Nothing Special   »   [go: up one dir, main page]
Scribd Logo
Upload

Welcome to Scribd!

  • 9 views

    Pumpd Up Fuzz Face

    Uploaded by

    Léo Herbreteau
    This document provides instructions for building a Fuzz Face PNP circuit board with a charge pump. Key points include: 1) A charge pump allows the positive-ground circuit to share a power supply with negative-ground pedals. 2) Germanium transistors are recommended but vary, so biasing is adjusted with a trimmer potentiometer. 3) Optional capacitors filter hiss that some germanium transistors produce.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd

    Pumpd Up Fuzz Face

    Uploaded by

    Léo Herbreteau
    9 views3 pages
    This document provides instructions for building a Fuzz Face PNP circuit board with a charge pump. Key points include: 1) A charge pump allows the positive-ground circuit to share a power supply with negative-ground pedals. 2) Germanium transistors are recommended but vary, so biasing is adjusted with a trimmer potentiometer. 3) Optional capacitors filter hiss that some germanium transistors produce.

    Copyright

    © © All Rights Reserved

    Available Formats

    PDF, TXT or read online from Scribd

    Did you find this document useful?

    Is this content inappropriate?

    This document provides instructions for building a Fuzz Face PNP circuit board with a charge pump. Key points include: 1) A charge pump allows the positive-ground circuit to share a power supply with negative-ground pedals. 2) Germanium transistors are recommended but vary, so biasing is adjusted with a trimmer potentiometer. 3) Optional capacitors filter hiss that some germanium transistors produce.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    9 views3 pages

    Pumpd Up Fuzz Face

    Uploaded by

    Léo Herbreteau
    This document provides instructions for building a Fuzz Face PNP circuit board with a charge pump. Key points include: 1) A charge pump allows the positive-ground circuit to share a power supply with negative-ground pedals. 2) Germanium transistors are recommended but vary, so biasing is adjusted with a trimmer potentiometer. 3) Optional capacitors filter hiss that some germanium transistors produce.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 3

    Fuzz Face PNP with Charge Pump

    This is an updated PCB from www.guitarpcb.com which includes a few modifications from the original circuit on which it
    is based.

    Part Value Part Value


    R1 1M C2 10u
    R2 33K C3 10u
    R3 470 or 330 C4 2u2
    R4 100K C5 10n
    R5 1M C6 20u
    R6 330 C7, C8 100-220p Ceramic (Optional-see text)
    D1 1n4001 Q1 PNP Transistor ~80-100 hFE
    BIAS 20K Trimmer Q2 PNP Transistor ~95-120 hFE
    IC1 7660S or compatible VOLUME A500K
    charge pump-see text
    C1 47u FUZZ B1K
    Notes about this build

     A charge pump has been added to allow this Positive-Ground circuit to share a power supply with negative
    ground pedals. Positive-Ground circuits typically cannot share a power adapter with negative ground pedals.
    This is ideal for pedal boards that use daisy-chained power and projects which contain multiple effects within a
    single enclosure.
     The charge pump you use must be compatible with the 7660/1044 pin layout. Some charge pumps have a
    frequency-boost feature which will increase the oscillator from the default 10kHz up to 35-45kHz. We
    recommend that you use a charge pump with this boost feature to avoid any whine or clock noise. We have
    seen a high failure rate with some manufacturers’ MAX1044 chips, so we prefer the 7660S (e.g.: TC7660SCPA).
    While all 1044 chips seem to have the boost feature, on the 7660 chips, the “S” designation after the number
    indicates that it has the frequency boost feature, whereas the original 7660 (without an “S”) chips did not.
     The original Arbiter Fuzz Face pedals were equipped with NKT275, AC128, or SFT363E transistors, depending on
    what date the unit was manufactured. None of these are readily available today, and those that do exist are
    quite expensive. Many of the most commonly available and affordable Germanium transistors available today
    come in a TO-5 metal canister, which this board was intended to accommodate. Examples of these include
    2n404, 2n404A, 2n1305, 2n1307, 2n1309, CV7355, etc. There are a number of Germanium transistors that come
    in smaller packages as well, which also fit on this board easily.
     Germanium transistors can be damaged by heat. We recommend that you socket the transistor holes, and then
    insert the transistors into the sockets after the heat has dissipated. If you don’t socket, it is recommended that
    you use a small alligator clip on the component side of the lead from the solder joint to act as a heat sink while
    soldering.
     Vintage germanium transistors vary greatly from one piece to the next, including gain values, leakage, etc. Some
    of these transistors may generate some high-end hiss, which is not desirable. To account for this, this board
    layout includes 2 small capacitors which were not in the original circuit, C7 and C8. These act as a filter for the
    hiss, but do not reduce the level of any of the high-pitch guitar notes. We recommend that you initially build this
    project without these, and determine if they are needed after performing a sound check. If used, recommended
    values are 100-220pf.
     This circuit also contains modern features such as a reverse-polarity protection diode, and 2 pull-down resistors
    that discharge capacitors when the circuit is not in use. There is also a biasing trimmer resistor that is described
    in more detail in the next section.
     This PCB has a ground for each audio jack sleeve. If you use another wiring scheme to ground the sleeve of the
    audio jacks, such as a GuitarPCB.com 3PDT board, star wiring, etc, you may leave these empty and just use the
    “T” or “tip” pads. Just make sure the board is connected to ground at some point or it will not work.

    Biasing

    In order to have this circuit sound like a Fuzz Face, you must use transistors in the recommended gain (hFE) ranges and
    correctly bias the circuit. There is a 20K trimmer potentiometer on this board designed to help you adjust the bias
    perfectly to adjust for variances in transistors. The “Test” pad on the board can be populated with a single SIP socket, or
    a thick lead from a diode, etc. If you have a digital multimeter with test clips, you can clip one DMM test lead onto this
    bias test pin and the other to ground, leaving your hands free to adjust the trimmer. To properly bias, adjust the trimmer
    until your DMM reads about 4.5-4.8 VDC, or half of the input voltage (most guitar effects wall adapters and new 9V
    batteries measure about 9.6 VDC).

    For more information (hyperlinks embedded within):

     Crash Course in Pedal Building by Bruce R.


     Technology of the Fuzz Face, by RG Keen.
     How and Why to Solder Correctly YouTube video by Curious Inventor
     Easy Pedal Wiring Diagram, Pots and Power by GuitarPCB.com forum members
     Boards with T and S style wiring options by tonmann
     Biasing Part One by tonmann

    Special thanks to:

     RG Keen, for his analysis of this circuit on geofex.com (see link above)
     Tonepad, as I referenced their charge pump circuit on their bipolar power project
     BeeJive Pedals, as I referenced their Fuzz Face circuit and borrowed a few of their ideas around the trimmer and
    bias test terminal on the layout.

    This document, PCB Artwork and Schematic Artwork © Bruce R and GuitarPCB.com. Use of PCB and schematic artwork
    for any purpose other than to build a board purchased from GuitarPCB.com without written permission is prohibited.
    Distribution of this document is also prohibited without written consent from GuitarPCB.com.

    You might also like