I completed my first Guitar Pedal based on a popular circuit called the Trotsky Drive. It is a single transistor Overdrive circuit to boost the output of the guitar signal into the clipping region for some distortion. The circuit initially uses a Vintage Transistor from Russia called a KT312 which is a NPN transistor. I did not have this transistor but I did have a 2N3566 button head transistor that works very nicely. I tried some traditional 2N2222 but was not impressed, so I left the 2N3566 in. I have a transistor base that you can take out and plug in other transistors to experiment. Initially I struggled with the wiring for the pedal switch as I was wiring it backwards to the jacks but one I got that sorted out the rest was successful. Certainly my pedal is less refined than the ones found in this site, but for a first attempt at a pedal project I was happy.
The switch on the side is a bright switch and this really has an effect that makes the tone quite a bit more crisp.
Here is a image of the transistor that I am using. A 2N3566. Looks like a little alien space ship.
I have the hood to the LED off and above that the gain and tone controls.
Another image of the 2N3566 but any number of transistors can be used.