Optical Heartbeat Detector

http://www.johnhenryshammer.com/TEChREF/opAmps/opamps.html http://www.8051projects.net/_heartbeat_sensor_using_infrared_LED http://www.htw-aalen.de/extern/dti/Ti_proj/puls_3/puls_3.htm (translated) http://www.htw-aalen.de/extern/dti/Ti_proj/puls_1/puls_1.htm (translated) http://www.htw-aalen.de/extern/dti/Ti_proj/puls_2/Start.htm (translated)