2 Watt Mini Audio Amplifier

2 Watt Mini Audio Amplifier circuit design

2 Watt Mini Audio Amplifier Circuit Diagram

This is the circuit diagram of 2 Watt mini audio amplifier. This circuit is inexpensive, easy and quite simple. This is general audio amplifier which can be used for computer, CD player or other devices which have headphone output.

The circuit was deliberately designed using no ICs and in a rather old-fashioned manner in order to obtain good harmonic distortion behaviour and to avoid hard to find components. The amplifier(s) can be conveniently supplied by a 12V wall plug-in transformer. Closing SW1 a bass-boost is provided but, at the same time, volume control must be increased to compensate for power loss at higher frequencies.

In use, R9 should be carefully adjusted to provide minimal audible signal cross-over distortion consistent with minimal measured quiescent current consumption; a good compromise is to set the quiescent current at about 10-15 mA.

To measure this current, wire a DC current meter temporarily in series with the collector of Q3.

2 Watt Mini Audio Amplifier Components list:

P1 = 10K Log.Potentiometer
R1,R2 = 33K 1/4W Resistors
R3 = 33R 1/4W Resistor
R4 = 15K 1/4W Resistor
R5,R6 = 1K 1/4W Resistors
R7 = 680R 1/4W Resistor
R8 = 120R 1/2W Resistor
R9 = 100R 1/2W Trimmer Cermet
C1,C2 = 10?F 63V Electrolytic Capacitors
C3 = 100?F 25V Electrolytic Capacitor
C4,C7 = 470?F 25V Electrolytic Capacitors
C5 = 47pF 63V Ceramic Capacitor
C6 = 220nF 63V Polyester Capacitor
C8 = 1000?F 25V Electrolytic Capacitor
D1 = 1N4148 75V 150mA Diode
Q1 = BC560C 45V 100mA PNP Low noise High gain Transistor
Q2 = BC337 45V 800mA NPN Transistor
Q3 =TIP31A 60V 4A NPN Transistor
Q4 = TIP32A 60V 4A PNP Transistor
SW1 SPST switch
SPKR 3-5 Watt Loudspeaker, 8, 4 or 2 Ohm impedance

2 Watt Mini Audio Amplifier Technical Data:

  • 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.

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6 thoughts on “2 Watt Mini Audio Amplifier

  1. kadhir rajashekar

    can you please explain the working of this 2 Watt Mini Audio Amplifier circuit diagram

  2. John

    Has anyone built this and does it work? Do you need heatsinks for the transistors? Mine get very very hot.

  3. Locky

    Hi there,I have a Minelab S.D.2000 metal detector,runs on 6.V. I would like to have an external speaker instead of headphones. Would this amp do the job. Sincerely,Locky.

  4. Royce

    just wondering about the values of resistors 7 8 and 9. they have the label R, is it suposed to be K ?

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