Oakley Eurorack Modular Series User manual

Oakley Sound Systems
Eurorack Modular Series
Eight Step Sequencer
PCB Issue 1
Builder's Guide
1.2
Tony Allgood
Oakley Sound Systems
CARLISLE
United Kingdom

Introduction
This is the Project uilder's Guide for the issue 1 Sequencer module from Oakley Sound. This
document contains a basic introduction to the board set, a full parts list for the components needed
to populate the boards and some hints on how to build the unit.
For the User Manual, which contains an overview of the operation of the unit and the calibration
procedure, please visit the main project webpage at:
http://www.oakleysound.com/sequencer-e.htm
For general information regarding where to get parts and suggested part numbers please see my
useful Parts Guide at the project webpage or http://www.oakleysound.com/parts.pdf.
For general information on how to build my modules, including circuit board population, mounting
front panel components and making up board interconnects please see my generic Construction
Guide at the project webpage or http://www.oakleysound.com/construct.pdf.
2

The Sequencer PC set
The issue 1 pot and switch board of the sequencer.
The electronics of the Oakley Sequencer is built on two printed circuit boards (PC s). The Pot and
Switch board hold the pots, switches, input and output sockets, LEDs, and the circuitry the controls
the LEDs and pots. All the front panel components are directly soldered to the Pot and Switch
board. The board is a double sided design meaning that there are electrically conductive copper
tracks on the top and bottom surfaces of the board. The surface mount components are all soldered
to the top side of the board.
The second board is called the main board. This holds the bulk of the sequencer circuitry, the
analogue output processing circuitry, the power supply conditioning, the +5V supply and the
precision +5V reference voltage used by the pot drivers on the Pot and Switch board.
The issue 1 Main Board fitted to the Pot and Switch Board and front panel.
The main board is a four layer design. This means that the board has layers of copper on top and
bottom sides, as well as two internal copper layers. The top internal layer is reserved for the two
3

main 0V connections used on the main board. The components, again a mixture of through hole and
surface mount devices, are soldered to the top of the board. However, because the boards used in
this project are fitted together so that their undersides face each other, the main board's components
are all accessible from the rear of the module. Although this means that you need to be a little
careful when handling the module, it does mean that fault finding is much easier than it would be if
the main board was facing the other way and no components would be visible.
The design requires plus and minus 12V supplies. The power supply should be adequately
regulated. The current consumption is around +85mA and -40mA. The 45mA difference between
the positive and negative rails is almost entirely due to the constant current LED drivers. The LED
driver circuits ensure that the module takes the same current whether the LEDs are on or off. This
reduces current spikes when the LEDs are turned on and off thus reducing unwanted noise on the
power supply lines in your modular.
The two boards are fitted back to back to allow easy access to all the components.
Power is routed onto the main board via the usual 10 way keyed IDC header. Reverse polarity
protection is provided by two Schottky diodes in series with the +12V and -12V lines. Internally the
Sequencer uses three 0V connections. One is used exclusively for the digital circuitry and LEDs,
another solely for the analogue circuitry like the pot drivers, and the third one for grounding the
front panel, ground lugs of the sockets and the pot's metalwork. These three 0V connections are
made using two pins each of the middle block of six pins on the 10 way power lead. It is imperative
therefore that any power supply distribution system connects all six middle pins of the ten way
power lead to the power supply's 0V (ground). This is the expected behaviour of any Eurorack
system but should the Sequencer not behave correctly be sure to check your power lead and power
distribution system first.
oth circuit boards are the same size, that is, 249 mm (wide) x 107 mm (high). The boards are
designed to go behind a panel that is 50HP wide.
4

Sequencer Parts Lists
The components are grouped into values, the order of the component names is of no particular
consequence.
Many of the parts for this circuit board are surface mount devices but not all of them. Take special
care when ordering your parts that you order the correct type of part. This parts list shows the type
of part needed whereas the circuit diagram does not.
A quick note on European part descriptions. R is shorthand for ohm. K is shorthand for kilo-ohm. R
is shorthand for ohm. So 22R is 22 ohm, 1K5 is 1,500 ohms or 1.5 kilohms. For capacitors: 1uF =
one microfarad = 1000nF = one thousand nanofarad. For electrolytic capacitors the maximum
working voltage is normally given with the value, eg. 1uF/63V is a one microfarad capacitor with a
working DC voltage of 63V.
To prevent loss of the small ‘.’ as the decimal point, a convention of inserting the unit in its place is
used. eg. 4R7 is a 4.7 ohm, 4K7 is a 4700 ohm resistor, 6n8 is a 6.8 nF capacitor.
Sequencer Main oard issue 1
Resistors
All single resistors except R30 are surface mount, size 0805 (or metric 2012) 1% 125mW metal
film.
120R R57
220R R51, R32, R48, R60, R63, R37
2K2 R31
3K3 R64, R50, R62, R52, R49, R61, R59, R47
10K R56
18K R7, R6
22K R54, R36, R35, R29, R38, R14, R34, R33, R58, R55, R13
39K R19, R20
47K R1, R8
62K R23, R16
82K R4, R5
97K6 R42, R45
100K R3, R12, R27, R11, R10, R25, R46, R2, R26, R44, R24, R41, R43, R15, R28, R9,
R40, R53, R39
130K R17, R22, R21, R18
47R, 1/4W through hole metal film R30
100K x 4 5-pin bussed* resistor network RN1
100K x 8 9-pin bussed* resistor network RN2, RN3, RN4, RN5
* A bussed or commoned resistor network is a single component that contains a number of 2%
resistors connected together. The commoned pin is labelled with a dot and must be put into the
board so that the dot lines up with the square pad on the PC .
5

Capacitors
The following capacitors are surface mount, size 0805 (or metric 2012) multilayer ceramic,
dielectric C0G (or NP0), working voltage 50V, tolerance +/-5%.
33pF C18, C19
47pF C31, C32
100pF C39, C48, C49, C46, C40
1nF C9, C21, C29, C10, C38
The following capacitors are surface mount, size 0805 (or metric 2012) multilayer ceramic,
dielectric X7R, working voltage 50V, tolerance +/-5%.
100nF C1, C12, C14, C42, C30, C3, C4, C20, C2, C5, C35, C7, C11, C15, C24, C26, C8,
C6, C23, C41, C34, C25, C13, C22, C44, C45, C47, C43, C37, C17, C36, C52, C27
The following capacitors are standard through hole electrolytic capacitors with 0.1” (2.5mm) or
0.2” (5mm) radial leads.
1uF/63V electrolytic C16
4u7/63V electrolytic C50, C51
10uF/35V electrolytic C33
47uF/25V electrolytic C28
Discrete Semiconductors
The following devices are surface mount parts.
1N4148WS signal diode D1, D17, D20, D3, D8, D10, D16, D13, D2, D9, D15, D7, D4, D19
AT42WS Schottky diode D5, D14, D6, D18
The following devices are standard through hole parts.
1N4001 diode D11
1N5819 Schottky diode D12, D22, D21
C550 NPN transistor Q1, Q2
Integrated Circuits
The following parts are all surface mount devices. All are small outline (SOIC) narrow body
packages.
74HC00D quad NAND gate U8
74HC02D quad NOR gate U22, U28, U3, U23
74HC14D hex schmitt trigger U27, U2, U15
74HC74D dual d-type flip-flop U5, U21, U7, U4, U6
74HC4053D analogue switch U12, U18, U19, U13, U16, U10, U17, U11
DG202 DY analogue switch U1
6

TL072ACD dual op-amp U20, U24, U29
AD712JRZ dual op-amp U9
TL074CDR quad op-amp U25
The following devices are standard through hole parts.
78L05 +5V regulator U14
LM4040-5.0V 5V reference U26
Trimmers (preset) resistors
The multiturn trimmers are ourns 3296W, Vishay T93YA or similar.
10K multiturn trimmer T1A, T2A, T3A, T1 , T2 , T3
5K multiturn trimmer SCL_A, SCL_
Miscellaneous
Leaded ferrite bead L1, L2
2 x 5 0.1” boxed header STRIPE
2 x 8 0.1” boxed header EXP1, EXP2
4 way 0.1” SIL socket CN9, CN12
10 way 0.1” SIL socket CN1, CN2, CN3, CN4, CN5, CN6, CN7, CN8, CN10, CN11
CN1 to CN12 are mounted on the underside of the board, facing down, and soldered from the top.
Special care must to be taken to ensure that these connectors are mounted perpendicular to the
board surface.
7

Sequencer Pot & Switch oard issue 1
Resistors
All single resistors are surface mount, size 0805 (or metric 2012) 1% 125mW metal film.
120R R19, R36, R20, R35, R7, R16, R13, R3
220R R34, R40
470R R21, R15, R17, R11, R1, R39, R29, R5
10K R37
12K R31, R42
51K R9, R10
100K R6, R8, R4, R32, R41, R2, R38, R26, R23, R24, R25, R33, R22, R30, R12,
R14, R27, R28, R18
100K x 4 5-pin bussed* resistor network RN1, RN4
220K x 8 9-pin bussed* resistor network RN2, RN3
* A bussed or commoned resistor network is a single component that contains a number of 2%
resistors connected together. The commoned pin is labelled with a dot and must be put into the
board so that the dot lines up with the square pad on the PC .
Capacitors
The following capacitors are surface mount, size 0805 (or metric 2012) multilayer ceramic,
dielectric C0G (or NP0), working voltage 50V, tolerance +/-5%.
47pF C6, C11, C9, C2
The following capacitors are surface mount, size 0805 (or metric 2012) multilayer ceramic,
dielectric X7R, working voltage 50V, tolerance +/-5%.
100nF C8, C7, C3, C10, C5, C4, C1
Discrete Semiconductors
The following devices are surface mount parts.
1N4148WS signal diode D1 – D34
C850 NPN transistor Q19, Q20, Q10, Q17, Q16, Q15, Q7, Q4, Q6, Q9, Q23, Q14, Q3, Q1,
Q18
C860 PNP transistor Q2, Q8, Q13, Q22, Q11, Q12, Q5, Q21
8

The following devices are standard through hole parts.
3mm green LED LD1 – LD15
See later in this document for details regarding the fitting of the LEDs.
Integrated Circuits
The following parts are all surface mount devices. All are small outline (SOIC) narrow body
packages.
CD4049U D hex inverter U1, U2, U4
AD712JRZ dual op-amp U3
TL072ACD dual op-amp U5
Potentiometers
All pots are Alpha 9mm vertical pots with 6.35mm round shafts.
50K linear 9mm VR_A, VR_ , VR1A – VR8A, VR1 – VR8
Switches
C&K D6R push switch SHIFT, LOAD
On-Off-On toggle switch GATE_1 – GATE_8, STATE_1 – STATE_8, MODE_1 – MODE_7,
OCT_A, OCT_
On-On toggle switch SYNC, EXT, MODE_8
Miscellaneous
4 way 0.1” SIL header* CN9, CN12
10 way 0.1” SIL header* CN1, CN2, CN3, CN4, CN5, CN6, CN7, CN8, CN10, CN11
* SIL headers fitted to the underside of the board and soldered from the top. ie. the pins face down.
Thonkiconn 3.5mm socket OUT_A1, OUT_A2, OUT_ 1, OUT_ 2, CV_IN_A, CV_IN_ ,
RESET, GATE_A, GATE_ , GATE_A , SHIFT_IN, LOAD_IN
18 knobs to suit. Davies 1900H or clones thereof are to be recommended.
9

Part Sourcing
For general information regarding where to get parts and suggested part numbers for Oakley
projects please see my Parts Guide at the project webpage or www.oakleysound.com/parts.pdf.
The front panel is obtained either from Schaeffer in Germany, or Front Panel Express (FPE) in the
US. The database for the panel is provided on the project webpage and this file can be opened,
edited and ordered using the Frontplatten Designer program available free from Schaeffer or FPE.
The cost of the 50HP wide panel was around 55Euros at the time of writing. The panel is 2.5mm
thick and has a natural silvery finish. The black text is printed, although it is possible to edit the
database to have the text engraved.
The pots are Alpha 9mm vertical pots as sold by Thonk and others. I use Thonk's standard ones
with 6.35mm (0.25”) round shafts. Other shaft types are available, like splined or D-type, and you
should purchase those that are compatible with your choice of control knob. I prefer the round
shafts as they require control knobs that have a fixing screw. Although these knobs take more time
to place and secure, the height at which the knob sits on the pot shaft is under your control. Push fit
knobs can sometimes not sit at the right height which is unsightly if they are too high, or graunch
against the pot's securing nut and washer if they are too low.
For control knobs I use Davies 1900H clones available from Thonk and others.
The two C&K D6R tactile switches are available from Thonk as their 'C&K Tactile switch'. You
can get them in different colours but I prefer black.
The toggle switches are a standard sub-miniature type that are designed to fit directly into a PC .
The three way on-off-off ones are available from Thonk as their DW2 sub-miniature switch. The
two on-on switch is available from Thonk as their DW1 sub-miniature switch. oth the DW1 and
DW2 switches are made by Dailywell and offer good performance for their price.
All of the 3.5mm sockets are the same type and are available from Thonk known either by their
Thonkiconn moniker or as part number PJ398SM.
The fixed 2.54mm (0.1”) interconnects are in two parts, the male header, and the female socket or
receptacle. I use both ten way and four way single in line (SIL) connectors in the Sequencer. The
ones I use are made by Multicomp, although more expensive types are available which may offer
increased longevity. These are the Multicomp part numbers for the parts I used:
10 way socket 2212S-10SG-85
10 way header 2211S-10G
4 way socket 2212S-04SG-85
4 way header 2211S-04G
You can carefully cut the ten way header to give you two four way headers. It is not possible,
however, to cut down the ten way socket to smaller sizes.
The 3mm light emitting diodes (LED) are green in my prototype. However, you can chose any
colour you wish so long as the LED's forward voltage (Vf) does not exceed 2.5V. Red, yellow, and
orange should work fine. I chose to use flat topped 'cylindrical' LEDs so that the flat top of the LED
10