Step Fader - manual & build guide

In order to make the sequencer run a clock signal must be plugged into the CLOCK input, the square out of an LFO or VCO could also be used here. The CLOCK-2 input.

The RESET inputs will make the sequence jump to the first step except in pendulum mode, that will reverse the play direction. Reset 1 & 2 aren't normalled.

There are also momentary toggle switches to manually reset (left) or jump to next step (right) for each sequencer.

MODE 1 & 2 buttons and trigger ins will cycle the PLAY MODES of each sequencer. Both buttons or triggers simultaneously will cycle the GLOBAL STYLES.

Every step has an ON/OFF/ON switch to activate one of the gate outs ,center position is no gate. Each row has 2 gate outs.

There is also one fader per step to set the CV out, those values are dimmed by the master faders. Each row has 1 CV out (0 to 8v range)

Apart of the CV and GATE outs of each sequencer there are summing CV and GATE outputs. Keep in mind that individual CV outs have a maximum of 8v and CV1+2 has 10,5v max. .

MODE-2 input can be set as INVERT CV 1+2 output with the JP3 jumpers on the back of the module.

The CV control over step repetition of the first sequencer can switched between the CV-IN & CV-2, which are the dedicated input and the CV of the second sequencer (pre-fader) respectively .

There are 2 Slew limiter circuits, with time pot, IN and OUT, so you can use them independently. Those are not high precision slew limiter, but precise enough to process v/oct and bring some portamento to your melodies.

The length of the second sequencer is controlled by the rotary switch. This reset signal can be routed to the first sequencer (with the switch X1/X2) getting as result interesting interactions.


The partial kit has the PCB with all SMD components populated (except JP2 header), 18 faders and the rotary switch.

All the components needed to complete the module are listed in the BOM.

First solder the headers on the back of the module, For the Arduino Nano only the lateral rows of pins are necessary. Cut those header pins so they don't stand out.

To avoid shorts with the faders, add some insulating tape.

Once all headers are soldered start with the other side of the PCB, solder the 18 faders first, keep in mind that temperature for hand soldering those shouldn't exceed 340ยบ during 3 seconds.

Solder the 2 push buttons and then place the rest of components.

Each toggle switch has 2 nuts, one will be on the front panel and the other behind it, so that parts get closer to 10mm tall.

Before soldering all those components place the front panel and screw the jacks and switches nuts. This will avoid the mechanical stress to the PCB.

To upload the firmware Download the firmware , one way to flash is using Xloader:

http://www.hobbytronics.co.uk/arduino-xloader

Open it, choose hexfile, device and com. Baudrate 57600 works fine, upload.

You can also flash the Nano with Arduino IDE.

1- In Arduino IDE select the board (NANO) the processor (Atmega328P - in my case Old Bootloader) and USB port

2- Open preferences and click on "Show verbose output during: upload"

3- Upload a sketch to the Nano: File->Examples->0.1 Basics->Blink

4- Copy the line that has something similar to (for MAC):

/private/var/folders/49/hlvnskjd2k31xmd09bvxcwhm0000gn/T/AppTranslocation/A8D33513-7903-4D96-8BF2-2BCF50865F76/d/Arduino.app/Contents/Java/hardware/tools/avr/bin/avrdude -C/private/var/folders/49/hlvnskjd2k31xmd09bvxcwhm0000gn/T/AppTranslocation/A8D33513-7903-4D96-8BF2-2BCF50865F76/d/Arduino.app/Contents/Java/hardware/tools/avr/etc/avrdude.conf -v -patmega328p -carduino -P/dev/cu.wchusbserial1430 -b57600 -D -Uflash:w:/var/folders/49/hlvnskjd2k31xmd09bvxcwhm0000gn/T/arduino_build_732480/Blink.ino.hex:i

In Windows it could be something like:

C:\Arduino102\hardware/tools/avr/bin/avrdude -CC:\Arduino102\hardware/tools/avr/etc/avrdude.conf -v -v -v -v -patmega328p -carduino -P\\.\COM3 -b115200 -D -Uflash:w:C:\Users\Usr1\AppData\Local\Temp\build1538115773179135859.tmp\Blink.cpp.hex:i

5- Place the Step Fader firmware file in the same folder, in my case (MAC):

private/var/folders/49/hlvnskjd2k31xmd09bvxcwhm0000gn/T/arduino_build_732480/

6- Open the Terminal (MAC) or Open the MS Windows application cmd (preferably use PowerCmd instead because it allows you to work with copy and paste like any Windows application) and paste the copied text, but change the last part "Blink.ino.hex:i" to "Step_Fader_v13.ino.eightanaloginputs.hex:i" and press enter.

If you see this everything has gone fine.:

avrdude done.  Thank you.

Keep in mind that the orientation of the Nano is with the USB opposite to the 2x3 pins header we left unpopulated in the pcb.

Connect the eurorack power cable to the JP1 header with the red stripe in the white mark, NOT in the JP2 smd header, that one is for a future expander with trigger outputs.