Heart beat sensor

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I bought one of this:

http://dx.com/p/digital-heart-be...

and i wonder. Howto interface it to an AVR? Tip to gnd, ring to VCC, and mddel as signal?

Who have used it before me, and are able to guide me?

HM

HM

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I am having a problem with the link, but it is probably my XP netbook's problem.

I briefly saw an image of the probe, and what I thought was a low price. Then the image disappeared and I got an error message, and now I can't open it at all.

Anyway, if the price is really low, then just get two of them and gently crack one open to see the circuitry and the cable wiring.

This will also let you see if you need a series resistor for the emitter LED, (you probably do, they are not generally in the sensor), and a resistor to bias the photodiode, (again, the answer is probably yes, it is needed, as it also is not likely in the sensor).

JC

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The picture shows 2 clamps that apparently are clamped to your earlobes. Does it measure the beat rate at each ear and take an average? ;)

The picture doesn't seem to agree with the specifications. With dimensions 0 in by 0 in by 0 in it must be made of a very dense material to weigh 0.63 oz.

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Near the bottom of the page is a link "Hacking the sensor". I took a quick glance and some guidance might be gotten from the discussion there.

I type, therefore my heart beats. :wink:

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WikiP has a good article on "Pulse Oximetry"

Imagecraft compiler user

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steve17 wrote:
The picture shows 2 clamps that apparently are clamped to your earlobes. Does it measure the beat rate at each ear and take an average? ;)

...

There is only one probe. The second is just a clip to attach to clothing.

The probe will consist of an LED on one side that emits through the ear lobe. The other is a photosensor to pickup the light. The blood pulsing through the lobe will cause the amount of light sensed to vary with the pulse. It is only a small change that needs amplifying then processing (comparator) to determine the pulse rate.

It is not obvious whether there is any electronics in the probe - I suspect not. So the amplification and processing has to be done by your circuitry.

Look up "photoplethysmography".

kevin