In this blog, we have to make an audio amplifier using LM386 and study how to remove noise in an audio amplifier.
As technology is evolving day by day electronic devices are also getting better, smarter, and smaller as well and so is my blog about.
We are going to study about how an ordinary audio amplifier using LM386 can be rebuilt with very small significant changes to get a better output audio signal.
By the end of this blog, you will be able to understand how easy it can be done and that too at a very cheap cost.
It’s very simple and cheap.
What is LM386?
- It is an integrated circuit containing a low voltage audio power amplifier.
- It is suitable for battery-powered devices such as radio, guitar amplifiers, etc.
- It is a type of operational amplifier.
- It takes an audio input signal and increases its potential anywhere from 20 to 200 times. That amplification is what’s known as the voltage gain.
Step 1:- Circuit Diagram of audio amplifier using LM386
Before moving ahead, let us have a look at the circuit diagram of general LM386 Audio amplifier.
Now, just have a look at the circuit diagram Noise Immune Audio amplifier using LM386.
All this circuitry we have to make on a small mini breadboard.
The circuit diagram or the connection of this setup is shown by using the following sketch.
So, let’s get started and check out the process.
Here is the complete list of components along with their purchase link on amazon.
✔ Hardware Requirements
Step 2:- Component Specification
Let us observed certain changes that we had made with the help of components in detail.
Next, we need an LM386 IC. It is so popular for audio amplification. This IC needs a minimum external connection port.
This IC also battery operated with a wide supply voltage range 4 to 12V or 8 to 16V depending on the different manufacturers series.
you need a 3.5 mm audio jack and separate this jack from the headphones.
Step 3:- Circuit Explanation and connection
Next moving to the circuitry, I am using the 9V battery but I recommend 12V power supply or a 12V nickel-cadmium battery for better performance.
Next, I recommend 0.1uf(104) disc type capacitor which is connected in parallel with pin no 6 to pin no 2 connected ground through pin no 2. Pin no 6 is +Vcc.
Extension to the basic circuit, a 0.1uf capacitor is connected paralleled across pin no.2 and pin no.6. The purpose of the connection is to resist the distortion and radio interference through audio input wires.
This disc type capacitor is connected parallel with the power supply for removing Bebber and protecting IC from the instant power supply.
The pin no 7 is the bypass. This pin is connected to a 10uf capacitor which is used for filtering.
In this 10 to 100uf of the capacitor works well.
You have seen a lot of circuits on the internet but in our circuit some changes at the output of the amplifier.
The pin no 5 is the output pin there is an RC high pass filter.
It passes (2MHz) high frequency to the ground, so it cannot interfere with the audio amplifier.
So this RC high pass filter circuit is replaced with the only 0.1uf (104) disc type capacitor.Again, we have to connect 100uf capacitor to filter low frequency noise and 0.1uf capacitor to filter high frequency noise.
After this, we have to connect the 0.1uf capacitor between pin no.6 and pin no.4 for protecting the circuit from direct contact of power supply, as it may cause damage to the circuit.
Lastly, an RC high pass filter is connected parallelly to the ground across pin no.5. This helps us in removing unwanted noise existing in the power supply.
I found that this is the best solution and it works for all the speakers. And it also helps that the noise from power supply doesn’t pass through the audio amplifier.
Step 4:- Important Tips
At the output of the LM386 IC, use a 1000uf (25V) electrolytic capacitor or use higher than that for removing DC offset it means no dc voltage pass into the speaker which will damage so capacitor prevents it and provide a wide base speaker.
if you are connected disc type capacitor at the output pin its prevents unwanted oscillation.