Thonk TouellSkouarn Strakal Brulu User manual

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October 25th 2013 www.thonk.co.uk 1
TouellSkouarn
Strakal Brulu Module
Eurorack DIY Kit
Instructions
Version 1.0
OVERVIEW
For the most recent version of this
document please visit
http://www.thonk.co.uk/documents/strakal
For all technical support please visit
http://bit.ly/1h4aVPk on Muffwiggler.
The Strakal Brulu manual is here
http://www.thonk.co.uk/documents/strakal/
StrakalBrulu_ReGrenvEo.pdf
All Thonk kits are sold under our standard Terms and Conditions -
http://www.thonk.co.uk/faq/
DIY INSTRUCTIONS
This document gives detailed instructions that assume you have purchased a
complete kit from www.thonk.co.uk. It also assumes no previous knowledge
of electronics. To learn to solder try http://youtu.be/I_NU2ruzyc4 and the
Adafruit guide to excellent soldering – http://bit.ly/1l77tF4!
Watch and understand that whole YouTube video! If you’re not achieving the
results shown in the video then you need to buy new tools or seek advice.
You will not end up with a working module otherwise.
TOOLS REQUIRED
Soldering iron, snipe nose pliers, wire strippers, small flat head screwdriver
and diagonal cutters AKA snips AKA side-cutters. A Digital Multimeter is
necessary for calibrating this module accurately but you can do it by ear to
taste. Thonk sell a range of inexpensive tools here - http://bit.ly/1jxqF3n
IF YOUR KIT IS DATED 2016
CLOSE THIS DOCUMENT AND
DOWNLOAD THE V1.3.1 MANUAL
INSTEAD:
thonk.co.uk/documents/strakal/

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October 25th 2013 www.thonk.co.uk 2
TouellSkouarn
Strakal Brulu Module
Eurorack DIY Kit
Instructions
Version 1.0
SOLDER JOINTS
Your solder joints should look like those shown as ‘OK’ below, they should
have that neat conical shape on BOTH sides of the PCB. If they don’t look
the same on both sides then stop! Work out why from the soldering guides
linked and don’t continue until you are getting those results.
This isn’t just OCD talking, you are very likely to end up with a destroyed,
damaged or defective unit if you’re not hitting that standard.
This photo is from the Adafruit guide to excellent soldering -
http://bit.ly/1jxqF3n and is reproduced under an Attribution-Sharealike
creative commons license - http://creativecommons.org/licenses/by-sa/3.0/

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October 25th 2013 www.thonk.co.uk 3
TouellSkouarn
Strakal Brulu Module
Eurorack DIY Kit
Instructions
Version 1.0
STRAKAL BRULU BUILD INSTRUCTIONS
1.
Start by emptying BAG A into a bowl
or container. This makes it much
easier to pick parts as you need
them and you’re less likely to lose
anything.
2.
The first job is to solder all the
resistors.
3.
Start by soldering the single 1K
resistors in position R18.
4.
Solder the two 100R resistors in
positions L1 and L2.
5.
Solder the two 100K resistors in
positions R4 and R13.

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October 25th 2013 www.thonk.co.uk 4
TouellSkouarn
Strakal Brulu Module
Eurorack DIY Kit
Instructions
Version 1.0
6.
Solder the two 1M resistors in
positions R7 and R8.
7.
Solder the single 220R resistor in
position R9.
8.
Solder the single 390R resistor in
position R17.
9.
Solder the single 470R resistor in
position R1.
10.
Solder the single 12K resistor in
position R16.
11.
Solder the single 15K resistor in
position R15.

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October 25th 2013 www.thonk.co.uk 5
TouellSkouarn
Strakal Brulu Module
Eurorack DIY Kit
Instructions
Version 1.0
12.
Solder the single 33K resistor in
position R2.
13.
Solder the five 47K resistors in
positions R5, R10, R11, R12, R14
14.
Solder the three 4.7K (4K7) resistors
in positions R6, R19, R20. You
should now have no resistors left.
15.
Solder the two 8 pin IC sockets.
Ensure the notches in the sockets
match the silkscreen.
16.
Solder the Vactrol.
Note the orientation of the text on
the Vactrol.
The plus symbol on the PCB should
be closest to the yellow dot on the
Vactrol body.
Note also that on one side of the
Vactrol the leads are further apart,
this end of the vactrol is positioned
closer to the edge of the PCB.
NOTE! – The orientation is vital.

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October 25th 2013 www.thonk.co.uk 6
TouellSkouarn
Strakal Brulu Module
Eurorack DIY Kit
Instructions
Version 1.0
17.
Solder the single 1nF ceramic
capacitor into position C9. The
orientation of this component does
not matter.
18.
Solder the single red 10nF film
capacitor into position C2. The
orientation doesn’t matter.
This capacitor has the marking
‘10nJ63’
19.
Solder the six red 100nF film
capacitor into positions C1, C6, C7,
C8, CD1, CD2. The orientation of
these components does not matter.
This capacitor has the marking
‘u1J63’
20.
Solder the single 1uF film capacitor
into position C4. The orientation of
this component does not matter.
This capacitor has the marking
‘1uJ63’.

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October 25th 2013 www.thonk.co.uk 7
TouellSkouarn
Strakal Brulu Module
Eurorack DIY Kit
Instructions
Version 1.0
21.
Solder the shrouded power header
into place.
NOTE! – The orientation is vital. The
gap in the rectangular shroud should
point inwards.
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22.
Solder the four 47uF electrolytic
capacitors into positions C3, C5, C8
and C11.
NOTE! – The orientation is vital. The
longer lead should go into the hole
marked +
NOTE! – Ignore this pad marked on
C5.
NOTE! – On all these electrolytics
there are two holes provided for the
negative or shorter lead, you can use
either.
do not use

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October 25th 2013 www.thonk.co.uk 8
TouellSkouarn
Strakal Brulu Module
Eurorack DIY Kit
Instructions
Version 1.0
23.
Solder the trimmer into place in the
positions identified. You may need to
bend the legs a little to get them to
fit. Make sure none of the legs are
touching.
24.
Next you need to modify all four
pots.
First snap off the little metal tab
shown. This is easily done with pliers
or snips.
If you don’t do this you may have
problems fitting the faceplate.
25.
Next you need to snip off the two
smaller feet on all the pots. You can
repeatedly bend them to snap them
off, but you must be careful to not
completely break off the metal plate
underneath.

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October 25th 2013 www.thonk.co.uk 9
TouellSkouarn
Strakal Brulu Module
Eurorack DIY Kit
Instructions
Version 1.0
26.
They should now all look like this.
27.
Put the four pots in the positions
shown but DO NOT SOLDER yet.
Fuzz – B10K
Feedback – B1M
Input Vol – A50K
Gain Out Volume – B100K
28.
Put the three jacks in the positions
shown but DO NOT SOLDER yet.
Note the Fuzz CV jack is rotated 90
degrees compare to in and out jacks.
Put a plastic washer onto each of the
pots.
29.
Now put the panel on and hand
tighten the three jack nuts and four
pot nuts.
NOTE! – The image shows a
prototype panel without graphics.
Mount your finalised panel with the
graphics the right way up.
Solder all the pots and jacks. Note
that unlike some builds only the main
three pins on the pots need
soldering.

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October 25th 2013 www.thonk.co.uk 10
TouellSkouarn
Strakal Brulu Module
Eurorack DIY Kit
Instructions
Version 1.0
30.
Remove the panel again.
31.
Next you will solder the smaller
Germanium Transistor.
NOTE! – The transistor orientation is
vital and is not intuitive. Ignore the
PCB silkscreen and follow the image
below.

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October 25th 2013 www.thonk.co.uk 11
TouellSkouarn
Strakal Brulu Module
Eurorack DIY Kit
Instructions
Version 1.0
32.
Next you will solder the
larger Germanium
Transistor.
NOTE! – The transistor
orientation is vital and is
not intuitive. Ignore the
PCB silkscreen and follow
the image on this page.
NOTE! – Later on you might need to
put a probe on the C pin of this
transistor, so mount it high off the
board as shown to give you more
options for access.

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October 25th 2013 www.thonk.co.uk 12
TouellSkouarn
Strakal Brulu Module
Eurorack DIY Kit
Instructions
Version 1.0
33.
Next insert the TL072 and TL071 ICs.
NOTE! – The IC orientation is vital, make sure the notch in the end of the IC
or the circle mark are positioned as shown.
34.
Put the metal panel back onto the
PCB and put on the knobs.
Insert power cable as shown. The
provided cable is keyed correctly.
But just in case you use another
cable, note that the -12v isn’t marked
on the board, the red stripe is at the
top, not the bottom.
NOTE! – Some of your power cables
may not be keyed correctly unlike the
one provided. It is advisable to only
use the cable provided. You should
maybe make a mark on the PCB to
indicate where the red stripe should
go if this is a concern to you.

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October 25th 2013 www.thonk.co.uk 13
TouellSkouarn
Strakal Brulu Module
Eurorack DIY Kit
Instructions
Version 1.0
35.
You can now power the module on. You should use a small Philips
screwdriver to calibrate the module via the blue trimmer. The best advice
from TouellSkouarn is to just trim by ear, I have found if you have the input
and output knobs set to midnight and then trim so the feedback knob squeal
(resonant self-oscillation) starts to happen sometime around 1 - 2 o’clock
then you have a good range of possibilities… but there is not really a ‘right or
wrong’ setting for the trimmer.
If you want to follow the official ‘factory’ default from Touellskouarn then with
the module powered on, set your multimeter to read DC voltage. Put the
Black or COM probe on the ground point shown on the PCB and the Red
voltage probe on the ‘C’ or collector terminal of the larger germanium
transistor.
To start turn the trimmer until the DC voltage is showing approximately -5V to
-7V.
Not trimming the module will not damage it, but these values are a good
starting point for use, the trimmer can alter the sound quite radically in
interesting ways though so exploration is encouraged. If it sounds good, it’s
good !

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October 25th 2013 www.thonk.co.uk 14
TouellSkouarn
Strakal Brulu Module
Eurorack DIY Kit
Instructions
Version 1.0
Suggested test points if you need to meter from the front of the board:
Note! If you left the C leg on Q2 long then don’t
forget to finally trim it down after!