This tutorial leads to the formulation of the LM386 Based Audio Amplifier Circuit. The LM386 is a low-voltage audio amplification commonly used in battery-driven music devices such as radios, guitars, toys, etc. This circuit is based on LM386 IC to amplify & can be used for many different applications, including mobile music players, intercoms, amplifiers, tv sound systems, ultrasonic drivers, and other applications. Even microcontrollers, can be used as an auditory sensors.
Hardware Component
The following components are required to make Audio Amplifier Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Battery | 5-12v | 1 |
| 2. | Potentiometer | 100k | 1 |
| 3. | Capacitor | 220uF, 10uF, 0.1uF, 0.05uF | 1, 2, 1, 1 |
| 4. | Resistor | 10k | 2 |
| 5. | Speaker | 8 ohm | 1 |
| 6. | Condenser Mic | – | 1 |
| 7. | IC | LM386 | 1 |
LM386 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of LM386
Audio Amplifier Circuit
Working Explanation
Pin 1 & 8 are the gain control PINs, by default the gain is set to 20 but we can increase it by using a capacitor on these pins. We have used 10uF capacitor C1 to get the highest gain i.e. 200. Pins 2 & 3 are the sound reference pins. Pin 2 is a negative input terminal mostly connected to the ground. The input terminal Pin 3 is a positive terminal for amplifying the sound signal. The positive terminal of the condenser mic connects to our circuit by a 100k RV1 potentiometer. The potentiometer includes a control valve for pitch. Here a capacitor 0.1uF is also used along with a potentiometer, to remove the DC component of an input signal & only allow the AC component (audio) to the operational amplifier lm386.
The output PIN 5 is the amplified sound signal from which we receive. The AC and DC elements of the output signal are unacceptable and cannot transmit to the Speaker. A 220uF C2 condenser uses to remove this DC part. The C5 capacitor (0.1uF) feature on the input side is similar.
In addition to this condenser, the C3 (.05uF) filter circuit and the R1 (10k) resistor at PIN 5 output were used. This filter, also known as the Zobel network, is used to remove sudden oscillations or rings in high frequencies.
Applications and Uses
By applying this circuit, It is possible to record voice from the microphone, construct small battery speakers in FM Radio Devices, and so on, also using the LM386 Audio Enhancer Circuit. Sound systems, line drivers, stepper motor drivers, ultrasonic drivers, etc., can also be used.
