Almost authentic tube sound with the FET booster

This mini-booster with field-effect transistors makes the guitar sound quite authentic as with an overdriven tube amp. At lower supply voltage (e.g., 9 volts), there is very little distortion. This can be increased by enlarge the operating voltage, e.g. by connecting two 9-volt batteries in series. If greater distortion is desired, two of these circuits can be connected in series without sacrificing the tube character of the sound.