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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ExperimenterUK
Mon Jan 07 2019, 03:31 AM
@REVOCATUS please post in the AVR forum
Mon Dec 24 2018, 09:25 AM
REVOCATUS MATEMU
sorry I mean referee boards for player substitution
Mon Dec 24 2018, 09:24 AM
REVOCATUS MATEMU
hi am.looking how to build referee by using Atmega 328 and its codes
Sat Dec 15 2018, 01:45 PM
Arslan ayoub
Hii ,, can I get the simulation of numeric keypad lock on proteus
ExperimenterUK
Mon Dec 03 2018, 05:17 PM
Please post questions in the forum. The chat box is for chat
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help!me!
help! I don't understand busy flag!
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ile
hello
Mon Nov 12 2018, 05:58 AM
Pavan_user
i have seen your replica of I2C programming using AT89C51 but i am unable to understand the "ack_bit" variable usage ...looks like it is always 1...can you elaborate how acknowledgment is working....
bgk3678
Tue Nov 06 2018, 02:36 PM
kindly any one give solution for my problem
ExperimenterUK
Mon Nov 05 2018, 09:48 PM
Pins high is the normal state. You need a program to set them low

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Yes that helps a lot.At first sight I can't see th...
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@ExperimenterUK I have updated the post with more ...
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Which 8051 chip are you using ?
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