This is a very simple overdrive effect. There are a lot of same kind of effects on the net, but I decided to design something simple. It's a great beginner project.
This is me playing with it:
First I play clean, the switch on the effect.
Step 1: Diode Clipping
Overdrive or distortion occurs, when signal is amplified too much. Amps have an upper limit of volume. If a sound signal is louder than then it's peaks are simply chopped off. That is called clipping (distortion).
We can simulate clipping, by placing diodes between the signal and ground.
Step 2: The Schematic
Now it's time to build one for yourself too!
This is what you need:
6.3mm stereo female jack
6.3mm mono female jack
220uF electrolytic capacitor
two 1N4148 diodes
Incase you don't know, how to read schematics, there are a plenty of tutorials available. Just Google