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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Comments

tpetar
18 Oct 2012: 20:11 PM
What compiler to use to compile source code?
  
tpetar
18 Oct 2012: 20:17 PM
Is there minimum and maximum values for value on LED ?
  
ajay_bhargav
31 Oct 2012: 22:31 PM
You can make use of AVRstudio to assemble this code.
  
sujuan
01 Nov 2012: 06:13 AM
can i know what type of atmega88 use in this circuit?and for the 7 segment display is common anode or common cathode?
  
tpetar
03 Nov 2012: 00:04 AM
AVRStudio cant compile this!
  
tpetar
03 Nov 2012: 00:38 AM
Say source is : Evil Genius MPP Issue 2010

Can someone help with some link to source?
  

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oneblade
Mon Apr 21 2014, 01:59 PM
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Mon Apr 21 2014, 11:34 AM
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Mon Apr 21 2014, 08:05 AM
kram.ram420
Mon Apr 21 2014, 07:53 AM
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Sun Apr 20 2014, 02:30 AM
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Conversation

Wed Apr 23 2014, 02:57 AM
NAD
hi can someone help me write the code to interface an alphanumeric keypad to pic16f877A??!
Wed Apr 23 2014, 02:56 AM
NAD
hi,
kram.ram420
Mon Apr 21 2014, 09:27 AM
Hi.. Please help me to get through microcontrollers..
Sun Apr 20 2014, 05:23 AM
ARPAN
HELLO. I AM USING 8051 WITH RFID , PASSWORD AND FINGERPRINT.I HAVE SFM 3030 FINGERPRINT MODULE HOW TO INTERFACE IT WITH 8051? DIRECTLY OR EXTRA CIRCUITRY IS REQUIRED?AND HOW TO USE TWO SERIAL DEVICES RFID AND FINGERPRINT WITH ONE 8051?
ExperimenterUK
Thu Apr 17 2014, 01:23 PM
@mba Great .. please do.
Thu Apr 17 2014, 12:27 AM
mba'
like the forum and wish to participate
ExperimenterUK
Wed Apr 16 2014, 04:45 PM
@viniciusheidrun..you should read my comment just before your post
viniciusheidrun
Wed Apr 16 2014, 01:43 PM
I'm doing a drive system with SIM900D modem and microcontroller AT89S52 via sms. I'm having trouble can not generate the. Hex to send to the microcontroller, whenever I compile the error, I'm using MCU 8051 IDE, what should I do so that my system receive sms and perform my task?
ExperimenterUK
Mon Apr 14 2014, 01:00 PM
@Haranadh,bipin chandra etc. Create threads for your questions.
Sun Apr 13 2014, 04:05 AM
Haranadh
we bought HC 06 Bluetooth modem instead of Module ,Can any one help me of using it as bluetooth module since i am doing this project?
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