Discussion in "General help Guidance and Discussion" started by    xmen    Feb 17, 2008.
Sun Feb 17 2008, 02:49 am
#1
hi.........i need sensor to detect our heart beat .... anything available please guide me.......


[ Edited Wed Feb 27 2008, 11:51 am ]
Tue Feb 26 2008, 01:44 am
#2
use super bright led and LDR
Tue Feb 26 2008, 02:31 pm
#3
hi TPS, can you explain how LED and LDR can help to detect heart beat?
Sun Mar 02 2008, 11:40 pm
#4


hi TPS, can you explain how LED and LDR can help to detect heart beat?

Ajay


Tue Mar 04 2008, 01:16 am
#6
curtsy binu


[ Edited Tue Mar 04 2008, 01:17 am ]
Tue Mar 04 2008, 11:16 pm
#7
thank you TPS
and... i hope binu has no problem with sharing his circuits
Wed Mar 05 2008, 12:49 am
#8
YES I hope so
Wed Mar 05 2008, 01:21 am
#9
just one thing now.. how putting this sensor on finger can detect heart beat?
what is connection of heart beat with IR sensor? :-s
Wed Mar 05 2008, 02:49 am
#10


Heart beat is sensed by using a high intensity type LED and LDR. The finger is placed between the LED and LDR. As Sensor a photo diode or a photo transistor can be used. The skin may be illuminated with visible (red) using transmitted or reflected light for detection. The very small changes in reflectivity or in transmittance caused by the varying blood content of human tissue are almost invisible. Various noise sources may produce disturbance signals with amplitudes equal or even higher than the amplitude of the pulse signal. Valid pulse measurement therefore requires extensive preprocessing of the raw signal.
The new signal processing approach presented here combines analog and digital signal processing in a way that both parts can be kept simple but in combination are very effective in suppressing disturbance signals. The setup described here uses a red LED for transmitted light illumination and a LDR as detector. With only slight changes in the preamplifier circuit the same hardware and software could be used with other illumination and detection concepts. The detectors photo current (AC Part) is converted to voltage and amplified by an operational amplifier (LM358). Output is given to another non-inverting input of the same LM358; here the second amplification is done. The value is preset in the inverting input, the amplified value is compared with preset value if any abnormal condition occurs it will generate an interrupt to the controller AT89C2051.

binu

Tags working heartbeat sensorIR based heart beat sensorheartbeat sensor using infrared LED

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