Power amplifier electronic circuits-tube audio rf amplifiers

Electronic Amplifier Circuits-Power amplifier, audio amplifier designs and circuits

April 25th, 2010

Simple 250 mW Audio Amplifier

Circuit Description

The circuit diagram given below shows 250 mW audio amplifier. This circuit contains three transistors Q1 (BC547), Q2 (BC327), Q3 (BC337) as central components. Transistor Q1 in this circuit acts as preamplifier where as Q2 and Q3 are output pairs. Transistors Q2 and Q3 are complementary transistors. Decoupling of DC from audio source is done by the capacitor C1 (10 uF). Resistor R2 (82K) is used in this circuit to provide better stability for the amplifier. Variable resistor POT R5 (10K) is used as volume control element.

The circuit is powered using a 9V DC supply. The value of impedance of speaker K1 can be 8 ohm. In order to get the optimum output from the circuit, decouple input and output grounds properly.

Circuit diagram

Simple 250 mWAudio Amplifier

Simple 250 mWAudio Amplifier

Notes

  • Use a Vero board to assemble components for this circuit.
  • This type of amplifiers finds applications in small radio sets and in high power amplifiers as preamplifier.

April 25th, 2010

40 Watts Audio Amplifier Using IC TDA 2030

Circuit Description

The circuit diagram given below represents 40W audio amplifier. This 40W power amplifier circuit is designed using IC TDA 2030 and two transistors as main components. The IC TDA 2030 is the core part of this circuit because it plays the main role in voltage amplification. The job of current amplification is done by the two transistors. Adequate heat sinks should be provided for IC and both transistors.

The input signal is fed to the non- inverting terminal (pin 1) of TDA 2030 IC through the decoupling capacitor C5 (470 nF). When voltage amplification is performed by TDA 2030, the power supply current to IC changes with respect to the variation in the input signal. The variations in positive and negative supply pins of the IC are coupled to transistors Q1 (BD 712) and Q2 (BD 711). These transistors are connected complementary to each other in circuit so that they perform current amplification.

Power supply for the circuit can be 12V to 40V. Use 40V supply and 4 Ohms speaker for maximum output. To optimize the circuit performance, input and output grounds must be properly decoupled.

Circuit Diagram

40 Watts Audio Amplifier Using TDA 2030

40 Watts Audio Amplifier Using TDA 2030

Notes

  • Use a good quality PCB to assemble components for this circuit.
  • Make PCB tracks broader through which high current flows.

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