VControlTotal

VControlTotal was born out of the idea of creating an affordable, home-built modular synthesizer. Commercial options are often prohibitively expensive, but it is possible to produce a device with mid-range quality at a significantly lower cost. While the project includes the electronic components for both the VCO (Voltage-Controlled Oscillator) and VCA (Voltage-Controlled Amplifier), this guide will focus on constructing the casing for both modules and their corresponding power supply.

This project was developed for 'Electrónica Creativa' (Creative Electronics), a BEng Electronic Engineering 4th year module at the University of Malaga, School of Telecommunication (http://etsit.uma.es/).

To build the VControlTotal project, you will need the following materials and tools:

1. 3mm MDF wood: Suitable for laser cutting.
2. 2 Schuko cables: Also known as Type F plugs.
3. 12V power supply: For powering the modules.
4. 12 screws (3mm): Including 11 with their matching nuts.
5. 4 screws (2mm): Along with 12 matching nuts.
6. Soldering board: For assembling the electronic circuits.
7. 15 double pins: For circuit connections.
8. Soldering iron and tin: Essential for assembling the electronics.
9. 3D printer: For printing additional components if needed.
10. Mountable AC power inlet: For integrating the power supply into the system.
11. Dremel tool or soldering iron: To create the holes in the MDF.

The design can also be created using any free or paid licensed software. Initially, the process is similar to designing any 3D model, but an additional step involves incorporating the interlocking joints to ensure a precise fit.

Designing interlocking pieces for this type of structure can be delicate, as the joints must fit perfectly if we want to avoid using glue. In this case, we used FreeCAD, an open-source tool, in line with our maker culture.

If you are starting a design from scratch, the best approach is to cut a couple of test pieces first to check how they fit together. If everything aligns correctly, you can proceed to cut the entire structure.

The easy way is send the corresponding MDF pieces to be laser-cut according to the provided design file, "VControlTotal". Once the pieces are cut, you'll need to drill the necessary holes and finish any imperfections on the surfaces. Make sure to send the design to the cutting service with sufficient time to allow for potential delays and adjustments.

Using a Dremel tool or by burning the wood with a soldering iron, create the required holes in the MDF. While the first option is more precise and recommended, I personally chose the second method. Make sure to clean up any rough edges to ensure a proper fit for all components.

At the same time, start connecting the mountable AC power inlet to the cable according to the schematic provided. Double-check the connections to ensure safety and proper functionality.

Now, proceed to solder the pairs of Eurorack pins according to the layout shown in the schematic. In our case, we will use a 10-pin connector. Be sure to leave space for the ground, +V, and -V cables, as these are essential for the proper functioning of the modules. Follow the schematic carefully to ensure that all connections are correct and secure.

There are two standard Eurorack sizes: 34 HP and 42 HP. In this project, we have used two 42 HP rails, one at the top and one at the bottom.

Design the top and bottom rails for the case , this design is from "Microcarpentry", making sure that their length is exactly 17.2 cm. This measurement corresponds to the width of the hole in the box, ensuring that the VCA and VCO modules can be properly placed later on.

Once the design is ready, use a 3D printer to print the rails. Make sure the printed rails fit well in the case and provide a secure mounting surface for the modules.

Our design follows a 5U format. In modular synthesis, 1U (Unit Height) is a measurement close to an inch, commonly used as a European standard for modular synthesis equipment. While the industry typically uses 3U modules, in our case, we designed both the VCO and VCA manually, requiring more space for proper functionality.

After receiving the laser-cut pieces and drilling the necessary holes, it's time to assemble the box. In my case, I had to file one of the corners slightly because sometimes the cuts aren't perfectly precise.

An important detail is to assemble the pieces carefully and evenly. This type of wood is very sensitive to twisting, and if not handled properly, it could break. Take your time to ensure that all pieces align well before securing them in place.

Now it's time to screw all the electronic components into place, including the 12V power supply, rack connections, and power inlet. Follow the instructions carefully, and ensure that each component is securely fastened as shown in the photographs. This step will finalize the structure for the modules and their electrical connections.

It's important to verify the proper functioning of the circuit, as mistakes can sometimes occur during the wiring process. Use a multimeter to check the continuity between the wire pairs. This ensures that all connections are correct and prevents potential issues when powering up the system. Take your time to double-check the connections before proceeding.