Thursday, May 13, 2010

10W Transistored Audio Amplifier circuit

Here's a circuit diagram from 10W audio amplifier. With a pair of transistors TIP41A/TIP42A main components, this amplifier audio system good enough for you because it can produce good bass with the lift curve reaches a maximum of +16.4 dB @ 50Hz.

10W Transistored Audio Amplifier circuit diagram

Component Parts:

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 R22 4W Resistor (wirewound)
D1 1N4148
IC1 NE5532

C1,C8 470nF 63V
C2,C5 100uF 25V
C3,C4 470uF 25V
C6 47pF 63V
C7 10nF 63V
C9 100nF 63V
Q1 BC547B NPN Transistor
Q2 BC557B PNP Transistor
Q3 TIP42A PNP Transistor
Q4 TIP41A NPN Transistor
J1 RCA audio input socket

Power supply parts:
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

  • Can be directly connected to CD players, tuners and tape recorders.
  • Schematic shows left channel only, but C3, C4, IC1 and the power supply are common to both channels.
  • Numbers in parentheses show IC1 right channel pin connections.
  • A log type for P2 ensures a more linear regulation of bass-boost.
  • Don't exceed 18 + 18V supply.
  • Q3 and Q4 must be mounted on heatsink.
  • D1 must be in thermal contact with Q1.
  • Quiescent current (best measured with an Avo-meter in series with Q3 Emitter) is not critical.
  • Set the volume control to the minimum and R3 to its minimum resistance.
  • Power-on the circuit and adjust R3 to read a current drawing of about 20 to 25mA.
  • Wait about 15 minutes, watch if the current is varying and readjust if necessary.
  • A correct grounding is very important to eliminate hum and ground loops. Connect in the same point the ground sides of J1, P1, C2, C3 &C4. Connect C9 at the output ground.
  • Then connect separately the input and output grounds at the power supply ground.


About Audio Amplifier
An audio amplifier is an electronic amplifier that amplifies low-power audio signals (signals composed primarily of frequencies between 20 - 20 000 Hz, the human range of hearing) to a level suitable for driving loudspeakers and is the final stage in a typical audio playback chain.

The preceding stages in such a chain are low power audio amplifiers which perform tasks like pre-amplification, equalization, tone control, mixing/effects, or audio sources like record players, CD players, and cassette players. Most audio amplifiers require these low-level inputs to adhere to line levels.

While the input signal to an audio amplifier may measure only a few hundred microwatts, its output may be tens, hundreds, or thousands of watts. More explanation about power audio amplifier can be found at

This is a video tutorial about how to a very simple audio amplifier based on the LM386 amplifier chip. It can be built for less than $20 (or might be less than $8 in some countries) and used to amplify any low level audio signal including a guitar, bass or mp3 player.

Watch the video:

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