Pulse sensor issue

I'm working on my diploma project and i have to implement a monitoring system, using an Arduino nano board, a pulse sensor and an IR temperature sensor. I'm also using a HC-05 Bluetooth module and a GPS module. If i supply the pulse sensor and the 2 modules previous mentioned from the 5V pin of the Arduino, the voltage readings from the pulse sensor get very noisy and distorted. If i'm supplying only the pulse sensor, the readings are good. What can be the issue? From what i have researched so far, the 5v pin should provide around 500mA, sufficient enough to power an HC-05 (requires at maximum 25mA) , the GPS module (~50mA), and the pulse and temperature sensors. In the first figure attached, the readings from the sensor, when the finger is not placed are normal. In the second figure, when i connect HC-05 to the same supply (5V) pin of the Arduino, the readings are bad. (the finger is still not placed on the sensor).

Thank you! :smiley:

IF this was my project with the problem you have described, I would first, try to power ALL the sensors from an independent 5 volt supply. Grounds all connected to the Arduino. See if the problem goes away.
Your 5 volt current is being supplied from a regulator chip. Look up the specs for the chip and see if your research is reasonable.

I agree with Paul_KD7HB your symptoms sound like a lack of sufficient power.

Does the power into the Nano support your current needs?

Also check your GPS peak current. See this post GPS current consumption

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