Protlith kit

The Stone Grey Distortion was originally derived from a distortion circuit called the ?CMOS Driver? from a Japanese electronics book published in the early 1980s. The CMOS Driver circuit was tweaked somewhat from the Japanese circuit, notably by changing the op-amp gain method, adding clipping diodes in the op-amp stage, and adding a tone control. However, the final Stone Grey circuit still strongly resembles the CMOS Driver and there is no doubt as to its origins.

This kit contains the pcb and all necessary parts to build a fully working effect. Just select the enclosure above, and get 3 knobs, up to 22mm diameter, for 6,3mm shafts separately.
Here is the BOM: Parts list

This project is by Aion Electronics, in collaboration with Musikding. If you have any problems with the contents of the kit, please contact Das Musikding (Klaus).

Here is the direct link to the manual with layout and schematic:
Instructions