Though LM386 audio amplifiers are very old. But they still have a lot of useful.

Thanks, designer.

Imagine your audio player is weak sound. You want to increase sound up. They are a good choice. Because of the low voltage supply and work well with a battery.

Some may see its features in LM386 datasheet. Next, we learn for example of LM386 projects of 3 circuits.

Mini LM386 amplfier

If saving energy is important for you. This circuit is suitable. Because you can use it with a 9V battery at 5mA current. But give the gain of output to approx 50. Or the power of 300mW to 500mW at 8 ohms speaker.

Imagine you make an AM receiver circuit. You can use this LM386 to amplify to a speaker 0.5W, 2 inches. With a 9V battery can listen sound for long.

Flexible of choosing parts
You can use similar devices. To instead each other.
For example:

• The loudspeaker—use 4 ohms or 8 ohms. @ 0.25W or 0.5W. And any size as free space.
• Voltage supply—use 4V to 12V. And low voltage low watts. It is correct.
• The voltage of capacitors—use High voltage instead of low voltage. For example, C5 is an electrolytic capacitor. You may use 50V instead.
  But… Of course, it is more expensive.

How to builds

If you want to build these circuits. You can finish them on the universal PCB or even the breadboard.

But sometimes you want a PCB board. You can make it with a PCB layout and components layout.

Figure 2 the PCB and components layout of the LM386 audio amplifier.

Parts lists
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

9V Power Amplifier using LM386

Also, the above circuit. This one of the 9V amplifier circuit diagram. I like it. Because of high gain 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 this noise to protect the input.
• And C2 increases the gain of the amplifier. If you want more gain. You can add more C2 value. But, more value, too distortion (should be lower 100uF).
• The output comes out of pin 5 of IC1.
• Then, through C4 coupling the stronger audio signals to better. And DC block and not passed to the speaker.

And while both R1 and C3 in series. They keep the high-frequency response better.
Parts lists
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

500 mW Power Amplifier using LM386N

Does it use with the 12V battery? Yes, LM386 can work within a car. Because of the long wide voltage supply range from 4V to 12V at 50mA only. Give power out of 500mW at 8 ohms speaker.

Some other features and the frequency response from 40Hz to 100 kHz rate. And the gain of 46 dB. And distortion Less than 1%.

How it works

First of all, Enter the power supply to the circuit. Then, LED1 lights up to show power on the circuit.

And, capacitors C6 and C7 filtered to smooth.

Then, Enter a signal to the input through C1.

It is the coupling signal to protect DC voltage noise in the circuit.

Next, the sound signal flows through VR1 to turn the volume up or down.

After that, the sound signal goes to pin 3 of IC1.

To increase the sound up. Then, the strong sound comes out of pin 5 through C5. It protects dc voltage and passes the low frequency better to power a loudspeaker.

The C4 and R1 are acting cut noise signal out away.

And, the pin 1 of IC1 has a jumper to access C3 to boost up to gain.
When the input signal is very small.
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

Conclusion

We love LM386, 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?

Keep Reading: LM386 Stereo Amplifier with Bridge model

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