amplified_ ear

http://www.redcircuits.com/page38.htm

Useful to listen in faint sounds

 

Parts:

P1_____________22K   Log. Potentiometer (see Notes)

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 (AA or AAA cell etc.)