EurorackWaveFolder

General

A slim (width 25mm) Wave Folder Eurorack module, based on the design from YUSYNTH. Two modulation parameters, shape and range, with a CV input for the range.

You can check this Youtube video to see the module in action.

Module Build and PCBs

If you want to build the module yourself, I uploaded the schematic, the BOM and the Gerber files for the PCB.

I used several SMD components for op amps and bypass caps.

There are two different versions for the control board, an "original" and a "Thonk" version. Reason is that for my own module, I am using specific potentiometers - 16K4 series from Supertech Electronics - and 3.5mm jack sockets - MJ-355 from Marushin - available at my local electronics shop.

However, since most DIY projects for Eurorack modules out there are using potentiometers from ALPHA and so-called THONKICONN jacks, as they are provided by Thonk in the UK, I also created a version with footprints for those components. Choose the one you need.

I created the Gerber files with the online tool EasyEDA and ordered it at JLCPCB. I cannot guarantee, if this set of zipped Gerber files works also for other providers, like e.g. PCBWay. I have not tried that. But I saw online, that others did it.

If you want to know about my DIY building process, take a look at those two YouTube videos:

Panel Layout

I added the information about hole coordinates for the front panel in the folder PanelLayout, referring to the component layout in the Gerber files. The layout is the same for both versions.

Calibration

The calibration requires a simple oscilloscope. I just used a free app with simple features on my Mac. There are two trimmers for calibration, labelled SYM and VOL. In addition, there is a check point, labelled CALOUT on the left side of the PBC (and in the schematic, in case you want to build your own PCB).

The procedure is the following:

Set both trimmers to mid-range.
Connect a sinewave (1KHz, 10Vpp) to the input with the Range knob turned fully clockwise.
Connect the Range CV to 0V (ground) and turn the CV knob fully clockwise.
Connect the check point CALOUT to the oscilloscope.
Adjust the trimmer SYM in order to have a symmetrical sine wave at the output. You may have also to play slightly with trimmer VOL as well to reduce gain if you have saturation on both the positive and negative peaks of the output sinewave.
Turn the CV knob fully counter-clockwise (no CV).
Adjust trimmer VOL in order to completly mute the output signal.

Additional Information about specific Components

If you want to use the Gerber files for having PCB manufactured, please note the following information about components used.

According to the original design, the two parallel BC547 transistors have to be matched ones. However, I did not pay real attention to that, and the result is still nice.
The design makes use of the SMD version of the quad op amp TL074. Any other SMD quad op amp with the same pinout should work, as well, e.g. UPC824.
There is another SMD dual op amp, NJM4580. Again, any dual op amp with the same pinout (TL072) is ok.
There is a number of SMD 0.1uF capacitors with the package size 1608.
In order to save space, I am always using small size resistors, about 3mm length, which are about half the size of usually used resistors.