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DIY amp directions

Started by Lauren, August 25, 2014, 07:10:38 PM

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Hi There,

My husband is an avid Fender guy and plays around with building his own guitars.  I would love to surprise him by building a guitar amp for him out of something cool, like a beer can, thermos, or lunch box.  I've seen some ideas online, and spent an hour at Radio Shack trying to piece some parts  together today based on an idea I saw on Instructables.com, but I don't think I've got a great plan.  I don't know how to read schematics, but I am willing to do that research to figure it out if necessary.  I would love a relatively simple but fully functional and very cool plan for creating an amp for him.  I'm thinking something like the Smokey Amp, but in another casing.  Hope you can help!!



This is the place, we've done some cool things here before.  I suggest taking a look at the Little Gem, it's real easy to build and if you follow the perfboard you don't even need to know how to read the schematic.  Here is the link: http://www.runoffgroove.com/littlegem.html

Do you know how to solder?  That you will need to know.  Unless you built it on a breadboard...that could be solderless for the most part.

As to ideas for what to put it in, the sky is the limit.  You could use a PVC pipe end cap, jewelry box...tupperware?  Most anything really.  Check out these threads on interesting amps:

Life is what you make it.
Still rockin' the Dean Markley K-20X


Hi Lauren, welcome.

What a delightful idea!

While it's a little more complicated I would suggest that the Ruby might be a better proposition;


This can be run from either a 12 volt battery pack and/or a 9-12 volt DC "wall wart"/plug-pack mains supply.

Joe's right, small amps like this have been built into all manner of things that happened to be to hand.  I go wandering around supermarkets, $2 shops, hardware stores, and thrift/op-shops  looking at things like sundry containers and even baking dishes thinking "amp chassis" and it's surprising what turns up when you look at stuff that way.

For example I've seen a few busker amps built into small plastic jerry cans like...


... with a hole cut in the side to accommodate a 6 or 8-inch speaker (bigger the better) with the circuit board stuck down inside using a few dabs of silicone sealant.


Soldering is not a hard skill to acquire.  You need rosin-cored electrical solder, a soldering iron of about 30 watts, and a damp cloth pad to wipe the tip before making each joint.

The classic method of learning how to solder is to make up a drink-coaster sized matrix of 10x10 bits of fine tinned copper wire, then soldering up all the joints.  Most people are doing satisfactory joints by the last one. (if not, do a second one and you'll be expert   :dbtu:)

- wipe the iron tip clean
- put a small dab of fresh solder on the tip (this is not to make the joint but to couple heat from the iron tip to the wires better)
- hold the iron tip against the wires to be joined for a couple of seconds to heat the joint up
- run a little fresh solder onto the joint.

Don't carry solder to the joint on the iron tip (all the flux quickly burns away).

Heat up the joint and let it melt the solder, not the iron tip.

A good joint should still show the general outlines of the wires, too much solder and it gets blobby (but you can melt off excess with the iron), not enough heat and the solder goes pasty rather than fluid.

You are sure to find some soldering instructional videos on YouTube.

Will be interested to follow how you get on.   :dbtu:
If you say theory and practice don't agree you haven't applied enough theory.


Thank you both so much for the replies!! I plan to make it a project over the long weekend and will post my results (and probably questions!). 

So excited to get started!


Build Thread!  Build Thread!

Progress; thinking, drawings, and pix.  Sound samples.
If you say theory and practice don't agree you haven't applied enough theory.



I purchased  a "mini breadboard and jumper wire pack" from RadioShack.  Does this replace my need for a circuit board? I am confused because in some places the directions seem to state it can be used in place of, and in others, it says that you should use the breadboard to test out circuits, which to me implies that I should then transfer it to a circuit board. (?) 

The plans I am using call for a LM386N-3 Audio Amplifier Chip.  I bought one at RadioShack that does not specify if it is -3, -4, -1, etc.  Can I tell from the description on the back? Does it matter?

The plans I found also call for mini blade auto fuses, 3 amps and 5 amps. It says they are optional.  It also says, "Too much current will not only burn up your amplifier, but it can kill you."  Not wanting to get killed by making this gift, do you think these fuses are a necessity?  Is there a real danger of me getting hurt by this 9 volt battery??

FYI: I am using directions from a book called "How to Make 9 Volt Portable
Guitar Amplifiers," by Mike Melvin and Tim Swike.  It is helpful because it explains the technology/science and has very detailed pics.  I looked at the links you guys shared with me, but I am too new at this to understand all of it without detailed explanation (especially the schematics).  Then I stumbled upon the book on Amazon, and for $11, I figured it was worth the investment. :)

Here is their list of parts:

8 ohm speaker, 3", 1.0 W
2K ohm volume potentiometer, audio taper
b1k ohm distortion control potentiometer, linear taper
2 prong output jack
LED bulb
220uF electrolytic capacitor, 35 v, axial leads
2k resistor
9v battery terminal
jumper wires
LM386N-3 amplifier chip
9v battery
mini toggle switches (on.on DPDT)
Output jack (mono, 1/4")
amplifier knobs
grill cover
soldering tools

I am heading out to RadioShack soon to exchange some of the things I bought when I thought I would follow a different plan.  I am hoping to find the things I am missing there!  Once I hear back from you guys, I will start braving the process of actually starting this project.

Thanks again!!


Breadboard can be used for prototyping or building.  As this is a one off project you can use the breadboard as the finished product.  If you decide you want to go into production, it would be easier to use printed circuit boards.

The 386 suffix denotes how much voltage the IC can withstand, any version is good for at least 9V, so you don't need to worry about it.

Fuses are optional.  You can't hurt yourself with a 9V battery (unless you really wanted to, and connect wires to it that you pierce your skin with).


I'm personally not mad on breadboards, but they are no way permanent, so what you need are "prototyping printed circuit boards".  These are small general purpose PCB which you solder to and are a lot more solid (+/- your soldering) when you are finished.

This is half of a small prototyping PCB called dab-board or donut board (cf Vero or strip-board);

...and this is exactly what I think you should be building.

The difference between the IC types are that as the numbers go up they are able to work at higher powers and higher supply voltages.  I don't think that's going to matter on a 9V battery supply coz the limits are 15V and 18V.  If you use a good quality round hole 8-pin socket you can easily change the IC if needs be.

You can download the datasheet for the chip you are using here;

Quote from: Lauren"Too much current will not only burn up your amplifier, but it can kill you."

Which realistically has somewhere about the same odds as alien abduction  :duh ; forget the fuse.

I suggested the Ruby;


...for a couple of reasons; not least there are very good diagrammes and pix of the actual construction, and if you have never built anything before, this is the way to go.  The second reason is that I think this amp will have much better performance than the other suggested design.
If you say theory and practice don't agree you haven't applied enough theory.


  Sorry, I seem to have messed up with my interpretation of "breadboard".  I was thinking you meant perfboard (vero or strip board) like the picture Roly posted.
  The radio shack breadboard you have is what I call "protoboard" and is not suitable for a permanent installation (and way more expensive).


Obligatory caution: building electronic stuff is highly addictive

It comes in colours but it is not safe for children or small furry animals.  Blood will be spilled.  Fingers will be burned.  You will get shocked (eventually, but not this time).  You will find yourself mumbling as you struggle with soldering something "Next time I'll ... "  and you know your hooked; tomorrow a stomp box, next a big valve amp...   :dbtu:



You actually don't even need the copper. (there is even more basic board that has the 0.1" holes but no copper called "matrix board")

This is built entirely using the leads of the components to make the connections, no added wires except for external connections.  Just stuff the component through and bend the leads to where they need to go, solder, trim (good fine side cutters needed!), next component.

I have a few old suture clamps/hemostats that I use for lead forming, but fine needle-nose pliers will do.

Only about 20-25 solder joints in all.

Start by placing the IC socket (in the right place, the right way around) and tack solder at two diagonal corner pins.  Build relative to that.

Watch the polarity of the FET, the IC, and the two electrolytic caps (and the battery connection!).

If you say theory and practice don't agree you haven't applied enough theory.


Thanks for the video clip...I'll probably need her inspiration as everything involved in this project is new to me, but at this point, I can't even get started enough to fail. Though I suppose that is a failure in itself. LOL. 

I will take your advice and try the Ruby, but I think that one must have some knowledge of how to read those schematics in order to figure out what components to purchase, b/c I didn't see a list and I have very little idea of what I need.  I recognize some of the parts, but not all. 

Would you be so kind as to give me a list of exactly what I need to purchase in order to do this?  I hate sounding so ignorant, but that's exactly what I am at this point!  And I am frustrated by my inability to get going, as I thought my husband would be jammin' on a homemade amp-in-a-thermos or something by now! :/

I appreciate your help, and l look forward to sharing my eventual success with you guys! Not much of a quitter, so I know I'll figure this out at some point.  :)




THANK YOU!  The first link seems to be just what I need!!

J M Fahey

HereĀ“s a simple version, with reasonably easy to follow instructions, a drawing (besides the schematics)  of how parts should be mounted and connected to each other and an important "extra" : a ready to solder PCB which I suggest you buy.

One less thing to worry about.


It still is your decision where to mount it, from (emptied :) ) beer can, to cigar box to Tupperware  to ild VCR tape box.

The first one is the most difficult, I remember mine, full of doubts, reading schematics 1000 times to make certain, solder either not sticking or melting all plastic parts within a mile, ugh !!!!

But when it finally works ....  <3)   <3)   <3)


Just got back from RadioShack...they had *most* of the things on the list, but not all.  I am going to post pics of what I bought, in the hopes you can confirm I bought the right things! 

I bought a big bag (500!) of Carbon-Film Resistors, all 1/4 Watt, because they didn't have the ones I needed in individual packages.  This includes the 10ohm, 3.9K, 1.5M, and 1K called for in the plans.

I found a 10K Linear Pot--but it was called a mini-volume control.  Is that right??  Could not find a 1K Pot and the 1K Trimmer was not a switch at all--it was a little blue thing that seemed very wrong based on the schematics, so I didn't buy it. 

Could not find the transistor.   :(

I already had the LN386.

Purchased the .047uF 50WVDC, 100uF 35WVDC, 220uF 35WVDC, and just realized I didn't buy the .1uF.  >:(  How do I tell the voltage rating? Is that indicated by the "35WVDC"? The plans say minimum of 16 Volts.

Bought the input and output jacks, a 5mm red LED light, batteries, snap connectors, 22 Gauge Stranded wire (they didn't have 24...is this ok??), desoldering braid, 60/40 rosin-core solder, and a small general purpose printed circuit board (the thing I am most uncertain is right). 

So far, I have spent close to $80 on this, I think!  Is that right? I realize I will be able to use many of the elements I purchased again in the future, so I guess it's not so bad. LOL.

SO, to recap: I am still missing the 10K Pot, the MPF102 Transistor, and the .1uF Capacitor.  Hopefully I can get started with what I have??

Getting excited to get this going!