to a source of electric power; and a phonograph pickup arm means coupled to said amplifier and engageable at a rest position with said pressure switch means to maintain the record player inoperative, and engageable with a dish in its use position on the turntable of said motor for reproducing the sound recording on said disk, said motor and said amplifier being rendered operative when said pickup arm means is moved from its rest position to its use position.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,490,750 Pinkler Apr. 15, 1924 1,593,690 Case July 27, 1926 1,608,487 Blattner Now. 30, 1927 1,525,913 Thomas Apr. 26, 1927 1,642,040 McCutchen Sept. 13, 1927 1,757,547 Ruben May 6, 1930 1,306,374 Thomas May 19, 1931 1,915,906 Thomas June 27, 1933 2,031,865 Thomas Feb. 25, 1936 2,096,861 Riggs Got. 26, 1937 2,203,933 Lowenhaupt July 23, 1940 2,257,840 Dubilier Oct. 7, 1941 2,230,330 Cisin Apr. 21,1942 2,318,183 Roberts May 4, 1943 2,341,746 Taylor et a1. Feb. 15, 1944 2,357,026 Scherbatskoy Aug. 29, 1944 2,359,489 Proctor Oct. 4, 1944

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