greenhouse radio pod
Thursday, September 26 2013
Fairly early this morning (by our standards) Gretchen packed the last few things into the Honda Civic Hybrid and then headed off on her Midwest book tour (to promote Kind; see her tour schedule). Her first stop would be Pittsburgh, PA, where she would be staying with her brother's family in their big new house and reading at a bookstore called the Big Idea. I haven't heard of many book tours to promote poetry collections, which, from a marketing perspective, are usually regarded as belonging to a write-only medium.
I didn't want to surprise any bears on the morning walk with the dogs, and so, while I didn't stick to trails (I prefer to explore the less-familiar places between or outside of trails), I mostly passed near places that Gretchen might have. Still, I couldn't resist passing through the massive block of forest between the main axis of the Stick Trail and the Farm Road (41.92559N, 74.108148W). Biologically, this region seems to be something of a desert, with stunted trees and little in the way of undergrowth. I rarely see much wildlife there. Judging from the terrain's rolling flatness and ancient stone walls, I suspect this forest used to be open range, perhaps cleared for sheep. It could have been that way for 200 years starting in 1700, and the sheep might have vaccuumed up what little nutrients the minimal layer of soil once contained.
For much of the afternoon, I worked on a project to better locate Mantid, the greenhouse's WiFi router. I needed to put it in such a way that it would be protected from the elements but also free to transmit without being immediately shielded by nearby objects. I wanted it to create a substantial hotspot around the greenhouse for use by whatever "internet of things" I might want to put down there. The greenhouse presents a bit of a problem because of its metal roofing, which is impenetrable by WiFi signals. So I decided to locate the router (as well as a DECT 6.0 phone repeater) on a pole rising diagonally from the east end of a girder supporting the south side of the roof. This would place the router and repeater just above the level of the roof itself in a place where it would have line-of-sight with both places inside the greenhouse and with the house itself (the latter being necessary for the DECT 6.0 repeater). To protect these devices from the rain, I'd use an elegant little 6 litre polypropylene trash can (which I would have to paint for protection from ultraviolet light). The resulting outdoor "radio pod" would be similar to a something that has been installed for years beneath an overturned bucket on the main mast rising from the solar deck.
Initially I thought I'd run 120 volts up into the radio pod, but six litres is not a lot of space once you start adding power strips and wall warts. So instead I decided to only run appropriate DC voltages to the pod. An old computer power supply wouldn't be the worst way to generate those DC voltages, though they tend to be a bit bulky. For a time I thought I might be able to repurpose an old power supply from a PlayStation 2. I even made several crackhead attempts (I was on pseudoephedrine) at a milling a housing for it (it was just a naked board with lots of dangerous exposed voltages). The first attempt was to try to hollow out a two by six (similar to what I did when making a "GPC" TV-B-Gone). But the wood started splitting and the router blade in my drill press didn't seem to be doing much. So then
I tried using a bending brake to fold some sheet metal into a box, but the results were a disaster. Then it turned out that the PlaySatation power supply doesn't even half a five volt rail, which was something of a deal breaker. I managed to salvage a power supply out of the brownhouse "basement," where it had only been used to provide 12 volts for that fan I recently removed. But then it turned out that that power supply, which was old enough to have been made in Japan, wasn't working reliably; it powered the router, but not enough for it to produce a configuration page from its internal web server. Evidently too many spiders had spun webs across the power supply's high voltage circuits. In the end I temporarily installed an old AT power supply, the kind that can be turned on with a simple switch. Its fan was so noisy that I could hear it from inside the greenhouse; I won't be tolerating it for long.
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