Why noise happen on my pulse sensor?

Hello, I wondering why my pulse sensor keep show the value when no finger on it, i have read many articles about my issues, but i still confused I'm using Arduino UNO R3, pulse sensor, keypad 4x4, and LCD for output Many articles said that it because of noise There is no problem when my finger on it, it show a correct value

so my question is how and why noise happen? is it because I'm using other component? any idea? thankyou so much

Give us a drawing of your circuit, and we might be able to help. Sketch it out on paper, take a picture of it, then post.

Sorry for late reply
this is my schematic

thankyou so much! :slight_smile:

Please identify your "pulse sensor".


No current limiting on the LEDs - or are they being used as inputs?