LM386 audio amplifier circuit with PCB

Although the LM386 audio amplifier is very old. But they still have a lot of usefulness. Thanks to the inventor of this IC. If you want to increase the sound volume of your audio player. The LM386 is a good choice, because of the low voltage consumption and functions well with a battery.

LM386 Datasheet

You just finished your own audio circuit, but the sound is too low.

Many people use LM386 to increase the sound volume to drive a speaker. Should you use it as well?

But…it would be better if you read the LM386 Datasheet first.

LM386 is a low voltage audio amplifier. It shapes like IC-741 in the DIP-8 form factor. Thus, it is small and easy to use. Even if the size is small but it does sound great.

Cr: LM386 of National Semiconductor. I like ICs from this company.

LM386 Pinout

We often use LM386 in the DIP-8 packet, there are 8 pins used for connections as same as other packets. For example, SOP-8, TSSOP-8, etc.

LM386 features and specifications

• Give enough power — Common Power of the output is about 700mW at VS = 9V, RL = 8Ω, THD = 10%. Imagine you listen to soft music at prefer corner.
• Consume a wide supply voltage range of 4V to 15V.
• Consume a low supply current — in case of no input signal is 4mA to 8mA.
• Internal voltage gain is set to 20 or 26dB (without other parts).
• The voltage gain can be increased to 200 or 46dB, by connecting a 10uF capacitor across pin 1(+) and pin 8(-).
• The gain between 20 and 200 can easily be controlled by connecting a resistor in series with the capacitor.
• Typical Low harmonic distortion: 0.2%
• The frequency response is from 40Hz to 100 kHz rate.
• Frequency bandwidth: 300kHz in common

By having a lot of benefits, many small electronic appliances use it as the speaker driver. Examples for, radio, MP3 player, Mini Portable speaker, Etc.

More the circuits, the more we understand

My thought is slow. I can not understand a large amount of information in a short length of time. Has this happened to you?

I have used images, they help me understand things more.

Also, I like the circuit diagram and circuits. I have learned and got so many ideas out of it.

Let’s learn more about LM386 circuits.

x20 Amplifier

The smallest amplifier gives a gain of 20 with the fewest parts.

It is indeed an amplifier circuit. Even with one IC and one capacitor.
But Its output current is quite low (low driving power). Thus, in real usage, we might need a louder sound. We can increase it in a simple way as below.

X200 great small amplifier

The gain of this circuit rises up to 200. Because we connect the C2 capacitor to the IC by the positive leg of C2 at Pin 1 and another at Pin 8.

But sometimes a too high gain is not good for us. We can control it with a resistor.

X50 lower gain of LM386 amplifier

We add the R2 resistor in series with C2 to reduce the gain to 50.

LM386 Amplifier with bass boost

Sometimes you may want more bass than normal. It also can be done easily. By adding R2 resistor and C2 capacitor in series as the circuit above.

This circuit has a bass booster. The output gain depends on a bass frequency. For example, Gain 25dB: 100Hz, and Gain 19dB: 2kHz.

Almost forgot, that some components on the circuit above have their use.

• We can adjust the volume by VR1.
• Both R1 and C3 will keep the sound good. They also improve the stability of a high-frequency load.

Do you know that LM386 can be used in other types of circuits?

LM386 Square wave oscillator

The LM386 can also be used to create a square wave oscillator circuit. It makes creating an audible alarm with the speaker easier. Because this IC is a type of op-amp. Thus it is a good choice when making an oscillator circuit as well.

According to the circuit above, the output frequency is approximately 1KHz, it can be changed by C2. More the capacitances less the frequency and vice versa.

What is more? Let’s build LM386 projects.

Mini LM386 audio amplifier

If saving energy is important for you, this circuit is a good choice. Because you can use it with a 9V battery at 5mA current. But it has an output gain of about 50 and power of 300mW to 500mW if used for 8 ohms speaker.

LM386 mini audio amplifier circuit

For example, you made an AM receiver circuit with the LM386 as the amplifier for a 0.5W, 2 inches speaker. Powered by a 9V battery that can provide enough energy for a long music session.

Flexible in choosing parts

You can use similar components, that can replace one another.

For example:

• The loudspeaker — can be 4Ω or 8Ω @ 0.25W or 0.5W in any size as the space required.
• Voltage supply — ranging from 4V to 12V. But lower the voltage, lower the watts as well. It is reasonable.
• The voltage of capacitors — The higher voltage can be used instead of the lower voltage. Like C5 is an electrolytic capacitor, 50V can be used instead of 16V. But… Of course, it is more expensive.

About LM386’s Pin 7

Pin 7 (bypass) is used to protect the input of the LM386 amplifier circuit from the noise created by the power supply. Usually, we connect it to the ground with a 10uF capacitor.

But if the power supply is mostly clean and stable (i.e. Battery, Linear regulator) then the capacitor is not needed.

How to builds

If you want to build these circuits. It can be built on the universal PCB or even the breadboard. But if you prefer the PCB board instead, you can make it as a PCB layout and components layout below.

The PCB and components layout of the LM386 audio amplifier

Parts list

0.25W Resistors, tolerance: 5%
R1: 10Ω
R2: 1.2K
VR1: 10K Potentiometer

Capacitors

C1, C2: 0.1μF 50V Ceramic
C3,C4: 10μF 25V Electrolytic
C5: 220μF 16V Electrolytic

Semiconductors and others

IC1: LM386, Low voltage audio amplifier
SP1: 8Ω 0.25W speaker
B1: Battery, 9V Or 9V power supply circuit

Look at more:

• 1.2 watts Super Small AMP using TDA7052
• TDA2822 Stereo amplifier

9V Power Amplifier using LM386

Other than the circuit above, this is also a 9V amplifier circuit but with a higher gain of up to 200.

LM386 mini amplifier

How it works

To begin with, the signal goes to the input pin 3, non-inverting input. This is a signal amplifier in the non-return phase form.

They have…

• The C1 absorbs the noise to protect the input.
• The C2 increases the gain of the amplifier. More gain can be achieved by increasing the C2 capacitance. But, a higher value will result in greater distortion (Should be lower than 100μF).
• The output comes out of pin 5 of IC1.
• Then, the signal passes through the C4 coupling capacitor, this makes the quality of audio signals better. And block all DC voltage going to the speaker.
• Both R1 and C3 are connected in series. They keep the high-frequency response better.

Recommended: Classic active tone control circuit using ICs

Parts list

0.25W Resistors, tolerance: 5%
R1: 10Ω
R2: 1.2K
VR1: 10K Potentiometer

Capacitors
C1: 0.01μF 50V Ceramic
C2: 10μF 25V Electrolytic
C3: 0.1μF 50V Ceramic
C5: 220μF 16V Electrolytic

Semiconductors and others
IC1: LM386, Low voltage audio amplifier
SP1: 8Ω 0.25W speaker
B1: Battery, 9V

Read Next: TDA2030 stereo amplifier circuit

500 mW Power Amplifier using LM386N

This is another interesting circuit. because it has the power of 500mW if used for an 8Ω speaker at distortion is Less than 1%.

This circuit is similar to the circuit above, let’s take a look at the different points that have been changed.

• The LED1 lights up to show if the circuit is on.
• And, capacitors C6 and C7 act as filters to smooth up the supply voltage.
• The sound signal flows through VR1, which controls the volume up or down.

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What is more?

Parts lists

0.25W Resistors, tolerance: 5%
R1: 10Ω
R2: 1.2K
VR1: 10K Potentiometer

Capacitors
C1: 3.3μF 25V Electrolytic
C2, C6: 0.1μF 50V Ceramic
C3: 10μF 25V Electrolytic
C4: 0.047μF 50V Ceramic
C5: 470μF 16V Electrolytic
C7: 100μF 25V Electrolytic

Semiconductors and others
IC1: LM386N4, Low voltage audio amplifier
LED1: Red LED 5mm.
SP1: 8Ω 1W speaker
B1: Battery, 4V to 12V

Download This Post as a PDF and all PCB layouts

Conclusion

We love LM386 audio amplifier, me too. Because it uses a battery. We can test and make them more. It is easy and cheap. What do you think about it?

Sure, this may not enough for you to read more LM386

Keep Reading: LM386 Stereo Amplifier with Bridge model