DIY Audio Amplifier for Electronics Hobbyists

We need an audio amplifier to listen to our favorite music. There are many amplifier modules and boards available in the market at a cheap price. For electronics enthusiasts like us , buying one of them doesn't sound good. The working principle of an amplifier is very simple and we can build a simple amplifier without investing more time. So I decided to build one and I wanted my amplifier to be more unique than the existing models. So I made an amplifier PCB in the shape of a guitar . This project will show you how to make an audio amplifier of your own.

Step 1: LM386 Amplifier IC

First, I selected the amplifier ic from many available. I chose the LM386 IC. I chose this ic because of its energy efficiency.

LM386 Audio Amplifier Features and Specifications

Supply voltage: 4-15V

Static power: 24mW@6V

Analog input voltage 0.4V (maximum)

Voltage gain: 20 to 200 (26dB to 46dB)

Speaker impedance: 4Ω

Available in 8-lead PDIP, SOIC, and VSSOP packages

After understanding the working principle of ic, I got the basic operation circuit diagram from the internet, made the circuit on a breadboard. Since the audio quality and gain depend on the value of the components, I tried more components and found the right value and finalized the circuit.

The IC is powered using pin 6 (usually 5 or 9V) and ground pin 4 is connected to ground. The inverting pin (pin 2) is usually connected to ground and the non-inverting pin (pin 3) provides the audio signal . This audio signal can come from a microphone or even from a 3.5mm jack. The 10k resistor is added in series with the audio signal and acts as a volume control. If you want to operate at full volume, you can ignore this potentiometer .

Pin 1 and Pin 8 are used to set the gain of the amplifier. If nothing is connected between these pins, the default gain will be 26dB, but we can connect a 10uF capacitor across it to get the maximum gain of the IC, which is 46dB. Pin 7 is used to connect a filter capacitor (0.1uf) for our amplifier IC to avoid unwanted oscillations. The amplified audio signal can be obtained from Pin 5, which is connected to an 8 ohm speaker through a filter capacitor. The RC network with 0.05uF and 10k resistors is optional.

Step 2: Amplifier Circuit Diagram

After finalizing the values ​​of the components, I designed the circuit on easy eda online platform.

Step 3: Components Needed

LM386 amplifier IC-1

4.7k variable resistor - 1

2-pin JST Connector - 2

3.5mm female audio jack - 1

0805LED-1

0805 resistor 100k-2

0805 resistor 1k-1

0805 capacitor .1uf-1

0805 capacitor .01uf-1

0805 capacitor .47uf-1

Electrolytic capacitor 100uf-2

Small 3w speaker-1

3.7-7.4v battery - 1

You can also build the same amplifier using THT components. That is, we can also build this amplifier without using a PCB

Step 4: PCB Design

After designing the circuit, I converted the circuit to a PCB. To make the PCB into a guitar shape, I used the insert image option of easyeda and added the guitar image to the PCB. Next, I placed all the components in the guitar image. Then I selected the board outline and drew lines on the guitar image. Then I dragged the lines and made the exact shape. It took me some time to do this after I finished the drawing that looked like this. Now I generated and downloaded the Gerber files for PCB manufacturing.

Step 5: PCB Fabrication

For PCB manufacturing, I went to Jlcpcb.com. jlcpcb provides 5 PCBs for only $2. After uploading, you can choose the color, quantity and thickness of the board. Then choose the shipping method and place the order. After 2 weeks, I received the PCB. You can see the cute guitar-shaped red PCB, everything looks good and the quality is perfect.

Step 6: Soldering

Now let's solder the SMD components here. I am soldering with my normal soldering iron. After finishing the soldering of the SMD components, I start soldering the through hole components. I started with the lm386ic. It's just a matter of placing the component on the correct hole and soldering it. After finishing the soldering work, our PCB will look like this.

Step 7: Testing

Now let's test it, I connected a 3w speaker, a battery and finally the AUX cable. You can see this working video . So this amplifier is enough to hear the music clearly. If you like this. You can try making this project at home.