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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Dibakar Bhanja Chowdhury
By using a 555 timer how can I expand the range of the mobile phone jammer? Please reply me asap
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how to write and execute a program that read the keypad button and display the number on 7 segment on intel8051 at89s52 in assembly language?
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sir iwant to ask about controller of three phase supply by using back to back thyristor instead of triac....will u give me some guideline?
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IR Remote Switch using TV remote (RC5 Protocol) is not working properly. opp1 & opp2 is in problem.plz help
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Hello everyone, using software uart is a very good idea for a second serial port. Thank you so much. I would kindly like to know how to connect this port to the PC?
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This is a community site. Feel free to help anyone needing advice
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ExperimenterUK Avatar
Posted By ExperimenterUK
Tue Jul 17 2018, 08:31 PM
Thank you.I'm happy it worked out for you.
LAMBO Avatar
Posted By LAMBO
Tue Jul 17 2018, 09:52 AM
hi sir sorry for the late reply thank u sir for he...
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Posted By ExperimenterUK
Thu Jul 12 2018, 08:27 PM
I'm glad we got there in the end :)>whats differen...
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Posted By LAMBO
Thu Jul 12 2018, 06:51 AM
hi sir as u mentioned above to change crystal and ...
ExperimenterUK Avatar
Posted By ExperimenterUK
Tue Jul 10 2018, 07:20 PM
I assume you meant a AT89S52.It seems to me that...
LAMBO Avatar
Posted By LAMBO
Tue Jul 10 2018, 06:06 AM
hi sir i have checked now much of the distortion ...
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Posted By ExperimenterUK
Mon Jul 09 2018, 06:55 PM
Okay that is very interesting.I have attached two ...
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Posted By LAMBO
Mon Jul 09 2018, 08:14 AM
hi sir as u mentioned above program i have tried ...
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Posted By ExperimenterUK
Fri Jul 06 2018, 11:58 PM
Okay..That motor creates a lot of sparks which mig...
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Posted By LAMBO
Fri Jul 06 2018, 01:33 PM
hi sir as u told >Try the original code againi hav...