Hi James,
The second board with the 3-pin plug is for connecting an electret without built-in FET to a phantom powered XLR mic input. It has the K596 FET on board next to the mic input pads. Read more about that circuit here:
and any / all of the posts about BM800 mics. This is the Generic China Mic circuit. A lot of these pencil mic boards barely work because the circuit was copied wrong. Let us know how yours turns out. I haven't tested any of the red ones.
I'm guessing about the smaller board, but it looks like it's made to hook an electret capsule with built-in FET to a 5V power supply and A/D converter, for instance to hook a small electret capsule to an analog input on a Raspberry Pi computer. The large chip looks like a "117" linear voltage regulator and the small "ABK" chip looks like a mic preamp. Look for info among the tiny computer fan websites.
Have fun experimenting!
Henry
