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30W Audio Power Amplifier

30W Audio Power Amplifier circuit diagram

Here the 30W audio amplifier circuit for you who need a low power amplifier, but has good audio output quality and made from distinct components. The circuit design does not have any innovation. In the power stage is a Darlington pair of transistors packed TOP3, which can be screwed onto a heatsink, adding between them and the heatsink suitable leaves mica and ointment silicone for better dissipation of temperature.

The bias current regulation becomes with TR1, as follows. Place the ends of the resistors R20 and R21 terminals a multimeter 200mV scale and TR1 regulate late to get an indication 12mV. This voltage drop corresponds to a quiescent current 30mA. Allow the amplifier in this setting for 15 minutes without input signal and check again. If necessary correct the setting at 30mA.

Parts List:
R1 = 1Kohm
R2 = 47Kohm
R3 = 1.5Kohm
R4,R5 = 10Kohm
R6 = 5.6Kohm
R7 = 10ohm
R8 = 47Kohm
R9 = 560ohm
R10,R11 = 8.2Kohm
R12,R15 = 120ohm
R13 = 680ohm
R14 = 330ohm
R16,R17 = 270ohm
R18 = 22ohm 1W
R19 = NC
R20,R21 = 0.39ohm 4W
TR1 = 250ohm trimmer
C1 = 470nF
C2 = 1nF
C3 = 68pF
C4,C8 = 22nF
C5,C6,C7 = 100nF
C9 = 47uF/25V
C10,C11 = 220uF/63V
D1 = 9.1V 0.4W zener
D2,D3 = 1N4148
Q1,Q2 = BC550C
Q3 = MPSA56

30W Audio Power Amplifier Top PCB Layout:

30W Audio Power Amplifier Top PCB Layout

30W Audio Power Amplifier Bottom PCB Layout:

30W Audio Power Amplifier Bottom PCB Layout