i'm new to the forum. I have some problem to Connect this device with one single battery. I think the problem is on the connection of the max4466 electret. It has a common ground and it make me impossible the connection with the pam 8403 that have separate ground. Audio- and battery -. How can i Connect it properly? Maybe a diode? i attached an image. when i use these chips with two different batteries it works very well. Please help me
Do NOT use a diode. Just connect the grounds together.
In a larger system with shielded wires and ground connections that really include a ground (earth ground, that is) connection things are more complicated.
In your simple circuit all of the ground connections will be at the same potential, so just tie them together.
If you measure between the ground connections on the amplifier board, you will find that they are all connected together. The - connections on the output side are a different thing. The amplifier is a bridge amplifier, so the - side isn't ground.
Thanks to ricardomenzer for pointing out the bridge output of the amplifier.
That show once again that it is better for the question to include links to the datasheets.