Of all the body responses one could monitor, heart rate is one of the most important because it fluctuates greatly depending on our state of mind and physical condition. Heart rate during physical activity gives us a direct indication of our fitness level, and heart rate changes throughout the night can be clear indicators of when a dream cycle has begun. A heart rate monitor is also a very easy device to use for extended periods because it can
be placed on the body in such a way that is not uncomfortable or in the way of any normal activity.

The heart rate monitor project presented here uses a sensitive light-detecting resistor to detect small changes in the light beaming through your finger as your blood pumps through the tiny arteries in the finger. This device is not the same as the heart rate monitors typically used in hospitals because those use skin probes that detect changes in electrical activity as the heart beats. This heart rate monitor actually “sees” your pulse through the body, so it can be used on a finger, toe, or even your earlobe.

The heart rate monitor is a combination of analog and digital circuitry, as shown below.



The LM324 quad op amp (IC1) forms a sensitive amplifier and a low-pass filter that will “lock” onto tiny variations in voltage that fall within the typical heart rate frequencies. The varying voltage comes from the light-dependent resistor (LDR), which changes a very small amount each time blood pumps through the tiny arteries in between the visible red LED and the LDR surface.




Complete Design



Insert Your Fingure Here







if you feel any doubt or need further details feel free to use Forum.
Source: Evil Genius MPP Issue 2010
[Submitted by coolmirza143]
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Conversation

Sat Apr 25 2015, 06:16 AM
rohan_verma
sir this circuit is tested?can i use it directly on developing PCB
Sat Apr 25 2015, 06:13 AM
rohan_verma
MSCOMM32.ocx cannot be copied in the systems folder even with administration rights.
Fri Apr 24 2015, 01:58 AM
mostfa
please fix the LCD Interfacing Tutorial as all pictures is gone
Fri Apr 24 2015, 01:57 AM
mostfa
LCD Interfacing Tutorial
Qasim359
Tue Apr 21 2015, 07:31 AM
hello every one i have made pic industrial and domestic timer and i can,t understand c code written in Hi-Tech please send me Mikroc code for this project anyone...................
ExperimenterUK
Wed Apr 15 2015, 05:07 PM
@Bibek.. and everyone. Create threads if you need help. The chat box is just for chat
ExperimenterUK
Wed Apr 15 2015, 05:06 PM
@mohd atif ..login..create a post/thread,then I can post a copy of the missing file
Mon Apr 13 2015, 07:03 PM
mohd atif
@experimenteruk I didn't get you
Sun Apr 12 2015, 04:18 AM
Bibek
hello, i have made a digital clock using rtc DS12887 and AT89S52 with date n callender. Now i want to add alarm features to it.....can any body help me with the code in assembly language
Sun Apr 12 2015, 03:22 AM
SANJU123
Hello, I am planning to do simulaton of the ' 4-way traffic controller'. As a first stage of the project, I tried to compile the code given in this website in keil microvision which controls 4-way traffic . I am using AT89C51. But when I am trying to compile the code it shows an error " Device is not supported by Toolchain". Can u please help me...

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Seven
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I doubt anyone has Mikroc code.It is probably more...
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A multimeter won't help :(The most practical way i...
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As I don't have CRO, Can we test the crystal with ...
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i can,t understand C Code written in Hi-Tech pleas...
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k..let me make all this simple for u so u can add...
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Please zip and attach the code in future. You forg...
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It is really hard to say which course and/or insti...
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Thanks rickey...I have reinstalled version.. Pro...