aion PHOBOS User manual

PHOBOS GERMANIUM FUZZ 1
PROJECT NAME
PHOBOS
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
Tone Bender Mk. III (3-knob)
A reproduction of the third version of the Tone Bender germanium fuzz sold by Macaris in London in the
late 1960s.
Germanium fuzz 1.0.1 (2022-07-01)
BUILD DIFFICULTY
This documentation is for the kit version of the project. If you purchased the PCB by itself, please
use the PCB-only version of the documentation instead. The circuit is the same, but the instructions
are completely different due to the specialized parts and assembly methods used in the kit.
IMPORTANT NOTE
Intermediate
LEVEL
GERMANIUM FUZZ
FUZZ
TONE
9V
PHOBOS

PHOBOS GERMANIUM FUZZ 2
TABLE OF CONTENTS
1Project Overview
2Table of Contents
3Introduction
4Packing List
5Packing List (Cont.)
6Tools Needed
7Component Identification
8Hardware Identification
9PCB Assembly Overview
10 Resistors
11 Diodes
12 Socket & IC
13 Trimmers
14 Capacitors (Non-Polarized)
15 Wire Headers
16 Capacitors (Polarized)
17 Germanium Transistors: Introduction
18 Germanium Transistors (Q1 and Q2)
19 Germanium Transistors (Q3)
20 Footswitch PCB
21 Input/Output PCB
22 Enclosure Layout: Panel Mounts
23 Enclosure Layout: Main & Footswitch PCBs
24 Enclosure Layout: Input/Output PCB
25 Final Assembly & Biasing
26 Final Assembly (Cont.)
27 Schematic
28 Full Parts List
29 Troubleshooting Information
30 Support & Resale Terms
31 Legal Information & Document Revisions

PHOBOS GERMANIUM FUZZ 3
INTRODUCTION
If this is your first pedal, welcome to the hobby and thank you for choosing Aion FX. You’ve just joined
a community of over 40,000 people around the world with a passion for building homemade noise
machines using obsolete electronics technologies, and we’re glad to have you!
If you’ve done this before, it’s great to see you again and we’re confident you’ll find this build experience
an enjoyable one.
Aion FX kits are designed to empower anyone to build a high-quality pedal, no matter the skill level.
The pedalbuilding hobby has traditionally had a steep learning curve, but don’t be overwhelmed—we’ve
done all the hard work for you. All you need to do is follow these instructions and you’ll be on your way
to transforming your tone.
There are a few things to go over before you get started.
• You’re going to have to get your hands dirty—there’s no way around it. Nothing here comes
preassembled, and you’ll have to learn the skills to put it all together. This document will walk you
through everything you need, but be prepared to learn a few things along the way.
• This will take time. Plan on about two hours start to finish. It may take even longer if it’s your first
time building. Don’t rush it. If you find yourself getting frustrated or overwhelmed, take a break
and come back in a couple of hours or the next day.
• No direct technical support is offered. There are several DIY forums and Facebook groups with
thousands of members who enjoy troubleshooting and teaching. But please be sensitive to the
fact that the staff at Aion FX is minimal, and every minute spent helping individuals in private is
time that can’t be spent on new project development.
• There is no implied guarantee of a final product. Aion FX provides the ingredients and the recipe,
but you are responsible for putting everything together to make it work. We’ve tried to make the
process as clear and accessible as possible, but it must be expressly stated that purchasing the kit
is not a guarantee that you will end up with a working pedal.
It’s recommended to read through all of the instructions before you start, particularly if you’ve never
built a pedal before. If you familiarize yourself with the entire process ahead of time and you know what
the goal looks like, each step will make more sense.
Now, on to the fun stuff!

PHOBOS GERMANIUM FUZZ 4
PACKING LIST
This is a list of all the parts that are included with the kit, grouped by value. For a list of all the parts
based on their PCB part numbers, please see page 28.
If you find that any parts are missing or damaged, please fill out the Missing Parts form.
Film Capacitors
NAME QTY
2n2 (0.0022) 1
100n (0.1) 2
220n (0.22) 1
Electrolytic Capacitors
NAME QTY
10uF 2
47uF 1
100uF 1
MLCC Capacitors
NAME QTY
220pF (marked “221”) 1
100n (marked “104”) 1
470n (marked “474”) 1
Diodes
NAME QTY
1N5817 1
1N4742A 1
1N34A (germanium) 1
Resistors
NAME QTY
1k 2
3k3 1
4k7 1
10k 3
18k or 18.2k 1
47k 1
220k 2
2M2 1
ICs
NAME QTY
TC1044SCPA or LT1054CP 1
8-pin socket 1
Transistors
NAME QTY
Transistors, germanium, matched for
Tone Bender Mk. III
3
Trimmers
NAME QTY
10k trimmer 2

PHOBOS GERMANIUM FUZZ 5
PACKING LIST (CONT.)
Potentiometers
NAME QTY
100kB 2
100kA 1
Dust cover 3
Knob 3
Mounting nut, potentiometer, 0.44" 3
Lock washer, potentiometer, 0.5" 3
Outer washer, potentiometer, 0.475" 3
Other
NAME QTY
LED bezel 1
LED, blue 1
9V battery snap 1
DC jack 1
Input/output jack 2
Mounting nut, jack, 0.54" 4
Outer washer, jack, 0.6" 2
Lock washer, jack, 0.5" (thin) 2
Enclosure 1
Enclosure screws 4
PCB, main circuit 1
PCB, footswitch 1
PCB, input/output/DC 1
Switches
NAME QTY
Stomp switch, 3PDT 1
Mounting nut, stomp switch, 0.6" 2
Lock washer, stomp switch, 0.6" 1
Dress nut, stomp switch, 0.77" 1
Wiring
NAME QTY
3-strand wire assembly, 70mm 2
4-strand wire assembly, 108mm 1
3-pin wire assembly header 2
4-pin wire assembly header 1

PHOBOS GERMANIUM FUZZ 6
TOOLS NEEDED
SOLDERING IRON
Temperature-adjustable is
recommended. The optimum
soldering temperature is 700-725º
F (371-385º C) for leaded solder, or
750º F (400º C) for lead-free.
WIRE SNIPPERS
Also called nippers or wire cutters.
The Hakko CHP-170 is the best you
can get for less than $10.
SCREWDRIVER (PHILLIPS)
Used for the enclosure screws. Get a
powered driver if you’ll be building a
lot of pedals!
SOLDER
Preferably 63/37 or 60/40 leaded
solder. Lead-free is more difficult to
use, so if that’s the only type you can
get, it’s best to watch tutorials that
are specific to lead-free solder.
NEEDLE-NOSE PLIERS
These are used for bending leads on
components and other general uses.
Use the smaller type with a tip that’s
approximately 0.05” (1.25mm) wide.
FLAT SCREWDRIVER (SMALL)
This is used for tightening the set
screws on the knobs. The tip should
be no more than 0.1” (2.5mm) wide.
DIGITAL MULTIMETER (DMM)
Most cheap ones in the $10-30 range
are fine for what we’re doing. Make
sure it has audible continuity testing
(i.e. it beeps at the lowest resistance)
and transistor hFE measurement.
FLAT-NOSE PLIERS
Many general-purpose uses, but par-
ticularly tightening the nuts of pots,
switches and jacks. Quicker than
changing out sockets on a ratchet.
RUBBER BAND
Yes, a plain old rubber band. This is
used to tighten the dress nut to avoid
scratching or denting it (which can
happen with metal tools).

PHOBOS GERMANIUM FUZZ 7
COMPONENT IDENTIFICATION
If you’ve never built a pedal before, you’ll need to know what all the components are. These are shown
actual size. (Not all of these types of components may be part of this kit.)
RESISTOR TRIMMER POTENTIOMETER
FILM CAPACITOR
SILICON DIODE
ZENER DIODE
LED
DC JACKWIRE ASSEMBLY HEADER
LED BEZEL
WIRE ASSEMBLY
ELECTROLYTIC CAPACITOR
GERMANIUM DIODE
OP-AMP / IC
TANTALUM CAPACITOR
SCHOTTKY DIODE
IC SOCKET TRANSFORMER
MLCC
RECTIFIER DIODE
TRANSISTOR OR JFET
Not polarized. Color may
vary by brand and type.
Not polarized. MLCC stands for
“multi-layer ceramic capacitor.”
Some Schottky diodes
also look like this.
These are very fragile, so be
careful when handling them.
Polarized. The positive side
is marked.
Polarized. The negative side
is marked.
Charge pumps and delay chips
also look like this. They may
have more than 8 legs.

PHOBOS GERMANIUM FUZZ 8
HARDWARE IDENTIFICATION
The hardware comes unassembled, so you’ll need to sort & identify each of the pieces. The diagrams
below are actual size, so you can set them against the printed page to identify them if needed.
I/O JACK
TOGGLE SWITCH
POTENTIOMETER
(SINGLE)
FOOTSWITCH
POTENTIOMETER
(DUAL)
MOUNTING NUT
MOUNTING NUT
MOUNTING NUT
MOUNTING NUT
DRESS NUT
OUTER WASHER
DRESS NUT
OUTER WASHER KNOB
LOCK WASHER
LOCK WASHER
LOCK WASHER
LOCK WASHER
DIAMETER: 0.54” / 13.7mm
DIAMETER: 0.36” / 9.1mm
DIAMETER: 0.44” / 11.2mm DIAMETER: 0.5” / 12.7mm
DIAMETER: 0.6” / 15.2mm
DIAMETER: 0.375” / 9.5mm
DIAMETER: 0.475” / 12mm
DIAMETER: 0.5” / 12.7mm
DIAMETER: 0.4” / 10.1mm
DIAMETER: 0.6” / 15.2mmDIAMETER: 0.77” / 19.6mmDIAMETER: 0.6” / 15.2mm

PHOBOS GERMANIUM FUZZ 9
PCB ASSEMBLY OVERVIEW
Now it’s time to start building!
The first thing you need to do is snap apart the PCBs
into 3 separate boards (if needed) and break off the
tabs from each using needle-nose or flat-head pliers.
You should be left with the PCBs shown to the right.
The general principle for PCB population is that you
want to work in layers from shortest components
(i.e. lowest-profile) to tallest so that when the PCB is
upside-down, everything is making contact with the
work surface and is held in place.
Generally speaking, you should populate the
components in this order:
1. Resistors
2. Diodes
3. IC sockets
4. Trimmers
5. MLCC capacitors
6. Film capacitors
7. Electrolytic capacitors
8. Germanium transistors

PHOBOS GERMANIUM FUZZ 10
RESISTORS
PART VALUE
R1 47k
R2 220k
R3 1k
R4 10k
PART VALUE
R5 3k3
R6 18k or 18.2k
R7 1k
R8 10k
PART VALUE
R9 10k
R10 220k
RPD 2M2
LEDR 4k7
Using the parts list above, populate the resistors by pushing them through the holes and bending the
leads outward at an angle to hold them in place. Resistors are not polarized, so they will work in any
direction. Turn the board upside-down to keep the components held in place while you solder.
You’ll use this same technique for most of the other components as well.
If it gets too crowded, just flip the board and solder everything you’ve done so far, then cut the leads
using the wire snippers to make room for more.
If this is your first time soldering, watch tutorial videos on YouTube and make sure you get it down
before you begin. You don’t want to practice or experiment on this board!
Note: R6 may be either a red 18k resistor or a brown 18.2k resistor depending on availability. In this
position, the 1% difference in value won’t have any impact on the circuit.

PHOBOS GERMANIUM FUZZ 11
DIODES
PART VALUE
D1 1N5817
D2 1N34A (Ge)
Z1 1N4742A
Next, you’ll populate the diodes. The 1N5817 is black with a silver stripe, while the 1N4742A is orange
with a black stripe. The 1N34A germanium is not labeled, but is significantly larger than the other two.
Diodes are polarized, so make sure to identify the polarity band (which indicates the cathode, or negative
side) and match the band to the footprint on the PCB. The germanium diode has several colored stripes,
but the cathode is indicated by a thick black stripe.
Precautions with germanium diodes
Germanium diodes are fragile and require more care than the other components. Make sure to observe
the following precautions when working with them.
• To prevent stress on the glass body of the diode, when bending the leads,
use needle-nose pliers or tweezers to clamp the lead as close to the body as
possible while you bend it down. The bend should be about 0.05–0.08” from
the body of the diode, so use pliers with a very narrow tip.
• Old-stock diodes can sometimes develop corrosion on the leads. It’s recommended to use
sandpaper or a small file to gently rough up the leads where they will make contact with the
solder. This will make adhesion much easier.
• Be quick when soldering. Germanium diodes can easily be damaged by overheating. Limit contact
with the soldering iron to 1-2 seconds maximum. If you don’t have a good solder joint, wait a
minute or two for it to cool before trying again.

PHOBOS GERMANIUM FUZZ 12
SOCKET & IC
Next up is the IC socket. You can’t bend the leads of a socket like you can with the other components, so
it won’t stay in on its own until it is soldered.
Again, it’s much easier to do this with gravity holding it in place for you, so you’ll want do the socket
before you do any of the taller components.
Installing the IC
Don’t insert the IC into the socket just yet. We will do this in a later step, after we’ve finished soldering
the tallest components (the polarized capacitors). This information is just listed here for reference.
The legs of the IC are bent outward slightly during manufacturing, so they’ll need to be bent back inward
before they can be inserted into the sockets.
It’s easiest to do this by laying the IC legs against the table and bending the body itself so all four legs on
the side are straightened out at once. Then, flip it and do the other side.
ICs may have two different orientation marks: either a dot in the upper-left or a half-circle notch in the
middle of the top side. Some ICs have both marks. This shows which way the IC should be rotated when
inserting it into a socket (the socket also has a half-circle notch).
PART VALUE
IC1 TC1044SCPA
or LT1054CP

PHOBOS GERMANIUM FUZZ 13
TRIMMERS
The bias trimmers come next. The two trimmers have the same value, so either one can be used in either
position. The trimmers can be soldered like normal components, by bending the legs outward as shown:
These trimmers are used to bias the germanium transistors. We will adjust them at the end once the
pedal is fully assembled.
PART VALUE
Q1/2 BIAS 10k (103)
Q3 BIAS 10k (103)

PHOBOS GERMANIUM FUZZ 14
CAPACITORS (NON-POLARIZED)
After the trimmers come the box film and MLCC capacitors. These are all several different heights, but
there aren’t as many, so just do them all at once. Bend the leads at an angle to hold them in place.
MLCCs and box capacitors are not polarized and will work in any direction. To keep things neat, though,
it’s best to put them all facing the same way so the values can easily be read.
Note: C6 (box film capacitor) may be either blue or red. The blue one will have the value printed on the
top, while the red type would have the value on the side. The text on the side of the blue capacitors is not
related to the value and can be ignored.
PART VALUE
C1 100n (0.1)
C2 220pF (221)
C3 220n (0.22)
C5 100n (0.1)
PART VALUE
C6 2n2 (0.0022)
C10 470n (474)
C11 100n (104)

PHOBOS GERMANIUM FUZZ 15
WIRE HEADERS
Install the two 3-pin headers (wire connectors) as shown above. These have a polarity pin, so as long
as they are pressed all the way down, there’s only one possible way to install them. They do fit pretty
tightly in the holes, though, so press firmly.
There’s also a 4-pin header on the I/O board that we will do in a later step.

PHOBOS GERMANIUM FUZZ 16
CAPACITORS (POLARIZED)
Populate the electrolytic capacitors. They are polarized (i.e. they will only work in one direction), so note
the vertical mark that indicates the negative side. The longer leg is positive and fits in the square pad.
At this point, we only have the transistors left to do, so now is a good time to go back and insert the IC
into the socket (page 12).
PART VALUE
C4 10uF
C7 100uF
C8 10uF
C9 47uF

PHOBOS GERMANIUM FUZZ 17
GERMANIUM TRANSISTORS: INTRODUCTION
Next are the germanium transistors. These are very different than modern
electronic components, so they need an introduction before we cover how to
install them.
Silicon vs. germanium
Compared to silicon, germanium transistors are imprecise and inconsistent,
even among the same part number. As a result, when classic fuzz circuits use
germanium transistors, it’s not the part number that’s important, but the
specifications of the individual device. Two transistors of different part numbers
with identical gain and leakage will sound exactly the same. Conversely, not all
transistors of the same part number will work in a particular circuit.
Because of this, be aware that this kit may include any of several different part numbers. In this
document we will refer to them as Q1-Q3, not by specific part numbers such as AC125 or MП16Б.
Matching
The transistors included in the Phobos kit have been measured and matched for best performance in the
Tone Bender circuit. There are three bags labeled Q1, Q2 and Q3.
It is extremely important that the transistors are not removed from the bags until it’s time to install
them, and only one at a time, to avoid inadvertently mixing them up. Q1 and Q2 are not always visually
distinguishable from each other, and outside of the bags there may be no way to tell which is which. The
pedal won’t sound right if the transistors are used in the wrong positions.
Temperature sensitivity
Germanium is a delicate semiconductor material and very sensitive to overheating. If the transistor is
overheated, it could be permanently damaged. It’s recommended to mount the transistors so they are
elevated above the PCB by about 3/8” (9.5mm) to allow some of the heat to dissipate before it reaches
the body of the transistor. If it takes longer than two seconds for the solder to form a good joint, move to
a different component and let the transistor cool a bit before trying again.
Old-stock precautions
Germanium transistors are not manufactured today except for some expensive industry-specific
applications, so nearly all of the germanium transistors used in guitar pedals are old-stock. The
transistors in this kit are 30 to 50 years old, sometimes even older.
While age has nothing to do with performance of the device itself, the leads may be corroded and solder
may not adhere well unless they are cleaned first. If you notice any corrosion on the leads, use medium-
grit sandpaper or a fine metal file to remove it, and ensure the leads are shiny before soldering.

PHOBOS GERMANIUM FUZZ 18
GERMANIUM TRANSISTORS: Q1 AND Q2
PART VALUE
Q1 Germanium
Q2 Germanium
Now that we’ve covered the basics of germanium transistors, it’s time to install them. Q1 and Q2 are
similar while Q3 is a different type, so we’ll cover Q1/2 first and then Q3 on the next page.
Note: Q1 may be one of two types, either with its legs in a triangle formation as shown in the main
PCB image, or with its legs in a straight line as shown in the diagram on the right. The PCB will match
the transistor configuration. The straight-line transistors have a painted white or red dot on one side
indicating the emitter. Make sure this lines up with the dot on the PCB silkscreen when you install it.
Remove Q1 from the bag. As mentioned on the previous page, it’s important to leave Q2 in its bag until
Q1 has been soldered so they don’t get mixed up.
Insert it into the pads on the PCB, being mindful of the orientation (either the “V” pattern or the emitter
dot). Keep it raised about 3/8” (9.5mm) above the PCB, then bend the legs on the bottom side to keep
it attached. Turn the PCB over and let it hang down while you solder it in place. Be quick and make sure
the transistor casing doesn’t get too hot or the transistor could be damaged.
Now, repeat the same steps with Q2. The legs of this one will always be in a triangular pattern.
Once the first two transistors are installed, check to make sure they aren’t making physical contact with
each other. The base pins are connected to the metal casing, so anything they touch will be shorted
against the base. If they’re touching, just bend them slightly away from each other and they should
remain that way.
Q1 ALTERNATE
CONFIGURATION

PHOBOS GERMANIUM FUZZ 19
GERMANIUM TRANSISTORS: Q3
Once Q1 and Q2 are done, you can remove Q3 from its bag. Q3 is a different type of transistor and
needs to be installed differently.
First, note the emitter tab. The diagram to the right shows the transistor
from the side, so the third leg is hidden behind the first.
Bend the legs down at a right angle as shown in the next diagram. The outer
legs should be bent around 0.25” to 0.3” from the body, and the center leg
(base pin) should be 0.15” to 0.2”.
Now, mount it to the PCB at a right angle with the top of the transistor
pointed toward the bottom of the PCB, as shown in the PCB graphic at the
top of this page. It will overlap some of the resistors. The third diagram
shows a side view.
Make sure there’s some clearance above the resistors. The resistors are
electrically insulated, so it’s not going to cause any problems if the metal
body of the transistor makes contact, but it’s best to keep them apart.
Before soldering, double-check the orientation against the PCB diagram above and ensure the emitter
tab is on the left. These transistors are rare, old, and expensive, and if this one is soldered incorrectly
then it could be easily damaged when removing them.
If everything looks good, go ahead and solder the legs in place. Be quick and make sure the transistor
casing doesn’t get too hot or the transistor could be damaged.
Q3 will partially overlap the biasing trimmers on the right-hand side of the board, so make sure there is
enough clearance that the trimmers can be easily adjusted later.
PART VALUE
Q3 Germanium
EMITTER TAB
EMITTER TAB

PHOBOS GERMANIUM FUZZ 20
FOOTSWITCH PCB
Next, it’s time to finish up the footswitch board. You should have done most of the on-board components
on this board in a previous step, but if not, go back and do those.
There will be one longer assembly with 4 wires and two shorter ones with 3 wires. The longer one goes
in the middle and the shorter ones go on the left and right sides. The wire assemblies should then be
soldered to the footswitch board as shown.
Once all three wire assemblies are soldered, set the footswitch PCB aside. We’ll solder the actual
footswitch and LED in a later step.
PARTS
3-strand wire assembly (2)
4-strand wire assembly
STEP 3
Then, solder the wires from the top.
This is the trickiest part of the whole
build. You want to solder the pads
without touching the iron to the
wires themselves and risking burning
through the insulation. It helps to
use a sharp or narrow tip on the
soldering iron.
STEP 2
Next, bend the wires back upward
and fit the ends of the wires into the
solder pads.
On the top side of the PCB, bend the
exposed wires backward so it holds
the wire in place. Pull the header
back up through the slot partway.
STEP 1
First, thread the wire through the
strain-relief slots, with the blue
side facing outward and the PCB’s
previously-installed components
facing up.
For now, pull it through as far as it
can go.
BLUE
MARKING