This Eurorack module provides a kind of wind or noise machine with four different selectable noise types, blue, white, pink, and a grainy noise (meaning that the there is signal peak only occasionally with the frequency of peaks being controllable by a potentiometer).
The module contains a state-variable filter with selectable modes, lowpass, bandpass, and highpass.
The output signal is send to two separate VCAs and two separate output channels.
There is CV control for the filter cutoff, which is following the 1volt/oct standard for the filter self-resonance, as well as CV control for the filter resonance.
Filter modes and noise types can be selected via two push buttons on the front panel. The selection does not only allow one mode, but also any combination of modes by pushing each button multiple times. Initially, this was an unplanned outcome of the module design, as I am using a dual binary up-counter IC (CD4520). I was looking for an IC with two counters integrated in order to reduce the number of ICs on the board. This is not a simple step counter like the CD4017, and the binary nature leads to not only single active bits, but also all combinations. So I decided to use this as a feature and combine different selected noise outputs, as well as sending the noise simultaneously through different filter modes and combine the output afterwards. This provides a larger variety of noises and filter effects.
A demo of the module with these selection options is available in this YouTube video:
I added two different versions for the control board in the folder GerberFiles, 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 another control board PCB for the "Thonk" version with footprints for those components.
The main PCB is the same for both versions.
I created the Gerber files with the online tool EasyEDA and ordered the PCBs at JLCPCB.
The module build is mainly THT, including all ICs. However, there are a number of SMD capacitors with the package size 1608 (imperial 0603) and a few MMBT3904/MMBT3906 transistors, package size SOT-23-3.
For the "Original" version three of the IC sockets on the control board need to be soldered in a specific way, as described in the next section. For the "Thonk" version, all sockets are to be soldered the usual way.
Concerning the resistor size, I am usually using small-size resistors, about half the length of the usual size, so they need less space on the PCB. If you want to use my Gerber files, you have to consider that fact. You might still use normal size resistors and put them in a standing position on the boards. Should also work fine.
On the control board, you will find electrolytic capacitors with a rectangle next to them. Since these capacitors are too tall for standing upright on the board with the main board on top of it, those capacitors need to be mounted in a rectangular position. The rectangle shows the position for each bent-over capacitor.
For the Thonk version of the build, there are several SMD capacitors to be soldered on the backside (with the potentiometers and jacks). Do not forget to solder them, before you mount the potentiometers and jacks onto the board.
The following information is not relevant, if you are using the "Thonk" version PCB.
There are three IC sockets to be soldered on the control board in a special way, although the ICs themselves are THT. Due to space reasons, there are no holes for the IC sockets. The socket legs need to be soldered to the PCB surface, like SMD components.
In order to do that, you need to use the type of sockets, where the legs can be bent, NOT the ones with stiff round legs!
All socket legs need to be bent to the outside, so they can be put flat onto the PCB. Soldering the socket to the board is very easy, since the legs and the space inbetween are big compared to real SMD components. The photo below with the socket soldered on the PCB is just for showing the result. Do not pay attention to the surrounding components, as it is taken from a different module.
All other sockets on the control board and the ones on the main board are to be soldered the usual THT way.