StewMac INTERVAL FUZZ Manual

©2020 StewMac • All rights reserved • i-2354 Updated September 2020
stewmac.com
POWER
This pedal requires a standard 9V DC center-negative
power supply (not included) and consumes less than
100mA. There’s no battery option.
TECHNICAL SUPPORT
If you have any questions at all, our Tech Support Team
is here to help. Email us at [email protected], and
we’ll respond quickly!
INTERVAL FUZZ
PEDAL KIT
INSTRUCTION GUIDE
www.st ewma c.c om
47nJ
.1J63
47nJ 47nJ
IN GND SW OUT
HIT THE SWITCH
AND GET YOUR
PURPLE HAZE ON!
This pedal doesn’t need any knobs to send your signal
into over-the-top fuzz and octave up tones. Although this
no-knob fuzz doesn’t have any controls on the pedal, it’s
easy to coax dierent eects out of it. The pedal is very
responsive to dierent pickups. Humbuckers will produce a
more saturated fuzz than single-coil pickups will.

2
PARTS LIST
TOOLS AND SUPPLIES REQUIRED
Soldering Iron #0502
Solder Wick #0504
Solder #0505
Wire Cutter #1607
Fine-gauge Wire
Stripper #1606
Guitar Tech Screwdriver
and Wrench Set #3693
TOOLS AND SUPPLIES HELPFUL
Not pictured:
Clear silicone adhesive and spray nish
Magnifying glass or
OptiVISOR #1685
Soldering Aids #0521
Multimeter #3607
3M Gold Fre-Cut
Sandpaper (220-grit) #5097
PC Board Holder #0500

3
Resistor values are indicated by colored bands, read from left to right.
The rst color in the code is usually the one painted closest to a lead wire.
See more about resistor color codes on page 5.
2.2M resistor (1) #7368
47K resistor (1) #7369
10K resistor (3) #7362
68K resistor (2) #7380
22K resistor (2) #7379
160K resistor (1) #7415
560K resistor (1) #7420
6.2K resistor (1) #7390
Brown Gray Black Red Brown
Red Red Black Red Brown
18K resistor (1) #7396
4.7K resistor (1) #7359
Yellow Violet Black Brown Brown Yellow Violet Black Red Brown
Blue Gray Black Red Brown
Brown Blue Black Orange Brown
Green Blue Black Orange Brown
Red Red Black Yellow Brown
Blue Red Black Brown Brown
Brown Black Black Red Brown
PARTS LIST
47nF capacitor (3)
#7307
100nF capacitor (1)
#7304
100µF capacitor (1)
#7339
1N4148 rectier diode (2)
#7470
100pF capacitor (1)
#7326
1N5817 rectier diode (1)
#7522
2N5089 transistor (2)
#7514
2N3906 transistor (1)
#7511
2N5
809
2N
3906
101J 100V
.1J63
100uF
47nJ

4
3PDT latching footswitch (1)
#1611
24" of lead wire (1)
#5960
2.1mm DC power jack (1)
#7468 1/4" mono jack (2)
#4652
Printed circuit board (1)
Breakout board (1)
IN GND SW OUT
5mm white LED (1)
#7422
5mm LED mounting bezel (1)
#7432
PARTS LIST CONT
Pre-drilled enclosure (1)
Pedal sticker sheet (1)Pre-drilled enclosure top (1)
Pre-drilled enclosure bottom - not pictured (1)
Screws - not pictured (4)

5
the one painted closest to a lead wire. When a gold
or silver band is present, it’s always one of the last
colors in the code. If you’re having trouble reading
the color bands, try using a multimeter to read the
resistor’s value. Just set your multimeter to ohms and
connect its test leads to each side of the resistor.
A number of dierent components are used to make
an eects pedal. Here is a look at the components
used in this kit:
RESISTORS
A resistor does exactly what it says—it resists the
ow of current. The designated value of the resistor
corresponds to how much resistance there is on the
ow of electrons.
A resistor’s value—the amount of resistance it
creates—is rated in ohms (). Larger ohm values
mean more resistance. For example, a 100
resistor creates ten times as much resistance
as a 10 resistor.
Resistor values are indicated by color bands, read
from left to right. The rst color in the code is usually
UNDERSTANDING ELECTRONIC
COMPONENTS
Band 1 Band 2 Band 3 Band 4 Band 5
1st Digit 2nd Digit 3rd Digit Multiplier Tolerance
6 8 x100
+/- 1%
68K +/- 1%
K=1,000
Blue
Read this band rst (closest to an end)
Gray Black Red Brown
BLACK 0 0 0 1
BROWN 1 1 1 10 +/- 1%
RED 2 2 2 100 +/- 2%
ORANGE 3 3 3 1,000
YELLOW 4 4 4 10,000
GREEN 5 5 5 100,000 +/- .5%
BLUE 6 6 6 1,000,000 +/- .25%
VIOLET 7 7 7 10M +/- .1%
GRAY 8 8 8 .01 SILVER
WHITE 9 9 9 .1 GOLD
0
SOLDERING
MORE HELPFUL
SOLDERING TIPS
AND TRICKS
•Keep your soldering tip
clean by wiping it often
on a damp sponge.
• Also keep it tinned by
occasionally melting
a little solder onto it.
•Don’t blow on the
hot solder or touch
anything until the joint
has cooled completely.
A good solder joint
is shiny—a sign that
it was left to cool
undisturbed.
• Plan so each joint is
only soldered once.
Resoldered joints are
messy and more likely
to fail.
The solder joints you’ll make on the printed circuit
board are very small, and too much heat can damage
the board. The idea is to make joints quickly, without
scorching the eyelets.
1. Hold components in place for soldering by
threading the leads through the board and bending
them apart on the reverse side. You will be making
your solder joints on the reverse side of the board.
2. Melt a small amount of
solder onto the tip of
the iron (“tinning” the iron).
3. Insert the tip into the eyelet and let it heat for 4-5
seconds before touching it with solder. This heats the
contact enough for the solder to ow nicely without
damage. Feed the solder to the eyelet, not the iron,
and you don’t need much solder, just enough to ll
the eyelet. Keep the iron on the connection for a
second longer; this pause gives time for all of the ux
to cook out of the joint. After the joint has cooled,
trim away the excess lead wire.

6
called nanofarads (nF), or trillionths of a farad, called
picofarads (pF). .001μF = 1nF = 1,000pF.
Resistors and capacitors may also be referred to with
shorthand notation on the printed circuit board
when there is a decimal in the value. For example,
the place on the printed circuit board for the 4.7K
resistor will read 4K7 and the spot for a 2.2nF
capacitor will read 2n2. This is done to save space on
the board and make the labels as clear as possible.
Some capacitors have polarity and some don’t.
It’s extremely important to install polarized caps
correctly in a circuit. The negative lead will often
be indicated by a stripe on the negative lead’s side
(often with arrows) and will be shorter than the
positive lead. The positive lead of an electrolytic cap
will be longer and won’t have the stripe on that side.
Installing capacitors with the polarity backwards will
make the circuit malfunction and quickly destroy the
capacitor—even causing it to explode.
CAPACITORS
The two main uses of capacitors are to store
electricity and to block the ow of DC current.
Capacitor values are typically printed on the
component. The key values with caps are their
voltage and capacitance.
The voltage spec for a cap refers to how much DC
voltage it can handle at any given time. If this rating
is exceeded, the capacitor will fail.
Capacitance, measured in farads, refers to how
much electricity a capacitor can hold. One farad
(1F) would be much too large for use in a pedal.
Caps for pedals are rated between millionths of a
farad, called microfarads (F), billionths of a farad,
101J
100V
102J
1u F
.1J63
++
UNDERSTANDING ELECTRONIC
COMPONENTS
DIODES
Diodes are used where you want electricity to ow
in only one direction, such as power rectication,
and also to limit how much current can ow, to
create “clipping” distortion.
Diodes are also polarized, so they need to be
installed in the correct orientation. The stripe
around one end marks the negative (–) lead of the
diode. On the printed circuit board, the printed
outline of the diodes also shows this stripe. Install
each diode so that its stripe matches the direction
shown on the printed circuit board.
stripe
2N5089
TRANSISTORS
Transistors are used to amplify electrical signals.
They have a at side and a round side. The location
on the printed circuit board also has a at side
and a round side. Match the orientation of the
component to this outline.

7
UNDERSTANDING ELECTRONIC
COMPONENTS
1. To minimize redoing steps,
make sure you have a solid idea of
the look and feel you’re going for.
2. Lightly sand the outside of
the enclosure with 220-grit
sandpaper and wipe clean any
debris.
3. Cover the holes from the
inside with masking tape.
4. On a piece of cardboard, place
the enclosure and bottom cover
on scraps of wood to lift them o
the cardboard when spraying.
5. With long, even strokes, spray
a light coat of primer or paint.
Allow 45 minutes of drying time
before the next coat.
6. If you’re using primer-
followed-by-paint method, paint
three coats with 45 minutes
between coats.
7. Now, add your included
stickers and any other desired
decoration (paint pens, acrylic
paint, Sharpie, etc.).
Allow drying time.
8. Add three coats of clear-coat
glaze with 45 minutes between
coats. Wait at least two hours
before adding parts.
You’re creating a pedal from the ground up, so add your own custom paint job too!
Painting your pedal and adding the stickers provided in this kit (or custom decals
that you can create on your own) in advance is not only fun, but it’s much easier than
disassembling the pedal to paint it once you have put it together.
PAINTING
YOUR PEDAL
ENCLOSURE
1
LEDs
LED stands for Light Emitting Diode,
and functionally LEDs are very similar to
regular diodes. LEDs are most often used
as indicator lights in pedals. They are
polarized just like diodes and electrolytic
capacitors and must be installed in the
correct orientation to work. The positive
(anode) lead of the LED will be longer and
the anode side of the LED housing will be
round. The negative (cathode) lead of the
LED will be shorter and the cathode side
of the LED housing will be at. LEDs are
mounted inside of a bezel, which protects
the LED and insulates the leads from
shorting against the enclosure or any
internal components.

8
1N4148 rectifier diode (2)
#7470
1N5817 rectifier diode (1)
#7522
It’s time to install your parts! Before soldering the diodes to your printed circuit board,
make sure you thread the leads through the correct side. The side of the printed circuit
board that has white values and outlines of the components is the correct side. In some
cases, components must insert into the printed circuit board in a specic direction due
to their polarity, so follow the graphics carefully.
INSTALL 3
DIODES
2
Note the stripe around one end of each diode. This
marks the negative (–) lead. On the printed circuit
board, the printed outline of the diodes also shows
this stripe. Install each diode to match the direction
shown, and solder in place.
Next, we’re going to add a bunch of resistors to our printed circuit board. As in the
previous step, you’ll nd an outline of each resistor and its value printed in their proper
location on the printed circuit board. Match resistors to the values on the printed circuit
board and solder in place.
Resistors are not polarized, so it doesn’t matter which lead goes in which eyelet.
They can be installed in either direction.
INSTALL 8
RESISTORS
3
BrownB lack BlackR ed Brown
RedR ed BlackR ed Brown
10K resistor (3) #7362
22K resistor (2) #7379
Yellow Purple BlackB rown Brown
4.7K resistor (1) #7359
Blue RedB lack BrownB rown
6.2K resistor (1) #7390
BrownG rayB lack RedB rown
18K resistor (1) #7396
47K resistor (1) #7369
Yellow Violet Black Red Brown
6.2K resistor (1) #7390
Blue Red Black Brown Brown
10K resistor (3) #7362
Brown Black Black Red Brown
22K resistor (2) #7379
Brown Gray Black Red Brown
Red Red Black Red Brown
18K resistor (1) #7396

9
Resistors have a low prole, sitting closer
to the board than taller components, so
installing these now will make installing
other parts easier later on.
INSTALL
6 MORE
RESISTORS
4
47nJ 47nJ
.1J63
47nJ
47nF capacitor (3)
#7307
100nF capacitor (1)
#7304
100µF capacitor (1)
#7339
100pF capacitor (1)
#7326
.1J63
101J 100V
47nJ
100uF
INSTALL 6
CAPACITORS
5
The 100F capacitor shown below is polarized and must be installed in the correct
orientation. Note the stripe running the length of the cap; this identies the negative (–)
lead (the negative lead is also shorter).
On the printed circuit board, each capacitor has a square-shaped eyelet marked positive (+).
The negative lead’s eyelet is round.
The remaining (3) capacitors below are not
polarized. However, best practice is to solder
these caps in place all facing the same direction.
68K resistor (2) #7380
Blue Gray Black Red Brown
2.2M resistor (1) #7368
560K resistor (1) #7420
Green Blue Black Orange Brown
Red Red Black Yellow Brown
4.7K resistor (1) #7359
Yellow Violet Black Brown Brown
160K resistor (1) #7415
Brown Blue Black Orange Brown

10
2N5089 transistor (2)
#7514
2N3906 transistor (1)
#7511
2N5
809
2N
3906
INSTALL 3
TRANSISTORS
6
Transistors are directional and need to be installed in
a specic orientation. Note that each one has a at
side. On the printed circuit board the location outline
also has a at side. Install each transistor to match the
outline.
2N5089
www.stewmac.com
47nJ
.1J63
47nJ 47nJ
The kit comes with 24" of lead wire.
Cut the wire into eight 2" sections and two 4" pieces.
Strip around 3/32" o both ends of all wires.
Solder the eight 2" leads onto the printed circuit
board in the locations shown in the diagram.
We nd it easiest to feed each lead
through the bottom of the printed
circuit board and solder it on the top
of the board.
TIP
INSTALL 8
LEAD WIRES
7

11
INSTALL
FOOTSWITCH
INTO
BREAKOUT
BOARD
8
Orient the breakout board with the text facing up,
reading left to right. Slide the lugs of the
footswitch up through the bottom of the board.
Solder each lug to the breakout board around it.
If the lugs of the footswitch don’t quite t in the
breakout board, use a pair of pliers to gently bend
the lugs of the footswitch until the breakout board
slides over the lugs.
IN GND SW OUT
IN G NDSW OUT
You can use the pedal
enclosure as a mount for
the footswitch while you
solder the breakout board
to it. Just lay the enclosure face-
up and drop the switch in its
hole. No need to fasten it with
a nut from the back if you don’t
want to.
www.stewmac.com
47nJ
.1J63
47nJ 47nJ
IN GND SW OUT
9
AT TAC H 6
WIRES TO
BREAKOUT
BOARD
Solder the four wires from the
bottom of the printed circuit board
to eyelets in the breakout board as
shown.
Solder one end of each 4" wire to
the last two eyelets on the breakout
board.

12
www.stewmac.com
47nJ
.1J63
47nJ 47nJ
IN GND SW OUT
The printed circuit
board is held in place by
the LED leads and the
leads to the footswitch.
Pass the longer positive lead of the LED
through the eyelet marked“A” and the
shorter negative lead through the eyelet
marked “K”. Solder these leads in place.
Install the footswitch through the top of
the case and slide a washer onto it from
the outside. Use a 14mm wrench to tighten
it up. The footswitch is the eect bypass
switch that turns the pedal on.
Do not connect any of the lead wires at this
point.
11
INSTALL
PRINTED
CIRCUIT
BOARD
5mm LED mounting bezel (1) #7432
5mm white LED (1) #7422
case
The LED mounting bezel consists of two main parts:
A ring that the LED ts into and a plastic plug that goes
over the LED from the back side to keep it in place.
Install the mounting bezel through the top of the
enclosure from the inside. Slip a lock washer and nut
on and tighten it up using a 3/8" socket. Insert the
LED into the bezel so the at side (the shorter lead)
faces to the right side of the enclosure when seen
from inside. Feed the leads through the plastic plug,
and press the plug down until it’s tight in the bezel.
The LED will be held in place when you solder the
leads to the switches and printed circuit board. For
a more secure mount, you can run a bead of clear
silicone adhesive around the plastic plug.
12
INSTALL
LED
INDICATOR
LIGHT
Like some of the caps and diodes,
the LED is polarized and has to be
installed in a specic direction. The
negative lead of the diode has a at
edge and is shorter than the positive.
++

13
12
INSTALL
THE
INPUT JACK
Insert the input jack into the left side hole in the top of the enclosure with the tip
connection facing down, as shown in the diagram. Add the washer, and thread the nut
onto the shaft enough so that the jack can rotate freely. You may need to rotate the jack
to provide easier access to setting the solder joints.
Solder the left-most wire at the top of the
printed circuit board to the input jack lug that
corresponds with the sleeve connection. The
sleeve lug should be the one closer to the DC
jack.
Solder the 4" wire on the left side of the
breakout board to the lug of the input jack that
corresponds with the tip connection. The tip lug
should be the one closer to the outside wall of
the enclosure.
Once the solder has cooled, orient the jack as
shown in the diagram, making sure none of the
connections on the jack are touching any other
components, and tighten the nut on the jack.
13
SLEEVE
SLEEVE
INSTALL
THE DC
POWER JACK
Insert the DC power jack into the center hole in the top of the enclosure making sure
the longer of the two lugs is on the left. Use a 14mm wrench on the included nut to
secure the jack into the enclosure.
Solder the inside left wire to the longer lug of the DC jack.
Solder the inside right wire to the shorter lug of the DC jack.

14
14
INSTALL
THE OUTPUT
JACK
Insert the output jack into the right side hole in the top of the enclosure with the tip
connection facing up, as shown in the diagram. Add the washer and thread the nut
onto the shaft enough so that the jack can rotate freely. You may need to rotate the
jack to provide easier access to setting the solder joints.
Solder the right-most wire at the top of the
printed circuit board to the output jack lug
that corresponds with the sleeve connection.
The shield lug should be the one closer to the
DC jack.
Solder the 4" wire on the right side of the
breakout board to the lug of the output jack
that corresponds with the tip connection. The tip
lug should be the one closer to the outside wall
of the enclosure.
Once the solder has cooled, orient the jack as
shown in the diagram, making sure none of the
connections on the jack are touching any other
components, and tighten the nut on the jack.
Shield lug Tip connection
Tip lugShield connection
COMPLETED
VIEW
15
www.stewmac.com
47nJ
.1J63
47nJ 47nJ
IN GND SW OUT
With the output jack secured, this is what your pedal
should look like.
Congrats on a job well done.
Now, simply attach the bottom of the enclosure with
the included screws, plug it in, and bend some tone!

15
HERE’S HOW THE PEDAL WORKS
POWER: Use a standard 9 volt DC power supply with a 2.1mm center-negative plug (not included). Do not
run at higher voltages! We recommend using a separate dedicated power supply for each pedal. Switching-
type power supplies, daisy chains, and power supplies not intended for pedals do not lter dirty power
well, and can cause unwanted noise.
CONTROL: Although this no-knob fuzz doesn’t have any controls on the pedal, it’s easy to coax dierent
eects out of it. The pedal is very responsive to dierent pickups. Humbuckers will produce a more
saturated fuzz than single-coil pickups will. Similarly, placing a boost or distortion pedal in front of the
Interval Fuzz will yield some amazingly dense and sputtering fuzz tones. If you’re looking for a more subtle
eect, try rolling the volume knob back on your guitar. Experiment with putting this pedal in dierent parts
of your signal chain to nd where it works best for you.
TRUE BYPASS: This pedal doesn’t have a buer amp, so when the pedal is switched o the signal passes
straight through from input to output with no circuitry in between. This means it has the greatest possible
delity to the original guitar signal; basically, when disengaged the pedal is no dierent than an extension
of the guitar cable. Usually you see this feature in high-end boutique pedals.
INPUT
OUTPUT 9V DC