I've made a bluetooth audio receiver using XS-3868 module (using this diagram) and connected a TP4056 charger module and a lithium-ion battery too. Everything works fine.
When the charger module is powered (using its micro-usb port), there is no noise as long as something is being played. But when the music stops, the speakers become silent, then after exactly 5 seconds a merely loud noise starts. If another song is started the noise stops. Even if I change the volume on my phone, to which the module responds by a small beep sound, the noise stops again for another 5 seconds.
Of course there is no noise if the charger is not powered and the module is on battery.
I can somehow understand the reason for noise when charger is powered (although I don't know how to fix it, and any help would be great), but my main question here is:
If the XS-3868 can stop the noise, how can I tell it to keep doing the good job, and not give in to the noise? I could not find anything about this feature in XS-3868 properties, or how to prolong that 5 seconds.
Edit 1: I just found the same question here and tried adding the capacitor mentioned there. The noise got much louder! Somebody explained it this way: "The OVc3860 audio output is differential. So If You connect it to amplifier You should do this as differential input. In fact on AGND of OVC3860 is avarange 0.6 V." I have no clue what that means.
Edit 2: I tried adding the resistor according to this too. No difference.
Edit 3: I just found a curious bridge between pin 17 and 18 of the OVC3860. I don't know if it is intended or I should try removing it! Here is a photo: