Transistored 10W Audio Amplifier

Build based operational amplifier NE5532 and a couple of power transistor TIP41A / TIP42A, this audio amplifier circuit has capability to deliver up to 10W audio power output into 8 ohm speaker..

Amplifier Parts list:

P1 22K = Log.Potentiometer P2 = 100K Log.Potentiometer R1 = 820R R2, R4, R8 = 4K7 R3 = 500R Trimpot R5 = 82K R6, R7 = 47K R9 = 10R R10 = 0.22 4W Resistor (wirewound) D1 = 1N4148 IC1 = NE5532

C1,C8 = 470nF C2,C5 = 100uF/25V C3,C4 = 470uF/25V C6 = 47pF C7 = 10nF C9 = 100nF Q1 = BC547B Q2 = BC557B Q3 = TIP42A Q4 = TIP41A

This circuit is related to the 18 Watt Audio Amplifier, and was designed mainly to satisfy the requests of correspondents unable to locate the TLE2141C chip. It works with the widespread NE5532 Dual IC but, certainly, its capability output is going to be comprised around the 9.5 – 11.5W range, because the voltage supply rails can not exceed ±18V.

As amplifiers of this variety are usually applied to drive small loudspeaker cabinets, the bass frequency range is rather sacrificed. As a result a bass-boost manage was inserted within the feedback loop of the amplifier, so as to overcome this issue with out top quality losses. The bass lift curve can reach a maximum of +16.4dB @ 50Hz. In any case, even when the bass manage is rotated totally counterclockwise, the amplifier frequency response shows a gentle raising curve: +0.8dB @ 400Hz, +4.7dB @ 100Hz and +6dB @ 50Hz (referred to 1KHz).

Transistored 10W Audio Amplifier Circuit Notes:

• This circuit can be immediately connected to CD players, tuners and tape recorders.
• Schematic exhibits left channel only, but C3, C4, IC1 along with the power source are frequent to both channels.
• A log type for P2 will make certain a much more linear regulation of bass-boost.
• Numbers in parentheses show IC1 proper channel pin connections.
• The maximum power supply voltage is -18V / +18V.
• Q3 and Q4 should be mounted on heatsink.
• D1 has to be in thermal contact with Q1.
• Quiescent current (better measured with an multimeter in series with Q3 Emitter) will not be crucial.
• Power-on the circuit and adjust R3 to read a electric current drawing of about 20 to 25mA.
• Set the volume manage for the minimum and R3 to its minimum resistance.
• Wait about 15 minutes, watch if the electric current is varying and readjust if necessary.
• A right grounding is extremely necessary to eradicate hum and ground loops. Connect for the identical point the ground sides of J1, P1, C2, C3 &C4. Connect C9 towards the output ground. Then connect separately the input and output grounds to the power supply ground.

Power supply diagram:

Power Supply parts list:
R11 1K5
C10,C11 4700uF/25V
D2 100V 4A Diode bridge
D3 5mm. Red LED
T1 220V Primary, 12 + 12V Secondary 24-30VA Mains transformer
PL1 Male Mains plug
SW1 SPST Mains switch

Transistored 10W Audio Amplifier circuit source: RedCircuits