This circuit requires a voltage of 6-12 Volts. To have a good quality of this series with the voltage necessary suplly good too. The definition of good that is filtered and does not release much ripple voltage and using large-capacity condenser elco issued for the bass is strong enough. See below this circuit : Technical information about power amplifier with IC 5G37 Datasheet IC 5G31A Vcc = 6-12 V Pout = 0,4 W RL = 8 Ohm Ft = 40-17 Khz Icco = 15 mA Package = TABS1-14 Manufactered = China