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.