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Electronic Stethoscope

Source: http://www.aaroncake.net/
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.

Schematic


Schematic for Electronic Stethoscope

Parts:


Part

Total Qty.

Description

Substitutions

R1

1

10K 1/4W Resistor

R2, R3, R9

3

2.2K 1/4W Resistor

R4

1

47K 1/4W Resistor

R5, R6, R7

3

33K 1/4W Resistor

R8

1

56K 1/4W Resistor

R10

1

4.7K 1/4W Resistor

R11

1

2.5K Pot

R12

1

330K 1/4W Resistor

R13

1

1K 1/4W Resistor

R14

1

3.9 Ohm 1/4W Resistor

C1

1

470uF Electrolytic Capacitor

C2, C3, C4

3

0.047uF Capacitor

C5

1

0.1uF Capacitor

C6

1

1000uF Electrolytic Capacitor

D1

1

Bi-Colour LED

U1, U2, U3, U4, U5

5

741 Op-Amp

MIC1

1

Electret Mic

J1

1

1/4" Phone Jack

MISC

1

Board, Wire, Sockets for ICs, Knob for pot, Stethoscope, Rubber tube

Notes:

1. MIC1 is an assembly made out of a stethoscope head and electret mic. Cut the head off the stethoscope and use a small piece of rubber tube to join the nipple on the head to the mic.

2. Be careful with the volume, as excess noise level may damage your ears.

3. The + and - 9V may be supplied by two 9V batteries wired in series and tapped at the junction.

4. R11 is the volume control.


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