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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Thu Aug 27 2015, 10:06 PM
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Thu Aug 27 2015, 10:03 AM
Nilesh Thakre
anybody please help me ,i face problem reading a message and identify the string of read message (8051 uc with sim300 gsm modem i have use)
ajay_bhargav
Thu Aug 27 2015, 07:17 AM
@KRIZZA, make the circuit, and load hex file you're done.
Thu Aug 27 2015, 03:39 AM
sk nawal
arm control ckt
Mon Aug 24 2015, 02:11 AM
KRIZZA
@ExperimenterUK BUILD PROJECT LIKE THIS
gkn06
Thu Aug 20 2015, 03:17 AM
hello anybody please
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Kiruba
I am new to ARM Development..I need help
Tue Aug 18 2015, 09:34 AM
mairja naser
pic30f2010 ic usb copy
ExperimenterUK
Mon Aug 17 2015, 10:32 PM
@krizza build what ?

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