Power Amplifier 35W with LM391

R1-3-5-8-10=1Kohm C1=2.2uF 63V TR1=10K Trimmer
R2-7-11=100Kohm C2=4.7uF 25V D1-2=IN4002
R4-6=4.7Kohm C3-17=47uF 63V IC1=LM391
R9-12=100ohm C4-8-9=1nF 100V MKT Q1=BD139
R13=47Kohm C5=47nF 100V MKT Q2=BD140
R14-15=0.15ohm 5W C6=22pF ceramic Q3=TIP2955
R16=1ohm 2W carbon C7-11-12-13=100nF 100V Q4=TIP3055
R17=10ohm 1W carbon C10=22pF ceramic L1=See text

A power amplifier that is based on the LM391, that is a complete driver of power transistors. It does not need despite few external elements in order to it works. With the TR1 we can regulate the calm current in 45mA. Inductor L1 is constituted by 20 coils of wire, with thickness 0.9mm, round resistor R16. Transistors Q3-4 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.

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