From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: searching for a pulse rate sensor
Date: Sat, 18 Jan 2003 23:40:16 GMT
NNTP-Posting-Date: Sat, 18 Jan 2003 15:40:16 PST
> "Barry Lennox" wrote in message
> > On 17 Jan 2003 18:18:39 -0800, firstname.lastname@example.org (Joe Blo) wrote:
> > >I am designing a project where I need a pulse rate sensor.
> > >I could scavange one from an off the shelf pulse-rate meter, but I
> > >would rather get one with a data sheet that helps me to determine how
> > >I can interface it to a microcontroller to read the pulse rate of a
> > >human.
> > I took a close took at the inside of one a while back, it had a
> > plastic housing that went over your finger, with an IR LED on one side
> > and a photodiode on the other. The theory is that the blood pulsing
> > through your finger modulates the amount of IR reaching the
> > photodiode.
> These sort are notoriously unreliable. The good ones work by a strap over
> the chest which monitors electrical signals in the same way an ECG machine
Then three electrode ECG would be what you want except that it is
notoriously unreliable. You can increase the number of electrodes, of
course, but there will be a limit on what it can handle when the
measurement subject is moving. Muscle noise is pretty pervasive.
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons email@example.com