Kassutronics Quantizer User manual

Quantizer Kassutronics
Board revision 1.1, build documentation revision A October 15, 2019
Description
A quantizer is a nearly essential utility in a
modular synth. By quantizing any incoming
control voltage to the 1V/Oct standard, the
Quantizer allows your VCOs to play in musical
tune. With two channels and exible custom
musical scales, the Quantizer can create two
voices or simple chords. Operating either free-
running or triggered from an external rhythm,
the Quantizer can generate all kinds of random
and pseudorandom melodies, or simply quan-
tize the voltage from a variable source such as
a ribbon controller. The Gate outputs indicate
whenever a new note has been quantized.
While the Quantizer is a digital module,
the user interface is designed to retain much
of the immediacy that makes analog synthe-
sizers so much fun. The musical scale is set
using a rather unique circle of illuminated but-
tons representing the semitones in an octave,
which can be enabled or disabled by pressing
the buttons. Breaking free from traditional pi-
ano keyboard layouts, the circle layout avoids
silly complexities in standard musical theory
and encourages experimentation. The rotate
buttons and allow you to change the root
note of the scale, and further highlight the cir-
cular nature of musical harmony. The module
automatically retains its state when powered
down.
More advanced options are supported
by a single menu layer, accessed with the
τ
Shift
button and explained by the blue icons.
These options allow dierent kinds of transpo-
sitions, gate length changes, and above all ex-
ible CV control of almost any parameter using
the A and B CV inputs. Under CV control
the Quantizer turns into a dynamic composi-
tion element.
For a more detailed description of the mod-
ules operation, see the separate User manual.
This document contains all information needed
to build a Quantizer for yourself. Please read
the Build instructions and Bill of materials
carefully before starting your build!
Quantizer
Gate A GateTrigTrig
Out BIn Out
In
1
1
2
0
4
1
5
1
0
7
6
8
Shift
A
B
τ
Front panel
Features
• Two channel quantizer
• External trigger inputs and free-running
mode
• Easy selection of scales
• Flexible CV control
• Save/recall of scales and autosave of cur-
rent state
• 10hp Eurorack format
• Arduino-compatible open-source code
• Mostly through-hole construction
Schematics, PCB layout and documentation
c
 2019 Caspar Ockeloen-Korppi.
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Power supply recommendations
Symbol Parameter Voltage Current (typ)
VCC Positive supply +12 V 70 mA
VEE Negative supply −12 V 30 mA
Typical performance characteristics
Parameter Typical value Unit
Output characteristics
Output voltage range ±5.33 V
Output voltage step size 83.3 mV
Output voltage accuracy and linearity
1
±1 mV
Ripple and noise (20 MHz bandwidth) 4 mVpp
Input characteristics (In, A and B jacks)
Input voltage range ±5.33 V
Hysteresis 10 mV
Timing characteristics
Sampling rate, per channel 4.8 kHz
Output rise time, tr 250 µ s
Delay, trigger to sample
2
, tts 150  350 µ s
Delay, sample to gate high
3
, tsg 450 µ s
Minimum trigger pulse length <10 µ s
1
Using well-matched resistors, see build instructions.
2
The Trigger delay function can be used to add an extra delay up to 11 ms.
3
The output changes voltage during this delay, and is settled completely before the gate goes high.
Output error and linearity Output ripple and noise vs bandwidth
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Timing diagram, triggered
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Build instructions
Main PCB
The main board contains the power circuitry, micro controller, analog input and output circuitry
and trigger/gate circuitry, all in through-hole parts.
1. For accurate 1V/Oct output on both output channels, resistors R5, R6, R15 and R16
should be matched to 0.1% or better. You can either buy 0.1% tolerance resistors, or
measure a bunch of normal 1% resistors and choose two closely matched pairs R5 = R6
and R15 = R16. Their value should agree within 10 Ω .
2. Optionally the input resistor dividers could also be matched, which will improve the
tracking at the extreme ends of the scale (around +5V and -5V). If you choose to do this
step, they should be matched in pairs R22=R20, R29=R26, R45=R47, R46=R48. Note,
however, that matching on these resistors is much less critical since the inputs will be
quantized anyway, and even standard 1% tolerance resistors are ne for most uses.
The following image shows the locations of matched resistor pairs. Red boxes
indicate pairs that must be matched for output performance, and yellow boxes indicate
pairs that can be matched for best input performance.
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Kassutronics Quantizer
3. J1 and J2 are for programming and debugging, and should be soldered on the bottom
side of the PCB. In most cases J2 will never be used.
4. The eurorack power header should also be soldered on the bottom of the PCB. Either a
shrouded or unshrouded header can be used.
5. I recommend using sockets for all ICs, especially for the microcontroller. Before inserting
the microcontroller, follow the power up test described in the next section.
Front panel PCB
The front panel PCB contains all buttons and jacks, as well as I/O expansion ICs and com-
ponents needed to read the buttons and drive the LEDs. Some of the components are surface
mount devices. The SMD pads were specically designed to allow easy hand soldering with a
normal soldering iron.
Pay special attention to the orientation of these components:
1. For SMD ICs pin 1 is marked on the silkscreen with a circle inside the component, and
an extended line next to the solder pad. On the chip itself markings may vary, but pin 1
is always in the bottom left corner when the text is in normal reading orientation.
2. The PB6149L buttons have 6 legs, but there are 7 holes in the PCB footprint. The
buttons must be rotated such that a small pastic alignment stub ts into the extra hole
in the PCB. Make sure to completely insert the buttons into the PCB before soldering.
3. The at side and shorter leg of the 3mm LEDs correspond to the square pad on the PCB.
4. All pin sockets should be soldered on the bottom side of the PCB such that they connect
with the corresponding pin headers on the main PCB.
5. J213-J217 are very close to the Thonkiconn jacks on the other side, getting all these
components in place is a bit of a puzzle. I recommend to rst solder J214-J217 (but not
yet J213), then the Thonciconns, and nally J213.
6. The leads of S204-S206 should be trimmed fairly short to make space for the trimpots
RV1-RV3 when the boards are connected together.
Powerup test
Before inserting the microcontroller and assembling the two boards together, follow these steps.
1. Inspect the boards for shorts or bad joints.
2. Measure the resistance between the +12V and GND and between the GND and -12V
power connections. The values will change while measuring due to the large capacitors,
but should increase to at least the k Ω range after several seconds.
3. With U3 (LP2951N) inserted, but not yet the microcontroller, apply power to the main
board. Measure the 5V3 power rail on pin 4 of J2 (backside of the PCB). Adjust trimmer
RV1 until the voltage is close to 5.34V.
4. With the main board still powered up, measure the 5VD power rail on J5 (frontside of
the PCB). It should read between 4.8V and 5.2V and is not adjustable.
5. Disconnect power and insert the ATMega328P microcontroller.
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Mechanical assembly
The front panel must be connected to the front panel PCB with M3 standos to ensure proper
operation of the push buttons. To obtain the correct spacing of 10.3 to 10.5 mm, use 10mm
standos + one M3 washer. Similarly, washers must be used between the Thonkiconn jacks
and the front panel. The recommended mechanical assembly is shown in the following diagram.
M3 x 10mm (4 pcs)
M3 x 11mm (4 pcs)
M3 washer (4 pcs)
M3 x 6mm screw (4 pcs)
Thonkiconn washer (10 pcs)
Thonkiconn nut (10 pcs)
M3 x 6mm screw (4 pcs)
Programming the microcontroller
If you have a pre-programmed microcontroller, skip this section.
The board is designed to be compatible with the Arduino Uno, and can be easily pro-
grammed from the Arduino software. The chip can be programmed through the ICSP header
J1.
1
Getting started
First, make sure you have a recent version of the Arduino IDE. I used version 1.8.5 while
developing the module. Download the latest Quantizer rmware source code from github and
open it up in Arduino. Press Verify to compile the code, and check that it compiles successfully.
Programming with the ICSP header
Here, I give the steps needed for programming briey. This is exactly the same as programming
an Arduino via it's ICSP header, so plenty of instructions can be found online in case you are
having trouble.
For programming, you need one of the programmers that is supported by Arduino. I used
the USBasp, which is cheaply available from Ebay, but there are several others that work
1
When the Arduino bootloader is installed on the chip, the board can also be programmed through the
serial header J2. This option is mostly useful for debugging and will not be discussed here.
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Kassutronics Quantizer
pretty much in the same way. See the USBasp website for drivers and instructions how to
install them.
2
The quantizer board has a 6-pin ICSP header, with the standard pinout also written on
the PCB. If your programmer only comes with a 10-pin header, you need to buy or make an
adapter cable to the 6-pin version. Now come the important steps:
1. Remove the Power device jumper from the programmer .
2. Power up the Quantizer board from a eurorack power supply.
3. Connect the 6-pin ICSP header to J1. Pin 1 is the bottom-right pin when looking at the
back of the module, and is labeled MISO.
4. In the Arduino IDE, choose Tools → Programmer and select the programmer you are
using.
5. Choose Tools → Burn Bootloader.
3
6. Choose Sketch → Upload Using Programmer.
If all goes well, the scale lights now light up with a Major scale and the quantizer is working!
Note: Programming the microcontroller via the ISCP header erases the EEPROM, resetting
the Quantizer to factory defaults.
Alternative: programming via the serial port
Once the Arduino Bootloader has been uploaded (using the Burn Bootloader command de-
scribed above or by starting with a preprogrammed Arduino chip), the Quantizer can also
be programmed via the serial header J2. This way the EEPROM doesn't get reset, which is
especially useful for rmware development.
The serial header can be connected to any 5V-compatible USB-to-serial adapter. Connect
RX (adapter) to TX (quantizer), and vice versa TX (adapter) to RX (quantizer). Connect
also GND and DTR, but do not connect 5V3 . Power the board through a eurorack power
source, and upload the sketch with the normal Upload button.
Calibration
To calibrate the output to 1V/octave, a multimeter with reasonably good precision is needed. I
recommend a 4-digit or better multimeter; however, if you only have a 3-digit it will still work.
You can always do a more precise calibration later if needed!
• Set the multimeter to DC Volt and connect it to the left Out jack.
• Press
τ
Shift
+ to enter keyboard mode. Button 0 should light up, and the output should
be around 0V.
• Adjust RV2 (the middle trimmer when looking from the side) such that the output voltage
is exactly 0.000V, within a few mV.
2
To get the USBasp working on Windows 10 I had to choose the libusbK driver; others report using the
libusb-win32 driver successfully. These are all included in the Zadig software linked from the USBasp site.
3
If you get an error target doesn't answer you may need to connect the Slow jumper on the programmer
during this step.
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• Press ve times, it will ash quickly. The output voltage should be close to 5V. Adjust
RV1 (the trimmer near the board edge) to make it exactly 5.000V, within a few mV.
• Go back down ve times with to check the 0V again, and adjust if needed. If you made
an adjustment, also check the 5V again. Finally, check the -5V output.
• Now, connect the multimeter to the right Out jack, and go back to octave zero (both
and are not lit up). Adjust RV3 to set this voltage to exactly 0.000V (within a few
mV).
• Finally, check the high and low octaves of the right output. They should be close to
correct and normally no further adjustments are needed.
Note: If the resistor matching was done accurately, all octaves on both outputs can be
matched to within about 2 mV. However, don't fuss too much about the accuracy here. An
error of up to 5mV will be comparable to the tracking accuracy of a typical analog VCO such
as my VCO 3340, and is totally acceptable. For reference, 1mV error corresponds to 1.2 cents
detuning.
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Bill of materials
Main PCB
Qty Designator Value Note
2 C2, C7 22p C0G ceramic, pitch 2.5mm
4 C22, C23, C28, C29 47p C0G ceramic, pitch 2.5mm
4 C1, C6, C8, C11 220p C0G ceramic, pitch 2.5mm
4 C20, C21, C26, C27 470p C0G ceramic, pitch 2.5mm
6 C5, C10, C24, C25, C30, C31 1n C0G/X7R cer., pitch 2.5mm
1 C12 22n Film, pitch 5.0mm
7 C3, C4, C9, C16, C18, C19, C32 100n X7R ceramic, pitch 2.5mm
4 C13, C14, C15, C17 10u Electrolytic, min. 25V, diame-
ter 6.3mm, pitch 2.5mm, max.
height 9mm
1
3 D1, D2, D7 1N4148 THT
3 D4, D5, D6 1N5817 THT
1 J5 1x2 Pin header, pitch 2.54mm
5 J8, J9, J10, J11, J12 1x3 Pin header, pitch 2.54mm
1 J3 1x5 Pin header, pitch 2.54mm
1 J2 1x6 Pin header, pitch 2.54mm
1 J1 2x3 Pin header, pitch 2.54mm
1 J4 2x5 Pin header, pitch 2.54mm
2 Q1, Q2 2N3904 TO-92, square pad = emitter
11 R1, R7, R8, R13, R14, R17, R18, 1k 1/4W or 1/8W, 1% metal lm
R49, R50, R53, R54
7 R9, R21, R28, R34, R36, R41, R42 10k 1/4W or 1/8W, 1% metal lm
4 R5, R6, R15, R16 10k 0.1% matched pairs
8 R20, R22, R26, R29, R45, R47 10k 1% or 0.1%, see instructions
R46, R48
7 R2, R10, R32, R33, R35, R37, R38 15k 1/4W or 1/8W, 1% metal lm
1 R27 47k 1/4W or 1/8W, 1% metal lm
4 R3, R4, R11, R12 68k 1/4W or 1/8W, 1% metal lm
10 R19, R23, R24, R25, R30, R31, R39, 100k 1/4W or 1/8W, 1% metal lm
R40, R43, R44
2 R51, R52 1M 1/4W or 1/8W, 1% metal lm
2 RV2, RV3 10k Trimmer 3296X or T910-X
1 RV1 5k Trimmer 3296X or T910-X
1 U4 78L05 TO-92
1 U2 ATMega328P ATMega328P-PU, DIP-28
1 U3 LP2951ACN DIP-8, ON Semi
1 U5 TL072 DIP-8
2 U1, U6 TL074 DIP-14
1 Y1 16MHz HC49 crystal
1
Nichicon UST1H100MDD or equivalent, pay close attention to dimensions.
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Front panel PCB
Qty Designator Value Note
4 C201, C202, C203, C204 100n 0805 SMD, X7R ceramic
2 D201, D202 LED 3mm, square pad = negative
1 J212 1x2 Socket strip, pitch 2.54mm
5 J213, J214, J215, J216, J217 1x3 Socket strip, pitch 2.54mm
1 J201 1x6 Socket strip, pitch 2.54mm
10 J6, J7, J204, J205, J206, J207, Thonkiconn Thonkiconn
J208, J209, J210, J211
16 R202, R204, R206, R208, R210, R212, 2.2k 0805 SMD
R214, R216, R218, R220, R222, R224,
R226, R228, R230, R232
2 R233, R234 10k 1/4W or 1/8W THT
16 R201, R203, R205, R207, R209, R211, 100k 0805 SMD
R213, R215, R217, R219, R221, R223,
R225, R227, R229, R231
16 S201, S202, S203, S204, S205, S206, Highly PB6149L-1
1
S207, S208, S209, S210, S211, S212,
213, S214, S215, S216
2 U201, U203 74HC165 SOIC-16
2 U202, U204 74HC595 SOIC-16
1
Highly PB6149L- x , where x indicates the LED color, is available from TME.
Mechanical parts
Qty Item
4 M3 hex stand-os, 10mm long, one male and one female thread
4 M3 hex stand-os, 11mm long, two female threads
4 M3 washers
8 M3 screws, cheese head
10 Washers for Thonkiconn jacks
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