Look at www.nodo-domotica.nl. They are exactly what you're describing.

Except that this method is not a good idea to control lights and sockets. This sort of setup is unreliable and has all sorts of limitations. It's basically the X10 of the 1990's, reimplemented poorly. Of course there are all sorts of alternatives that have been developed, like ZWave and Zigbee. But they're not DIY projects.

For 10$ or under, you can buy an off the shelf 433 mhz setup from cheap suppliers.

There are literally thousands of people who try to build their own, and the result is usually of the quality as described in the linked article. What this woman is doing (turn AC on and off through cutting off power) will wreak havoc on her AC as it will turn off all the circuitry AC's have to gradually control temperature. She notes this as a 'todo' in her description, which is roughly equivalent to saying 'yeah I build this soap box car and I ran it down the hill, now all I need is to put in pedals and then I can go off racing Nascar'. Uh, no, not even close.

Look, I see the appeal in building something yourself, but not in something that is both as simple and ill-functioning as this - what's the point of building something badly that you can buy COTS from any hardware store for only slightly more than what she spend on this thing? Internet-enabled remote controls for AC's can be bought for 75$ or less, and they interface with the circuitry of the AC directly and let you control temperature set point, fan movement and everything else without putting undue stress on the machine.

I do more or less agree with you, but:

> what's the point of building something badly that you can buy COTS from any hardware store for only slightly more than what she spend on this thing?

Tinkering. Hacking. Learning.

> turn AC on and off through cutting off power) will wreak havoc on her AC

I don't know alot about AC's (I generally eschew them), but there is one line in the article:

Make sure that your AC is always set to be ‘on’, we’re bypassing the air conditioner’s normal on/off control system.

I can't image they've got a complicated startup sequence if they've got an "always-on" setting? Or am I wrong?

I think he means an air conditioner with a physical on/off switch. If the unit has an electronic control that needs an "on" press to turn it on after power is applied, this external relay won't work.

I just did a similar thing that the linked tutorial uses for controlling lights. I use an arduino+RF emitter to control store bought RF controlled mechanical relays (3 for $20) and an rpi to host a server (used as ios mobile bookmark) that talks to the arduino. It's a pretty easy setup and the RF emitter with an antenna gets through walls. But I'm not sure it'd scale to a whole house, and much less reliably.

You can also build your own wifi controlled outlets using sparkcores like in this tutorial[1]. That author addressed your question about powering the modules that control the switches by "stripping apart an old USB power adapter, and soldering up AC wire from the power cable as well as an additional two wires to the back of where the USB port was soldered to the board on the +/- power pins."

Googling around you can find other sites like [2] for building your own controllers. But to be honest if you're looking for a whole home solution that's reliable and safe it's probably best to use some pre-bought kit for that purpose like Insteon - but I could defintely be wrong. Good luck!

[1] https://www.hackster.io/daniel0524/building-a-wifi-outlet [2] http://www.openhomeautomation.net/

If the switches are for lights, you could consider some other options. X10 is pretty dated, but the upside is the cost of 'socket rockets' is pretty low. Anyhow, for a project like this, I don't have automation as much as I have control but I built a simple system to talk to a handful of protocols. https://github.com/dandroid88/webmote

Low cost, long enough range and not wired can be a bit tricky. If you are ok replacing sockets, putting an adapter in, replacing switches etc you can get the features you want, but probably not at your desired cost point. Those solution would steal a bit of power from the 110 lines. If you are trying to hack something with some relays, I would suggest a sleepy radio, plus a thing called a latching relay. A latching relay allows you to connect/disconnect without continuously applying power and instead only applying power when changing the configuration. Still though, the batteries are going to be a pain once you start using anything electromechanical or radios unless you are really careful at each step.

You could use outlets that have USB chargers built in. That would provide you with a hopefully steady 5v source to use. They claim 3.6A charging, so that should provide plenty of power for something like a small microcontroller or even a rPi.

http://www.homedepot.com/p/Leviton-Decora-15-Amp-Combination...

I am using Insteon hardware for the purposes you describe. However, the nodes are about 5x your desired cost.