US1762834A - Apparatus for the electrical transmission of sound from gramophone records - Google Patents

Description

.Itfne 10, 1930. L PEARSON 1,762,834

APPARATUS FOR THE ELECTRICAL TRANSMISSION OF SOUND FROM GRAMOPHONE RECORDS Filed Nov-. 1928 M IL . his is provided Patented June 10, 1930 A LAURENCE HERBERT PEARSQ N, OF NOTTINGHAM, ENGLAND APPARATUS FOR rHR nLEc'rRIcAL 'rRANsM'IssIoN or soUNn FROM REcoRns Application filed November 3, 1928, Serial No.

This invention comprises improvements in or relating to apparatus for the electrical transmission of sound from gramophone records, the class of apparatus to which the invention has more particular reference being that .wherein an electrical device known as a pick up or collector is. attached to the gramophone tone arm and coacts with the record so as to induce in said pick up varying electrical impulses which are suitably amplified and conveyed to a loud speaker or equivalent reproducing instrument.

Apparatus of this kind is able for use in cinemas and other places of amusement'for supplying orchestral and other music. 1

According-to the present invention apparaembodying a plurality of gramophone record turn-tables, an electrical pick up for coacting with each record, sound amplifying means, means for transmitting sound from the records of said turn-tables in succession and means whereby after the last record of a series has been completed re-transmission from the records in succession may be automatically recommenced or automatically stopped.

It is to be understood that in connection with apparatus functioning in accordance with the present invention means for superimposing one record upon another may also be incorporated but any known or desirable means for superimposing may be employed and such means per se constitute no part of the present invention. I

A feature of the invention consists in the provision of relays and means whereby on manipulation of a unit control the relays are set for the records to be brought into opera: tion in succession. A further feature consists in the provision of a two-way electrical switch associated with the series and so.

the last or final record of arranged that in one position the switch functions to cause the records to be brought into operation in succession and in the same sequence as before whilst in the other position the switch functions to terminate transmission from the records.

For thepurpose of more fully describing formers T T particularly suit- 316,919, and in Great Britain October 5, 1928.

the nature of .this invention reference will now be made tothe accompanying drawing wherein is shown a circuit diagram illustrating a convenient method of carrying out the invention.

In the particular embodiment illustrated, three gramophone turntables are indicated at G G G each of the tone arms TA TA TA associated therewith having detachably attached thereto an electrical pick up P P P, included in the primary circuits of trans- T respectively. The record turntables are driven by independent electric motors M M M Associated with eachtone arm is a sliding contact TC TC TC which are adapted to be traversed between parallel guide barsB into and out of engagement with pairs of .spaced contacts C C C, said last named contactsbeing carried by an insulator which is adjustable length-Wise of thebarsB. Each of the said contacts C 0 ,0 is so adjusted that the respective sliding contacts TC, TC

TC, in traversing the bars B as the tone arms traverse the record bridge such contacts when transmission from the records is completed. The electrical current in ut terminals are indicated at I, a line switcli being preferably included at IL, and MOS is a master switch which governs the current supply to the apparatus and is moved to the on or off position by selectively energizing and de-enerhe two relays CR CR gizingt In operation, the master switch MOS is first closed (as shown in the diagram) by energizing relay CR This may be accom plished b .drawing ri ht bac so as to cause the sliding contact T 1 to engage and bridge a pair of fixed con-- rags SC, thus closing the circuit of relay Simultaneously with the closing of switch MCS consequent upon contact T0 bridging the contacts SC, relays RY and RY are energized to attract their respective armature AR AR Associated with-the relays KY RY are respectively relays KY KY The arrangement of these relays and armatures AR AR is such that the armatures, after being operat d by one of the relays, will reemornonn the first tone armTA main in such operative position even after the relay in question ceases-to be energized. For this reason the armatures AR AR are preferably balanced armatures.

The energization of the relays RY RY and the operation of the armatures AB AR thereby, as previously described, effects closure of contacts MS TS M8 TS and consequently by the simple operaton of the contact TC in the manner described the Whole apparatus'is electrically (as distinct from mechanically) set for starting.

Assuming that it is desired to transmit the sound from the three records in succession the records will preferably be first .placed on each turntable and after the apparatus has been electrically set as before described each pick up will be brought into-contact with its respective record. Then upon completion of the circuit of the motor M by closure of switch MSG transmission of soundfrom the first gramophone record is commenced, the pick up P -being located in the primary circuit of the transformer T as previously explained and the secondary of such transformer being across potentiometer V to thermionic valve VA As the tone arm TA traverses the record of the first gramophone the contact TC moves alon the guides B and when the end of the recor is reached such contact bridges fixed contacts C and thereby energizes relay KY The effect of energizing such relay is to attract the armature AR and open contacts M3 and TS and bring the motor M to rest. At the same time contacts MS are closed and thereby complete the circuit of motor M driving the second gramophone record and contacts TS are closed which short the secondary of transformer T and thereby prevent the transmission of further sound from the firstirecord. By virtue of shorting the secondary of transformer T the transmission of any slurring sounds is definitely avoided.

It will also be noticed that the armature AR opens the contacts T8 which when closed short-circuit the secondary of transformer T included in the circuit of the pick up P of the gramophone G and transmission of sound from the record of such gramophone is thereby enabled,'the said pick up being connected through transformer T and potentiometer V to valve VA it being understood that whilst the first gramo bone was in operation closure ofcontacts T 2 and T5 prevented the transmission of sounds from the pick up P, P respectively and thereby avoid-- ed interruption such as would be occasioned if the pick ups were disturbed during. the transmission of sound from gramophone G Upon completion of transmission of sound from the gramophone Gr contact TC slidin along the bridge B closes the contact C an thereby operates relay RY which attracts the armature AR opens the contacts M8 record of gramophone TS? andthereby brings the motor lVL to rest and opens the short circuit across the secondary of transformer T closes contact MS and so completes the circuit of motor M and at the same time closes contacts TO to shortcircuit the secondary of transformer T and thereby prevent transmission of further sound from the pick up P and the avoidance of unders-irable noises due to slurring or other causes.

The pick up P bein in contact with the now transmits the sound from such record through the medium or thermionic valve VA which-is connected to a potentiometer V included in the secondary circuit of transformer T the primary of which is in series with the pick up P Upon completion of the transmission of sound from the record ofgramophone G the contacts C are bridged. Associated in the circuit of such contacts is a two-Way switch SSE. In one position, when in contact with the contact S, relay CR is energized upon the contacts C 1 being bridged by ing of course that the pick up of such gramophone has been previously -moved back to the starting position, although not sufliciently far back "for contact T0 to bridge contacts SC, it being appreciated that when the switch SSR is incontact with contact R completion of the contacts C by the sliding contact 'lC forms the same function as closure of contacts SC by sliding contact TC The contact S is preferably marked Stop and the contact R Repeat and when it-is desired to repeat transmission the contact is moved to the position R and during the time that sound is being transmitted from the third gramophone record the first and second gramophones are adjusted to their starting position and if it is desired-the records are changed during this time.

'In order to avoid the transmission of sound from the records before the turntables have obtained the desired speed of rotation governors may be associated with each motor,

the arrangement being such that when the motor speed falls belew a pre-determined minimum a short-circuit is effected and transmission of sound thereby prevented. Conveniently the governor may function to shortcircuit the transformer secondary circuit. By these-means the transmission of slurring sounds during the time that the motor is initially-gaining speed is definitely avoided and under no circumstances will sound be transmitted unless the speed of the motor assumes posing effects i each case the arrangement 1,762,834 I I I and maintains the requisite predetermined minimum. v

.The purpose of the potentiometer V V V is to control the volume output from'each pick up and this provision enables difierent types of records to be handled satisfactorily.- Moreoverif sound from another independent record is being superimposed upon that produced by any one of the records brought into I operation in sequence in the manner herein described'the provision of the aforesaid potentiometer enables control of the S'llPGIlIIlto be obtained.

Although in the drawings only three rec-" ords have been shown it is to be understood that any number may be provided, and in as described herein is such that whensound is beingtransmitted from one record the electrical output circuit from the other records 'is shorted so that manipulation or movement of the pickups associated with the other records will not 111- terfere with the transmission from the record that is being played at any time, Again ineach case the arrangement will befsuch that after transmission from a record has been n com leted the output circuit 'is immediate 1y 5 ort-circuited' so that no slurring noises or other noises which ma arise subsequent to, transmission are passe through the amplifier.

I claim 1; Apparatus turntable for coacting with eac sound amplifying means,

loutput circuits of th tion of sound from gramophone records comprising "a plurality of turntables and driving motors therefor, an electric pick u for each record, a pair of rela s associated with each turntable other than the lastof the series of turntables, balanced armatures adapted for operation by said relays, I I n the motor circuits and pick ups-associated with the several turntables, and a unit control switch associated with the tone arm of the first turntable, said switch operating the re-. lays to close the motor circuit ofsuch turntable and short-circuit tpick ups of all the ther turntables and .a manuallyoperable switch controlling the opening and closing of the motor circuit ofvthe first said relays controlling turntable LAURENCE HERBERT PEARSON.

for the electrical reproduc- I tion of sound from gramophon'e records comf I plurality of turntables and drivin risin a p g pick up for eac motors therefor, an electric turntable for coacting witheach record, sound last of the series of turntables,

the several turntables, a

tion of sound from gramophone recor prising a plurality of turntables and driving am 1i in means, a air 3i relays associated wit gch turntable otheflthan the last of the series ,ofturntables, balanced armatures adapted for operation by said relays, said relays controlling the motor circuits and output circuits of the pick ups associated with air of contacts associated with each turntab e, a member moving in unison with the table and said member closing the-respective contacts to operate the respective relays.

'2. Apparatus for the electrical reproduc com- an electric pick u for each turntable for coacting with eac f record, sound amplifying means, a pair of relays as-' sociated with each turntable other than the balanced armamotors therefor,

tures adapted for operation by said relays,

saidrelayscontrolling the motor circuits and output circuits of the pick ups associated with the several turntables, a unit switch associated with the first turntable, said switch operating the relays associated with each 'tive balanced turntable, said relays actuating their respec armatures to close the motor c1rcu1t of the first turntable and short-circuit tone arm of each turne output from the;

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