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Amplified stethoscope?
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Amplified stethoscope?

by roxanne91 on Wed Sep 19, 2012 2:35 pm

Hello, I am a student studying interdisciplinary sculpture. I am working on a project right now where I want the head of a stethoscope to connect to a speaker. I will need two of these, so at least two people can hear their hearts beating together at the same time. My idea is to have a rectangular column made of wood where I will embed the electronics/speakers. The stethoscopes and attached cords will come out of the column, enabling people to pick them up and use them.

Is this possible?
What kind of microphone can pick up the sounds from a stethoscope?

I have already searched the web for solutions and talked to teachers. So far I have not found a fool-proof solution. I have looked at acoustic and electronic/amplified stethoscopes. It seems that the best route will be to take the head of an acoustic stethoscope and embed a microphone into the tubing somehow which will then somehow connect to a speaker/microphone. Any help is greatly appreciated!
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Re: Amplified stethoscope?

by adafruit_support_bill on Wed Sep 19, 2012 4:48 pm

An electret microphone cartridge would be a good sound pickup. Some are pretty small. You might be able to find one small enough to stick in the end of the stethescope tube. Sparkfun makes one with an atached pre-amp: https://www.sparkfun.com/products/9964?

To power the speakers, we have a nice compact amplifier module: http://www.adafruit.com/products/987

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Re: Amplified stethoscope?

by roxanne91 on Thu Sep 27, 2012 11:14 am

How would I attach the preamp to the amplifier? Are you sure this would be strong enough?

I have tried using one of these microphones (i took it out of the plastic and into the earbud of the stethoscope) :http://www.colourbox.com/preview/2513691-887921-microphone-for-connection-to-the-computer-isolated-on-white-with-clipping-path.jpg From there i plugged it into my mac and attached speakers to my laptop. I then tried adjusting the input/output on my mac to amplify the sound (idk if this actually does anything) When i turned the input and output all the way the speakers made loud sounds (I think this is called feedback). Either way I could not hear my heartbeat through the speaker.

Are these devices you suggest different and strong enough to pick up my heartbeat you think?

Thanks!
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Re: Amplified stethoscope?

by roxanne91 on Thu Sep 27, 2012 11:18 am

Also, I am now considering using an alternative route with use from the arduino Pulse sensor since I have not been able to find a good solution to this.
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Re: Amplified stethoscope?

by adafruit_support_bill on Thu Sep 27, 2012 11:28 am

That microphone most likely is based on an electret microphone module. Possibly with a built-in pre-amp. I would expect that it should be able to pick up the sound from the stethescope. But feedback is always a problem when you have the microphone in a position to pick up its own amplified signal.

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Re: Amplified stethoscope?

by 123Splat on Thu Sep 27, 2012 3:56 pm

Use the electret as your steth-head (sound pickup) and feed the mic cartridge output to an audio IC op-amp. You can output the op-amp directly to earphones or speakers.
You could also couple the op-amp out, through a capacitor, to the Arduino and try to coune pulses, but that's about all you can do with the arduino in this app.
you can mix several opamp outputs together with FETs, or just resistive network, for multiple listeners.
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