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

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

Comments

[art.z]

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]

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]

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]

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]

it plugs into pin 6 and 4 i think.

[kenkaniff]

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

Thanks!

[shawntherobot]

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]

Awesome thanks.

[patrick.ward21]

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

[gmuñoz1]

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

[Misac-kun]

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

[art.z]

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]

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

[David97]

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]

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]

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"]

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

[ankitgarg2005]

Thank a lot!

[TitanTechRobotics]

Thank You!  This is a great series.
-TTR

[REA]

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

[WerdnaN]

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

[frenzy]

that's a pretty big typo, thanks!

[rtty21]

The only thing I found odd was the "..047uf" capacitor in step 3 line 8. I assume that it is a simple typo. But that isn't my real comment. my REAL comment is this:
The inst'able was GREAT! i'm glad i subscribed to your BOSS channel! keep up the awesome work! 5 stars!

[lazyNinja]

love the know your ic series. it might be good though to suggest possible changes to the circuit in an additional step. that may inspire a little more exploring, and exploration fosters understanding.

[rickharris]

This may seem picky but from the data sheet the LM 386 is a power audio amplifier, its internal gain is nominally 20 although this may be raised to 200 with external components.

An Operational amplifier has a much higher gain than this.

[bertus52x11]

Thanks for the great sequence.
Keep writing about this, I need it!

[theformatter]

Hmmmm. Step 2 - three outputs and no inputs?