I've been doing some planning to build a home automation system on top of the existing power infrastructure of my house.
The first thing would be making my light switches smart. My original plan is to replace the current switch with my own (push switch) that would talk to a microcontroller that would in turn switch a relay and report the status to the control center. Powering the 3v microcontroller and a 5v relay would be done by a 220vac to 5vdc 3.5W buck converter. But the problem is that behind a single pole switch lies only two wires, Hot and Switched. Most boxes don't have the Neutral present.
I can't connect the converter and a relay in series because the microcontroller would not get any power if the light is off, and if I connect them in parallel the light would be constantly on, regardless of the relay status.
What is left for me to do?