The idea behind this project is to create a natural sounding overdrive sound using minimal components. It should also be suitable for a booster for an already driven amp.
Please take note of the transistor pin voltages shown below, specifically the source of the J201 JFET. It may be necessary to audition different J201 for the best sound. MPF102 and 2N3819 will not provide the desired sound in this circuit. Various J201 may have a range of source voltages, even when the drain voltage is set at 4.5 volts. Having a source voltage near 115mV should produce results that are very similar to the sound clips.
The LED serves as protection against potential damage to the MOSFET caused by static electricity (thanks to Joe Davisson for this idea). A 9.1v zener diode may be used as well (as seen in the Jack Orman's AMZ Mosfet Booster), with the same orientation. Jake Nagy's Blue Magic predates the Peppermill and exhibits a similar topology. However, the development of the Peppermill was not influenced by the Blue Magic design and any resemblance is coincidental.