Heart Rate Monitor Circuit - I Need Help.

Discussion in 'General Electronics Chat' started by EAEA93, Jun 15, 2014.

  1. EAEA93

    Thread Starter New Member

    Jun 15, 2014
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    Hey, I'm a medical student that currently working on a project, but unfortunately I know little about electronics.
    So can you guys help me with a circuit where the input is the heart rate (from a clip on a finger) and it gets activated when the pulse is diminished (when the pulse is normal it does nothing).
    I'd be really happy if you could help me.
    Thank you.
     
  2. wakibaki

    New Member

    Jun 12, 2012
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    What do you mean, 'diminished'? Do you mean slow or weak?

    If you were going to be my doctor, I'd really prefer you learned to express yourself a bit more precisely.

    w
     
  3. absf

    Senior Member

    Dec 29, 2010
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    Last edited: Jun 15, 2014
  4. paulktreg

    Distinguished Member

    Jun 2, 2008
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    Is this something you have to build from scratch or can you use pre-assembled modules?

    (If he comes back).
     
    Last edited: Jun 15, 2014
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    How do you define a 'normal' pulse?
     
  6. EAEA93

    Thread Starter New Member

    Jun 15, 2014
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    Hey,
    let me rephrase it, if the device detect any pulse this is considered normal no matter whats the rate, it only gets activated when there is no pulse at all.
     
  7. EAEA93

    Thread Starter New Member

    Jun 15, 2014
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    Actually you are right :p

    Thank you so much for the links, I appreciate it.
     
  8. EAEA93

    Thread Starter New Member

    Jun 15, 2014
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    It's okay if I use pre-assembled modules. Any ideas?
     
  9. EAEA93

    Thread Starter New Member

    Jun 15, 2014
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    Any pulse that is detected would be considered normal (despite the rate), abnormal pulse = no pulse at all.
     
  10. ScottWang

    Moderator

    Aug 23, 2012
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    >http://www.ebay.com/itm/Professiona...758?pt=LH_DefaultDomain_0&hash=item35d49ad5ce
    I think this product is only using human eyes to see, not for the Patient who was lay down on the bed.
    This is a very weird label -- Does not ship to Taiwan, then why it label the NT$?

    pulse monitor -- This is more useful and can be expending the function by the user.
     
    absf likes this.
  11. BR-549

    Well-Known Member

    Sep 22, 2013
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    How long to you have to wait after the last pulse......to determine no pulse? What is the finger clip output? Voltage or current? Does the finger clip need to be powered? What do you want to activate? Does it take voltage or current? Is it require power? Details man....we need details.
     
  12. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Finger clips are terrible and will miss pulses from time to time.

    They also hurt, so people will not want to leave them on for very long.

    So that is two reasons the core design needs to be addressed.
     
    absf likes this.
  13. wayneh

    Expert

    Sep 9, 2010
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    But they are widely used. My mother wore one for a week in the hospital recently.
     
  14. EAEA93

    Thread Starter New Member

    Jun 15, 2014
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    First of all thank you for your reply..
    10 seconds is enough to confirm no pulse, initially it's just going to activate in LED, and it will require power. About the voltage and current I'm not really sure man :(, you got to help me with that since I don't know the difference.
     
  15. EAEA93

    Thread Starter New Member

    Jun 15, 2014
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    Well you are both right, they are widely used and at the same time a lot of people are complaining about it..
    I will use the finger clip only for the prototype, but my idea is something that is wrapped around the arm to measure the brachial pulse.
     
  16. BR-549

    Well-Known Member

    Sep 22, 2013
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    Ok, I'm going to assume(it gets me in trouble) the finger clip outputs a small voltage on pulse. You will have to amplify(and buffer) and possibly invert the pulse depending on the sensor. Connect the output of the amp to the reset pin on a 555 timer. Configure timer for 10 sec. Connect the led with resistor to the output or latch of the timer. This should get you started. However, if you really don't know the difference between voltage and current, I would suggest you stick to medicine. It will take all of your time. Best of luck.
     
  17. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    absf likes this.
  18. turbine2

    New Member

    May 20, 2014
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    If it's anything like the oxygen saturation sensors used in hospitals what happens is that one side lights an LED, the other is a sensor that measures the amount of light (at a couple of wavelengths) that gets through. It needs a pulse to work but the variance between pulses is very small (2% variance in output). The sensors from what I can see are expensive (despite their being marked as disposable) but I'm not sure if that's down to the sensitivities involved or predatory pricing.
    The pulse is measured by the absorption of light of oxygenated vs deoxygenated blood. This URL gives a pretty good explanation http://www.howequipmentworks.com/physics/respi_measurements/oxygen/oximeter/pulse_oximeter.html
    Hope that helps,
    David
     
  19. wayneh

    Expert

    Sep 9, 2010
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    It's like the $12 band-aid you get in the ER. You can make your own fairly inexpensively. The ones you see in the hospital create a lot of continuous (to the eye) red light. I have to believe this is partly by design, to show it is connected and functioning.
     
  20. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Wow. That's unusual, they normally stick some wires on you and ECG monitor for long periods (more than a few minutes of monitoring).
     
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