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Electronic Stethoscope

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An electronic stethoscope is an easy and fun listening device to make. It only requires some basic knowledge of electronics, and can be built with some basic easy to find parts. I have been having a great time using it to crack saf... I mean listen to my heartbeat. Yes! I have been having a great time listening to my inner workings.
 
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Step 1: Go get stuff

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You will need:

- 1-1/2" flat round cabinet knob
- LM386 Low Voltage Audio Power Amplifier (Model: LM386 | Catalog #: 276-1731)
- MPF102 Transistors (Model: MPF102 FET | Catalog #: 276-2062)
- 1K Ohm 1/4-Watt Carbon Film Resistor (Model: 271-1321 | Catalog #: 271-1321)
- 1M Ohm 1/4-Watt Carbon Film Resistor (Model: 271-1356 | Catalog #: 271-1356)
- 10 ohm 1/4W 5% Carbon Film Resistor (Model: 271-1301 | Catalog #: 271-1301)
- 4.7K Ohm 1/4-Watt Carbon Film Resistor (Model: 271-1330 | Catalog #: 271-1330)
- (x2) 0.047µF 50V 10% PC-Mount Capacitor (Model: 272-1068 | Catalog #: 272-1068)
- 220µF 35V 20% Radial-lead Electrolytic Capacitor (Model: 272-1029 | Catalog #: 272-1029)
- 100µF 35V 20% Radial-lead Electrolytic Capacitor (Model: 272-1028 | Catalog #: 272-1028)
- 0.1µF 50V Hi-Q Ceramic Disc Capacitor (Model: 272-135 | Catalog #: 272-135)
- Project Enclosure (3x2x1") (Model: 270-1801 | Catalog #: 270-1801)
- Multipurpose PC Board with 417 Holes (Model: 276-150 | Catalog #: 276-150)
- JVC® Gumy Earbuds (Model: HAF150B | Catalog #: 55042619)
- 10K-Ohm Linear-Taper Potentiometer (Model: 271-1715 | Catalog #: 271-1715)
- Hexagonal Control Knob (Model: 274-407 | Catalog #: 274-407)
- 1/8" Mono Panel-Mount Audio Jack (Model: 274-251 | Catalog #: 274-251)
- 6-Ft. Mono 1/8" Plug to Mono 1/8" Jack with Shielded Cable (Model: 42-2472 | Catalog #: 42-2472)
- Fully Insulated 9V Battery Snap Connectors (Model: 270-325 | Catalog #: 270-325)
- Enercell® Alkaline 9 Volt Battery (Model: 23-853 | Catalog #: 23-853)
- 90dB Piezo Pulse (Model: 273-066 | Catalog #: 273-066)

I do not think the Piezo is sensitive enough, if i was to use a microphone will this improve my chances of repairing this problem. Could someone please respond to my questions?

We made the Electronic Stethoscope and it does not work, when we turn unit on i hear static and if i lightly tap the Piezo i hear the tapping but i dont hear any heart beat, not sure what to do???/

realinstaprom3 months ago
Got a new crossbow. Now only if somebody would get me a zombie...
apefeet4 months ago
It's my first time doing this stuff so I'm wondering if I can replace the MPF102 transistors because the shops near me don't have them
brancara5 months ago
How important is it to have a 90dB piezo pulse? How can I tell what type of Piezo pulse I have?
hello
I have seen the draft electronic stethoscope and my really liked but I need to know how to calculate the value of the resistance and capacity of the circuit
thank you kindly answer me
I hope to answer as soon as possible
jed64171 year ago
Where do you wire the battery in circuit board?
Where the 9V is and where the GND is. All points going into 9V go to the positive and all points going to GND go to the positive part of the battery.
Can someone lend me a schematic? It will a great help. Thanks!
pegawonder1 year ago
I am a novice interested in building one of these... Several of the parts are missing and I'm scared to order another piezo for example without understanding the impacts of different dB and electrical ratings. Any ideas anyone?
i.saralynn1 year ago
Could this plug in to speakers?
yungtiec1 year ago
How to wire the panel mount audio jack? Im still prototyping on breadboard and Im hopelessly stuck...
das0072 years ago
is there any equivalent of lm386. I do have lm380 can i use it.....?
I'm actually building this with LM358. It should work but make sure you use the correct pinouts.
mat19782 years ago
I'm so building this one :)
siafulinux2 years ago
Nicely done!
Polarize2 years ago
Great instructable :D nice video as well, although it would of been nice to see the stethoscope actually working :P
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