SynthCube Barton bmc039 User manual
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Circuit Description
This module is a rhythmic step sequencer. Sequences are programmed by using push
buttons to turn the steps on or off. Two sequences are output simultaneously while only one at a
time can be edited, a toggle switch selects which output is being edited. It features EEPROM
storage of patterns, and sequences up to 32 steps long.
General Assembly Preparation
1) Check that the kit contains all of the parts noted in the BOM; notify us of any discrepancy using
info@synthcube.com
2) Gather additional materials and tools necessary for your build:
a. Tools (soldering iron, pliers, wire cutters/stripper, etc)
b. Solder of your choice
c. Digital camera to document your progress
3) Prepare the pots for assembly:
a. Break off the metal tab
b. Slide the metal tab into the slot in the shaft- this adds some strength to the shaft for mounting
knobs
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PCB Assembly Instructions
1. Solder in components in the following order:
a. Diodes*
b. Resistors
c. Ceramic Capacitors
d. Resistor Arrays
e. Headers and sockets
f. Voltage Regulator
g. Electrolytic Capacitors
h. Ferrite Beads
i. *Note that one of the small signal diodes incorrectly has the footprint
printed on the wrong side. You can install this diode on either side of
the PCB so long as you honor the orientation.
2. Wash board by soaking in 90%+ Isopropyl Alcohol for at least 15 min. Rinse
under cold water and use a brush (small scrub brush or old toothbrush) to clean
away flux.
3. Power up the PCB with no ICs, make sure there’s no magic smoke. Check
voltages according to schematic to ensure everything is placed correctly and
the voltage regulator is working properly.
4. Prepare the panel by removing the plastic film and sanding any rough edges.
5. Test fit the LED bezels. You may want to enlarge the holes slightly using a 3/16
bit
6. Insert the LED bezels into the panel, do not put LEDs in them yet.
7. install all the pushbutton switches into the panel, being sure to keep all the
solder lugs aligned in the correct orientation.
8. Install the switch, removing extra mounting hardware and mounting the switch
body directly to the panel - there is no room for a lock washer.
9. Test fit the panel to the PCB to ensure that all the switches are aligned properly.
10. If all is well, press the LEDs into the bezels from the backside. rotate each one
so that the shorter leg points toward the bottom of the module
copyright 2020 synthcube.com info@synthcube.com Page 4
11. insert the potentiometers into the PCB and hold in place by folding over the
locating pins on the side. Do not solder the pots now, they need to be able to
move slightly to facilitate the marriage of the PCB/Panel.
12. Bring the PCB and Panel assemblies together as one, getting each LED and Switch
lead in the correct location. Begin at one end and bring the two together at an
angle, using a small tool to nudge leads into the correct location. Once they are
seated together, put the washers/nuts on the potentiometers to hold the whole
thing together
13. Solder all the LEDs, pots and switches into place. Make sure everything is where
it needs to go .
14. Install the jacks into the panel. They will fit perfectly if mounted with the square
sides to the bottom of the module.
15. Clip off the solder tabs for the jack switch on all jacks but the clock in - furthest
right if looking at the module from the back. (Looking at the jack from the back
side, with the squared corners down, the switch lug is on the right.
16. Run a piece of bus wire, or plain twisted copper wire through all the ground lugs
(left side of jack). Now you’ll see why we removed those switch lugs!
17. Using wire, connect the ground bus we just created to one of the ground
terminals of the MOTM power connector footprint sticking out under the euro
power header.
18. Connect the other jacks up to their corresponding solder pads. From L to R:
a. O2 - Out 2
b. O1 - Out 1
c. CO - Clock Out
d. RS - Reset
e. CE - Clock Enable (connects to switch of Clock In jack)
f. CI - Clock In
19. Power it up, make sure there’s still no magic smoke. Check voltages again to
ensure everything is wired correctly and the voltage regulator is working
properly.
20. Install ICs- test and enjoy!
Total Parts :
102
BMC039 STEP RHYTHM
Module :
Type
Mfg Part
Number
Manufacturer
Short Description
Value
Unit
Qty
Part Notes
Reference
Designator
BOM
Line
Package
SKU
CAP
MLCC - Leaded .01uF 2.5mm LS
10nF
K103K15X7RF5TL2
Vishay
0.01
uF
9
1
Line
2.5mmLS
CAPK103K15X7RF5TL2
DIO
1N5817 Schottky Diodes &
Rectifiers Vr/20V Io/1A
1N5817
ST Micro
1
each
2
2
Line
DO-41
DIO1N5817
DIO
1N4148 Signal Diode thru hole
1N4148TR
Vishay
1
each
15
3
Line
DO-35
DIO1N4148TR
ECAP
Electrolytic Cap - Leaded 105C
Radial GA
EEA-GA1H100H
Panasonic
10
uF
2
4
Line
2.5mmLS
ECAPEEAGA1H100H
HDR
Shrouded Keyed Power Header
2X5 10-pin
30310-6002
3M
10
pin
1
5
Line
0.1
HDR30310-6002
HDW
M3 X .5 X 6mm Pan Zinc Screws
258568
Fastener
Superstore
1
each
4
6
Line
M3
HDW258568
HDW
#4 Flat Washer Nylon
336514
Fastener Express
1
each
4
7
Line
#4
HDW336514
IC
TL074 Quad OpAmp
TL074CN
Texas
Instruments
1
each
1
8
Line
DIP14
ICTL074CN
IC
TL071 Op Amp
TL071CN
Texas
Instruments
1
each
1
9
Line
DIP8
ICNTL071CN
IC
IC & Component Sockets 8P TIN
PIN GOLD CONT
110-43-308-41-
001000
Mill-Max
8
pin
1
10
Line
DIP8
ICN11043308
IC
IC & Component Sockets 14P TIN
PIN TIN CONT
110-44-314-41-
001000
Mill-Max
14
pin
1
11
Line
DIP14
ICN11044314
IC
IC & Component Sockets 28P TIN
PIN TIN CONT
110-44-328-41-
001000
Mill-Max
28
pin
1
12
Line
DIP28
ICN11044328
JCK
3.5mm jack stereo black barrel
LJE0352-4R
Li Sheng
1
each
5
13
Line
n/a
JCKLJE0352-4R
KNB
KNOB BLK NO SKIRT WHITE INDEX
LINE SILVER CTR 13mm 0.5 xsmall
CFAZMB6W7S64W
7E
Chia Shin
1
each
4
14
Line
n/a
KNBCFAZMB6W7S64W7E
LED
Lite On Standard LED Red 3mm
LTL-1CHP
Lite-On
1
each
11
15
Line
3mm
LEDLTL-1CHP
PTB
100K OHM LIN POT ROUND SHAFT
PCB 9MM RA
RD901F-40-15R1-
B100K-00DL1
TaiwanAlpha
100
kOhm
4
16
Line
9mm
PTB901F4015R1B100K
RES
Metal Film Resistor 1Kohm 1%
271-1K-RC
Xicon
1
kOhm
14
17
Line
1%MF
RES271-1K-RC
RES
Metal Film Resistor 100Kohm
271-100K-RC
Xicon
100
kOhm
4
18
Line
1%MF
RES271-100K-RC
Type
Mfg Part
Number
Manufacturer
Short Description
Value
Unit
Qty
Part Notes
Reference
Designator
BOM
Line
Package
SKU
RNW
Resistor Networks & Arrays 8pins
100Kohms Bussed
4608X-101-104LF
Bourns
100
kOhm
1
19
Line
SIP-8
RNW4608X101104LF
SEMI
Ferrite Beads thru hole
BL01RN1A1F1J
Murata
1
each
2
REPLACE 2 X 10R
RESISTORS
20
Line
n/a
SEMIBL01RN1A1F1J
SW
Pushbutton MOMENTARY PANEL
MOUNT RED KNOB SPST-NO
A-5051
Tayda
1
each
12
21
Line
SPST
SWA-5051
SW
MINI TOGGLE SWITCH SPDT ON-
ON
A-4567
Mountain
Switch
1
each
1
22
Line
SPDT ON-ON
SWA-4567
VREG
LM7805 Lin Volt Reg 1A Pos Vol
Reg TO-220 (A-179)
LM7805CT
Fairchild
Semiconductor
5
v
1
23
Line
TO-220-3
VREGLM7805CT
WIR
EURO 10-16 PIN POWER CABLE
CBL1016EURO25
synthCube
10
each
1
24
Line
n/a
WIR1016EURO25
BMC039. Step Sequencer.
Last updated 2-2-2016
If you have any questions, or need help trouble shooting, please e-mail
Michael Bartonmusicalcircuits.com
I Overview/Features
II Schematic
III Construction
A.Parts ist
B.The PCB
C.Photos/Wiring
I. Overview/Features
This module is a rhythmic step sequencer. Sequences are programmed by using push
buttons to turn the steps on or off. Two sequences are output simultaneously while only one at a
time can be edited, a toggle switch selects which output is being edited. It features EEPROM
storage of patterns, and sequences up to 32 steps long.
CONTRO S
1.Step on/off buttons – These are the 8 buttons which turn individual steps of the pattern on or off.
The LEDs next to the buttons indicate whether the step is on or off.
2.Speed Knob – This controls the speed of the internal clock. When an external clock is input, this
knob controls a divider for the external clock, dividing by 1, 2, 4 or 8.
3.Page Knob – Because there are only 8 buttons used to control up to 32 steps, this knob selects
which steps are being edited. When the sequence length is set to 8 or less, this control does nothing.
4.Length Knob – This sets the length of the sequence. Available lengths are 2, 4, 8, 16 and 32. This
control and the Page knob affect both sequences simultaneously.
5.Bank Knob – This selects which bank is being used for the SAVE and LOAD functions. There
are 5 available banks to save/load.
6.Edit Toggle – This selects which channel is being edited. When the switch is down Output 1's
sequence is being edited, and when up, Output 2's sequence is edited.
7.Erase Button – This button erases the current sequences.
8.Reset Button – This button will return the sequences to the first step on the next clock input.
9.Save Button – This saves the current sequences to the selected bank.
10.Load Button – This loads the sequences selected by the bank knob. If the selected sequence's
length is different from the length currently selected by the Length knob, it will override the length
knob until the length knob is adjusted.
INPUTS
1.Clock input – An external clock can be applied to this input.
2.Reset Input – This input works in parallel with the Reset Button, when the input goes high the
next clock tick will go to the first step of the sequence.
OUTPUTS
1.Clock Output – This outputs triggers in time with the clock.
2.Output 1 – This outputs triggers for sequence 1.
3.Output 2 – This outputs triggers for sequence 2.
II. Schematic.
Above is the schematic for this module, minus the power supply connections. In the center
is the 16F913 PIC which is the heart of the module. To the left of the PIC are the external inputs for
the Clock and Reset. The Reset input goes through a switching diode to keep the pushbutton from
affecting the output driving the Reset input. Each of these goes to a comparator with a threshold
set to .12V, and the outputs go through a network of diodes and resistors to keep the voltage within
a range which won't damage the PIC. An eight pin 100K resistor buss to ground acts as the pull-
down resistors for all of the PICs digital inputs.
Below the external inputs are the potentiometers for the control knobs. Each of these is a
linear 100K potentiometer wired as a variable voltage source. The wipers are filtered by .01uf
capacitors to keep high frequency noise out.
Below the PIC are the LED outputs for the sequence display. Each is in series with a 1K
current limiting resistor. Below and to the right of this are the outputs, each of which is composed
of an op amp wired as a buffer with 1K resistors in series with the wirepad and the display LED.
To the right of the PIC is the switch reading network. Pins 21-24 are the outputs, these are
each connected to three switches through switching diodes, the outputs of these switches are then
sent to Pins 25-27 which are the inputs. When a button is pressed, there is only one input that can
send a 5V signal through it and only one output that can receive that 5V signal. This allows us to
read 12 switches using only 7 pins of the microcontroller.
To the right is the schematic for the power
connections. The two power connector footprints are in
parallel with each other. The positive and negative
power rails are filtered by a 10 ohm/ 10uf passive low
pass filter. The op-amps then have .01uf capacitors at
their power pins for further filtering. The 5V buss is
provided by an onboard 7805 voltage regulator.
III. Construction
A.Parts ist
Semiconductors
Name Quantity Notes
16F913 1 Should be provided with your PCB
TL074 1 14 pin DIP package
TL071 1 8 pin DIP package
Switching diode 15 1N4148 or other small signal switching diode
Schottky diode 2 1N60P or other schottky
7805 Regulator 1 TO 220
LED 11 3mm Red
Resistors
Name/Value Quantity Notes
10 ohm 2 1/4w metal Film for all resistors unless otherwise noted
1K ohm 14
100K ohm 4
100K ohm buss 1 8pin SIP package. Or can be made with 7 resistors
B100K Pots 4 Parallel PC mounted. Like This.
Capacitors
Name/Value Quantity Notes
.01uf 9 Ceramic disc. Value not critical
10uf 2 Electrolytic, at least 16V rating.
Other
Name/Value Quantity Notes
Power connecter 1 Eurorack or MOTM
Pushbutton 12 OFF-(ON). Like this.
Toggle switch 1 SPDT. Like this.
Stereo jack 1 For clock input.
Mono or Switching Jack 4
Knobs 4
28 pin DIP socket 1
14 pin DIP socket 1
8 pin DIP socket 1
B. The PCB
The PCB is two sided. All of the components which attach to the panel are on the bottom, and all of
the other components are on the top. I recommend stuffing and soldering all components on the top
first. When stuffing and soldering components on the bottom, I recommend only soldering one pad
for each component before attaching it to the panel, this will make fitting everything in the holes
easier and put less strain on the PCB. After everything is secured to the panel, then resolder these
connections and finish soldering these components.
The current PCB has three errors. The screenprinting for the diode next to the Step 1 led should be
on the top of the PCB, not the bottom. If you attach the diode on the bottom, it won't negatively
affect the circuit, it's just annoying. Secondly, the Schottky diodes aren't marked with an “S” like
they are in other designs I've done. Thirdly, there is not a wirepad marked for Ground. The easiest
place to get a ground connection is to use one of the center wirepads for whichever power connecter
is unused.
Above is an image of the PCB.
C. Wiring/Photos
Above is a photo of the wiring.
“CI” is connected to the tip of the Clock input jack
“CE” is connected to the ring of the Clock input jack.
“RS” is connected to the tip of the Reset jack.
“CO” is connected to the tip of the Clock Output jack.
“O1” is connected to the tip of the Output 1 jack.
“O2” is connected to the tip of the Output 2 jack.
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