Home Electronic Projects

Home Electronic Projects

X-10 Under the Hood

Home automation has much in common with car modification and repair — anyone can plug in parts or bolt on wheels, but you need to look under the hood and understand what’s going on in there before you take on anything significant. This chapter will teach you the internals of how X-10 home automation works and give you the know-how to design and build your own systems that work reliably and do what you want.

Wireless RS-232 Link

It’s almost inevitable that a PC in a geek’s house will be connected to sensors and actuators. Serial (RS-232) ports are still the most common way to do that, although USB is finally very common, and building your own USB devices is, with some constraints, within reach. Either way, it’s really inconvenient to have to run wires from the PC to all over the house.

Home Television Server

In stark contrast to the pre-rural electrification farmhouse of yore, the geek’s house is a thicket of networks. Considering anything that passes a signal (and hence information) from one point to another as a network, here are the ones we identified in our own home:

Wired and wireless telephone — Plain old telephone service (POTS) voice over paired telephone wires or radio signals.Wireless telephone includes both radio connections from wired telephone jacks to handsets and ones from remote sites to cellular handsets.

Wireless PDA — Radio connections from remote sites to handsets, supporting e-mail and POTS voice.

Broadcast television — Radio connections from remote sites to local antennas and coaxial cable distribution, supporting 6 MHz standard definition (SDTV) analog signals.

Cable television — Coaxial cable from the cable company’s external demarcation point to a modem supporting broadband Internet. Other people also use the cable television feed distributed throughout the house for both SDTV and HDTV reception.

Satellite television — Coaxial cable from an external parabolic dish and low noise amplifier through amplifiers and switches supporting reception of digital MPEG-2 encoded television signals.

Wired and Wireless LAN — Ethernet over Cat 5 or Cat 6 cable, or IEEE 802.11 radio, interconnecting the broadband modem, switches, routers, servers, and client computers supporting IP networking and Internet access.

More than anything, this list shows that up to now the cost of electronics has been high enough to force connections to be tailored to the specific information being sent — no one network technology carried all the different signals used in a home.

IP networks are changing that distribution. The telephone companies learned years ago that it was less expensive and more reliable to run their voice networks using Internet IP packet switching than the older voice circuit switching, and are finally learning that they can benefit by extending telephone service to consumers over IP networks using voice over IP (VoIP) technology. In this chapter, you’ll see that although the standards for television over IP aren’t as well defined as they now are for voice, you can gain significant benefits by moving your television reception off coaxial cable networks and onto your LAN.

Security Monitoring

More people than we thought seem to have vacation cabins. Not expensive, grandiose second homes, but literally cabins or small homes in remote places they use to escape the city they live in. These places are by their nature seldom occupied, making them more inviting targets for break-ins or vandalism than you’d like. There’s good reason for security monitoring.

Television Mute on Phone Ring

Telephones aren’t always where you can hear them readily — less so if the television is turned up loud — and even reasonable volume on the television can lead to missed calls. It’s easy to detect rings, though, and with the right electronics you can turn off the television sound when a ring happens.

Anything Inventory

We have a lot of conversations where one of us is at a store calling back home to ask “Do we need anything else from here?” Whether the topic is DVDs, groceries, wine, or anything else, the answer given usually depends far too much on the vagaries of memory, because in addition to needing to know what’s required for some upcoming event or project, answering requires knowing what we already have.

Kitchen PC

We’re of the opinion that the words geek and kitchen can and should coexist in sentences with meanings that don’t inevitably lead to ordering take out. Cooking well is really just a matter of interest — we know the average geek is smart enough — so if great food’s not sufficient incentive, how about a nice bit of electronics and software?

Automated BBQ Temperature Control

We like smoked barbeque a lot — sidebars in this chapter show you our favorite recipes for pulled pork and for beef brisket — but to be right it has to cook on a very low heat for a long time to let the fat render out.We also like the flavor we get by smoking with charcoal logs — an electric smoker just doesn’t do the job right.

That combination, long, slow cooking with charcoal, is hard to do well.We keep the smoker at around 225°F, a temperature so low that it’s easy for the fire to go out. You can do it if you’re willing to tend the fire constantly, but we’re not that patient.

Automated Sprinkler Control

How often have you driven past a lawn being watered in a full rainstorm, stepped in a small bog of mud left over from too much watering, or shaken your head in frustration over that one dry spot on the grass you can’t keep up with? Doesn’t that sound like an opportunity?

Car PC

This project is to build a PC into a car, integrating a cell phone for Internet access, and integrating applications such as MP3 player, DVD player, and navigator. Yes, you can take it with you. It may not be cheap — running hundreds to thousands of dollars, depending on what you want to do, but you can do it.