35W Power Audio Amplifier based LM391

Here the 35W power audio amplifier circuit based on LM391. Inductor L1 is constituted by 20 coils of wire, with thickness 0.9mm, round resistor R16. The transistors Q3-4 are the final amplification section, it should be placed on heatsink. If are used the Q3-4 in packing TIPxxxx they can be placed straight above in PCB. If however they are used transistor in packing TO-3, then it will be supposed they are connected with short cables in the corresponding places on PCB.

Schematic Diagram:

35W Power Amplifier based on LM391 circuit diagram

Component part list:

R14-15=0.15ohm 5W
R16=1ohm 2W carbon 5%
R17=10ohm 1W carbon 5%
C1=2.2uF 63V
C2=4.7uF 25V
C3-17=47uF 63V
C4-8-9=1nF 100V MKT
C5=47nF 100V MKT
C6=22pF ceramic
C7-11-12-13=100nF 100V MKT
C10=22pF ceramic
TR1=10K Trimmer
L1=See text

PCB Layout:

35W Power Amplifier based on LM391 pcb layout

Component Placement:

35W Power Amplifier based on LM391 component placement

Take a note that this amplifier requires dual polarity power supply. Build the power supply using center tap transformer with output current 2A minimum and output voltage 30V, use about 6800 uF – 10000 uF electrolityc capacitors (elco). Good luck.

source: http://users.otenet.gr/~athsam/power_amplifier_35w_with_lm391.htm

One thought on “35W Power Audio Amplifier based LM391

  1. sumobawok

    please send to me any subwoofer amp diagram with pcb and component list

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