Simple LM386 Op Amp

I’ve been wanting to build myself a little amp for my phone, mp3 player, etc. for awhile. Originally, I wanted to build something completely from discrete components but finally gave into using the LM386 IC. The datasheet is very helpful and even includes several circuits to try out. It’s a very simple circuit to get the little amp built and working, but I kept having trouble with terrible distortion rendering the amp unusable. I kept tinkering, troubleshooting, researching, and so on, only to discover that one of the power rails on my breadboard is bad. Lame. Once I figured that out, then the circuit really is simple! You can find variations of this circuit all over the internet, but I ended up using the circuit from Dino over at Hack A Week. This guy is pretty awesome and has very informative and entertaining instructional videos. His circuit and BOM is listed below.

  • Enclosure of your choice
  • 10 ohm resistor
  • 10K potentiometer
  • 220 uf polarized capacitor
  • 100 uf polarized capacitor
  • 10 uf polarized capacitor
  • .01 uf ceramic capacitor
  • .047uf ceramic capacitor
  • 2x 1/8″ mini audio jacks
  • 2x 1/4″ audio jacks
  • 9 volt battery clip
  • 9 volt battery
  • small perforated circuit board
  • Some hookup wire
  • A speaker of your choice for output.
LM386 Op Amp from Hack A Week
LM386 Op Amp from Hack A Week

A lot of the discrete parts for this project I salvaged from various things. I used my little LEXPON Multifunction Transistor Tester to test my components and to double check values on the capacitors. Dino’s BOM for the project is for a finished device, but you can skip a bunch of the items to just build it on a breadboard and get it working. I had a 10k pot with a built in on/off switch that I used and I also wired in a little LED to remind me to turn off the circuit and not run down the battery. Using a salvaged 1w speaker plugged directly into the circuit on the breadboard, I got pretty clear audio from the output on my laptop. It’s always exciting to get stuff like this to work no matter how simple. Now to do something useful with it…