Introduction: High-Tech Spy Stethoscope!

Picture of High-Tech Spy Stethoscope!
Hear through walls AND record what you hear with this High-Tech Electronic Spy Stethoscope for under $25! See the Test Results in the Video!

Step 1: What You Need...

Picture of What You Need...

1) Stethoscope. I picked mine up at a local drug store (Walgreens) for $10
2) A pair of Stereo Multimedia Microphones. Chosen because of the low cost and decent specs. $12 on Ebay.
3) 3.5mm (mini) Stereo Y-Adapter. ($0. I had one laying around but they are probably a couple of bucks)

Step 2: Disassembly...

Picture of Disassembly...

I disassembled the multimedia microhones using an X-Acto knife and assorted tools. I cut it down the middle to get to the cabling and also popped the top off the header to get the mics out. I ended up with 2 mics and 3.5mm connectors.

Step 3: Stethoscope Disassembly...

Picture of Stethoscope Disassembly...

Remove the earpieces from the Steth. Then I drilled out the earpieces to the diameter of the mic housings. I used a Dremel with a grinding attachment to fine tune it.

Step 4: Reassembly...

Picture of Reassembly...

I used a small dot of hot glue and inserted the microphones into the earpieces and then reassembled the earpieces on the Stethoscope.

Step 5: Final Results!

Picture of Final Results!
After plugging the two 3.5mm connectors into the Y-Adapter and then plugging the single stereo connector into my MP3 player, I was ready to test it out! Check out the video! Hope you like it and give it a try!


DIAGONALLIS (author)2018-01-14

How Is the Audio of this? can you hear people well? how well?

Henry75 (author)2016-01-07

If you're looking for the smallest GPS tracker with audio and video recording with MMS message, here you go:

All you need to do is hide it somewhere in a room, under a table, in a closet or a handbag, it's so small nobody will even notice it.

rynoxville (author)2007-10-20

i cant find the mics anywhere

Rolf (author)rynoxville2015-03-12

I found this YouTube video interesting:

.One more thing, all the other schematics I have looked at using LM386 have pins #2 & #3 reversed from the schematic published here.

This might not cause any problems, since nobody else has commented about this discrepancy.

storch54 (author)2013-11-15

You are a genius!!
I am a physician blood pressure specialist
I need to measure BP sometimes 30 times a day
This device is fantastic because I do not have to plug the dirty stethoscope ear plugs into my ears !!

i.saralynn (author)2012-09-19

How could these microphones be connected to an amplifier/speaker instead of an mp3 player?

lbell6 (author)2011-10-10

If you want to spend $400 you can get a stethoscope for the hearing impaired that has an amplifier on it. Take the diaphragm and secure it to the wall with a bracket and then there will be headphones Not as fun as analog scanners before phones went digital but a nice party favor.

Foaly7 (author)2009-07-15

Does the adapter turn the headphone port on an MP3 player into a microphone?

DrWilson (author)Foaly72010-06-22

no just makes two ports instead of one. your mp3 has to have a mic port & recording capabilities

Foaly7 (author)DrWilson2010-06-24

Well my MP3 has a built in microphone, so I can't make this without a new MP3 player.

MCzone (author)Foaly72011-06-12

you could rip it apart and extend the mic to the ear piece

Derin (author)2009-03-23

XD sam quit calling here ur old enough to be my father

Carmelite (author)Derin2009-06-04

wierd thing is i was using my earbuds and the apparently the mic only picked up the sound from the left side o.O

tbenefi33 (author)2009-05-26

Thanks for sharing I'm know what I'm going to be doing while on vacation.

flashcactus (author)2009-03-01

i think that if u put only one mic into one earpiece and leave the other earpiece alone, u could hear wot u r recording and record only the info u need.

ee0u30eb (author)2009-02-24

Buy a spy ear kids toy, open it up, desolder the mic and resolder it with longer wires..... use this for your mic (doing it with just one mic as per your other comments). I added a 1.5AA battery to mine instead of the button cell. Gives nice amplification and a handy headpohne input jack to give the option if listening direct or plugging it into a recorder.

thefutureisnow (author)2009-02-05

Wouldn't it be easier to just buy the condenser mics from Radio Shack? I know they sell them.

flaresam (author)2008-10-28

awwww, im not that old.....

CarStalkerZ (author)2008-10-17

do you need a cat to do his instructable ...................i have 2 very annoying cats always around me when im working

JohnQ (author)2008-10-17

Great idea! Do you have any plans for making a portable electronic stethoscope? I use one at work, but my hearing is bad, so I need one to amplify sounds.

bengerszewski (author)2008-06-29

Either the video isn't there anymore, or it's not showing up for me. A link would be helpful.

dracox (author)2008-06-16

does mp3 player outputs the sound?

illdoyourdrugs (author)2008-05-02

Ha. Smart man. Love your ideas. Been a fan for a long time now. Keep it up

technodude92 (author)2008-04-04

hey kip. great idea, just one thing. the stethoscope dosen't have stereo. the same sound comes up the tube and splits into two ear pieces. I.E. you get the same sound in both ears. you only need to use one mic.

Mario1 (author)2008-04-01

as thay say hehejo
but i am from the old school if i was kipkay i would trace sam and i would beat him until he pass out :D Just kidding :)
P.S sorry for the bad english!

PizzaPlanet (author)2008-02-22

Dude kipkay i have the same exact cat even with the white mustache

shooter129 (author)2008-01-25

you can get the microphones from

judelizowski (author)2008-01-22

How come the cat is in every video?.... Oh and i should add that this is a great instructable!!! keep up the good work kipkay!!!!

Bas (author)2007-11-05

--- I tested it on my wife talking on the phone: "Sam, quit calling here, you're old enough to be my father" -- lool..

Mistica (author)2007-11-04

TEE HEE KITTY!!! how cute!!!

Knowlton (author)2007-09-26

Would it work the same if you cut the stethoscope at the "Y" point and used one mic?

Kipkay (author)Knowlton2007-09-27

It should. I just liked the 'stereo' look and the extra boost of mic #2.

sping (author)Kipkay2007-10-09

Each of the two mics is getting half the input volume because they're sharing it... No boost at all. One mic would work better, and you might as well place it right at the stethoscope sender, without the tube.

good point

Kipkay (author)Knowlton2007-10-01

Sure. I just like the double boost of 2 mics and keeping the whole stethoscope together.

_soapy_ (author)Knowlton2007-09-27

Yes, it would, and it would save you a load of work, a Y adapter and a microphone, and probably give better audio quality too.

kaboomspray (author)2007-10-05

and ruin the stethoscope? no

Nirjuana (author)2007-10-05

Just if you add a low-power amplifier and then you cab hear stuff even better and use ordinary headphones to listen.

000khalil000 (author)2007-10-03

hey man i like your idea. its really nice. keep it up and let me know if ya come up wit other projects. great work man

SteveUK (author)2007-09-26

For things like listening through walls, a contact microphone is probably easier. It's just a little microphone that's designed to pick up vibrations in solids. It really needs a solid surface though, so it wont be any good on your cat :) I think they use a kind of contact mic with guitars, so you might be able to just use one of those.

neo111 (author)SteveUK2007-10-03

Would it be possible to build something that could pick up the vibrations from a pane of window glass etc, using Mics? I am asking because I saw the great instructable about snooping with the home made laser and it had to be directly opposite the target window. However, a mic system could be left in place and then broadcast the pick up if it would work. No need to be opposite then. I have no idea if this can even be done though.

bowmaster (author)2007-09-29

What is toyr cats name?

Kipkay (author)bowmaster2007-10-01

That is Tux!

HamO (author)2007-09-26

why did you use two mics but the originally single diaphragm? Just curious.

RazorG606 (author)2007-09-26

Yet, another great instructable!

Mr. Morbid (author)2007-09-26

hmm.. definitely gonna try this as soon as i have to make a trip to radio shack or somewhere similar. Cant wait... these are my favorite kind of instructables!

John Smith (author)2007-09-26

I KNEW from the second I read the title that it was you that made it... you know what gave it away? Your healthy obsession wih exclamation points! anyway, good instructable.

SmartPhoneCardTrick (author)2007-09-26

Cool instructable!

About This Instructable




Bio: Tinkerer, hackster and prankster. Hit me up on Facebook: Thanks for checking out my Instructables!
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