my biggest fan

Post date: Aug 02, 2016 2:23:7 AM

I mentioned this earlier, but here's the finished project. A whole-house-fan controller:

Inside of a salvaged project box, there's a Pi Zero with my WiFi adapter, a 12V transformer/rectifier/filter assembly salvaged from a wall wart, a 12v to 5v cell phone charger circuit board, and a 12A relay mounted on the back of a duplex receptacle. There's also an NPN transistor to switch the 12V going to the relay coil, using the resistor-less drive technique from a previous blog post.

The software is a hodge-podge of a shell script and a couple of short Python programs that use the pygooglevoice library. The whole thing periodically queries my Google Voice account looking for texts and parses them. For example, to turn the fan on, I send my Google Voice number a text such as "fan on". I also implemented an off command, and a command to shut down the Pi gracefully. Sometime later I might implement some time commands such as "fan on for 1 hour".

So far it's working great!