Here is circuit of Mini amplifier 1.2 watt will use TBA820M chip, The TBA820M chip features a very low minimum working supply voltage of 3V, low quiescent current, good ripple rejection, no crossover distortion and low power dissipation. Maximum supply voltages is 16 Volts into 16 Ohms speaker, 12Volts into 8 Ohms and 9Volts into 4 Ohms.
The work of the circuit, feed power supply 9Volt reach the circuit LED1 will stick bright tell the event works of the circuit. Which C7 will voltage filter smoothly then feed, power supply , give with IC1. At pin 6 when feed input sound signal reaches pin 3 ways s of IC1. by have C1,R1,R2 perform coupling and decrease signal sound level just rightly. The part of pin 2 of IC1 have R3 and C2 perform fix the expansion ratio and enhance the stability of tall frequency improve. From that time a signal had that to enlarged then change go out pin 5 ways s of IC1 change C4 coupling signals go to still a loudspeaker. By have R4 and C5 perform eradicate the noise goes out.