An electronic stethoscope is an easy and fun listening device to make. It onlyrequires some basic knowledge of electronics, and can be built with some basic

(http://cdn.instructables.com/FJM/980I/GOSDJJAG/FJM980IGOSDJJAG.LARGE.jpg)

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randofo(/member/randofo/)Randy Sarafan loves you!(http://www.randysarafan.com)

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My name is Randy and I run theAutodesk Design Studio. I'm also theauthor of the books 'Simple Bots,' and '62Projects to Make with a Dead Computer'.Since I am always making new things,subscribing ...read more »(/member/randofo/)

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easy to find parts. I have been having a great time using it to crack saf... I meanlisten to my heartbeat. Yes! I have been having a great time listening to my innerworkings.

Step 1: Go get stuff

You will need:

­ 1­1/2" flat round cabinet knob­ LM386 Low Voltage Audio Power Amplifier (Model: LM386 | Catalog #: 276­1731 (http://www.radioshack.com/product/index.jsp?productId=2062598))­ MPF102 Transistors (Model: MPF102 FET | Catalog #: 276­2062(http://www.radioshack.com/product/index.jsp?productId=2062616))­ 1K Ohm 1/4­Watt Carbon Film Resistor (Model: 271­1321 | Catalog #: 271­1321(http://www.radioshack.com/product/index.jsp?productId=2062343))­ 1M Ohm 1/4­Watt Carbon Film Resistor (Model: 271­1356 | Catalog #: 271­1356 (http://www.radioshack.com/product/index.jsp?productId=2062351))­ 10 ohm 1/4W 5% Carbon Film Resistor (Model: 271­1301 | Catalog #: 271­1301(http://www.radioshack.com/product/index.jsp?productId=2062338))­ 4.7K Ohm 1/4­Watt Carbon Film Resistor (Model: 271­1330 | Catalog #: 271­1330 (http://www.radioshack.com/product/index.jsp?productId=2062346))­ (x2) 0.047µF 50V 10% PC­Mount Capacitor (Model: 272­1068 | Catalog #: 272­1068 (http://www.radioshack.com/product/index.jsp?productId=2102516))­ 220µF 35V 20% Radial­lead Electrolytic Capacitor (Model: 272­1029 | Catalog#: 272­1029 (http://www.radioshack.com/product/index.jsp?productId=2103623))­ 100µF 35V 20% Radial­lead Electrolytic Capacitor (Model: 272­1028 | Catalog#: 272­1028 (http://www.radioshack.com/product/index.jsp?productId=2102510))­ 0.1µF 50V Hi­Q Ceramic Disc Capacitor (Model: 272­135 | Catalog #: 272­135(http://www.radioshack.com/product/index.jsp?productId=2062365))­ Project Enclosure (3x2x1") (Model: 270­1801 | Catalog #: 270­1801(http://www.radioshack.com/product/index.jsp?productId=2062279))­ Multipurpose PC Board with 417 Holes (Model: 276­150 | Catalog #: 276­150(http://www.radioshack.com/product/index.jsp?productId=2102845))­ JVC® Gumy Earbuds (Model: HAF150B | Catalog #: 55042619(http://www.radioshack.com/product/index.jsp?productId=11313786))­ 10K­Ohm Linear­Taper Potentiometer (Model: 271­1715 | Catalog #: 271­1715(http://www.radioshack.com/product/index.jsp?productId=2062354))­ Hexagonal Control Knob (Model: 274­407 | Catalog #: 274­407(http://www.radioshack.com/product/index.jsp?productId=2102830))

Related

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(http://cdn.instructables.com/FGV/OTQV/GOOP5RU5/FGVOTQVGOOP5RU5.LARGE.jpg)

stethoscope (/tag/type­id/category­

technology/keyword­stethoscope/)

electronic (/tag/type­id/category­

technology/keyword­electronic/)

listening (/tag/type­id/category­

technology/keyword­listening/)

device (/tag/type­id/category­technology/keyword­

device/)

radioshack (/tag/type­id/category­

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Tags:

"The Three MagicStethoscopes" (/id/The­Three­Magic­Stethoscopes/)by samuelkoromaA simple weirdcommunication device(/id/A­simple­weird­communication­device/)by gruffalo childMUSICAL SCULPTURE ­­"The Secretary'sNightmare" (/id/MUSICAL­SCULPTURE­The­Secretarys­Nightmare/)ATTiny85 Traffic Light(/id/ATTiny85­Traffic­Light/)by nthdesign(/member/nthdesign/)Metronome(/id/Metronome/)by randofo (/member/randofo/)

­ 1/8" Mono Panel­Mount Audio Jack (Model: 274­251 | Catalog #: 274­251(http://www.radioshack.com/product/index.jsp?productId=2103453))­ 6­Ft. Mono 1/8" Plug to Mono 1/8" Jack with Shielded Cable (Model: 42­2472 |Catalog #: 42­2472 (http://www.radioshack.com/product/index.jsp?productId=2103366))­ Fully Insulated 9V Battery Snap Connectors (Model: 270­325 | Catalog #: 270­325 (http://www.radioshack.com/product/index.jsp?productId=2062219))­ Enercell® Alkaline 9 Volt Battery (Model: 23­853 | Catalog #: 23­853(http://www.radioshack.com/product/index.jsp?productId=3897297))­ 90dB Piezo Pulse (Model: 273­066 | Catalog #: 273­066(http://www.radioshack.com/product/index.jsp?productId=2062399))

Step 2: Cut

Using a sharp pair of scissors, trim your circuit board lengthwise so that only thecenter pads are left.

(http://cdn.instructables.com/F1T/56CG/GOQY3CSU/F1T56CGGOQY3CSU.LARGE.jpg)

(http://cdn.instructables.com/FIE/PYTK/GOQY2528/FIEPYTKGOQY2528.LARGE.jpg)

Note: You may want to use a dust mask while doing this, as circuit board dust isbad for you when inhaled. Cutting the board with scissors, greatly reduces, butdoes eliminate dust.

Step 3: Build

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Build the circuit tightly and as close to one side of the board as possible.

For now, don't worry about including the power switch, audio jack, potentiometeror piezo. These will be handled later.

Step 4: Trim

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(http://cdn.instructables.com/FU6/TAY1/GOSDJJ66/FU6TAY1GOSDJJ66.LARGE.jpg)

Once the bulk of your circuit has been built. Trim the board as small as possiblein such a way that it won't interfere with the circuit itself, and remember to leavea few solder pads for the parts that you still need to connect.

Step 5: Mark and drill

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Flip your case on its side. Make two _ _ _ marks _ _ _

Drill these marks using a 1/4" drill bit.

Step 6: Mark and drill again

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On the two smallest sides of the case make centered marks.

Drill an 3/16" hole on the side closest to the other holes that you have just made.

Drill a 1/4" hole where the mark is on the opposite side of the case.

Step 7: Wires

(http://cdn.instructables.com/FUR/2F7T/GOQY3CY4/FUR2F7TGOQY3CY4.LARGE.jpg)

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With the potentiometer knob facing towards you, solder a black wire to the leftpotentiometer pin.

Solder red wire to the other two pins.

Step 8: More wires

Solder a red wire to the center toggle switch pin.

Solder the red wire from the 9V battery clip to either of the other pins.

Step 9: Some more wires

(http://cdn.instructables.com/FWK/3M7Q/GOOP5SNG/FWK3M7QGOOP5SNG.LARGE.jpg)

(http://cdn.instructables.com/F7D/XZOI/GOOP5SZ9/F7DXZOIGOOP5SZ9.LARGE.jpg)

Attach a single red wire to the two pins on the bottom of the audio jack.

Attach a black wire to the ground pin on the side.

Step 10: Install

Install the potentiometer and toggle switch right next to each other inside thecase.

Install the audio jack into the 1/4" hole on the opposite end of the case.

Step 11: Drill

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Drill and 1/8" hole near the edge of the cabinet handle.

Step 12: Mount

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For our purposes, the flat side of the cabinet handle will be considered the front.

Pass the red and black wires of the piezo through the hole you just drilled fromfront to back.

Epoxy the piezo to the cabinet handle such that the flat side of the piezo is facingout.

Be careful to leave a tiny bit of space between the cabinet handle and the solderpoints on the piezo (just in case the handle is conductive).

Step 13: Trim

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Take your audio cable and cut a 3 foot section of cable out of it.

Don't worry about preserving the ends. We just need the shielded cable.

Step 14: Expose

(http://cdn.instructables.com/FAA/QNSE/GONGI4BD/FAAQNSEGONGI4BD.LARGE.jpg)

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(http://cdn.instructables.com/FF6/E3AO/GOSDII18/FF6E3AOGOSDII18.LARGE.jpg)

Peel back the cable and twist together the shielding to form one single wire andexpose the signal wire to form another.

Step 15: Attach

(http://cdn.instructables.com/F6Q/O0G1/GONGI4ED/F6QO0G1GONGI4ED.LARGE.jpg)

(http://cdn.instructables.com/FP9/CYOR/GOSDJJ6Z/FP9CYORGOSDJJ6Z.LARGE.jpg)

Electronic Stethoscope  by randofo (/member/randofo/)

+ Collection Download (/id/Electronic­Stethoscope/?download=pdf) 21 Steps   Favorite (/id/Electronic­Stethoscope/)

Solder the red wire from the piezo to the signal wire of the cable.

Solder the black wire to the cable's shielding.

Epoxy it all to the back of the cabinet handle in such a way that the solder jointswon't make contact with either each other or the handle itself.

Step 16: Passing through

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Show All 7 Images

Pass the other end of the audio cable through the remaining hole in the case.

Tie a single knot to prevent it from passing back through.

Strip back the cable and separate the wires as you did in Step 14.

Step 17: Solder it all up

Complete the circuit as specified in the schematic.

Note that the audio cable's shielding goes to ground and that the center pin fromthe toggle switch goes to +9V.

The power switch goes between the red wire on the battery connector and the+9V in connection on the circuit board.

(http://cdn.instructables.com/FA7/NJM4/GOSDJJ90/FA7NJM4GOSDJJ90.LARGE.jpg)

(http://cdn.instructables.com/F8X/CVRU/GOSDII3O/F8XCVRUGOSDII3O.LARGE.jpg)

Step 18: Power

Plug in your 9V battery and install it inside the case.

If all has been done right, it should fit snugly.

Step 19: Case closed

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Put the lid on the case and screw it shut.

Step 20: Knob

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