First Started by designing the enclosure in Autodesk Fusion 360. My goal was to create a design that was simple, compact, and easy to assemble while maintaining a clean, modern, and product-like appearance.

The enclosure was carefully designed to accommodate all the major components, including the HEPA filter, ventilation fan, sensors, display, and electronics, while ensuring proper airflow throughout the system.

If you'd like to explore the design in more detail, you can view the model directly in your browser using the Fusion 360 Web Viewer. The design files are also available for download below.

Files

1. Housing
2. Motor Mount
3. Filter Base
4. Bottom Plate
5. TPU Gasket
6. Display Cover

To begin the assembly process, we first need to disassemble the 150 mm Anchor Smart Air exhaust fan and remove the parts that are not required.

Start by removing the front cover of the fan. Next, carefully remove the center cap and fan blade to expose the motor assembly inside.

Start by unscrewing the motor from the fan housing. Once the mounting screws are removed, carefully disconnect the wires and lift the motor out of the frame.

Since the original fan housing is no longer needed, it can be set aside. For this project, we only need the motor nad the fan blade, as it will be installed into the custom 3D-printed motor mount designed for AirSense.

Now it's time to install the motor into the 3D-printed motor mount. Start by placing the motor inside the motor mount and aligning the mounting holes with the supports provided in the printed part. Once aligned, secure the motor using the appropriate screws.

Carefully slide the fan blade onto the motor shaft and ensure it is seated properly. Once the blade is in place, attach the center cap to secure it.

After installation, rotate the blade by hand to make sure it spins freely and does not rub against the motor mount or enclosure. This quick check helps ensure smooth operation once the fan is powered.

Next, place the TPU gasket onto the bottom plate. Align the mounting holes on the gasket with the corresponding holes on the bottom plate and ensure it sits flat against the surface. The gasket helps create a tight seal between the filter and the enclosure, reducing air leakage and improving the overall filtration efficiency.

With the motor assembly and bottom plate prepared, it's time to join them together. Place the motor mount onto the bottom plate, making sure all mounting holes are properly aligned. Once everything is positioned correctly, insert the M3 screws through the holes and tighten them evenly.

Make sure the assembly sits flat and secure without any gaps. The TPU gasket should remain properly aligned between the parts to maintain a good seal.

After tightening all the screws, give the assembly a quick inspection to ensure everything is firmly attached and the fan blade can still rotate freely.

To support the filter and provide a mounting surface for the main assembly, attach the 3D-printed base to the back side of the HEPA filter.

Apply a small amount of super glue around the contact area of the printed base, then carefully position it on the filter. Make sure it is centered and properly aligned before the glue sets. Only a minimal amount of adhesive is required. Excess glue is unnecessary and may seep into unwanted areas.

With the filter assembly complete, the next step is to install it inside the stainless-steel dustbin that serves as the main enclosure for AirSense.

Carefully lower the HEPA filter into the dustbin and position it in the center. The 3D-printed base should help keep the filter properly aligned and stable inside the enclosure.

Take a moment to ensure the filter sits straight and does not interfere with the walls of the dustbin. A properly aligned filter will help maintain good airflow and simplify the remaining assembly steps.

Since the ESP32-S3 cannot be powered directly from the AC mains, we need a power supply to convert the mains voltage into a safe 5V DC output.

You can use any suitable 5V SMPS module for this purpose. In my case, I repurposed an old smartphone charger that was no longer being used. These chargers already contain a compact and reliable SMPS circuit, making them perfect for DIY projects.

Start by carefully opening the charger enclosure and removing the internal power supply board. Be gentle during this process to avoid damaging any components or tracks on the PCB.

Once removed, inspect the board and identify the AC input and 5V output connections. This compact power supply will be used to power the Arduino and other low-voltage electronics inside AirSense.

⚠️ Warning: This section involves working with mains voltage. Always disconnect power before handling the circuit and take appropriate safety precautions.