I made a circuit that plays music, with Arduino nano, df player, speaker and amplifier. It works just fine with usb. I would like to connect it to an external power source now but I'm not sure which battery to choose or even if my wiring is correct. My last attempt was connecting all grounds. I've tried to use 9V battery, 1xAAA and 2xAA. Arduino's diod is on but df player seems not to be supplied with power. Thank you for any help.