From Goldstomp Works:

The Dr. Pufflesteen CMOS Overdrive is a two-stage CMOS/TTL hex inverter overdrive/distortion circuit. It provides a fairly neutral EQ with a gentle clean and off-clean compression and emphasis on upper harmonics. It does a steel-string folk sound up to tight heavy(ish) controlled distortion.

The Dr. Pufflesteen is based on the classic Tubesound schematic and Red Llama values with changes to both, as well as additional components and controls. This pedal began as a modification