OCD PedalThe OCD (which stands for Obsessive Compulsive Drive) is an Overdrive Pedal developed by Fulltone.
Its a very famous pedal for its drive capabilities (also higher territories, almost distortion like) and its retaining the bass frequencies (a tube screamer kinda pedal is more mid-rangy)
The OCD is a very simple circuit and easy to build. Its a basically a standard op-amp drive circuit (like a tube screamer) with an enhanced tone stack.
Additionally theres a switch between LP and HP. The HP mode adds additional resistor in parallel, which decreases the output resistance and increases the output / headroom.
The components required are all easy obtainable.
There are some Projects to build an OCD, one is the Madbean Egodriver (can be ordered via the discontinued Projects page). The Egodriver is great, because of its additional feature, the clipping option. Clipping can be switched between the default MOSFET stage or an additional LED stage. LEDs sound really great for this circuit.