GB350998A - Improvements in apparatus for recording sounds upon wax or other like discs or blanks - Google Patents

Improvements in apparatus for recording sounds upon wax or other like discs or blanks

Info

Publication number
GB350998A
GB350998A GB7809/30A GB780930A GB350998A GB 350998 A GB350998 A GB 350998A GB 7809/30 A GB7809/30 A GB 7809/30A GB 780930 A GB780930 A GB 780930A GB 350998 A GB350998 A GB 350998A
Authority
GB
United Kingdom
Prior art keywords
coil
impedance
shunt
resistance
resonance
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
Application number
GB7809/30A
Original Assignee
Alan Dower Blumlein
Herbert Edward Holman
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
Priority claimed from BE377565D external-priority patent/BE377565A/xx
Priority to GB7809/30A priority Critical patent/GB350998A/en
Application filed by Alan Dower Blumlein, Herbert Edward Holman filed Critical Alan Dower Blumlein
Priority to GB1968806X priority
Priority to US518524A priority patent/US2024271A/en
Publication of GB350998A publication Critical patent/GB350998A/en
Priority to US561755A priority patent/US2016622A/en
Expired legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04RLOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00Circuits for transducers, loudspeakers or microphones
    • H04R3/002Damping circuit arrangements for transducers, e.g. motional feedback circuits
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B64AIRCRAFT; AVIATION; COSMONAUTICS
    • B64CAEROPLANES; HELICOPTERS
    • B64C27/00Rotorcraft; Rotors peculiar thereto
    • B64C27/02Gyroplanes
    • B64C27/021Rotor or rotor head construction
    • B64C27/026Devices for converting a fixed wing into an autorotation rotor and viceversa
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00Silicon; Compounds thereof
    • C01B33/20Silicates
    • C01B33/32Alkali metal silicates
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04RLOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00Details of transducers, loudspeakers or microphones
    • H04R1/16Mounting or connecting stylus to transducer with or without damping means
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04RLOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00Circuits for transducers, loudspeakers or microphones
    • H04R3/04Circuits for transducers, loudspeakers or microphones for correcting frequency response
    • H04R3/08Circuits for transducers, loudspeakers or microphones for correcting frequency response of electromagnetic transducers
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04RLOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R9/00Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/12Gramophone pick-ups using a stylus; Recorders using a stylus

Abstract

350,998. Moving-coil recorders and microphones. BLUMLEIN, A. D., 57, Earl's Court Square, and HOLMAN, H. E., 64A, The Chase, Clapham Common, both in London. March 10, 1930, Nos. 7809 and 14042. [Class 40 (iv).] A moving-coil recorder, microphone, or other instrument, connected to an operating circuit having an impedance higher than that of the coil, is damped by shunting it with a network of impedances whose total impedance is low at frequencies near the resonant frequency of the mechanical system, and high at frequencies remote from resonance. When the shunt consists of, or is, at frequencies close to resonance, equivalent to, an inductance, resistance and capacity in series, the ratio between the magnitude of these components is the same as the ratio between the magnitudes of the effective mass, damping and compliance of the mechanical system in the region of resonance when the moving coil is closed by this shunt. Circuit arrangements. The shunt of inductance, resistance and capacity in series across the moving coil 1 of a microphone, Fig. 1, requires a high capacity unless a coil of high impedance can be used, and a step-up transformer 2, Fig. 2, may be introduced to increase the apparent impedance of the coil. The shunt of Fig. 2 has an impedance comparable with that of the coil at low frequencies, and to compensate for the increase in impedance of the coil at high frequencies a resistance and capacity is connected in parallel with the inductance of the shunt. Resonance between the valve capacity and the secondary of the transformer 3 is controlled by a resistance 4 across the transformer secondary. The shunt of Fig. 3 is suitable for a sound-recorder, where the low-frequency response is depreciated to prevent excessive amplitude on the record, and therefore the impedance of the shunt below resonance is not required to rise. The condenser in parallel tunes the recorder and its shunt to resonance at a high frequency where its impedance is matched with the amplifier output. In the shunt of Fig. 4, a monitoring circuit is connected across a resistance 15 shunted by a condenser 16. The condenser 9 may be considered as tuning the moving coil or as causing the impedance of the shunt to rise rapidly at high frequency and then to tune the moving coil. The inductance 8 produces a cut-off at a frequency well above the working range to remove the effect of chance high-frequency resonances. The main network consists of inductances 10, 13, resistances 12, 14, and a condenser 11. At low frequencies it is equivalent to inductances 10, 13 in series with resistance 14. In the region of resonance, the capacity 11 and resistance 12 delay a rise in impedance and at high frequencies the network is equivalent to the inductance 10 in series with a resistance 12 and is raised to a very high impedance by capacity 9. The capacity 5, inductance 6, and resistance 7 form a rejector circuit which modifies the characteristic of the recorder. This damping system may also be applied to a moving coil instrument optically recording sound. Construction of microphone. The microphone, Fig. 8, has a magnetic system comprising an inner polepiece r<1> of cobalt iron, rear plate q<1>, casing p<1>, and the outer polepiece h<1>. The air gap is correctly dimensioned by a spacing ring t<1> of brass or cadmium bronze, which is a force fit on the central polepiece r<1> and a good fit in a groove in the outer polepiece h<1>. The inner turns of the winding s<1> are preferably of thinner gauge wire than the outer turns. The moving coil d<1> is formed of thin aluminium wire wound on a former e<1> which has a longitudinal saw-cut to prevent short-circuited turns and may be insulated with a coating of aluminium hydroxide. The former e<1> is riveted to a diaphragm consisting of a layer of Balsa wood a<1> preferably covered on each side by a thin sheet b<1> of aluminium. Alternatively the diaphragm may be a flat sheet of aluminium or other light aLoy with cores of similar material attached to the back to add rigidity. The mounting is preferably an extended annulus c<1> of the back aluminium layer and passes through the centre of gravity of the suspended system. The annulus c<1> is preferably thinned by chemical action, e.g. dissolving by caustic soda, and is tensioned by a ridge n<1> of a front plate m<1> formed with a grille o<1>. The mounting annulus c<1> is clamped at its edge between the holder g<1> and a ring l<1>. The front plate m<1> is formed to prevent sound waves falling on the diaphragm mount, and holes in the former and plugs w<1> of cottonwool prevent excessive air damping. The leads to the moving coil are taken through a passage v<1> to terminals on the holder g<1> or at any other convenient point. Construction of sound-recorder. The soundrecorder, Figs. 5, 6, and 7, has a magnetic system consisting of the polepieces f of a magnet (not shown) at right-angles to a transformer core a with a bulbous portion b. The moving coil d consists preferably of a single, rectangular turn of aluminium, thickened at its ends, and cut from a solid block and moves in the gap g between the polepieces f and the bulbous core b. Currents are induced in it by the coils c of the transformer core a, b. The coil is pivoted about a vertical axis by a shaft e bearing against knife edges under the action of springs h attached to the shaft and passing through holes in the knife edges. The neutral position of the coil is controlled by springs m attached to screws n, and may be adjustable to tune to the frequency of resonance. The shaft e may be integral with the coil or may pass through holes in the thickened portion of the coil and a clearance hole in the core b. The stylus arm i is clamped to the shaft and the stylus k is carried on one arm. A balance weight l serves to balance the stylus arm both statically and dynamically.
GB7809/30A 1930-03-10 1930-03-10 Improvements in apparatus for recording sounds upon wax or other like discs or blanks Expired GB350998A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
GB7809/30A GB350998A (en) 1930-03-10 1930-03-10 Improvements in apparatus for recording sounds upon wax or other like discs or blanks
GB1968806X 1930-09-12
US518524A US2024271A (en) 1930-03-10 1931-02-26 Moving coil electromechanical device
US561755A US2016622A (en) 1930-09-12 1931-09-08 Moving coil electromechanical device

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
BE377565D BE377565A (en) 1930-03-10
NL55929D NL55929C (en) 1930-03-10
GB7809/30A GB350998A (en) 1930-03-10 1930-03-10 Improvements in apparatus for recording sounds upon wax or other like discs or blanks
GB13581/31A GB350954A (en) 1930-03-10 1930-03-10 Improvements in electro-mechanical sound recording devices more especially of the moving coil type
FR712807D FR712807A (en) 1930-03-10 1931-01-22 Improvements to airplanes
US518524A US2024271A (en) 1930-03-10 1931-02-26 Moving coil electromechanical device
FR712887D FR712887A (en) 1930-03-10 1931-03-07 Improvements to electromechanical moving coil devices

Publications (1)

Publication Number Publication Date
GB350998A true GB350998A (en) 1931-06-10

Family

ID=32512445

Family Applications (2)

Application Number Title Priority Date Filing Date
GB7809/30A Expired GB350998A (en) 1930-03-10 1930-03-10 Improvements in apparatus for recording sounds upon wax or other like discs or blanks
GB13581/31A Expired GB350954A (en) 1930-03-10 1930-03-10 Improvements in electro-mechanical sound recording devices more especially of the moving coil type

Family Applications After (1)

Application Number Title Priority Date Filing Date
GB13581/31A Expired GB350954A (en) 1930-03-10 1930-03-10 Improvements in electro-mechanical sound recording devices more especially of the moving coil type

Country Status (1)

Country Link
GB (2) GB350998A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE868076C (en) * 1937-10-07 1953-02-23 Western Electric Co Device for electro-mechanical vibration transmission
DE915946C (en) * 1949-05-31 1954-08-02 Telefunken Gmbh Dynamic moving coil microphone

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE868076C (en) * 1937-10-07 1953-02-23 Western Electric Co Device for electro-mechanical vibration transmission
DE915946C (en) * 1949-05-31 1954-08-02 Telefunken Gmbh Dynamic moving coil microphone

Also Published As

Publication number Publication date
GB350954A (en) 1931-06-10

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