This tutorial was also posted in my blog. Check it out for more DIY projects!

This is a A/B/Y box. It acts as a switch. You can plug in a guitar and have it's output go into two amplifiers.
You can choose between the amplifiers or use both at once.
This is a very simple build. As a beginner I had only moderate work.

Step 1: Bill of Materials

Bill of materials:
2x 5mm LEDs
2x 4,7k Ohm Resistors
2x DPDT Switches (http://www.banzaieffects.com/files/images_detailed/d_4217.gif)
3x 1/4 jacks (P-10 jacks - http://www.effectsconnection.com/oscommerce/images/marshallstylemono.jpg)
Wires
Plastic container
9v battery clip (http://www.amqrp.org/kits/NCKeyer/elmer/P7190015a.jpg)

Tools needed:
Something that can drill, such as a Dremell
Soldering Iron & Solder

Step 2: Prepare the Compartment

You'll need a plastic or metal compartment.

There should be four holes on top (2 for the LEDs and 2 for the DPDT switches), one hole in front (for the input and two holes on the back for the output.

You could also have an extra hole for a 9v input plug but I didn't use one in this project.

Step 3: Electronics

Now for the fun part... connecting everything.

Follow the schematics available bellow. They are pretty simple.

The drawing was made with BEGINNERS in mind so it doesn't follow any conventions. I believe it is pretty self explanatory.

I tested everything out using a breadboard before soldering. This is a specially useful step for amateurs.

Testing the circuit.

Video

invalid movie: http://vimeo.com/5571157

Step 4: Testing

Now you should have your A/B/Y box.

You plug in your guitar in one end and the amplifiers on the output ends.

By pressing the A/B switch you can choose between any one of the amplifiers as the output.

By pressing the A/B or A+B switch you can choose between using only one of the outputs or using both at the same time (that's the difference between A/B and A/B/Y box).

Enjoy.

Testing the finished ABY box.
http://vimeo.com/5571171