The Process of Building a Cigar Box Guitar Amp - Little Gem or The $5 Crackerbox Amp by tech-tut
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I have been an electronics hobbiest for several years, and there is something special about making musical toys. The most fun that I have is making Cigar Box Amps to sell locally, on Etsy.com, and sometimes eBay. I also run a website, tech-tut.com, that I try my best to describe what I'm doing and building. I'm finally attempting a highly detailed process that I can't exactly publish on my site, so here I am on Instructables. This is my first Instructable ever, and I value any feedback to make it the best it can be.

Building a Cigar Box Guitar Amp is not difficult, but it can be time consuming, especially if you want it to be near-perfect. Some things that don't always work out for me are the hole diameters and the occasional scratch in the soft wood of the cigar boxes. Even some of the nicer, tougher cigar boxes give way easily if your fingernail slides across the grains.

The time frame to complete a Cigar Box Amp ranges from a little over an hour to four hours depending on whether you have an assembly line or not. It also depends on the cigar box. If you have a thin box, it won't take you as long. Thick wooden boxes take longer to file the holes (unless you have potentiometers and jacks with long threads).

Overall, you will enjoy your Cigar Box Amp. Whether you buy one pre-assembled or built it from scratch in your favorite cigar box, you can expect that people will be impressed.
 
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Step 1: Gather the Necessary Parts

This is the toughest part. You need to decide what you want to install your amplifier in. The easy choice for me is to use a cigar box, but Make magazine ran an article that used cracker boxes.

Next, you need to go shopping for parts. There are kits that you can buy with nice printed circuit boards out there. I've never used one because I like the "from scratch" method.

These are the parts from my latest Jameco.com order:

Quantitiy---Part Number----------Description
1-------------24133-------------------LM386-3 700mw opamp
1-------------140514-----------------100 ohm pot
1-------------29197-------------------5k ohm pot
1-------------281746-----------------stereo Switchcraft 1/4" jack
2-------------102788-----------------chickenhead knobs 
1-------------2006764----------------5mm blue LED (Everyone likes blue, right?)
1-------------23077--------------------5mm LED holder
1-------------216452------------------Battery snap
1-------------1954818----------------speaker, 4-inch, 5w
1-------------690380------------------10ohm resistor (has to be bought in qty 100)
1-------------690865------------------1k ohm resistor for LED
1-------------1947351----------------.047uF capacitor
1-------------15229--------------------.01uF capacitor
1-------------30496--------------------220uF Electrolytic capacitor
1-------------93761--------------------100uF Electrolytic capacitor
1-------------151590-------------------voltage jack
1-------------43140---------------------perfboard or other circuit board
Grill cloth (Optional...find scraps of fabric locally) 

Wire, solder, soldering iron, wire strippers, wet sponge, spray glue, hot glue gun, hot glue sticks, sand paper (220 grit works fine), rotary cutoff tool, drill and bits, hole saw (3-3.5"), drill press (optional), files, pliers, tape measure, calipers (optional), pencil.

The original circuit was labeled the "$5 Crackerbox Amp" in Make Magazine volume 9, but the parts order above is just under $30 buying the minimum quantities. You still have to find a cigar box and pay for shipping. :)

You may be able to find some of the above parts cheaper locally. Half the fun is shopping around for parts. 

justasking says: May 19, 2013. 6:24 AM
I want to ask about the Voltage for 0.1 & 0.47 capacitors? Can i use LM386 N1 in cigar box amp? Im hoping for your response. Thank you.
celtictrinityknot says: Jan 15, 2013. 10:06 PM
Can I leave the voltage jack out if I dont want to use a wall wart, or does the circuit still need it? I just want the amp to turn on when the cord is plugged in instead of the battery. thanks!
tentwistle says: Nov 21, 2011. 6:17 AM
can anyone tell me what a voltage jack is, what its for and where to get one please?
lentzell says: Oct 2, 2011. 11:04 AM
Great job, man, but really, the star in the video is your kid. A lot of fun. Mine were that little not long ago...
Guitarra 05.jpg
jmantelli says: Sep 20, 2011. 12:30 AM
This is the best instructions Ive seen for this!going to try my hand at this one this weekend for my cbg! Did you fix the drawing? As someone mention the drawing inputs were wrong but picture was right???
tech-tut (author) says: Sep 20, 2011. 5:11 AM
I only reference the schematic from http://runoffgroove.com/littlegem.html. I've built about 30 amps using these very steps with no issues. If the exact link to the schematic in question can be supplied I'll be happy to look at it if it was something that I created.

If you run into issues I can be contacted at 'robbie [ at ] tech-tut.com'. I usually answer back quickly (within 2 hours) if it is a question I can answer.
XxBiohazardxX says: Sep 4, 2011. 10:14 PM
awesome....but, can I use other model of Jack DC? for example this...
3422.jpg
tech-tut (author) says: Sep 5, 2011. 7:41 AM
Yes. Any DC jack is fine. If you have three contacts they will fit perfectly wihout any modifications.
boekamp87 says: Aug 19, 2011. 5:16 PM
Forgot to add a pic of my build.
IMG00064-20110816-1759.jpg
boekamp87 says: Aug 19, 2011. 5:13 PM
This was a fun build, thanks. I made a Heineken Mini-keg amp out of it.

Only thing, I think your hand drawn schematic might be wrong--specifically the input section. I did it completely to the schematic, and the unit worked but the speaker (a decent one) sounded awful. So I desoldered everything and went by your picture instead (really just switched the position of a few wires on the input) and it works perfectly now.

Anyway, thanks again. My build came out great and I'd have never figured this stuff out myself.
andrezfen says: Jul 30, 2011. 9:43 PM
mine is here too..
IMG_3385.JPGIMG_3345.JPG
pquin3 says: Mar 14, 2011. 9:07 PM
Okay, cool, that was a fun build, kind of like figuring out a code, but those electronics are REEELY SMALL! Love it with my CBG, but I can't say its working exactly right yet, and I'm not an electronics wizard at all. Problem is, with the gain turned down, I get almost no volume, even with the volume turned all the way up. With the gain turned even a little up (say 25%) the feedback is really over the top. So what say you, electronics wizards? Did I screw up the circuitry? Could it be the Piezo pickup? Would a solenoid pickup work better? Or is this the consequence of wandering around blind without really knowing what I'm doing?
chuckw68 says: Mar 1, 2011. 8:36 AM
I just finnished mine.You can see it on my You Tube channel. seach chuckwier on You Tube.
It was fun and easy to build. I have no electonics expirence. This was a great instructable.
dirtyroger says: Oct 11, 2010. 4:35 PM
Well this is an amazing build, its gonna have to be my new project after i've finsihed my CBG.

I've started a blog for my first CBG build here dirtyguitarguide.com
radiorahim says: Aug 22, 2010. 12:57 AM
Cool. I'm glad you decided to use a 4" speaker for the second one, I was going to say the 2" speaker was too small. I made a cigar box amplifier too. I didn't have a hole saw or access to a jig saw so I had to trace the hole with a 1/4 drill bit and join the individual holes together. I'll upload some pics soon.
radiorahim says: Sep 19, 2010. 10:12 AM
Here's mine.
P1010856.JPG
F-17 says: Aug 16, 2010. 9:22 PM
Thats pretty Cool man, its like one of those tiny clip on amps
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