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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ajay_bhargav
Fri Dec 12 2014, 04:38 AM
@Abdul BAsit, Post in forum please. We will help you.
Wed Dec 10 2014, 06:41 PM
Abdul BAsit
I am working on smoke detector using AT89S52 and dont know how its wors..kindly send me circuit diagram and code for its hardware & software implementation
Tue Dec 09 2014, 11:30 AM
Irinel
Please send me the content of that cd-rom (embedded c - michael j pont. Thank you.
Tue Dec 09 2014, 02:45 AM
kmyo
please give me the operation of 12v trickle charger
Sun Dec 07 2014, 07:50 AM
hidawi
we need the circuit diagrom of the remote control of iduction motor by android appliction
PsySc0rpi0n
Tue Dec 02 2014, 10:30 AM
I have no idea... I'm new to micro controllers
Tue Dec 02 2014, 08:35 AM
samarnath dev
how can usb key bord interfasing to dot matrx led moving, by asm51 ?
Tue Dec 02 2014, 08:32 AM
samarnath dev
how can usb key bord interfasing to 8051 by asm code?
Fri Nov 28 2014, 06:31 AM
babar
aoa ,, i need a project for 8051 microcontroler can some one plz give me the pdf form of this project android control robot
Fri Nov 28 2014, 06:30 AM
babar
hi

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ExperimenterUK Avatar
Posted By ExperimenterUK
Wed Dec 17 2014, 11:21 PM
i've tried this code but faced a syntax error on l...
ExperimenterUK Avatar
Posted By ExperimenterUK
Wed Dec 17 2014, 09:53 PM
Thank you sir for help! I did change the code sir ...
sankalp_s Avatar
Posted By sankalp_s
Wed Dec 17 2014, 04:11 PM
ORG 000H ; starting address SJMP LABEL1 ORG 0...
engr1931 Avatar
Posted By engr1931
Wed Dec 17 2014, 08:09 AM
Thank you sir for help! I did change the code sir ...
ajay_bhargav Avatar
Posted By ajay_bhargav
Tue Dec 16 2014, 05:05 AM
Did you check our tutorial?http://www.8051projects...
ajay_bhargav Avatar
Posted By ajay_bhargav
Tue Dec 16 2014, 04:55 AM
ORG 000H ; starting address SJMP LABEL1 ORG 0...
ajay_bhargav Avatar
Posted By ajay_bhargav
Tue Dec 16 2014, 04:44 AM
Well Mode 2 is only 8-bit so its even simpler, max...
software_developer Avatar
Posted By software_developer
Sat Dec 13 2014, 08:05 AM
Hello Sir,I want to access one file from SD card u...
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Posted By sankalp_s
Fri Dec 12 2014, 06:29 PM
Thank u sir for your response. sir can u explain m...
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Posted By PsySc0rpi0n
Fri Dec 12 2014, 04:37 PM
Does that method of reading timers works if I use ...