KY-039 Finger Detection Heartbeat Measuring Sensor Module

This KY-039 Finger Detection Heartbeat Measuring Sensor Module uses bright infrared (IR) LED and a phototransistor to detect the pulse of the finger, a red LED flashes with each pulse. We chose a very high resistance resistor R1 because most of the light through the finger is absorbed, it is desirable that the phototransistor is 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.