• Raspberry Pi 3 - The mini-computer with Apache2 server on it
• Nova Fitness SDS011 - PM2.5/10 detector
• QinHeng Electronics HL-340 - default USB-Serial adapter - DON'T use it! It's a buggy device
• Prolific PL2303 - use this one (or anything based on, for example, PL2303)!
• 4-channel relay board - to control the fan control voltage and its gear
• Raspberry Pi's deconstructed 5V/3A charger
• Case - I used this one but could be anything
• 230V fan - I used one of these
• Filter mats
• Cables, jumpers etc.
• SKILL WITH MAINS ELECTRICITY - no joke here, this is a must
  
  

Whole architecture is now based using Mikrotik pre-configured router:

• OpenVPN as VPN service
• local DNS service for modules' local addresses

Moreover, most of data communication uses MQTT protocol along with publish-subscribe pattern.

Encryption and server-side-related operations is done by network's configuration and it's not a part of this repository.