Proteza Auditiva

#1
geopalade

Posted 16 November 2004 - 10:05

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Ma poate ajuta cineva cu o schema pentru proteza auditiva? A mai construit cineva asa ceva pentru persoane cu deficiente auditive? As fi recunoscator pentru o schema.

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#2
mister_rf

Posted 16 November 2004 - 14:21

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Gasesti aici o schema simpla realizata cu 4 tranzistoare.[ http://www.redcircuits.com//ListenAmp.GIF - Pentru incarcare in pagina (embed) Click aici ]

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#3
geopalade

Posted 16 November 2004 - 16:30

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Mersi frumos. Sunt curios cum functioneaza si daca are amplificarea neliniara (mai ales ca Q1 si Q3 nu au polarizare in curent continuu).

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#4
mister_rf

Posted 16 November 2004 - 21:56

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Q1 are polarizare in cc, dar depinde de nivelul de semnal. Se realizeaza in acest mod o amplificare constanta...

Quote

The heart of the circuit is a constant-volume control amplifier. All the signals picked-up by the microphone are amplified at a constant level of about 1 Volt peak to peak. In this manner very low amplitude audio signals are highly amplified and high amplitude ones are limited. This operation is accomplished by Q3, modifying the bias of Q1 (hence its AC gain) by means of R2.
A noteworthy feature of this circuit is 1.5V battery operation.
Typical current drawing: 7.5mA.

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#5
nelu F

Posted 17 November 2004 - 09:49

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Amplificarea este variabila (nu constanta) functie de nivelul de la intrare pentru ca la iesire sa nu fie variatii mari ale semnalului (deranjeaza). Se face astfel o compresie a dinamicii semnalului care este utila scopului propus (proteza auditiva). Q3 functioneaza ca o rezistenta variabila comandata in tensiune.

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#6
mister_rf

Posted 17 November 2004 - 09:56

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Da ai dreptate, am folosit termenul de "amplificare constanta" pentru efectul perceput la iesire, lipsa variiatiilor bruste de nivel , cele care deranjeaza foarte mult auditia in cazul unor treceri de la semnale mici la semnale cu intensitate puternica... :) Termenul corect:" volum constant" este in nota atasata -> "constant-volume amplifier"...

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Proteza Auditiva

#1 geopalade Posted 16 November 2004 - 10:05

#2 mister_rf Posted 16 November 2004 - 14:21

#3 geopalade Posted 16 November 2004 - 16:30

#4 mister_rf Posted 16 November 2004 - 21:56

#5 nelu F Posted 17 November 2004 - 09:49

#6 mister_rf Posted 17 November 2004 - 09:56

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#1
geopalade

Posted 16 November 2004 - 10:05

#2
mister_rf

Posted 16 November 2004 - 14:21

#3
geopalade

Posted 16 November 2004 - 16:30

#4
mister_rf

Posted 16 November 2004 - 21:56

#5
nelu F

Posted 17 November 2004 - 09:49

#6
mister_rf

Posted 17 November 2004 - 09:56