This is a 18W audio amplifier circuit based on power IC HA13118. The supply voltage required for this circuit is 8 – 18V DC, at least 1 to 2 Amps. Maximum output power will only be obtained with a power supply of 18V at greater than 2 A, using a 4 ohm speaker. The power supply should be well filtered to reduce mains hum, a regulated supply will reduce noise even further. Extra filtering is unnecessary if operating from a battery supply.
Resistors : R1, R2___________________ 2R2 ohm Capacitors : C1, C2, C4, C5, C6_______ 100uF/16V electrolytic capacitor C3_______________________ 10uF/16V electrolytic capacitor C7, C8, C12______________ 100nF C9_______________________ 2,200uF/25V electrolytic capacitor C10______________________ 1uF/50V electrolytic capacitor C11______________________ 100pF Misc. I.C._____________________ HA13118 Heatsink
C10 is the input coupling capacitor and blocks DC from the input. C11 bypasses any RF which may be present at the input. C1 & C2 provide an AC ground for the inverting inputs of the IC. R1/C7 and R2/C8 provide a high frequency load for stability with difficult speakers. C5 and C6 provide “bootstrap” feedback for the IC. C9 and C12 provide power supply filtering. Don’t forget that heatsink is a must for this circuit.