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Hearing aid circuit diagram using transistors

2016-05-07 06:20  
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Hearing aid circuit diagramis very useful when in the area wrote that the lack of a good sound system such as conference rooms, meeting rooms, lecture halls. every?word?sounded?clear.hearing aid circuit diagramwe?also?be?Able?to?watch?TV?with?the?volume?set?a?very slowresponse, so as not to disturb the family, and neighbors are resting or sleeping reply. Thehearing aid circuit diagram?core of the circuit is constant-volume control amplifier. All the signals taken-up by a microphone that amplified at a constant level of about 1 volt peak to peak. In this way a very low amplitude of the audio signal is amplified and limited high amplitude. This operation is done by Q3, changing the bias Q1 (his then AC gain) by R2. The following is a schematic hearing aid circuit diagram drawing:

Simple hearing aid using transistors Hearing aid circuit diagram using transistors

A noteworthy feature of this circuit is 1.5V battery operation. Due to the constant-volume control, some users may consider P1 volume control is not necessary. In most cases negligible, connect C6 to C3. In this case using the slider or switch SPST switch SW1. To note the stereo output Jack socket (J1) connection: only the two inner connection is used, leaving open the external one. In this way the hearing aid circuit diagram earphones are connected in series, the hearing aid circuit diagram ?which allows mono operation and optimal load impedance to the Q4 (64 Ohm).

Part :

P1_____________22K?? Log. Potentiometer

R1,R9__________10K?? 1/4W Resistors
R2______________1M?? 1/4W Resistor
R3______________4K7? 1/4W Resistor
R4,R7_________100K?? 1/4W Resistor
R5______________3K9? 1/4W Resistor
R6______________1K5? 1/4W Resistor
R8_____________100R? 1/4W Resistor

C1,C2_________100nF? 63V Polyester or Ceramic Capacitors
C3,C6___________1μF? 63V Polyester or Ceramic Capacitors
C4_____________10μF? 25V Electrolytic Capacitor
C5____________470μF? 25V Electrolytic Capacitor

D1___________1N4148? 75V 150mA Diode

Q1,Q2,Q3,_____BC547? 45V 100mA NPN Transistors
Q4____________BC337? 45V 800mA NPN Transistor

MIC1__________Miniature electret microphone

SW1____________SPST Switch (Ganged with P1)

J1_____________Stereo 3mm. Jack socket

B1_____________1.5V Battery


Source circuit :?www.redcircuits.com

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