Hello everyone,
I've been experiencing some issues with my DFPlayerMini, lately.
If Arduino Nano is connected with the USB port of my PC, everything seems working perfectly like it should.
But If I take as power source of my Arduino a 9V battery, the speaker plays weird sounds which aren't the expected result.
Also, I would like to add that if I give power to the DFPlayerMini with another battery, it works.
This is how my circuit looks like on the breadboard:
This is the electrical scheme of the circuit:
And this is a video of what kind of weird sounds I get...
Note that there's a dc motor, but the result is the same.

