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
Wed May 25 2016, 05:05 AM
@ Ramanjaneyulu, post in forum,explain your problem
Mon May 23 2016, 11:34 PM
Ramanjaneyulu
Hi, I Am using at89c4051 for my application, I want 5u sec dely.. Up to 1milli sec iam able to producing delay. Beyond the 1milli second, I am unable to produce the acceurate dely. Plz any one help me
Sat May 21 2016, 09:51 PM
A K
i want to mak an auto dialer using gsm and atmega 16. please helpe me how to write a code to auto dial a number saved in sim
Sat May 21 2016, 10:42 AM
Alec
Hi im trying to program my 89s51 with a usbasp so any ideas on the circuit?
Wed May 18 2016, 10:08 AM
Tashu joshi
anyone know how to develop
Wed May 18 2016, 10:07 AM
Tashu joshi
i'm working for resporatry system using 8051,
Wed May 18 2016, 10:06 AM
Tashu joshi
i'm developing a respiratory system using Arduino
Fri May 13 2016, 11:03 AM
MEGHANA
i need c code for counting frequency of two sensors and compare these frequencies and it has to give high/ low signal after comparision
ExperimenterUK
Tue May 10 2016, 05:02 PM
@Suren ..create a thread in the 8051 Discussion Forum to discuss your problem
Tue May 10 2016, 04:04 PM
Suren Avushyan
how can I increment address not the content of it, like 0x70 and get 0x71

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zaft93
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CELEBI
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ExperimenterUK Avatar
Posted By ExperimenterUK
Sun May 15 2016, 10:58 PM
zaft93 Avatar
Posted By zaft93
Sun May 15 2016, 01:55 AM
ExperimenterUK Avatar
Posted By ExperimenterUK
Fri May 13 2016, 07:59 PM
If you want only one relay to be on at a time the ...
CELEBI Avatar
Posted By CELEBI
Fri May 13 2016, 06:16 AM
Yes. It must be as you said. It must be 1.5 second...
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Posted By ExperimenterUK
Thu May 12 2016, 08:35 PM
Here is one way.If you have the Keil compiler you ...
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Posted By ExperimenterUK
Thu May 12 2016, 05:20 PM
Sorry I don't understand what you want.Is that 1.5...
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Posted By CELEBI
Thu May 12 2016, 08:53 AM
Hello Guys, I want to make a Project with 89s51 bu...
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Posted By ExperimenterUK
Wed May 11 2016, 09:28 PM
No this is all I've got, the algorithm I think is ...
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Posted By Suro1996
Wed May 11 2016, 09:27 PM
Is this all the code you have ?As it is, it will n...
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Posted By Suro1996
Wed May 11 2016, 07:31 PM
Hello, I am new to assembly programming and I am h...