By Jeff Kohrman

I needed yet another portable amp to play my ukulele, preferably something with a bit of a bite to it, and cheap enough to not care if it gets beat up or destroyed.  My first thought was an LM386.  The LM386 is a cheap, low voltage audio amplifier which is readily available at your local RadioShack (if you don’t want to wait and get it cheaper).  By “cheap,” I mean you can probably pick one up from even the highest priced electronics shop for less than $2 a piece, and that is way overpriced.  I got mine from elexp.com for a lovely quantity discount.  These amplifiers typically have a very high amount of gain, so we’ll design one with a gain of about 200.  Check out the schematic.

Pardoning my messy schems, it’s a fairly straightforward circuit.  Here’s what you’ll need.

• One LM386
• One 10K Potentiometer
• One LED (to show power)
• One 330 ohm resistor (I used a 390 ohm, it’s just for the LED)
• One 220uF Electrolytic capacitor
• One 10uF Electrolytic capacitor
• One .1uF Ceramic disc capacitor (Thanks Aaron!)
• One guitar (Mono phone) jack
• One 8 ohm speaker
• One 9 Volt battery
• One switch (for power, not listed in schematic)

Try breadboarding the circuit before soldering it together.  This will give you an idea of how it will sound once in it’s finished housing.

Once you’re confident that everything is working well, grab yourself a piece of protoboard and solder everything together accordingly, and stick it in your case of choice.  Here’s my “finished” circuit.

Try to keep everything small, but only as small as you’re comfortable working with.  You don’t want to overstress your skills, especially if you’re a beginner.  Don’t want to get discouraged from electronics this early!  Anyway, shove your completed project into your enclosure, and test it out (You probably should’ve tested it before this at least once..).

Works?  Awesome, you’ve just built a cheap and easy amp!

Still stuck?  Send us some comments, and we’ll be sure to help you out as best we can!