2 Watt Mini Audio Amplifier based Transistors

mini audio amplifier circuit

This mini audio amplifier circuit is designed for low power audio amplifier with small dimensions such as CD player, iPod, Walkman, computers and others. The circuit shown here is a single channel, if you want to build it a stereo you just make two exactly the same circuit.

You can see this mini audio amplifier circuit is so simple and easy to build. This circuit is one of a series that fully using transistor, instead of using the IC. One of the advantages that using the transistor, harmonic distortion is relatively lower than the amplifier circuit with IC. Besides audio transistor components more easily obtained.

This amplifier can work well on a 12VDC power supply. Switch SW 1 serves as a bass-boost. But if you want to activate SW1, the volume control should also be increased to reduce power losses at high frequencies.

Some things you should consider in assembling this amplifier circuit is; R9 must be adjusted carefully so that the audio signal on the speaker inaudible distortion. At the time of standby, the current in the collector of Q3 should be at 10-15 mA. This can be done by making measurements using a multimeter.

2 Watt Mini Audio Amplifier based Transistors Components list:

P1 = 10KLog.Potentiometer
R1,R2 = 33K1/4W Resistors
R3 = 33R1/4W Resistor
R4 = 15K1/4W Resistor
R5,R6 = 1K1/4W Resistors
R7 = 680R1/4W Resistor
R8 = 120R1/2W Resistor
R9 = 100R1/2W Trimmer Cermet
C1,C2 = 10?F63V Electrolytic Capacitors
C3 = 100?F25V Electrolytic Capacitor
C4,C7 = 470?F25V Electrolytic Capacitors
C5 = 47pF63V Ceramic Capacitor
C6 = 220nF63V Polyester Capacitor
C8 = 1000?F25V Electrolytic Capacitor
D1 = 1N414875V 150mA Diode
Q1 = BC560C45V 100mA PNP Low noise High gain Transistor
Q2 = BC33745V 800mA NPN Transistor
Q3 =TIP31A60V 4A NPN Transistor
Q4 = TIP32A60V 4A PNP Transistor
SW1SPST switch
SPKR3-5 Watt Loudspeaker, 8, 4 or 2 Ohm impedance

2 Watt Mini Audio Amplifier based Transistors Specs:

  • Output power: 1.5 Watt RMS @ 8 Ohm, 2.5 Watt @ 4 Ohm, 3.5 Watt @ 2 Ohm (1KHz sinewave)
  • Sensitivity: 100mV input for 1.5W output @ 8 Ohm
  • Frequency response: 30Hz to 20KHz -1dB
  • Total harmonic distortion @ 1KHz & 10KHz: Below 0.2% @ 8 Ohm 1W, below 0.3% @ 4 Ohm 2W, below 0.5% @ 2 Ohm 2W.