If you are into making things with electronics you probably need to test them out from time to time. Paul Falstad has a really great on line circuit simulation app. It’s a Java applet.
Try it out here: http://falstad.com/circuit/
Here’s a picture of a Fuzz Face I mocked up. Notice the scope at the bottom. The scope on the left is the output and the scope on the right is the input, a 40hz sine wave. Hmmm, no distortion have check the values again.
JKowalski posted a nice tutorial on this over at the DIYStompbox forum, here.