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120W Power Amplifier + Power Supply


120W Power Amplifier + Power Supply
This is 120W power amplifier schematic using TO-3 package complementary transistors, NPN and PNP polarity. The well-known power transistor pair of 2N3055 and MJ2955 used in this circuit.  +/- 50V symmetrical (split/dual polarity) power supply with minimum 3A electric current should be used for maximum performance.








120W Power Amplifier Part List

Transistors

    2N3055 (substitution: MJ15003 or 2N3772) : 2
    MJ2955 (substitution: MJ15004 or 2N3771) : 2
    TIP42 : 2
    TIP41 : 1
    2SC2229 or 2SC2230 or C1573 : 2
    A1015 or A872 or A733 : 2

Capacitors

    100uF/50V electrolytic capacitor: 2
    470nF (474) nonpolar polyester capacitor: 1
    100pF (101) nonpolar ceramic capacitor : 2
    470pF (471) nonpolar ceramic capacitor : 2
    10pF nonpolar ceramic capacitor : 2
    100nF (104) 100V nonpolar polyester capacitor : 2

Resistors

    0.33 Ω (5W) : 4
    10 Ω to (1W) – brown, black, black : 1
    100 Ω (1W) – brown, black, brown : 2
    33 Ω (1/4W) – orange, orange, black : 1
    150 Ω (1/4W) – brown, green, brown : 3
    10KΩ (1/4W) – brown, black, orange : 1
    1KΩ (1/4W) – brown, black, red : 1
    4.7KΩ (1W) – yellow, violet, red : 1
    68KΩ (1/4W) – blue, gray, orange : 1
    56KΩ (1/4W) – green, blue, orange : 1
    33KΩ (1/4W) – orange, orange, orange : 1
    3.3KΩ (1/4W) – orange, orange, red : 2

Diodes

    3A Diode 1N5404 : 2
    1A Diode 1N4007 : 3
    Zener diodes between 20 and 24 volts : 1

Others

    3A fuse
    small 3-pin (GP) connector
    large 6-pin connector (Molex)
    aluminum heatsink
    potentiometer of 20K if you want to add volume control