circuit analysis

Discussion in 'The Projects Forum' started by babb27, Jun 9, 2011.

  1. babb27

    Thread Starter New Member

    Mar 16, 2011
    attached is a AMZ mini-booster guitar effect pedal schematic. I have two questions regarding the function of this circuit.

    1. C1 is 0.05 F this is a huge capacitance. I know you can add capacitors in parallel to achieve this value but it would take too many.

    From what I understand this capacitor (C1) acts as a block for any DC component that the input signal may be carrying. So is this a typo and is there another value that would be acceptable?

    2. What is the purpose of C2? at higher frequencies this will act like a short circuit. that is all i can understand about its function.

    please correct me if i am wrong on this analysis:

    R1 and C5 act to set the input impedance of Q2.

    R4 R2 R3 act as a bias point for Q1.

    C4 helps stabilize the power supply. AKA a decoupling capacitor. or to filter out any noise that the supply may have.

    C6 helps to increase the gain at higher frequencies

    C3 blocks any DC component to the output.
  2. KJ6EAD

    Senior Member

    Apr 30, 2011
    C1 is probably supposed to be 0.05 μF (50 nF). This bill of materials from an updated version supports that theory:

    Your circuit is an adaptation of the JFET μ amp. It's shown at the bottom of page 5 in this application note:

    Circuit theory is described here:
    Last edited: Jun 9, 2011
    babb27 likes this.
  3. babb27

    Thread Starter New Member

    Mar 16, 2011
    thanks for the quick response and the links!