Tonight, we’re having part 2 of the Hackerfarm Wireless Workshop where we get into the hands-on labs to control things wirelessly. There’s something I’ve been wanting to do for awhile in the workshop, though. I’d like to show people how to wirelessly control electrical appliances. It’s such a useful thing and drives home how powerful it is when you can communicate wirelessly. It can be used to remotely turn on things like water pumps (for farms), turn off lights, regulate the temperature of a room using an air conditioner (for things like fermentation or cheesemaking), etc. Things always get hectic before a workshop so I end up giving up on that as a lab and just do the standard things like turning on LEDs, printing things to displays, and reading sensors. I figured this time, I’d take some time to build out the equipment to do this. I put together some relay controllers in sealed enclosures that would allow people to turn on and off things like fans, lights, and humidifiers without having to worry about electrocuting themselves.

I started out with waterproof enclosures that we use for our outdoor device deployments. I drilled two holes in them for the cable glands so that we could pass cable through the enclosure without compromising the waterproof seal.

Then I mounted the relay modules. These are electrically isolated 5V relay modules. I mounted them on a custom acrylic base that I made out of some scrap acrylic sheet I had lying around. Acrylic is nice to work with since you can just score and snap it to size. It’s also pretty easy to drill holes into.

I cut up some old electrical cable I had and wired it into a two-prong male plug. I try to keep a bunch of these around to make custom extension cords. They come in really handy and are pretty cheap.

Then I connected the other side to the relay board so that we can switch them.

Next do the same with the female adapter plug. I also keep a bunch of these around for custom extension cords.

These are the finished boards. You plug the appliance into the female side, plug the male side into the wall outlet, and then control it using the three wires coming out of it. These boards will hook into the Hackerfarm wireless boards so we’ll be remotely controlling fans and lights tonight. Yay!