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Hack 50 The NoCat Night Light

Put your AP where everyone can see iton
the ceiling.

Back in March 2003, some friends and I were
hanging out at a really good coffee shop in Sebastopol, CA. This
particular coffee joint is housed in an old wooden train station
building, with very high ceilings, old-style hanging industrial
lamps, and even a couple of old trains still on the tracks, serving
as small shops.

Unfortunately, there's no wireless available at this
shop. (There was, once upon a time, back when
O'Reilly was located across the street from it. But
that was ages ago, and even then the signal wasn't
all that it could have been.) As we sat around drinking our high
octane beverages, we got to talking about the best way to provide
coverage in such a huge space. The room we were in was a common room,
open at all hours (the front entrance is huge, and
doesn't even have a door.) While you could put an
access point in one of the enclosed shops in the building, coverage
in the open area would likely be spotty at best. You would want the
AP to be located high up off the ground, where everyone could see it.

Almost simultaneously, we all looked up and noticed the lamps hanging
from the wooden rafters. What if you could house an AP in a package
the size of a large light bulb, and install it in an existing light
socket? This seemed like a good idea, but how would you get network
access to it without running CAT5 to the socket? Easy:

Powerline Ethernet.

With the recent release of the Siemens'

SpeedStream series, such an insane,
caffeine-induced idea as an AP in a light bulb might be a
possibility. These devices are quite small, about the size of a
standard wall wart (Figure 4-8). They sport a CF
wireless adapter that acts as the AP (actually, it's
the same card as the popular Linksys WCF11 but with a different
sticker.) The brilliant bit is that the wireless network bridges
directly to the AC power, so a standard Powerline
Ethernet adapter anywhere on the same power circuit can provide
Internet access to as many APs as you care to plug in. At a mere $85
retail, we couldn't resist picking one up and seeing
what we could do with it.

One of our first concerns was practical rather than technical.
Obviously, if you're going to replace a light bulb
with an access point, the room will likely get darker. That is,
unless the AP can also provide light as well. After fooling with a
couple of lighting ideas, we finally soldered some copper romex onto
a fluorescent bulb as a prototype. The romex is rigid enough to hold
the lamp steady, and easy to solder to. The fluorescent bulb would
obviously be dimmer than a 300-Watt spot lamp, but it would be better
than nothing. And as a flourescent runs much cooler, it probably
wouldn't turn the guts of the access point to
liquid. This solved the light issue well enough for the moment, but
how could we connect the whole thing to a standard light bulb socket?

One trip to the hardware store later, we had a variety of Edison
plugs, sockets, and adapters. We settled on a simple extender type of
device, with a female socket on one side and a male plug on the
other. Again, the contacts were copper, making it easy to solder on
more romex (Figure 4-9). We had the basic design
together, but what could we possibly use for housing?

Tupperware, of course. Adam painted the inside of a Tupperware bowl
white, and the entire device just managed to squeeze inside. We first
attempted to take the SpeedStream unit apart to save space, but
it's already tightly packed inside (much of the unit
is occupied by a large transformer). Besides, keeping the original
enclosure made us all feel a bit more relaxed about plugging the
thing in. The Edison plug poked through the bottom of the bowl, where
we simply screwed on another connector to keep it tightly attached.

So with all of the technical considerations accounted for, all that
was left was the all-important marketing phase of the project. Some
electrical tape and one vinyl sticker later, the NoCat Night Light
was born! See it in all of its glory in Figure 4-10.

But how well would it actually work? Wouldn't the
fluorescent throw off all sorts of noise that would interfere with
the AP? We certainly thought so. Unfortunately, we
didn't have a machine handy with which to do real
throughput testing, but DSL reports showed a very respectable 2 Mbps
or so. This was well above the rated capacity of the cable modem
network we were using, so we were definitely satisfied with the
results.

One big improvement to the design would be to replace the fluorescent
bulb with a bright LED array, or even a simple socket so you could
use whatever (low temperature) light source you like. This design
makes much more sense than Siemen's original, as it
gets the AP up off of the ground and above your head, where
presumably many more people can see it. Adding more APs is as simple
as screwing in a light bulb, as they bridge directly to the same AC
Powerline segment, and terminate at the same Ethernet.

Keep in mind that this design is a prototype, and while it works in
casual testing, it hasn't been tested for hours of
continuous use. At the very least, it would be a good idea to
insulate the bare contacts and find a better way of ventilating the
fluorescent bulb (or replacing it altogether with an LED array).
Build it at your own risk, but by all means have fun while doing
it.