Reverse engineered circuit diagram of heart pulse sensor circuit board out of a treadmill. Notice that the output is level shifted for use by CMOS logic running on 4.5V regulated down from the 6V battery. The CMOS logic also controlls the power to the analog circuitry and infrared LED.
Here is a picture of the earclip which clips to your earlobe. Infrared light shines through your earlobe and excites the phototransistor.
I do not gaurantee the accuracy or safety of any information herein.
|   ||HOME||   |