This project is a replica of the original vintage Electro-Harmonix LPB1 (Linear Power Booster) or LPB2. The only difference between an LPB1 and LPB2 was the enclosure and switch, LPB1 plugs into your guitar, LPB2 is a stompbox. We named this project CB1 (Clean Boost 1) and it is a stompbox version similar to the LPB2. The LPB2 is actually a much better boost (less ugly distortion) if you move the volume to the front of the circuit instead of the stock version where the volume is at the end. Schematic and diagrams of the input volume mod are listed below.

Description from General Guitar Gadgets.