Stethoscopes are not only useful for doctors, but home mechanics, exterminators, spying and any number of other uses. Standard stethoscopes provide no amplification which limits their use. This circuit uses op-amps to greatly amplify a standard stethoscope, and includes a low pass filter to remove background noise.
Note:
R1 - 10K 1/4W Resistor
R2, R3, R9 - 2.2K 1/4W Resistor
R4 - 47K 1/4W Resistor
R5, R6, R7 - 33K 1/4W Resistor
R8 - 56K 1/4W Resistor
R10 - 4.7K 1/4W Resistor
R11 - 2.5K Pot
R12 - 330K 1/4W Resistor
R13 - 1K 1/4W Resistor
R14 - 3.9 Ohm 1/4W Resistor
C1 - 470uF Electrolytic Capacitor
C2, C3, C4 - 0.047uF Capacitor
C5 - 0.1uF Capacitor
C6 - 1000uF Electrolytic Capacitor
D1 - Bi-Colour LED
U1, U2, U3, U4, U5 - 741 Op-Amp
MIC1 - Electret Mic
J1 - 1/4
