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heart beat sensor, oximeter hack

 
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sliders_alpha
Semi Newbie


Joined: 19 Jan 2009
Posts: 8

PostPosted: Mon Jan 19, 2009 2:05 pm    Post subject: heart beat sensor, oximeter hack Reply with quote

hi,

i need to measure my heart beat rate in order to fulfill a project.
my goal is to know if i'm in REM phase or not while i'm sleeping.

after some research i've found that you can do it simply with an infrared LED and an infrared sensor.
i then found this sensor (works only with a finger, i can't get any reading on my earlobe even with amplification):



after some random wiring i then foud how he was wired.
i succeded in reading my heartbeat.


better pictures : http://sliders.alpha.free.fr/sleeproject/all.jpg
me ("moi" in french) and three friends

BUT

this sensor is HIGHLY influenced by movement (and i'm moving when i'm sleeping) and can be pluck away very easily.
plus, as you can see it my readings are very different on different people (those reading where done today
with the same sensor and the same amplification circuit).

i then found this sensor on EBAY :



NELLCOR DS-100A Finger SPO2 Oximeter Sensor Cable Probe

theres is a lot of connection, finding how it works with random wiring is almost impossible
without damaging 3-4 of them, and they are quite expensive (25$ each).

so, does anyone here know how to use them or could give me a datasheet
my google research didn't return anything worth it yet, and obviously won't because
i don't know a lot of medical/technical english keyword.

thanks

ps : if someting isn't undurstandable, quote it, i'll try correct it
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Reverend Jones
HG Contributor


Joined: 15 Aug 2007
Posts: 39
Location: Jonestown, Guyana

PostPosted: Tue Jan 20, 2009 8:56 am    Post subject: Reply with quote



Pin 1, 4, 6, 8 - no connection
Pin 2 - anode of the IR LED, cathode of the red LED - usually red wire
Pin 3 - cathode of the IR LED, anode of the red LED - usually black wire
Pin 5 - phototransistor anode - usually white wire
Pin 7 - shield, connects to copper shield over the phototransistor
Pin 9 - phototransistor cathode - usually green wire

The oximeter applies first one polarity, then the other, to pins 2 & 3 to alternately measure conductance of IR and red light through the patient's finger.
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sliders_alpha
Semi Newbie


Joined: 19 Jan 2009
Posts: 8

PostPosted: Tue Jan 20, 2009 11:12 am    Post subject: Reply with quote

thanks, how did you find this?
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sliders_alpha
Semi Newbie


Joined: 19 Jan 2009
Posts: 8

PostPosted: Tue Jan 27, 2009 2:47 pm    Post subject: Reply with quote

i just received it today.

here are my first readings :

red led VF : 1.9V @ 20mA
ir led VF : 1.3V @ 20mA

are you sure that it is a phototransistor? because only diode have anode and cathode, phototransistor have emmitter and colector
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Reverend Jones
HG Contributor


Joined: 15 Aug 2007
Posts: 39
Location: Jonestown, Guyana

PostPosted: Wed Jan 28, 2009 9:07 am    Post subject: Reply with quote

The NELLCOR DS-100A data sheet shows it as a 2 leaded npn phototransistor with the leads labeled anode & cathode.
Collector = anode & emitter = cathode.
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Alan
Site Admin


Joined: 29 Jan 2006
Posts: 1399
Location: Winnipeg, MB

PostPosted: Wed Jan 28, 2009 6:12 pm    Post subject: Reply with quote

sliders_alpha wrote:
i just received it today.


I look forward to seeing some details of the project you are building. Smile
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sliders_alpha
Semi Newbie


Joined: 19 Jan 2009
Posts: 8

PostPosted: Mon Feb 09, 2009 12:22 pm    Post subject: Reply with quote

project is now paused because of real life issue (my graduation project is not as easier as i though^^)
and i suspect this sensor to be broken so i need to buy a other one.

but i'll be back =D
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