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)
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endoacusticam5 months ago
rynoxville7 years ago
i cant find the mics anywhere
Rolf rynoxville5 months ago

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.

storch541 year ago
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.saralynn2 years ago
How could these microphones be connected to an amplifier/speaker instead of an mp3 player?
lbell63 years ago
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.
Foaly76 years ago
Does the adapter turn the headphone port on an MP3 player into a microphone?
DrWilson Foaly75 years ago
no just makes two ports instead of one. your mp3 has to have a mic port & recording capabilities
Foaly7 DrWilson5 years ago
Well my MP3 has a built in microphone, so I can't make this without a new MP3 player.
MCzone Foaly74 years ago
you could rip it apart and extend the mic to the ear piece
Derin6 years ago
XD sam quit calling here ur old enough to be my father
Carmelite Derin6 years ago
wierd thing is i was using my earbuds and the apparently the mic only picked up the sound from the left side o.O
tbenefi336 years ago
Thanks for sharing I'm know what I'm going to be doing while on vacation.
flashcactus6 years ago
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.
ee0u30eb6 years ago
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.
Wouldn't it be easier to just buy the condenser mics from Radio Shack? I know they sell them.
flaresam6 years ago
awwww, im not that old.....
CarStalkerZ6 years ago
do you need a cat to do his instructable ...................i have 2 very annoying cats always around me when im working
JohnQ6 years ago
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.
Either the video isn't there anymore, or it's not showing up for me. A link would be helpful.
dracox7 years ago
does mp3 player outputs the sound?
Ha. Smart man. Love your ideas. Been a fan for a long time now. Keep it up
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.
Mario17 years ago
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!
PizzaPlanet7 years ago
Dude kipkay i have the same exact cat even with the white mustache
shooter1297 years ago
you can get the microphones from allectronics.com
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!!!!
Bas7 years ago
--- I tested it on my wife talking on the phone: "Sam, quit calling here, you're old enough to be my father" -- lool..
Mistica7 years ago
TEE HEE KITTY!!! how cute!!!
Knowlton7 years ago
Would it work the same if you cut the stethoscope at the "Y" point and used one mic?
Kipkay (author)  Knowlton7 years ago
It should. I just liked the 'stereo' look and the extra boost of mic #2.
sping Kipkay7 years ago
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)  Knowlton7 years ago
Sure. I just like the double boost of 2 mics and keeping the whole stethoscope together.
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.
kaboomspray7 years ago
and ruin the stethoscope? no
Nirjuana7 years ago
Just if you add a low-power amplifier and then you cab hear stuff even better and use ordinary headphones to listen.
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
SteveUK7 years ago
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 SteveUK7 years ago
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.
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