Electronics people here,,, good day to you
would you mind helping me what is this kind of pin configuration and how to solve the GAIN with this mini amplifier....
heres the circuit

i know that the gain is 20 and if the boost is turned on, it will have 200 gain...
but, how to solved is my problem...
can you help me guys...


thanks a lot....

 

Read here:
http://www.national.com/ds/LM/LM386.pdf
Page 3.
Then look at the top schematics on page 5.

 

The circuit you posted is missing very important parts that stop it from oscillating. The datasheet shows a 0.05uF capacitor (or 47nF) in series with a 10 ohms resistor from the output pin to ground on EVERY schematic.
Also a very important supply bypass capacitor is missing.

The datasheet shows the internal schematic of the amplifier IC and you can see how the internal negative feedback resistors establish the gain to be 20 or 200.