It is primarily used for auscultation, which is listening to the internal sounds of the body, like heartbeats, but there are also engineering stethoscopes which are used for listening to internal sounds of various machines and other small-scale acoustic monitoring processes.
This electronic stethoscope is a very simple project with only a few parts needed. The idea is taking a broken ordinary stethoscope and modify it to have an electronic one. This is basically a 3 transistor amplifier with a microphone which gets attached to a short plastic tubing using heat-shrink tubing.
The amplifier must be opened to have the stethoscope diaphragm attached to the microphone in a firm and secure manner, but once this is done the electronic stethoscope is complete.
A fun and quite simple project, this electronic stethoscope has a few advantages over an ordinary one because it possesses volume control. Posted by mylibs Filed in 0. Thank you a lot for sharing this with all folks you actually understand what you are speaking about! We may have a link change contract among us.
Name required. Mail will not be published required. Notify me of followup comments via e-mail. Says: January 10th, at pm Thank you a lot for sharing this with all folks you actually understand what you are speaking about! Tiberiu Says: January 11th, at am Thanks for your comment, glad to see you found something useful! Follow me on:.Circuit diagram. Circuit Description: U1a operates as a low-noise microphone preamp.
Its gain is only about 3. C2 has a fairly high value in order to pass very low frequency about 20 to 30Hz heartbeat sounds. U1b operates as a low-noise Sallen and Key, Butterworth low-pass-filter with a cutoff frequency of about Hz. R7 and R8 provide a gain of about 1. C3 and C4 can be reduced to 4. The U4 circuit is optional and has a gain of 71 to drive the bi-colour LED. It has a gain of It can drive any type of headphones including low impedance 8 ohms ones.
Stethoscope head or jar lid, Rubber Sleeve for microphone. A thick jar lid can be used as a stethoscope head. The microphone must be spaced away from the skin but the stethoscope head must be pressed to the skin, sealing the microphone from background noises and avoiding acoustical feedback with your headphones.
Keep the microphone away from your headphones to avoid acoustical feedback. Circuit diagram Circuit Description: U1a operates as a low-noise microphone preamp. Download this project in.Little modification was necessary, mainly just scraping a bit more space in the microphone tube.
The end result is a super cheap electronic stethascope that can be hooked to a computer or other speakers for multiple people to listen to. Other than that, the concept is excellent. Absolutely use a piece of tubing and de-couple that thing from the mic to reduce the creaking that case will do if you try to use it as-is. Be careful adding long tube extensions. Hence the search for a retractable set of earphones with in-ear buds on.
This sounds like the kind of thing that should have been not just built, but put into service in hospitals years ago. I gotta make one of these…. Nothing wrong with pierced nips. I actually wanted to use that for the article image. We thought this one showed the product better though.
Same as with antennas, ear is the best amp. This was my final year engineering project. Made an electronic stethoscope with a datalogger on the other end and recorded the sounds. The idea was for training, you could demonstrate the sound of an arrhythmia to a entire class of students so they knew what to look for. You could map it visually and hear the playback to help comprehension. Plus your GP could keep a record onfile so they could compare your heart patterns over your lifetime, thought you might be able to predict things eventually with enough data.
Earphones tend to tangle up, especially when rushing between patient. The beforementioned battery aspect is valid too. Another aspect is that you need to disinfect these after each patient otherwise you tend to transfer nosocomial diseases to your weakest patients. No, you can buy a high quality stethoscope for Why use this old design.
Or use a Bonic ear can do the job as well. This site uses Akismet to reduce spam. Learn how your comment data is processed. By using our website and services, you expressly agree to the placement of our performance, functionality and advertising cookies.
Learn more. Report comment. Did you really need to NOT see the picture? Stethoscopes are good for troubleshooting machinery as well as humans. Isolate them thar mics boyos!
Vik :v. Guys on the squad might give me a funny look though. Sets off my irony alarms. Heh… This was my final year engineering project. This is not meant to be a quantum leap in technology, just a hack. Leave a Reply Cancel reply. Search Search for:. Hackaday Links: April 12, 14 Comments.The post explains how to make an electronic stethoscope amplifier circuit for enabling a loud audible reproduction of the heart beats which is being diagnosed.
The article also reveals how the same can be applied within a cellphone through a wireless circuit. The idea was requested by Dr. The sound of a heart beat can be extremely weak and therefore it cannot be heard without a minimum suitable device such as a stethoscope. A stethoscope is a basic device which relies on picking and transferring the air vibrations through a tube into the ears of the user.
The vibrations are caused by the heart beats on the stethoscope's sensing diaphragm when it is brought at a close proximity to the chest where the heart is situated, and the diaphragm movement sets the air column inside the tube into a correspondingly push-pull vibrating motion. This surely means that even though the air vibration or the sound vibration generated by the heart could be small enough but it's loud enough to be heard without the aid of electrical device, which implies that the sound may be sufficiently strong to be amplified using an audio amplifier, because if a naked ear can hear these minute vibrations so can the amplifier MIC.
In order to reproduce the sound over a loudspeaker, the signal needs to be amplified significantly and also in the course it must be suitably processed to remove any associated disturbances. The circuit diagram of the proposed electronic stethoscope amplifier is designed using two stages, one consisting of the opamp based tone control circuit, and the integrated proper amplifier stage.
The tone control stage is built around the opampand with the help of the associated RC networks and the pots. The upper pot controls the low frequency limit, while the lower pot is used to control the upper frequency limit. Both these pots can be appropriately set for achieving the best possible sound clarity. In addition to the sound processing, the opamp stage also acts like a preamplifier for elevating the very low amplitude of the heart beat pulses to a suitable level for the power amplifier input.
This enables the power amplifier to pick the signals at above the required minimum detectable level and amplify it on the loudspeakers optimally. The main sensing stage of this electronic stethoscope circuit is formed by an electret MIC which can be seen configured across the input of the tone control stage via an RC network.
In order to enable the MIC to sense the minute heart beat signals, the mic is enclosed within a rubber pipe with a rubber funnel like mouth opening. The funnel like opening is supposed to be stuck over the chest of the patient just above the heart area for allowing the MIC to detect the concentrated heart rate sound and convert it into minute proportionately pulsating electrical pulses.
The opamp circuit responds to these signals and processes it appropriately as per the setting of the low pass and the high pass filter pots. The finalized signal is applied to the input of the power amplifier configured around the TDA amplifier circuit which is capable of generating a strong 10 watts of amplification over a 8 ohm loudspeaker. The pot between the output and the TDA input determines the volume of sound and can be adjusted for the same.
In the request we also see the mentioning of a android phone compatible unit, which is difficult to achieve using the above circuit since the minimum operating voltage of this circuit can be over 12V so it cannot be operated easily using a cellphone existing battery.
A simpler yet a more advanced method for achieving an electronic stethoscope amplifier functionality with a cellphone is to go wireless. A small FM transmitter circuit can be used and positioned near the chest of the patient, and the heart pulses can be heard or recorded loud and clear over any cellphone equipped with an FM radio, which is commonly included in all standard cellphone regardless of its sophistication level.
Once the heart beats are recorded inside the android phone, this can be easily used with a suitable app for converting the same into a graphical format and for enabling a more scientific assessment of the patient heart condition.
I have built this project and it works well as a normal amp, but it is not sensitive enough to pick UP any heartbeats. Any suggestions as to how I can make this more sensitive?Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson.
Chosen because of the low cost and decent specs. I had one laying around but they are probably a couple of bucks. 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. 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.
I used a small dot of hot glue and inserted the microphones into the earpieces and then reassembled the earpieces on the Stethoscope. Question 1 year ago on Step 1.
I also just found these mini multi Media Microphones but not sure the dissambly would be as easy as yours? So do you think these will work and mic can be removed like yours? Question 1 year ago. I watched your video several times and I think I found a similar Audio cable Mic and I wanted to show the ebay link and to make sure these will work? Also, on the bottom of the ad they were just a whole bunch other cables listed just like these, its already has a mic and I guess I just need to get earpieces from the Steth to fit them in.
And there is only connector at the end that would connect to the Y-adapter. I think these will work:. 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. Reply 5 years ago on Introduction. 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!! 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.
Reply 9 years ago on Introduction. Reply 8 years ago on Introduction. Reply 10 years ago on Introduction. Buy a spy ear kids toy, open it up, desolder the mic and resolder it with longer wires I added a 1. Gives nice amplification and a handy headpohne input jack to give the option if listening direct or plugging it into a recorder. Introduction: High-Tech Spy Stethoscope! By Kipkay Kipkay Videos Follow.
More by the author:. About: Tinkerer, hackster and prankster. See the Test Results in the Video! Add Teacher Note. After plugging the two 3. Check out the video!All papers were in order. She let us know about the road problems. For us, the Itinerary book was very nice but didn't have to be such high quality. We had a wonderful time in Iceland.
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