This project uses bright infrared (IR)
LED and a phototransistor to detect the pulse of the finger, a red LED
flashes with each pulse.
Pulse monitor works as follows: The LED
is the light side of the finger, and phototransistor on the other side
of the finger, phototransistor used to obtain the flux emitted, when the
blood pressure pulse by the finger when the resistance of the
phototransistor will be slight changed.
With a very high resistance resistor R1,
because most of the light through the finger is absorbed,it is desirable
phototransistor sensitive enough.Resistance can be selected by
experiment to get the best results.
The most important is to keep the shield
stray light into the phototransistor. For home lighting that is
particularly important because the lights at home mostly based 50HZ or
60HZ fluctuate, so faint heartbeat will add considerable noise.
Package includes:
1 x Finger Detection Heart beat Sensor