Editor’s Note – This is the fourth part of an ongoing series by journalist and geek Marty Winston in his quest to design the perfect smart home of the future with the best technology of today.
One brief historical note here. On November 9, 1965, some thirty million people in the Northeast U.S. and Canada were left powerless in the Great Blackout. I was trapped in mid-town New York. It was decades before cell phones. And the only way to communicate was by pay phones. Why? Because they were run on reliable DC current.
Doorbells and Batteries
Imagine you have a house with a hundred of the most advanced and desirable home automation products you can buy today. Some get their power from wall warts, but most are powered by batteries. Now jump ahead 6 months to 2 years.
Some of those batteries will have failed. So some of the building blocks of your automation will have stopped working. The first sign of that is when the automation starts turning flaky and unreliable. That’s exactly how it will be perceived, as “the automation,” a singular entity.
How many people will understand a system well enough to troubleshoot it? How many will be able to trace the problem down to a single product and to identify it as a battery failure? How many will remember where all of the hundred pieces are located?
Batteries as Boomers
I don’t want to overplay the more literal interpretation of that subhead, though certain types of batteries in certain circumstances are quite capable of exploding. Mostly, though, when batteries get past their retirement age, they leak. That tends not to be good for the devices that house them and may also have unpleasant consequences for the immediate neighborhood.
Ah, you say, then it’s just a matter of getting those batteries changed ahead of the curve. Great theory, but in practice, it comes down to this:
People are terrible at babysitting batteries. And anyway, that’s an avoidable concern.
Marty’s Battery Substitute
Our autonomous house project doesn’t allow battery power for small devices. We wire them up in a way you may not anticipate.
You may never have looked inside a desktop computer case, but there’s a rectangular block in there that connects to the wall plug on the outside and to absolutely everything inside that needs power. It’s called a PSU (power supply unit). The power it delivers is very well regulated and is available at significant current levels.
In our house, we tap its 3.3 VDC (Colts DC), 5 VDC, and 12 VDC power feeds and send them through the house, through conduit, over 4-conductor cable (the fourth conductor is the common ground; the conduit helps prevent interference or accidents or peckish rodent snack breaks).
I don’t mean that we reach inside computers to tap that power. A PSU is a relatively inexpensive item. Shorting out 2 of its connector pins keeps it turned on. We set these up in several DC power stations at various points through the house (DC Voltage can fade over long wire runs, and it fades faster with thinner gauges of wire).
DC Power Stations
Sounds like hyperbole; isn’t.
We don’t plug the PSU directly into the wall; we plug it into a UPS (uninterruptible power supply). That means it will keep delivering DC even during power failures. It also means that the power reaching the PSU is protected from power line pollutants like surges, spikes, sags, and electronic noise. The UPS doesn’t have to provide power for long since the house also has a backup generator. A UPS doesn’t cost much more than a PSU, but you may want to consider one that’s PFC compatible (no need to explain that here, just look for it in the product’s feature claims).
We also plug a small 10/100 Ethernet switch into that UPS; it has nothing to do with power but does help us reach all of our Ethernet-connected gear with less total cabling.
Doorbells
The first thing we want you to know about all those “home automation” doorbell products is this:
Bad guys know that if they hear a voice at the doorbell and nobody has come to the door, no one is home. You’re not fooling anybody.
The second thing you should know is this:
Any time you connect a house to the Cloud, it only takes a minute for a hacker in Russia to share that connection. Your house joins a large pool being scanned by their automation, and they already know how to use it to figure out when nobody’s home. They have cronies in many neighborhoods who are delighted to choose those times to pay a visit, especially since people who can afford the automation that creates the vulnerability tend to have better stuff to steal.
Our approach to doorbells is a little different.
One Ringy-Dingy
Ultimately, we see a doorbell’s job as providing notification inside the house of something of interest outside. Our thinking started with having a doorbell that rings one way when somebody pushes the doorbell button and a different way when they don’t.
We expanded our thinking to a library of about two dozen distinctive sounds. They also tell us when somebody is parked at the front door, when somebody enters or leaves each of the 3 garage spaces, when somebody enters or leaves the driveway and when mail arrives.
You’ll come to understand the various technologies we use to know about these things in future columns and on the http://40yearhouse.com site.
Swing the Ring
Instead of having one chime near the front door, we have small amplifiers and speakers in each of the CAP ceiling-mounted sensor pods, each controlled by a Raspberry Pi up there. That lets us be very selective. We don’t have to let the rings be heard in empty rooms, or at bedtime in kid or guest bedrooms, for example. We even added a little knock-on-the-door single-location sound for when somebody leaves a vacant room without closing its door.
We were, in part, inspired by the NuTone LA600WH, a doorbell that plays MP3 files. It comes with some very realistic actual doorbell sounds but you can easily customize it to play a college fight song or a chirping bird or a growling lion or whatever tickles you.
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