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Comment by kilroy123 | Hacker News Reader

Wow that power controller is pretty cool. I'm curious how that works...

It sends a signal through the power socket, but do you have to have special light bulbs?

Standard X10 protocol, unchanged since the mid 70s. 4 bits of house address (usually a letter) plus 4 bits of unit address (usually a number) gives 256 theoretical devices.

As far as long lived protocols go, X10 is up there... 1975 to 2016 and counting...

And still useful. I use it to control a water pump to push water to sprinklers on my roof for the hot Atlanta summer months. 1 Gal of water evap from the roof is ~8000BTU's (I'm told - someone correct me if that's wrong).

8000 BTU is about right. It's impressive that you actually got that water to evaporate from the roof in a decent amount of time in Atlanta though, since it's so humid. I'm not sure that it does much, since either your roof or your attic floor is insulated.

A gallon over a big enough area, with a roof that's dark, in 90+degree ambient temperature and direct sun... evaporates within a few minutes. Sometimes < 1 minute by visual inspection, anyway.

re: "doing any good", yes, that's hard to say. The ROI may not be for years, if ever. It was as much a "I have an idea,let's see it through" project as a real money saver.

The attic is insulated, and with a radiant barrier, to boot.

Yeah, a dark asphalt roof and direct sun would do it, as I've observe in my parents' house in Houston. You're also right the the ROI is probably zero or negative since your attic is insulated and has a radiant barrier so the temperature of the roof itself is close to irrelevant.

> dark asphalt roof and direct sun would do it

But if you were going for cooling, you wouldn't go for a dark asphalt roof.

HOA. Not much choice. We got the lightest we were allowed.

Yes. It was a fun project though.

The controller app is a bash shell script. :-)

I work on the AFB about 2 hours south of you. It was a scorcher this year.

Thank you! I had no idea what protocol was so old. I thought it was from the 90s.

I didn't see that. What page?

It sounds like X10 (was developed in the 1970s).

https://en.wikipedia.org/wiki/X10_(industry_standard)

You needed to add a receiver near the load. They had a couple of variations of a box with prongs on one side and an outlet on the other to switch plug-in devices and a replacement wall switch for other lights.

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