http://www.8051projects.net/ Learn to make simple microcontroller projects, pic, 8051, avr and arm projects. download 8051 projects, tutorials, libraries, sample codes. join the microcontroller discussion forum and ask doubts regarding electronics. the best source for 8051 over internet. en-gb 2009-01-07T22:41:03-08:00 contact@nospam.com hourly 1 2000-01-01T12:00+00:00 http://www.8051projects.net/forum-t5948.html 2009-01-07T22:41:03-08:00 hi.........i need sensor to detect our heart beat .... anything available please guide me....... http://www.8051projects.net/forum-t5948.html 2009-01-07T22:41:03-08:00 ۞ TPS ۞ use super bright led and LDR http://www.8051projects.net/forum-t5948.html 2009-01-07T22:41:03-08:00 Ajay hi TPS, can you explain how LED and LDR can help to detect heart beat? http://www.8051projects.net/forum-t5948.html 2009-01-07T22:41:03-08:00 abbas1707 Ajay wrote ...hi TPS, can you explain how LED and LDR can help to detect heart beat? http://www.8051projects.net/forum-t5948.html 2009-01-07T22:41:03-08:00 ۞ TPS ۞ http://www.8051projects.net/forum-t5948.html 2009-01-07T22:41:03-08:00 ۞ TPS ۞ curtsy binu http://www.8051projects.net/forum-t5948.html 2009-01-07T22:41:03-08:00 Ajay thank you TPS and... i hope binu has no problem with sharing his circuits http://www.8051projects.net/forum-t5948.html 2009-01-07T22:41:03-08:00 ۞ TPS ۞ YES I hope so http://www.8051projects.net/forum-t5948.html 2009-01-07T22:41:03-08:00 Ajay just one thing now.. how putting this sensor on finger can detect heart beat?what is connection of heart beat with IR sensor? http://www.8051projects.net/forum-t5948.html 2009-01-07T22:41:03-08:00 abbas1707 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 http://www.8051projects.net/forum-t5948.html 2009-01-07T22:41:03-08:00 leejok2003 thanks for the info! i am just finding one of those... http://www.8051projects.net/forum-t5948.html 2009-01-07T22:41:03-08:00 Arun Kumar V you can also get a heart beat sensor from here : http://www.sunrom.com/index.php?main_page=product_info&products_id=556&currency=INRArun