Copyright 2000 R.G. Keen. All rights reserved.
Module 9 is a Big Muff Style feedback diode clipper - that is, it does distortion by putting diodes around the feedback path of an single transistor rather than a diode. This is very similar in principle to the clipping stage of Ibanez' Tube Screamer series. For a detailed discussion of the workings of a feedback diode clipper, see "The Technology of the Tube Screamer".
Here's the schematic and layout:
Here's the parts list and what each part does (Note - caps in uF unless noted; pots are audio taper unless noted):
|R4||10K to 15K|
|R5||100 - 150|
|D1, D2||See Text||Usually 1N914/1N4148 silicon, may sub other types for special clipping needs.|
|C1||1uF, see text|
|C3||1uF, see text|
|C4||1uF, see text|
|Q1||2N5088||High gain silicon NPN; 2N5088 recommended, but actual type number doesn't matter much.|