MagicHat - 5 - Blood pressure sensor

2 Apr 2015

I made some modifications to the original circuit I talked about in my previous post and made it on a bread board. Here is the resulting circuit

I placed my finger on the sensor, and I got a quite clean signal

The signal is 200 mV peak-to-peak. Since the ADC has a 10 bits resolution over a 5V range, the signal will be read as 80 ADC steps, which should be enough to make heart beat detection easy

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amgalbu over 10 years ago in reply to Workshopshed +1

Hi Clark Thanks for your comments!! Actually mi idea was to use the Arduino Yun to detect heart-beat (both IBI and BPM). I think there is enough power in the Atmel328 for that task! My only doubt is wthether…
Workshopshed over 10 years ago in reply to amgalbu +1

www.youtube.com/watch
amgalbu over 10 years ago in reply to amgalbu +1

Sorry, Arduino Yun has a Atmel324

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Workshopshed over 10 years ago

I was watching the EEV blog the other day and Dave was looking a.t an old speach recognition circuit. That used a comparator to turn audio into a square wave and the frequency was read directly via a digital pin on the microcontroller. Obviously if you are using the SAM to analyse the signal you might do that in software.
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amgalbu over 10 years ago in reply to Workshopshed

Hi Clark
Thanks for your comments!!
Actually mi idea was to use the Arduino Yun to detect heart-beat (both IBI and BPM). I think there is enough power in the Atmel328 for that task!
My only doubt is wthether to increase gain or not... during my tests I saw that noise increases too, so I think what you see on the scope I the best tradeoff I can currently get. Probably a two-stages amplifier would perform much better

Cheers
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clem57 over 10 years ago in reply to Workshopshed

http://www.bizapedia.com/ca/VOICE-CONTROL-PRODUCTS-INC.html a listing for the company he mentioned for the chip. It basically went defunct!
Clem
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amgalbu over 10 years ago in reply to amgalbu

Sorry, Arduino Yun has a Atmel324
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Workshopshed over 10 years ago in reply to amgalbu

Yes, a bit more RAM than the Uno and it behaves more like the Leonardo in that it does not have a separate USB chip so you need to watch resets.
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Workshopshed over 10 years ago in reply to clem57

And of course Radio Shack not about either
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clem57 over 10 years ago in reply to Workshopshed

Workshopshed
Actually not quite true. I found a guy from Radio Shack this weekend at an iMake and they are still around. It is hard to tell what they will be without the many store fronts. The online still there too.
Clem
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clem57 over 10 years ago in reply to Workshopshed

Workshopshed
Actually not quite true. I found a guy from Radio Shack this weekend at an iMake and they are still around. It is hard to tell what they will be without the many store fronts. The online still there too.
Clem
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