So I started this project long ago and was only able to sporadically pay attention to it. I finally got it mostly done and have created a website that has better descriptions, more thorough documentation, as well as schematics, PCB design files, parts lists, firmware, android app code, 3D print CAD designs, etc.
You can find all this at my website http://www.diyelectronics.io/ As I say on that site, I am sure there will be an error or three that I have carelessly missed, hopefully only in documentation or web site operation creation. I have all of these working so presumably the designs are sound.
The Light Switch and Power Brick have very dangerous voltages inside (170 VDC) - if you choose to try them, be VERY VERY careful as these voltages are lethal. The sprinkler controller (named precipiSTATION) is low voltage and safer. It is a fairly full function controller, and has some level of complexity in its firmware and android app as a result.
Everything is open source under the MIT license (except precipiSTATION which is trademarked).