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how do I make pulse oximeter

Discussion in 'Electronics Homework Help' started by palahasan, May 26, 2015.

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  1. palahasan

    palahasan

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    Oct 28, 2014
    Hi,my homework is pulse oximeter.My teacher says;not use microprocessor.I researched a lot, but I didn't understand.How can I make a simple pulse oximeter not using microprocessor?Help me please.
     
  2. davenn

    davenn Moderator

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    hi there

    so what have you found out about pulse oximeters so far ?
    what googling have you done for information on circuit designs
    there are masses of circuits and info available

    present some links to possibilities here and they can be discussed :)

    Dave
     
    Last edited: May 26, 2015
  3. palahasan

    palahasan

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    Oct 28, 2014
  4. davenn

    davenn Moderator

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    well you could use that but then decide how to use the output signal to drive a meter or other display rather than the arduino

    google circuits for pulse oximeters and then click on images ... there are 100's of ideas to get you started

    Dave
     
  5. palahasan

    palahasan

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    Oct 28, 2014
    I want to circuit design that measuring on display.
     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    well you could use that but then decide how to use the output signal to drive a meter or other display rather than the arduino

    google circuits for pulse oximeters and then click on images ... there are 100's of ideas to get you started

    not Dave
     
  7. hevans1944

    hevans1944 Hop - AC8NS

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    All good advice by @davenn and @(*steve*) . Since this IS homework... DO your homework: search the Internet and get back to us with what you found that DOESN'T require a microprocessor.
     
  8. palahasan

    palahasan

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    Oct 28, 2014
    I found many complex circuit design.Is there a simple circuit that you will recommend?
     
  9. davenn

    davenn Moderator

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    I doubt that you will find a simple circuit. The project is a complex one
    show us links to several that appealed to you
     
  10. hevans1944

    hevans1944 Hop - AC8NS

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    I have to wonder about the motivations of your teacher. A pulse oximeter is not simple to build, and a microprocessor is invaluable in converting the raw light transmission data to blood-oxygen percentage. There are also (patented) algorithms, easily implemented with a microprocessor, that are used in commercial instruments to improve reliability and accuracy of the measurements. Why does your teacher insist you not take advantage of existing technology?

    It's a good thing you aren't studying surgery, because your teacher would probably demand you perform the procedure without a scalpel!
     
    davenn and chopnhack like this.
  11. chopnhack

    chopnhack

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    Apr 28, 2014
    Is the purpose of the assignment to work out the solution in analog devices?
     
  12. hevans1944

    hevans1944 Hop - AC8NS

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    The simple answer, if you want it to actually work and provide accurate blood oxygen percent readings, is... you can't.

    Oh, you could rig a pair of red and infrared LEDs on a spring clamp you place on a finger or an ear lobe, and then alternately pulse the LEDs on and off, reading the light transmission on a silicon photodiode appropriately compensated for temperature and dark current, That's easy enough to do with analog circuits. Then you need to read the ambient light when both LEDs are off to subtract that from the readings you get when either LED is on. And then you need to come up with sample-and-hold circuits that sample in synchronism with the blood pulse to distinguish between veinous and arterial blood. And then you need to ratio those sampled analog signals with an analog divider circuit and pass the ratio output to a non-linear analog function transformation circuit to perform the actual blood oxygen percentage calculations. You can then display the resulting analog signal on whatever meter display you want.

    Simple, huh? I don't think so. But you probably got all that from the "research" you have done so far.
     
  13. palahasan

    palahasan

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    Oct 28, 2014
    Can you share the circuit schematic?
     
  14. hevans1944

    hevans1944 Hop - AC8NS

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    You are kidding me, right? This is homework, so go find your own circuit schematic(s). All I did in the previous post was outline an analog approach. If I were to build an analog pulse oximeter, I would start from scratch and use the latest analog devices available. Well, actually, I wouldn't even attempt to build an analog-only pulse oximeter. It would definitely have a microprocessor. And to top it off, why bother? I already own a commercial pulse oximeter that measures and displays my pulse rate and percentage of blood oxygen and runs on two AAA dry cells. I don't believe in re-inventing wheels that someone else has perfected and made commercially available at reasonable prices... unless it is part of a learning experience. So, go learn some stuff.
     
  15. palahasan

    palahasan

    17
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    Oct 28, 2014
    ''Surely there is ease after hardship.''--Al-Insırah
    Thank you.
     
  16. davenn

    davenn Moderator

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    I have already told you there are dozens of circuits on google ... I even gave you the link to one of them

    thread closed
     
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