In this tutorial, I will show you how to make an LM386 audio amplifier circuit. The LM386 is a low power audio frequency amplifier which is very commonly used in small audio amplifier circuit project. The IC consumes very little power and it can be operated by a 9V battery. It can easily drive an 8 Ω speaker or two 4 Ω speakers. We can use volume control and treble control in this circuit. The IC also comes with an 8 pin PDIP package and requires very fewer components to work.
So, it is a low-cost audio amplifier IC which can be powered using a battery and also a portable device to drive an 8 Ω speaker then this IC might be the right choice for you. Here is a simple circuit schematic is given below.
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- LM386 Op-Amp IC
- 1000 uF/25V Capacitor
- 100 uF/25V Capacitor
- 10 uF/25V Capacitor
- 220 uF/25V Capacitor
- 0.1 uF Ceramic Capacitor
- 10 KΩ Potentiometer
- 10 Ω Resistor
- 8 Ω Speaker
- 9V Power Supply
- Jumper Wires
The IC is powered using the pin 6 directly to the positive power supply and the ground pin 4 is directly connected to the ground. The inverting pin 2 is normally grounded and the Non-inverting pin 3 is provided with the audio frequency. This audio signal can be inputted from a 3.5 mm coaxial cable. A 10 KΩ resistor is also added in series with the audio signal to control the volume.
The pin 1 and pin 8 of the amplifier IC are used to set the gain of the amplifier. You can skip the pins for default gain which is 26 dB, but we can connect a 10 uF capacitor across it to get the maximum gain of which is 46 dB. Pin 7 is used to connect a filtering capacitor (0.1 uF) to avoid unnecessary oscillations. The amplified audio signal can be obtained from the output pin 5 which is connected to an 8 Ω speaker. It is also connected with a filtering capacitor whose value is 220 uF.
Working Principle of Audio Amplifier Circuit
The working of the circuit using this LM386 op-amp is very straight forward.
When the circuit is powered on and also audio input is given at the input terminal, the LM386 amplifier all the circuit turned on and drives the output speaker.
One of the main problems with this audio amplifier circuit diagram is its horrible noise. But if the circuit is built on a breadboard, the amount of noise is too less than implemented on a Vero board or PCB board.
Application of Audio Amplifier Circuit
LM386 is one of the important IC for amplification of a signal. In our case, it is used for the audio amplifier circuit and it is also very useful for portable speakers and laptop speakers.
They can also be used in TV sound systems, line drivers, servo drivers, ultrasonic sensor drivers, and FM radio, etc.