# circuit analysis

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

1. ### babb27 Thread Starter New Member

Mar 16, 2011
21
1
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.

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2. ### KJ6EAD Senior Member

Apr 30, 2011
1,426
363
C1 is probably supposed to be 0.05 μF (50 nF). This bill of materials from an updated version supports that theory: http://www.generalguitargadgets.com...f?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a.

Your circuit is an adaptation of the JFET μ amp. It's shown at the bottom of page 5 in this application note: http://www.national.com/an/AN/AN-32.pdf.

Circuit theory is described here:
http://www.geofex.com/article_folders/foolwfets/foolwfets.htm

http://www.geofex.com/Article_Folders/modmuamp/modmuamp.htm.

Last edited: Jun 9, 2011
babb27 likes this.
3. ### babb27 Thread Starter New Member

Mar 16, 2011
21
1
thanks for the quick response and the links!