Dan Amstrong Blue Clipper Fuzz.
This pedal will go over well with the minimalist crowd – the front of the pedal features a lone volume knob, a blue LED and an on/off switch. The switch is not the normal button you”ll see on most stompboxes – it”s very easy to press and a simple brush past could possibly engage the pedal. The battery is changed by removing some very stubborn screws on the back cover – it took me a while to get into the unit, and once inside, I noticed that the manufacturer was fairly conservative in the amount of solder used, raising the real possibility that you may have to climb inside the case with a hot iron someday. That said, the construction seemed solid and the case is built like a tank. If you”re looking to add thick fuzz that can play naughty or nice, this pedal is the way to go.
Go to that page to read the explanation about above circuit design.