Introduction: Know Your IC: LM386

Picture of Know Your IC: LM386

Welcome to the next installment of "Know Your Integrated Circuit"!

Know Your IC seeks to demystify common Integrated Circuits and allows people to understand them to a point where they can use them in their own projects.

This episode will feature the LM386 a popular op amp chip. We will go over the chip functions and a bit of history.

And we will teach you how to build a simple amplifier with the chip!




Step 1: Introducing Op Amps

Picture of Introducing Op Amps

Op-amps are a little hard to explain, but essentially they take something small and make it big!

Op-amps are perfect when you need to take a signal and have it go much higher than the original, for example doing audio amplification.  Wikipedia has a great history of the op-amp and it's development. 

LM386 is made specificly for low voltage applications. Different op-amps will have different requirements, always check out the data sheet! The LM386 can take 4V-12V or 5V-18V depending on the wiring and pump that up 20 to 200 times.

You can use this chip to build any of the following:
AM-FM radio amplifiers
Portable tape player amplifiers
Intercoms and
Small Servo Drivers


Step 2: Pin-Outs

Picture of Pin-Outs

The pin-out of the LM386 is as follows:

Pin 1: Gain
Pin 2: Input -
Pin 3: Input +
Pin 4: Ground
Pin 5: Vout (Output)
Pin 6: Vs (Power)
Pin 7: Bypass
Pin 8: Gain

The input obviously goes to pins 3&2. The most interesting part about this chip i feel is the gain function. If you put a capacitor between pins 1 and 8, you can control the amount of gain the amp has. The bypass allows you to access the input un-amplified, if you so desire.

Step 3: Project: Audio Amp

Picture of Project: Audio Amp

Our project we will be doing to demonstrate the LM386 is a simple audio amp. A similar design is used in "cracker box" amps.

This version is completed using minimal parts, you will need:
1 LM386
1 10 Ohm Resistor
1 220uf Electrolytic Capicitor
1. .047uf Film Capicitor
1 9v battery
1 10k Ohm Potentiometer
1 8ohm Speaker
1 1/8" mono audio jack
some solid hook up wire
1 breadboard

Step 4: Project: Layout

Picture of Project: Layout

Once you have the parts layout the circuit, please review the circuit and the layout pictures i've included. If any parts smell like burning or are hot, disconnect the power right away!

Pin 1: Unused
Pin 2: Ground of audio plug
Pin 3: To the Potentiometer  and to the audio plug
Pin 4: Ground
Pin 5: Power of speaker
Pin 6: Power from Regulator
Pin 7: Unused
Pin 8 Unused

Once its together plug in your iPod and rock out. You can control the volume with the knob. 

Step 5: Final Thoughts

Picture of Final Thoughts

Now that you have your own little amp you can easily make projects like the cracker box amp. Using Integrated circuits can be fun and easy once you get into it!

Hope you enjoyed this latest Know Your IC installment. Feel free to do you own as well, and maybe we can get a full guide together.

Thanks for Reading!

Comments

ElvisT (author)2016-04-24

I am doing a project that involves converting sound energy to electrical energy. my greatest worry is how to use the ics without powering them. please can you help me out?

congobill (author)2016-02-28

Hi could you please tell me if I have to read the IC number legs (any IC) from the top or from the bottom ?

Thank

Guillaume

makeosaurus (author)2016-02-18

To a str

makeosaurus (author)2016-02-18

How would you connect rt

yaser_e_ (author)2015-12-20

Excellent

jeet_ (author)2015-10-07

hi , what is the need for two capacitors in the output plz reply

abreldoronio (author)2015-08-11

But I used TBA820M amplifier instead of LM386.

.Is there any difference?

abreldoronio (author)2015-08-11

Hi! I'm making my project like in this picture.It used LM386 board amplifier..But it doesn't show where the terminal of input is connected..Can you help me with this?..Thank you..

Dr_momo (author)2014-08-11

Hi All,

I'm buying the parts to get started with this instructable, one thing is confusing me, what voltage is the .047uf film capacitor supposed to be? There are a bazillion options and I am totally new to electronics...help!

Many thanks.

bilden (author)Dr_momo2015-07-08

Hi!

There is a 9Vbattery in the picture so buy one suitable for that range of voltage. Buy several if youre uncertain!

Dr_momo (author)bilden2015-07-10

Thanks Bilden!

Bozho (author)2014-11-16

Hi, I have a question regarding the LM386. I saw some schematics online that feature this amplifier, and in most of them pin 2 (- input) was grounded, and input signal with a 10k potentiometer is hooked up to pin 3 (+ input). I was wondering, why is pin 2 always grounded, and can we use this IC in a negative feedback configuration as we do with a standard operational amplifier, such as LM741? Thanks in advance.

Raphango (author)2014-11-05

Excellent! =D

Raphango (author)2014-11-05

Excellent! =D

Gisty22 (author)2014-04-19

can i put female audio jack instead of the speaker so i can connect it to my transmitter

natere21 (author)Gisty222014-09-12

Yes. This is exactly what I did. I have a 1/4" TS (tip, Sleeve) audio jack instead of the TRS 1/8" mini plug shown in the tutorial.

natere21 made it! (author)2014-09-12

Thanks for the tutorial! nice little mono preamp. all you need is 2 of these, an regulated power supply (filtered!) and some power gain stages for an nice DIY stereo amp! :)

joesinstructables made it! (author)2014-05-14

Worked perfectly, thanks for posting.

jdoeson (author)2013-07-16

What's the point of the .047uF capacitor and the resistor coming off pin 5? They don't seem to be necessary in my setup (part of the GND line?)

I'm using the 250uF film capacitor, but I tried using a few electrolytic capacitors that also worked fine (though had small volume differences): 100uF, 470uF and 1000uF.

I'm actually using this for a "HDD speaker". It sounds ok, and I can make the HDD actuator move pretty well with this, though I think I need to boost the voltage to make that sucker really dance.

foggy34 (author)jdoeson2014-02-02

Hey, im wondering the same question as you about the 250uf cap. i have a set of plans that says to use a 10uf cap. but i cant get the thing to work...grr. when you tried the 1k and the 100 which was louder? thank

gauzz (author)2013-08-20

What is the difference if i use it with different voltages, I plan to make one that works at 12 volts so if I use a 9v battery or a 5 volts regulator will it sound lower?

LGT300 (author)2013-08-13

Can i use a 5k potentiometer

jdoeson (author)2013-07-16

Sorry I meant the 250uF electrolytic cap not film. The .047uF cap is film, and unused in my project.

jdoeson (author)2013-07-16

By the way - thanks for this instructable. A learning experience for us novices.

tealk (author)2013-04-08

hey! another question. can i use 50K potentiometer?

tealk (author)2013-04-08

hi, do i need to use potentimeter? can i use 10k ohm variable resistor like this http://www.mikroprinc.com/proizvodi/pasivne-elektronske-komponente/otpornici/promenljivi-otpornici/trimer-potenciometri/jednoobrtni-trimer-potenciometri/pt10l-10k/index.php?

voltronvw (author)2012-09-22

Hi, I got the amplification alright but the potentiometer won't adjust volume. It's
a 10k audio taper potentiometer 250vdc .25w ..I had continuity between
1st and 2nd connectors on the potentiomenter so I believe its functional...
any ideas?

make sure you add the wires to the top part of the potentiometer the bottom is for the battery

AlexMayu (author)2012-07-27

I was wondering if I need any of the resistors and capacitors for pin 5 if for instance I'm just analyzing the output signal from pin 5 using an analog pin on a Arduino.

art.z (author)2011-08-04

Hi, I have a question.

Is a 220uF 35V capacitor enough for the output? Or it will have to stand higher voltages?
I noticed that the capacitor I have is smaller than the one you're using and I don't have a voltage meter to make sure.

Also, do I ground everything on the negative pole of the battery? Even pin 4?

Thank you!

Ririshi (author)art.z2012-03-07

Pin 4 IS the ground of the chip. Just think of putting a little lamp in a circuit to a battery, you would do the same thing. All other things with the gnd sign go to the - of the battery, too. I think your cap is enough, as I use a 10V and it didn't burn (lol).

jimmy558 (author)2012-02-08

nice design...
but can clear the whole circuit of breadboard coz we not geting which pin of ic is connected with which components, plz make an other clear picture and also write info in description plz.

kenkaniff (author)2011-10-29

I'm still new to circuits, and there's one thing I don't understand about your pictures...

Where exactly does the 9V battery connect to?

schumi23 (author)kenkaniff2011-11-25

it plugs into pin 6 and 4 i think.

kenkaniff (author)schumi232011-11-25

I'll have to test that before I do any soldering.

Thanks!

shawntherobot (author)kenkaniff2011-12-05

i believe 6 is the + and all the other ones with three lines are - and the other V in is also + for the potentiometer (variable resistor).

kenkaniff (author)shawntherobot2011-12-05

Awesome thanks.

patrick.ward21 (author)2011-11-28

Thanks! I've been looking for a simple explanation to op-amps for a while. This is a great instructable.

gmuñoz1 (author)2011-11-28

I liked the model. But where the battery is connected?

Misac-kun (author)2011-04-14

and if you put an potentiometer on pins 1 and 8? will it be able to control the volume?

art.z (author)Misac-kun2011-08-04

You will be able to control the gain!

I'm pretty sure It's the same thing!
But I saw another instructable that put 2 potentiometer, 1 between pins 1 and 8 and 1 before the speaker! (Weird)

David97 (author)art.z2011-09-18

I saw a datasheet explaining the gain and how to control it.

David97 (author)David972011-09-18

It says in application hints. 'If a resistor is placed in series with the capacitor, the gain can be set to any value from 20 to 200.'

Redfox888888 (author)2011-08-14

So, i've been working with these chips, trying to build a noisy Cricket. but i think i killed both the ones i have. is there any way to tell if i really killed it?

Rolcrz (author)2011-06-16

Hello! I read through your instructable and found it very useful and easy to follow. However, when building the actual circuit and powering it on, I encounter a peculiar problem: I seem to be catching radio stations! Even if I connect the jack to my mp3 player, all I hear is the same darned radio station! Any idea what could be causing it?

Abhishek Singh"Techie" (author)2011-04-02

hi frenzy......i need help on LM 747!

ankitgarg2005 (author)2011-03-09

Thank a lot!

JaredsProjects (author)2011-02-17

Thank You!  This is a great series.
-TTR

REA (author)2011-02-14

of course this 'ible comes to my attention after i break the second pin. -_-

WerdnaN (author)2011-02-12

I believe that pins 2 and 3 are inputs, not outputs.

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