heart rate monitor

Does anyone else have just one green LED at the back of the heart rate monitor on the Lenfo LEM8? I noticed two holes and was wondering if there should be two green LED's. My reading are all over I'm even getting a reading from my desk.

Jan 15, 2019 18:36:08 GMT 1 ohbugger said:

Does anyone else have just one green LED at the back of the heart rate monitor on the Lenfo LEM8? I noticed two holes and was wondering if there should be two green LED's. My reading are all over I'm even getting a reading from my desk.


Mine also have 2 'holes'. One is the green led, the other is the 'reader'. My lem7 has the same setup. Note that the accuracy is 'ok', considering that the thin air also do have a pulse... But I have compared to other heart rate monitors and my lem8 is +/- 2 bpm. It takes longer to react to changes (in the bpm) though...

Thanks krapulant.

One spot is the green laser diode, the other is the photo transistor. The photo transistor recognizes your heartbeat everytime your heart beats, blood is pumped through your vessels and the green light is absorbed by the " passing by blood" the photoresistor “sees” the difference in light brightness and counts it as a heartbeat…