US2330134A - Reproducing apparatus - Google Patents

Reproducing apparatus Download PDF

Info

Publication number
US2330134A
US2330134A US442218A US44221842A US2330134A US 2330134 A US2330134 A US 2330134A US 442218 A US442218 A US 442218A US 44221842 A US44221842 A US 44221842A US 2330134 A US2330134 A US 2330134A
Authority
US
United States
Prior art keywords
record
sound
conductor
record strip
contact member
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US442218A
Inventor
William H Meincke
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to US442218A priority Critical patent/US2330134A/en
Application granted granted Critical
Publication of US2330134A publication Critical patent/US2330134A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B33/00Constructional parts, details or accessories not provided for in the other groups of this subclass
    • G11B33/02Cabinets; Cases; Stands; Disposition of apparatus therein or thereon
    • G11B33/06Cabinets; Cases; Stands; Disposition of apparatus therein or thereon combined with other apparatus having a different main function

Definitions

  • Figure 1 is a perspective view illustrating an apparatus constructed in accordance. with the present invention illustrating its general appearance and manner of use
  • Figure 2 is a diagrammatic view illustrating the mechanical elements of the apparatu and the electrical wiring diagram thereof, and;
  • Figure 3 is a fragmentary plan view of a portion of a preformed record strip bearing a record to be transcribed into typewritten form.
  • the reference character A designates a cabinet which is preferably of the portable type as illustrated.
  • This cabinet forms means for housing the major portion of the apparatus which, as heretofore stated is illustrated diagrammatically in Figure 2 of the drawings.
  • the apparatus is operated by a preformed record strip 38 which ma be of any suitable material upon which a sound track may be impressed by a sound recording apparatus and which is also capable of perforation.
  • the record strip is also possessed of such qualities as will render it capable of being fed relatively to certain elements of the apparatus by means of a suitable mechanism similar to the film strip feeding mechanism of a motion picture camera or projector for whichpurpose it is provided with marginal openings for engagement by the feeding mechanism.
  • FIG.3 of the drawings A section of such a record strip is illustrated in Figure3 of the drawings.
  • the record strip comprises a body portion In of relatively thin narrow form having marginal perforations 40 for engagement by feeding mechanism.
  • a sound track 39 is impressed thereon which preferably extends along one edge of the record strip, and it also has a plurality of longitudinally extending spaced memori of perforations designated, I40, I, I42, I43, I44 and I45.
  • This strip is also illustrated in transverse section on an enlarged scale in Figure 2 of the drawings.
  • the reference character B designates an amplifier and electric current is supplied thereto by a circuit, the positive leg of which includes two conductors 20 and 2
  • the conductor 20 leads to the terminal 22 of a record strip rewind motor 23 which operates the record strip feeding mechanism, which however, is not herein illustrated.
  • the conductor 2! is connected to the conductor 20 as at 24.
  • the negative leg of this circuit consists of a conductor 25, which is connected as at 26 to the switch lever 21 of a switch .28 and aconductor 29 which lead from the contact 30 of lever of which is connected as at 36 to a conductor 38 which-in turn is connected as at 39' to the conductor 25.
  • the switches 28 and 34 are illustrated in Figure 1 of the drawings as foot operated types which close their respective circuits when pres sure is applied and which open said circuits when the pressure is relieved.
  • the conductors of these circuits and switches are illustrated in Figure 1 of the drawings as cords or cables which may be plugged into the cabinet A.
  • These brushes are mounted in a carrier 58 which is held normally away from the record strip 38 by springs 51, its movement in this direction being limited by suitable stops 58.
  • the carrier 58 is moved in the direction of the record strip to move the brushes into contact therewith by the "electro-magnet 48, the carrier being provided with an armature 58 which is attracted to the electro-magnet 48 when the latter is energized by closing of the circuit to the motor 40 upon operation of the switch 28 as heretofore described,
  • the brushes 58, 52, 53, 54 and 55 are so spaced upon the carrier that they track respectively with the series of perforations I40, I, I42, I48, I44 and I45 and the sound unit 68 is so positioned thereon that its stylus 8
  • the reference numeral 65 designates a plate mounted to the rear of the record strip 38 and this plate is electrically connected with the conductor 28 as at 88 by a conductor 81 which is connected to the conductor 28 as at 88.
  • the sound reproducing element 68 is connected to the amplifier A by two conductors 68 and 69 and the reference character D designates a head phone or set connected to the amplifier B by conductors H and 12 illustrated in Figure 1 as a cord or cable which plugs into the cabinet A. r
  • the cabinet A has a plurality of visual signals, there being seven illustrated in the present embodiment of the invention.
  • the visual signal designated 15 in Figure 1 of the drawings is an indicator which shows the extent to which the record strip has passed through the feeding mechanism and consequently', the portion thereof which has been reproduced as well as the portion which has not passed in the presence of the reproducing unit.
  • This indicator is preferably of the mechanical type and may be operated from the record strip feeding mechanism.
  • the remaining visual signals are preferably in the form of electric lamps which are illuminated automatically at intervals by the record strip 38 in its passage in the presence of the brushes 50. 5
  • the visual signal 55' is considerably larger than the remaining illuminated signals and it is desirable also to have it clearly distinguished from the others preferably by being of a different color, the purpose of which will be hereinafter described. 1
  • , 52, 53', and 54' has associated therewith an identification preferably in the form of a guide into which may be inserted a suitable card which will serve to indicate to the operator the identification of the sound record received through the head phones D.
  • the record strip 38 is preformed in a suitable recording apparatus such for example as the apparatus illustrated in the application filed simultaneously herewith.
  • the sound track 39 upon the record strip while more or less continuous, is recorded in separate sections by a number ofdifferent persons or characters and each of the separate series of perforations bears a definite relation to a section of sound tract.
  • the manner of making the record strip 38 by the recording apparatus of my co-pending application heretofore referred to is more or less arbitrary in that any one of the series of identifying perforations may relate to the sound recorded by any particular party so long as this relation is maintained throughout the recording operation, any one party, as for example. the witness, need have no identification means for his recording since the reproducer, under such circumstances, would know that reproduced sound unaccompanied by any visual signal would in every instance be the recorded voice of the witness.
  • This action sets in operation, the driving motor 40 to feed the record strip forwardly and moves the carrier towards the record strip 38 sufliciently to effect engagement of the stylus SI of the sound reproducing unit 60 and the several. brushes 50, 52, 53, 54 and 55 into engagement with their respective areas of the sound record strip 38.
  • the recording of the sound track 39 is transmitted through the sound reproducing unit 60, the amplifier B and the head phones D to the operator who makes a typewritten or other copy of the subject matter thus transmitted to her.
  • this portion of the sound record would have associated therewith a series of perforations, for example, the series designated ill on the record strip 38, which series of perforations would, as this portion of the sound record was reached, permit the brush 5
  • the rheostat switch 43 permits of the adjusting the speed of operation of the driving motor 40 to her convenience.
  • the circuit heretofore described will be closed to the rewind motor to operate the film feeding mechanism in the reverse direction and rewind the desired amount of the record strip.
  • the present invention provides an apparatus by means of which a sound record which has been recorded by several persons may be reproduced and that each individuals portion of the sound record will be identified with the individual by whom it was recorded.
  • Apparatus for reproducing recorded material from a preformed record which includes a plurality of separately recorded sound recordings to the single contact member and being movable into and out of position to engage the single contact member, means for feeding the preformed record between the single contact member and the individual contact members of said group to prevent contact thereof with the single contact member except through the perforations of the preformed record, means for operating one of said visual signals by each contact member of the group of contact members upon its engagement with the single contact member through one of the series of perforations in the preformed record, means for moving said group of contact members into, position to engage the single contact member and the preformed record, and sound reproducing means for reproducingthe separately recorded sound recordings of th preformed record.
  • Apparatus for reproducing recorded material from a preformed record including a plurality of separately recorded sound recordings and a plurality of separately recorded mechanical recordings in the form of separate series of perforations each of which series of perforations constitutes an identification recording for one of the separately recorded sound recordings
  • said apparatus comprising in combination, a plurality of visual signals, a single contact member, a group of contact members including a contact member for each of said visual signals, said group of contact members being movable into and out of position to engage the single contact member, means for normally holding said group a of contact members out of position to engage the single contact member, means for feeding the preformed record betweenthe single contact member and the group to prevent contact of the several contact members of the group when they arein position to engage the single contact member, except through the series of perforations of the preformed record sound mechanism including a sound reproducing unit for reproducing the separately recorded sound recordings of the preformed record, means for operating one Of said visual signals by each contact member of the group of contact members, a sound mechanism for reproducing the separately recorded sound recordings

Description

' Patented Sept. 21, 1943 UNITED STATES 1 OFFICE REPRODUCING APPARATUS William H.Meincke, White Plains, N. r.
Application May. a, 1942, Serial No. 442,218
3 Claims.
particularly it pertains to an apparatus for reproducing both audibly and visually, subject mat- I ter previously recorded upon a record strip by the recording apparatus disclosed in another appli-- cation filed simultaneousl herewith by me.
It is an object of the present invention to provide an apparatus by means of which a preformed record may be reproduced, both in audible and visual form to enable a typist to construct a true and accurate typewritten copy thereof.
In my co-pending application for recording apparatus, I have described the apparatus as used for recording court proceedings and in this application. this apparatus will be described as reproducing the record made by the recording apparatus of such a procedure.
' In the drawings,
Figure 1 is a perspective view illustrating an apparatus constructed in accordance. with the present invention illustrating its general appearance and manner of use,
Figure 2 is a diagrammatic view illustrating the mechanical elements of the apparatu and the electrical wiring diagram thereof, and;
Figure 3 is a fragmentary plan view of a portion of a preformed record strip bearing a record to be transcribed into typewritten form.
Referring to Figure 1 of the drawings, the reference character A designates a cabinet which is preferably of the portable type as illustrated. This cabinet forms means for housing the major portion of the apparatus which, as heretofore stated is illustrated diagrammatically in Figure 2 of the drawings.
The apparatus is operated by a preformed record strip 38 which ma be of any suitable material upon which a sound track may be impressed by a sound recording apparatus and which is also capable of perforation. The record strip is also possessed of such qualities as will render it capable of being fed relatively to certain elements of the apparatus by means of a suitable mechanism similar to the film strip feeding mechanism of a motion picture camera or projector for whichpurpose it is provided with marginal openings for engagement by the feeding mechanism.
A section of such a record strip is illustrated in Figure3 of the drawings. The record strip comprises a body portion In of relatively thin narrow form having marginal perforations 40 for engagement by feeding mechanism. A sound track 39 is impressed thereon which preferably extends along one edge of the record strip, and it also has a plurality of longitudinally extending spaced serie of perforations designated, I40, I, I42, I43, I44 and I45. This strip is also illustrated in transverse section on an enlarged scale in Figure 2 of the drawings.
Referrin to Figure 2 of the drawings, the reference character B designates an amplifier and electric current is supplied thereto by a circuit, the positive leg of which includes two conductors 20 and 2|. The conductor 20 leads to the terminal 22 of a record strip rewind motor 23 which operates the record strip feeding mechanism, which however, is not herein illustrated. The conductor 2! is connected to the conductor 20 as at 24. The negative leg of this circuit consists of a conductor 25, which is connected as at 26 to the switch lever 21 of a switch .28 and aconductor 29 which lead from the contact 30 of lever of which is connected as at 36 to a conductor 38 which-in turn is connected as at 39' to the conductor 25.
'The switches 28 and 34 are illustrated in Figure 1 of the drawings as foot operated types which close their respective circuits when pres sure is applied and which open said circuits when the pressure is relieved. The conductors of these circuits and switches are illustrated in Figure 1 of the drawings as cords or cables which may be plugged into the cabinet A.
Leading from the terminal 39 of the driving motor 40 there is a conductor 4| which is connected' to the conductor 29 as at 42 and this conductor includes a rheostat switch 43. Leading from the terminal 44 of the motor 40 which, drives the record strip feeding mechanism in the forward direction, there is a conductor 45 which is connected to the conductor 20 as at 41 and this conductor 45 includes an electro-magnet 46, the purpose of which will be hereinafter described.
From the foregoing it will be apparent that upon operation of the switch 28 by the operator, the circuit of the motor 40 will be closed and the electro-magnet 46 will be energized and upon operation of the switch 34 by the'operator, the circuit to the rewind motor 23 will be closed to set this motor into operation.
Mounted in the cabinet A and movable towards and away from the record strip 38, there are 'a plurality of brushes 5!], 5|, 52, 53, 54 and 55.
These brushes are mounted in a carrier 58 which is held normally away from the record strip 38 by springs 51, its movement in this direction being limited by suitable stops 58. The carrier 58 is moved in the direction of the record strip to move the brushes into contact therewith by the "electro-magnet 48, the carrier being provided with an armature 58 which is attracted to the electro-magnet 48 when the latter is energized by closing of the circuit to the motor 40 upon operation of the switch 28 as heretofore described,
Also mounted upon the carrier 58 there is a sound reproducing unit 80 and the stylus 8! of which is moved into engagement with the record strip 38 simultaneously with the several brushes 50, BI. 52, 58, 54 and 55.
The brushes 58, 52, 53, 54 and 55 are so spaced upon the carrier that they track respectively with the series of perforations I40, I, I42, I48, I44 and I45 and the sound unit 68 is so positioned thereon that its stylus 8| registers with the sound track 38 of the record strip 88.
The reference numeral 65 designates a plate mounted to the rear of the record strip 38 and this plate is electrically connected with the conductor 28 as at 88 by a conductor 81 which is connected to the conductor 28 as at 88.
The sound reproducing element 68 is connected to the amplifier A by two conductors 68 and 69 and the reference character D designates a head phone or set connected to the amplifier B by conductors H and 12 illustrated in Figure 1 as a cord or cable which plugs into the cabinet A. r
The cabinet A has a plurality of visual signals, there being seven illustrated in the present embodiment of the invention.
The visual signal designated 15 in Figure 1 of the drawings is an indicator which shows the extent to which the record strip has passed through the feeding mechanism and consequently', the portion thereof which has been reproduced as well as the portion which has not passed in the presence of the reproducing unit. This indicator is preferably of the mechanical type and may be operated from the record strip feeding mechanism.
The remaining visual signals are preferably in the form of electric lamps which are illuminated automatically at intervals by the record strip 38 in its passage in the presence of the brushes 50. 5|, 5!, 58, 54 and 55 and the plate 65 and the manner in which this is accomplished will now be described.
In both Figures 1 and 2 of the drawings, these visual signals are designated by the reference numerals 50', 5i, 5!, 53', 54' and 55'.
Leading from the brush 50 there is a conductor 18 which leads through the lamp of the visual signal 58' and which is connected as at 18 to the conductor 28. Leading from the brush 5!, there is a conductor 19 which leads through the lamp of the visual signal 5| and which is connected as at 88 to the conductor I1. Leading from the brush 52, there is a conductor 8| which leads through the lamp of the visual signal 52' and which is connected to the conductor 11 as at 82. Leading from the brush 53 there is a conductor 83 which leads through the lamp of the 'visual signal 58' and which is connected as at 84 to the conductor 11. Leading from the brush 54 there is-a conductor 85 which leads through the lamp of the visual signal 54' and which is connected to the conductor 11 as at 85. Leading from the brush 55 there is a conductor 81 which leads through the ramp of the visual signal 55' and which is connected as at 88 to the conductor 20.
It will be noted that the visual signal 55' is considerably larger than the remaining illuminated signals and it is desirable also to have it clearly distinguished from the others preferably by being of a different color, the purpose of which will be hereinafter described. 1
By reference to Figure 2 of the drawings it will be noted that the circuits of the several illuminated visual signals are normally open by reason of the fact that their respective brushes are out of contact with the plate 65. It will also be noted that this same condition exists when the brushes are moved into position to engage the plate 65 except where any one of the brushes. tracks a perforated area of the record strip 38,
When, however, a series of perforations presents itself to any of the several brushes. that particular brush is permitted to contact the plate 65 through the perforations and thereby complete the circuit to its corresponding visual signal to illuminate the lamp thereof.
Each of the visual signals 58', 5|, 52, 53', and 54' has associated therewith an identification preferably in the form of a guide into which may be inserted a suitable card which will serve to indicate to the operator the identification of the sound record received through the head phones D.
Having described the apparatus, I will now give a typical operation thereof in the reproduction of a record of court proceedings recorded upon the record strip 38.
As heretofore stated, the record strip 38 is preformed in a suitable recording apparatus such for example as the apparatus illustrated in the application filed simultaneously herewith.
The sound track 39 upon the record strip while more or less continuous, is recorded in separate sections by a number ofdifferent persons or characters and each of the separate series of perforations bears a definite relation to a section of sound tract.
For example, in a court proceeding there is an operator for the recording apparatus who replaces the court stenographer; a Judge: a witness; a counsel for the plaintiff, a counsel for the defendant and perhaps other persons whose various conversations would combined, form the complete recording of the sound track 39 of the record strip.
The manner of making the record strip 38 by the recording apparatus of my co-pending application heretofore referred to is more or less arbitrary in that any one of the series of identifying perforations may relate to the sound recorded by any particular party so long as this relation is maintained throughout the recording operation, any one party, as for example. the witness, need have no identification means for his recording since the reproducer, under such circumstances, would know that reproduced sound unaccompanied by any visual signal would in every instance be the recorded voice of the witness.
With the parts in their neutral or off position, in which they are shown in Figure 2 and with the record strip in feeding position, the reproducing apparatus is ready for operation.
The operator exerts' a pressure on the foot switch 28 to close the same, such action closes the circuits heretofore descrlbed in the driving motor 40 and the electro-magnet 46 to energize the same. I
This action sets in operation, the driving motor 40 to feed the record strip forwardly and moves the carrier towards the record strip 38 sufliciently to effect engagement of the stylus SI of the sound reproducing unit 60 and the several. brushes 50, 52, 53, 54 and 55 into engagement with their respective areas of the sound record strip 38.
As the record strip is fed through the apparatus, the recording of the sound track 39 is transmitted through the sound reproducing unit 60, the amplifier B and the head phones D to the operator who makes a typewritten or other copy of the subject matter thus transmitted to her.
In the foregoing manner, the apparatus continues to operate so long as the switch 28 is retained closed. v
If the sound record being reproduced be the voice of the witness, there would be no visual signal to the operator.
If, however, the sound record change from the witness to another party, as for example, where the judge would intercede with a question to the witness, this portion of the sound record would have associated therewith a series of perforations, for example, the series designated ill on the record strip 38, which series of perforations would, as this portion of the sound record was reached, permit the brush 5| contacting the plate 65 and complete the circuit to'the visual signal 5| indicating that the sound record being reproduced was the voice of the judge.
It is believed that further description of this portion of the apparatus is unnecessary since it will be obvious from the foregoing that as the several brushes are permitted to contact the plate 65 the circuit to the corresponding visual signal will be established and thus the several sections of the sound record he identified through the medium of the cards carriedin the guides 80.
The rheostat switch 43 permits of the adjusting the speed of operation of the driving motor 40 to her convenience.
It will be noted that the visual signal v that it signifies that that portion of sound record,
whatever it may be, is to be marginally indented in the typewritten copy. I I
Should the operator desire to read back a portion of the record strip, she removes her foot from the switch 28, permitting it to open and thus rendering inoperative, the entire apparatus.
If, with the parts in the inoperative position, the operator closes theswitch 34, the circuit heretofore described will be closed to the rewind motor to operate the film feeding mechanism in the reverse direction and rewind the desired amount of the record strip.
From the foregoing, it will be apparent that the present invention provides an apparatus by means of which a sound record which has been recorded by several persons may be reproduced and that each individuals portion of the sound record will be identified with the individual by whom it was recorded.
In view or the foregoing, it will also be obvious that the operations are carried out in such a manner as to permit of making accurate typed or otherwise scribed copies of the subject matter recorded upon asound record strip.
Having thus described the invention, what I claim as new is:
1. Apparatus for reproducing recorded material from a preformed record which includes a plurality of separately recorded sound recordings to the single contact member and being movable into and out of position to engage the single contact member, means for feeding the preformed record between the single contact member and the individual contact members of said group to prevent contact thereof with the single contact member except through the perforations of the preformed record, means for operating one of said visual signals by each contact member of the group of contact members upon its engagement with the single contact member through one of the series of perforations in the preformed record, means for moving said group of contact members into, position to engage the single contact member and the preformed record, and sound reproducing means for reproducingthe separately recorded sound recordings of th preformed record.
2. Apparatus for reproducing recorded material from a preformed record including a plurality of separately recorded sound recordings and a plurality of separately recorded mechanical recordings in the form of separate series of perforations each of which series of perforations constitutes an identification recording for one of the separately recorded sound recordings, said apparatus comprising in combination, a plurality of visual signals, a single contact member, a group of contact members including a contact member for each of said visual signals, said group of contact members being movable into and out of position to engage the single contact member, means for normally holding said group a of contact members out of position to engage the single contact member, means for feeding the preformed record betweenthe single contact member and the group to prevent contact of the several contact members of the group when they arein position to engage the single contact member, except through the series of perforations of the preformed record sound mechanism including a sound reproducing unit for reproducing the separately recorded sound recordings of the preformed record, means for operating one Of said visual signals by each contact member of the group of contact members, a sound mechanism for reproducing the separately recorded sound recordings, and means for moving the contact a single contact member, a group of contact members arranged in spaced relation to the single contact member and being movable into and out of positions to engage the single contact member, means including an electric motor for feeding the preformed record between the single contact member and the individual contact members of said group to prevent contact thereof with the single contact member except through the medium of the mechanical recordings of the 10 preformed record, means for operating one of said visual signals by each contact member of the group of contact members upon engagement with the single contact member through the motor circuit.
WILLIAM H. MEINCKE.
US442218A 1942-05-08 1942-05-08 Reproducing apparatus Expired - Lifetime US2330134A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US442218A US2330134A (en) 1942-05-08 1942-05-08 Reproducing apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US442218A US2330134A (en) 1942-05-08 1942-05-08 Reproducing apparatus

Publications (1)

Publication Number Publication Date
US2330134A true US2330134A (en) 1943-09-21

Family

ID=23755973

Family Applications (1)

Application Number Title Priority Date Filing Date
US442218A Expired - Lifetime US2330134A (en) 1942-05-08 1942-05-08 Reproducing apparatus

Country Status (1)

Country Link
US (1) US2330134A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2478539A (en) * 1943-01-18 1949-08-09 Lu Garda Rieber Spiral sound record strip
US3015491A (en) * 1957-03-07 1962-01-02 Philips Corp Switching arrangement for dictation apparatus

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2478539A (en) * 1943-01-18 1949-08-09 Lu Garda Rieber Spiral sound record strip
US3015491A (en) * 1957-03-07 1962-01-02 Philips Corp Switching arrangement for dictation apparatus

Similar Documents

Publication Publication Date Title
US2777901A (en) Binaural apparatus for teaching languages
US3708891A (en) Spoken questionnaire method and apparatus
US3488867A (en) Recording-reproducing apparatus for teaching cards
US3662121A (en) Plural recorder and interspersing playback
US3171902A (en) Apparatus and method for controlling remotely-operated dictation equipment
US4051540A (en) Instruction indicating apparatus for a record and/or playback device
US3838211A (en) Teaching system and devices
US3605285A (en) Random access audio-visual educational apparatus
US2330134A (en) Reproducing apparatus
US3142909A (en) Electronic sound repeater mechanism
US3484955A (en) Teaching machine
US4091427A (en) Electric control system for magnetic sheet recording and reproducing apparatus for audiovisual instruction
US3373508A (en) Teaching apparatus
US2900191A (en) Dictation apparatus
US3648387A (en) Educational aid
US3659357A (en) Audio-visual apparatus
GB1313226A (en) Information replay methods and apparatus
US3601554A (en) Information replay methods and apparatus
US2655564A (en) Method of obtaining stereophonic sound
US1955497A (en) Sound recording and reproducing apparatus for use in connection with motion pictures
US3777417A (en) Sound teacher
US3598927A (en) Educational apparatus with programming facilities
US3279799A (en) Sound recording and reproducing apparatus
US3588380A (en) Switching parameters for recording/playback or magnetic media having different coercivity and/or retentivity characteristics
US3703041A (en) Magnetic teaching machine with selectively operable repetitive and non-repetitive learning modes