FuzzDog QuagmireFuzz User manual

Quagmir Fuzz
Highly tweakable
Band Of Gypsys in a box
Contents of this document are ©2023 Pedal Parts td.
No reproduction permitted without the express written
permission of Pedal Parts td. All rights reserved.

Important notes
If you’r using any of our footswitch daught rboards,
DOWNLOAD THE DAUGHTERBOARD DOCUMENT
•Download and read the appropriate build document for the daughterboard
as well as this one BEFORE you start.
•DONOT solder the supplied Current imiting Resistor (C R) to the main
circuit board even if there is a place for it. This should be soldered to the
footswitch daughterboard.
POWER SUPPLY
Unless otherwise stated in this document this circuit is designed to be
powered with 9V DC.
COMPONENT SPECS
Unless otherwise stated in this document:
•Resistors should be 0.125W. You can use those with higher ratings but
check the physical size of them.
•Electrolytics caps should be at least 25V for 9V circuits, 35V for 18V
circuits. Again, check physical size if using higher ratings.
LAYOUT CONVENTIONS
Unless otherwise stated in this document, the following are used:
•El ctrolytic capacitors:
ong leg (anode) to square pad.
•Diod s/LEDs:
Striped leg (cathode) to square pad. Short leg to square pad for EDs.
•ICs:
Square pad indicates pin 1.

Schematic + BOM
R1 1M
R2 68K
R3 22K
R4 47K
R5 1M
R6 1K
R7 10K
R8 10K
R9 100K
R10 100K
R11 100K
R12 15R*
R13 1K
R14 220R
R15 68K
R16 22K
R17 47K
R18 1M
R19 1K
R20 10K
R21 1K
R22 220R
R23 220R
R24 100K
C1 100p
C2 100n
C3 1n
C4 4n7
C5 100p
C6 220p
C7 100n
C8 3n3
C9 10n
C10 22u elec
C11 22u elec
C12 22u elec
C13 22u elec
C14 22u elec
C15 22u elec
C16 22u elec
C17 22u elec
C18 22u elec
C19 220u elec**
C20 220u elec**
C21 220u elec**
D1 1N5817
Q1-4 BC549C
BIAS 10KB
FUZZ 1KC
HI 100KA
OW 100KA
VO 100KA
T1 50K trim
*Absolutely not critical.
12R in the original, but
you’ll not notice any
difference with any value
10-47R in here.
**That’s a ludicrous
amount of filtering. 100u
will be more than enough,
and you don’t really need
all three.

PCB layout ©2023 Pedal Parts td.
The power and signal pads on the PCB conform
to the FuzzDog Direct Connection format, so can
be paired with the appropriate daughterboard for
quick and easy offboard wiring. Check the
separate daughterboard document for details.
Be very careful when soldering the diodes and
transistors. They’re very sensitive to heat. You
should use some kind of heat sink (crocodile clip
or reverse action tweezers) on each leg as you
solder them. Keep exposure to heat to a
minimum (under 2 seconds).
Snap the small metal tag off the pots so they can
be mounted flush in the box.
You should solder all other board-mounted
components before you solder the pots. Once
they’re in place you’ll have no access to much of
the board. Make sure your pots all line up nicely.
The best way to do that is to solder
a single pin of each pot in place then melt and
adjust if necessary before soldering in the other
two pins. If your pots don’t have protective
plastic jackets ensure you leave a decent gap
between the pot body and the PCB otherwise
you risk shorting out the circuit.
BIASING
Adjust the trimmer until you get around 2V on
the collector of Q2 (shown above). Test the range
of sounds you get when adjusting the BIAS pot.
Tweak the trimmer until you’re happy. There’s no
fixed correct value.
There are extra pads for
T1 to allow different types
of trimmer to be used. As
long as one leg goes into
each column as shown
here you’re good.

Test the board!
Ch ck th r l vant daught rboard docum nt for mor
info b for you und rtak this stag .
UNDER NO CIRCUMSTANCES will troubl shooting h lp
b off r d if you hav skipp d this stag . No xc ptions.
Once you’ve finished the circuit it makes sense to test is before starting on the switch and ED
wiring. It’ll cut down troubleshooting time in the long run. If the circuit works at this stage, but it
doesn’t once you wire up the switch - guess what? You’ve probably made a mistake with the switch.
Solder some nice, long lengths of wire to the board connections for 9V, GND, IN and OUT. Connect
IN and OUT to the jacks as shown. Connect all the GNDs together (twist them up and add a small
amount of solder to tack it). Connect the battery + lead to the 9V wire, same method. Plug in. Go!
If you’re using a ribbon cable you can tack the wires to the ends of that. It’s a lot easier to take them
off there than it is do desolder wires from the PCB pads.
If it works, carry on and do your switch wiring. If not... aw man. At least you know the problem is
with the circuit. Find out why, get it working, THEN worry about the switch etc.
Your compl t d circuit board
including pots

Now’s the time
to refer to the
daughterboard
document for
your chosen
bypass method.
Enjoy your pedal!

This template is a rough guide only. You should ensure correct marking of your
enclosure before drilling. You use this template at your own risk.
Pedal Parts td can accept no responsibility for incorrect drilling of enclosures.
FuzzDog.co.uk
Recommended drill sizes:
Pots 7mm
Jacks 10mm
Footswitch 12mm
DC Socket 12mm
Toggle switches 6mm
35.5mm
Drilling template
without battery
Hammond 1590B - 60 x 111 x 31mm
It’s a good idea to drill the pot and
toggle switch holes 1mm bigger i
you’re board-mounting them.
Wiggle room = good!
27mm