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).