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

Step 2: 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

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

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

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!