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Amplificatoare audio ale instrumentelor muzicale

tehnica mecanica


Amplificatoare audio ale instrumentelor muzicale

An audio amplifier is usually used to amplify signals such as music or speech.



III.1 Sistemul de fabricatie al amplificatoarelor de chitara

Un amplificator de chitara este de fapt  o cutie care contine un amplificator, ce amplifica semnalul electronic, si un difuzor.  Unele amplificatoare 13413x2321n folosesc circuite si cipuri din siliciu in timp ce altele folosesc traditionalele tuburi vidate.

Partea electronic a amplificatorului este gazduita inauntrul unei carcase de metal, acest model de sasiu este facut dintr-o foaie de otel mai mica de  1mm grosime. O masina ghidata de computer, taie conturul si face o serie de gauri si fante pentru controale.

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Un muncitor foloseste un dispozitiv de indoire ghidat de calculator pentru a indoi sasiul taiat.

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In alta parte a fabricii placuta de circuite a amplificatorului capata forma.  Aceasta va sta in interiorul sasiului.

O masina  de gaurit actionata de calculator face mici gauri intr-o placa laminata care este placata cu cupru.

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Gaurile sunt pt. diferitele component electronice.

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O imprimanta serigrafica automata, aplica o diagrama a circuitului electric cu cerneala rezistenta la amoniu.

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Apoi placa va intra intr-o masina de developare  care foloseste amoniul pt. a dizolva stratul de cupru.

Cuprul acoperit de diagrama de cerneala ramane intact. 

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Masina apoi spreiaza placa cu hidroxid de sodium pt. a dizolva cerneala lasand in urma doar diagrama circuitului in cupru.  Aceaste trasee de cupru de pe diagrama circuitului vor alimenta componentele care vor fi montate pe cablaj.

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Masini automate monteaza componentele mai mici.

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Un muncitor tine contrapersiune pentru ca o masina sa fixeze componentele mai mari pe placa pana vor fi lipite.

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Apoi muncitorii instaleaza piesele cu forme neregulate manual totodata si soclurile lampilor care dau putere amplificatorului.

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Cablul pamblica care uneste diferitele parti ale circuitului si firele care conecteaza componentele externe.

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Componentele montate sunt fixate peranent de placa printr-un process numit lipire in val.

Practic placa este trecuta printr-o baie de aliaj staniu-plumb topit (fludor)

In doar cateva secunde metalul lichid se intareste si lipeste definitiv componentele pe placa.

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Sasui de otel indoit va fi vopsit in negru, Cu ajutorul unei imprimantei serigrafice se aplica marcajele de control, logourile si alte informatii.

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Asamblarea finala: Mai intai, se insurubeaza placa in sasiu.

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Apoi se cupleaza lampile de preamplificare in soclurile corespunzatoare de pe placa. Aceasta lampa sporeste semnalul electric venit de la chitara si il trimite catre lampa finala care mareste nivelul de tensiune facand semnalul mai puternic si mai tare.

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Dupa montarea butoanelor de control si acoperirea spatelui sasiului muncitorii introduc si fixeaza in cleme lampile finale al carui numar variaza in functie de puterea la care a fost proiectat amplificatorul.

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Sasiul electronic este introduis intr-o cutie de lemn. Cutia este construita dintr-un lemn special pt. boxe dar se poate construi si din placaj sau plastic.

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Dupa tapitzarea cutiei si ranforsarea colturilor instaleaza ultimele 2 componente : arcul de reverb

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si difuzorul.

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In timp ce semnalul electric de la chitara trece prin amplificator, o parte din semnalul electric deviaza la un capat al arcului, facandu-l sa vibreze, celalalt capat preia aceasta vibratie si o trimite inapoi prin amplificator  ca un semnal intarziat

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Acea reverberatie se combinata cu semnalul original pt. a produce un sunet mai mare

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[edit] Other amplifier types

[edit] Carbon microphone

One of the first devices used to amplify signals was the carbon microphone (effectively a sound-controlled variable resistor). By channeling a large electric current through the compressed carbon granules in the microphone, a small sound signal could produce a much larger electric signal. The carbon microphone was extremely important in early telecommunications; analog telephones in fact work without the use of any other amplifier. Before the invention of electronic amplifiers, mechanically coupled carbon microphones were also used as amplifiers in telephone repeaters for long distance service.

[edit] Magnetic amplifier

Main article: magnetic amplifier

A magnetic amplifier is a transformer-like device that makes use of the saturation of magnetic materials to produce amplification. It is a non-electronic electrical amplifier with no moving parts. The bandwidth of magnetic amplifiers extends to the hundreds of kilohertz.

[edit] Rotating electrical machinery amplifier

A Ward Leonard control is a rotating machine like an electrical generator that provides amplification of electrical signals by the conversion of mechanical energy to electrical energy. Changes in generator field current result in larger changes in the output current of the generator, providing gain. This class of device was used for smooth control of large motors, primarily for elevators and naval guns.

Field modulation of a very high speed AC generator was also used for some early AM radio transmissions.[1] See Alexanderson alternator.

[edit] Mechanical amplifiers

Mechanical amplifiers were used in the pre-electronic era in specialized applications. Early autopilot units designed by Elmer Ambrose Sperry incorporated a mechanical amplifier using belts wrapped around rotating drums; a slight increase in the tension of the belt caused the drum to move the belt. A paired, opposing set of such drives made up a single amplifier. This amplified small gyro errors into signals large enough to move aircraft control surfaces. A similar mechanism was used in the Vannevar Bush differential analyzer.

[edit] Optical amplifiers

Main article: Optical amplifier

Optical amplifiers amplify light through the process of stimulated emission.

[edit] Miscellaneous types

There are also mechanical amplifiers, such as the automotive servo used in braking.

Relays can be included under the above definition of amplifiers, although their transfer function is not linear (that is, they are either open or closed).

Also purely mechanical manifestations of such digital amplifiers can be built (for theoretical, didactical purposes, or for entertainment), see e.g. domino computer.

Another type of amplifier is the fluidic amplifier, based on the fluidic triode.

[edit] References

^ Robert S. Symons (1998). "Tubes: Still vital after all these years". IEEE Spectrum 35 (4): 52-63.

[edit] See also


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