The principal component of the amplifier kit is the LM 386 IC. This IC is specifically designed as a low wattage amplifier for small scale projects. The signal enters through R1, the 10Kohm potentiometer. This also serves as a volume control for the circuit. The signal is introduced to pin 3 of the IC.
The amplifier output is passed directly to speaker through C2. The capacitor is used to isolate the speaker from the dc power that drives the amplifier.
The circuit composed of R2, the 1K ohm resistor, and C1 the 10uF capacitor, establishes the gain of the amplifier. For this circuit, the gain is set at 50.To increase the gain you can either increase the value of the capacitor or decrease the value of the resistor.
The 0.uF capacitor placed across the power source is used to eliminate noise that can be generated by power source.