Author Options:

Powered Stethoscope - NOT the KipKay one... Answered

Hello from Arizona!

I'm switching my career from Computers to Medical and will be taking an EMT course. One of the things you MUST be able to do is take blood pressure.  To do so, however, you need to be able to hear the pulse through a stethoscope.  Unfortunately, I have a slight hearing deficit.

I've seen the KipKay video and would like something like this, but it needs to fit (sorta) into a regular stethoscope format.  I can't have external boxes & wires hanging off of it.

Would someone be so kind as to help me lay something out with suggestions on parts, etc.?
Commercial versions of this start at $250, so if I can get away w/it for <$50> or so it'd be great!

Thanks for any help.

Lake Havasu City, AZ


Now if I can take apart something & figure out the amp/preamp stuff, this may very well work.

If it doesn't take more power than the bell & howell, I might be able to take them both apart and splice them. Franken-scope! :)

One side comment -- providing you with a commercial amplified stethoscope, at $250, is most certainly a reasonable accommodation. If you meet all of the qualifications to perform the primary functions of the job, your employer can/should/must provide you with reasonable accommodations to perform your job. Nor can a potential employer refuse to hire you because they would then have to provide such an accommodation.

If you want to make one of your own, you can slightly simplify the design above. You only need one microphone -- a stethoscope isn't stereo, it's just an air tube with a fork. Put a single microphone where the pickup is located, and wire it to the earpieces. For power, I'd consider a couple of small button cells in shrink wrap.

You can probably do what you need by taking a combination wired mic-earphone set for a cell phone, and shorting the mic wire to the earpiece wire(s).

Thank you for the side-note. Yes, *IF* I am able to get hired, they would have to accommodate my disability. Unfortunately, this course is at a local community college and a required piece of equipment (along with paper, pens, books, etc.) is a stethoscope. Perhaps trade-schools are different (with your hardware being included in the tuition), but nothing around here allows for this. :(

I've included another pic, and hopefully I'm getting closer to what you have in mind. I can Dx a PC down to the removable parts & make it dance & sing from DOS 4.0 up to Win7, but my experience in the actual ELECTRONICS of a unit is limited.

Battery placement / voltage, positive / negative, where / how to short the wires from the cell phone Mic. and volume are still nagging at me, but I think it's becoming less Hazy.


powered stethoscope 2.jpg

Here is the basic problem: you may need a pre-amp as well as an amp.

IF the signal is loud enough to eliminate need for the pre-amp, you can put together a small one (about the size of a 2 inch square proto board) but that might be a little cumbersome. 

Another idea would be to find a working amp from one of the "cheaper" type hearing aids (not sold by medical personnel ) at a garage sale or flea market and wire it in.

As to the wiring question:  the "speaker(s)" would be wired to the amp, the positive side of the output to the positive side of the speakers in parallel, since you aren't looking for a stereo effect :-)
The ground side is grounded to common ground (as the amp and the batter will have). 

A mic to speaker will not work directly wired, without the amp or pre-amp and amp.

you could even take one of these apart and use it. just isolate the microphone and move it out to a more advantageous location. it's already got the pre-amp and amp and what not built in, plus it has volume control so you can adjust for those faint pulses that old people have.

you wouldn't "really" need to worry about it being too much more bulky than any other of the options. just wear it on your belt and have a protected set of wires going to the mic/mic holder (probably a normal stethescope bell with a hole in it to hold the mic) from the original case and then you would just wear normal headphones/earbuds to listen to it.

That's an idea, you might even be able to put ear buds in place of the two pieces that go into your ear on the scope itself.

But is it a disability? You state slight impairment, whereas the reasonable accommodation only applies to "substantial impairment".

Not being a d*ck, just had to deal with all this myself recently.

The project should be pretty interesting for you, as a basic start to electronics. If you dismantle an existing mic/headphone unit, then you shouldn't need circuitry in addition (now having said that, watch it turn out to be wrong :-/). Your diagram above is just what I had in mind. You should be able to run the system on two 1.5V button cells (like a couple of hearing aid batteries). The "negative terminal" on the battery is ground in this system. When you open up the headphone/mic unit, pay attention to which wires go to the center pin of the jack -- that will be the + side.

You write, "Unfortunately, this course is at a local community college and a required piece of equipment (along with paper, pens, books, etc.) is a stethoscope." And the college is required to provide you with an accommodation for you to use that required equipment.

Title II of the ADA (along with Title III) and Section 504 of the Rehab Act cover post-secondary schools. Title II covers community colleges and other state-funded schools (Title III covers private schools), while Section 504 covers schools which receive federal funding.

You should contact the school's Office for Students with Disabilities (if they have one) or their ADA/504 Compliance Office (they must have one) to find out what you need to do to ensure that they make a reasonable accomodation, and find out what forms you need to complete. You can do this prior to enrolling in the class.

I just wanted to say it's great to have someone here who's legitimately knowledgeable on this subject (at least, in the US).

"Knowledgeable," maybe. I've picked up details over the years, and I know how to do research. In this case, I was actually a bit restrictive in talking about employment. The same rules apply to schools and technical training courses, and predate the ADA.

Very short notice (less than three hours as I type), but I just spotted this item on ebay.  Not in full working order, but probably repairable by a semi-competent solderer.

"Bosch Electronic Stethoscope 1976 V EST40 Leather Case"