Fuzzy is our take on the Fuzz Face circuit. It's designed to be easy to build and tune. It uses npn-transistors instead of pnp to simplify the power circuitry. It has biasing pots for both transistors to allow builders to try different npn transistors: silicon, germanium, low or high gain.


Biasing the transistors

Use a multi-meter to get to a good bias starting point:

  1. Clip the black lead to any ground point on the pedal (e.g. the audio jack ground) with an alligator clip;
  2. Clip the red lead to the collector of Q2, using the trim-pot try to get the voltage to ~4.5V;
  3. Move the red lead to the collector of Q1, get it anywhere between 0.6V and 1.5V;
  4. Go back and forth between collectors of Q2 and Q1 a couple more times to make sure that the values are as listed above. Biasing one transistor might throw off biasing of the other.

Once you get the initial bias, I recommend plugging the pedal and tweaking the bias by ear. Bias point of Q2 affects the sound the most, but feel free to experiment with both!