AC Power Amplifier Circuit Diagram


A circuit diagram of an AC Power Amplifier Circuit using MC1438R IC and two 2N3904 transistors is a popular and reliable amplifier circuit. This amplifier is capable of amplifying audio signals from various sources such as MP3 players, phones, laptops, and other audio devices. In this article, we’ll take a closer look at the circuit diagram and explain how the amplifier works.

Circuit Diagram

of AC Power Amplifier Circuit

AC Power Amplifier Circuit Diagram
AC Power Amplifier Circuit Diagram

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Components List

Components Required for the AC PowerMono Amplifier:

The following are the components required to build the amplifier circuit:

  • MC1438R IC x 1
  • 2N3904 NPN Transistors x 2
  • 50uF Capacitor x 1
  • 5uF Capacitor x 1
  • 2uf Capacitor x 1
  • 0.1uf Capacitor x 1
  • 20k Resister x 1
  • 10k Resister x 2
  • 5.1k Resister x 1
  • 620 ohms Resister x 1
  • 510 ohms Resister x 1
  • 120 ohms Resister x 1

The Circuit Diagram of AC PowerMono Amplifier using MC1438R IC:

The circuit diagram for the AC PowerMono Amplifier is relatively simple to follow. However, it is crucial to pay attention to the specific values of the components used in the circuit for optimum performance. The circuit is built around the MC1438R IC, a versatile audio amplifier that can function as a voltage-controlled amplifier, gain controller, and oscillator.

The circuit works in two stages; the first stage amplifies the input signal using a transistor, and the second stage boosts the signal further using the MC1438R IC. The output of the amplifier is fed through a speaker, which can be of any size, depending on the required power output.

Working Explanation

of AC Power Amplifier Circuit

The first stage of the circuit amplifies the input signal using a single 2N3904 transistor. The input signal is fed to the base of the transistor via a coupling capacitor, which only allows the AC component of the input signal to pass through. The base of the transistor is connected to a biasing resistor, which ensures that the transistor is always biased correctly.

The amplified signal from the first stage is then fed through another coupling capacitor and input resistor to the MC1438R IC. The IC amplifies the signal further, and the amplified signal is then fed through two 100uF capacitors, which act as coupling capacitors to the output stage.

The output stage consists of another 2N3904 transistor, which is biased correctly using a 100-ohm resistor. The amplified signal is then fed through a 10k resistor, which acts as a load resistor, and then to the speaker.


The AC PowerMono Amplifier is a reliable and easy-to-build amplifier that can deliver a decent amount of power output. By simply following the circuit diagram and using the right values for the components, you can successfully build your amplifier. This amplifier is excellent for use in small to medium-sized rooms, and it has proven to deliver excellent performance. Regardless, it is always crucial to take necessary safety precautions when working with power supplies and electronic components.

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AC Power Amplifier Circuit Diagram
AC Power Amplifier Circuit Diagram
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