June's Everyday Practical Electronics mag has such a project.
Based on a 16F876 it might be worth checking out.


-----Original Message-----
From: Roman Black [mailto:fastvid@EZY.NET.AU]
Sent: 27 May 2002 09:43
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC] Heart Rate/Pulse Monitor


Shawn Mulligan wrote:
>
> Thanks for the response Ben. I like the idea of the piezo/acoustical
> solution as well. A simple bandpass filter and a little hysteresis =
should do
> it. Furthermore, the bandpass filter would be fairly transportable =
between
> designs.
> Shawn
>
> >Of the top of my head, a reasonable third way would be to strap a =
simple
> >microphone onto the chest over the heart. I wonder if a flat piezo =
disc
> >would surfice.... I'd filter the output using a bandpass filter to =
remove
> >extraneous noise (ie speech) and voila. Not sure if it's been done =
that way
> >before but for simply testing the pulse rate a full ECG/pulse-ox =
solution
> >appears overkill.


Shawn, i'm not sure what you need this for, but have
you considered a commercial (sporting) monitor? I have
a Polar brand A5 which is very good, the (electrical)
chest strap transmits RF to the wristwatch, seems
reliable for triggering too. You can also just buy the
chest straps by themselves too, if you wanted to detect
the signal yourself and feed it into a PIC etc. Any
sports store should have them in stock, but the strap
itself will be a special order.

I built a kit years ago that used IR clamp on a finger,
and used many clamp types in gyms over the years, they
just don't work that good.
-Roman

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