Many Electronic circuit projects in simple ways of learning

LM386 amplifier stereo 2 watts

This is 2 watts + 2 watts Stereo small LM386 amplifier x3  ICs. It is cheap and easy to builds for beginner.

A basic of amplifier

The most normal power amplifier as Figure 1 that connected to directly a positive of speaker and the negative terminal of speaker to ground terminal of circuit. In Figure 1 setting to the power amplifier have gain about 2 times. Thus, when have signal input is 1 volts will have output equal 1 volts x 2 times = 2 volts

Figure 2 we add the amplifier 2 into the amplifier section 2 will has the difference feature of the section 1 by setting has gain is 2 times.

01-the normal amplifiers

Figure 1 the normal amplifiers

Which is higher loud than the first model. This is called the BTL model (Bridge output Transformer less). Advantage of not requiring the high voltage power supply, it can provide high power magnification option.

02-How to use the amplifier BTL model
Figure 2 How to use the amplifier BTL model

The sound from the speakers to the way in Figure 2 is 2 times of the method in Figure 1.

How it works
In figure 3 is fully 2 watts + 2 watts Stereo Using Three LM386

03-2 watts + 2 watts Stereo Using Three LM386
Figure 3

Audio signals is fed into the input, VR1 is the volume louder – light sound. The IC1, IC2 and IC3 is the heart of the circuit, each IC on resistors and capacitors connected with the appropriate values. The power can be 1 watts (from datasheet).

Both IC1 and IC2 will works to increase the sound output to the the speaker, which is the left channel. At the same times, IC2 and IC3 will work together, To amplifier to the right speaker. If equal to watt is about 2 watts.

It is seen that, we use 3 ICs each unit is 1 watts. But it was a combination of all the 4 watts, the profits of the 1 watts.

The parts you need.
IC1-IC3____LM386___Mini Amplifier

Resistors 0.25W 5%
R1,R3______47 ohms
R2,R4,R5___ 10 ohms
R6_________ 1K

Electrolytic Capacitors
C1,C8__________ 4.7uF 50V
C2,C5,C9________22uF 16V
C4,C7,C11,C12___ 470uF 10V

Ceramic capacitors
C3,C6,C10________ 0.047uF 50V

VR1___10K (A) Potentiometer
LED1___LED as you like.
Switches, PCB, Box,wires and more.

How to builds
First of all,find all parts as list in circuit diagram.
Then builds a pcb as Figure 4 actual-size of Single-sided Copper PCB layout
then assemble all parts on pcb as Figure 5 the components layouts

04-actual-size of Single-sided Copper PCB layout
Figure 4

05-the components layouts
Figure 5

This Post Has 11 Comments

  1. Which is the software that you are using to generate the PCB layout.

    Thanks for feedback.
    This PCB layout is designed by illustrator Adobe 8.0
    It old software for book.

  3. It’s a weird circuit; I’ve been toying with this little ic’s in the pursue of more power, and did a bridge amp which sounds right with the correct speakers; I used 8″ 8 ohm sensitive speakers ( big magnet) and sounded amazingly loud for the size of the devices; with smaller ones the sound is plain deceiving; the first time I tried the circuit was with 8″ 25 ohm from an intercom and the loudness is unbeileibely loud. This little things have hard times at this pace so should be heathsinked; for my tests with 8 ohm I used 1/4″ aluminium plate with 3″ by 4 1/2″ size ( approx) mounted the ic’s carefuly against it used stripped pcb and built the cct. You may surprise the sound you can get from this little things. Someday I’ll build an entire “mini” audio system with the modules I built; I know not if I’m using 8 or 25 ohm speakers but should be well done TL enclousures with separate tweeters; The devices were fixed with a complementary piece made with the same material fixed with 1/8″ stove screws with lots of care; you won’t want to brake the ic’s either bend the aluminium locking parts.

  4. Hi I am from Iran Reza
    I wanted to remove particulate filter circuit metal detection and measurement of the volume of metal in the ground and without errors thanks

  5. at 6v to 9v the maximum output is 500mW to 700mW per IC.

  6. hi what is external output ?

  7. plz reply

  8. I’d seen this diagram and i build it.. luckily i made it but what speaker that suits in this mini amplifier?i want to use 1 woofer and 2 tweeter can you email me please..thanks

  9. I want to purchase 200 peices audio amplifier pcb with audio jack & usb connector for giving 5v power to circuit. please contact me on 9146032723

  10. This is Brilliant!
    And i don’t see any reason why the principle can’t be used with other OpAmp-like Power ICs as well.
    Thanks for sharing this idea.


  11. Oh, wait a moment!
    What’s up with R1 and R3? Aren’t they almost shorting the input signal to ground?
    Shouldn’t they be at least 47K instead of just 47 ohm?

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