Tag Archives: video

Homemade Toshiba TLP-671 video projector wall mount

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The mounting plate itself is built from a piece of 1/2″ MDF. I traced around the bottom of the projector, cut it to shape using a sabre saw, drilled the holes, rounded the corners and edges with a file, and applied a couple coats of black spray paint. Four holes in the center of the plate are fit with T-nuts, on the underside, to receive flat-head bolts passing through the horizontal pipe flange. Two holes in the front corners of the plate allow attachment by machine screws into threaded hard-points in the bottom of the projector case (which is the top, in this configuration, because the projector is mounted upside-down).

The back edge of the projector is secured by small aluminum binding triangles, shown in a detail photograph in the gallery, below. Each triangle has three screws—two with “wood” threads that secure the triangle to the back edge of the mounting plate, and one with “machine” threads that mate with threaded hard-points in the back side of the projector case.

The mounting arm, obviously, is made from pipe fittings. I believe these are nominal 1.5″ diameter. The horizontal flange is connected to a 90-degree elbow by a short nipple. The elbow, from there, is connected to a longer nipple and then to a second, vertical pipe flange which is secured to a wall stud with wood screws. Power and video cables are would ’round the mounting arm for strain relief on the connectors before running off to the wall outlet and the video source.

The mounting operation consisted of 1) attaching the mounting plate to the video projector, 2) attaching the mounting arm to the wall, 3) attaching the mounting plate with projector to the mounting arm at the horizontal flange, and 4) attaching the running the cables. The only major drawback of this design is that it does not easily allow for adjustment of “pitch.” As can be seen, a pair of fender washers “shims” had to be interposed between the back edge of the horizontal pipe flange, and the mounting plate, to lower the back end of the projector and raise the image projected on the opposite wall. Otherwise, the mount has worked out just as I’d intended.

Warm canned air kills ants

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My friend Jon, whose new house has a bit of an ant problem, has observed that gas from a “Dust Off” type spray duster kills them very quickly. His intuition, and mine, was that this is an unexpected phenomenon. I was intrigued at the possibility that the fluorocarbon that’s pressurized to make this so-called “canned air” (it is generally 1,1,1,2-tetrafluoroethane) might have some unexpected toxicity—unexpected, of course, because fluorocarbons are generally assumed to be relatively inert, biologically.

In any case, we Googled first, and discovered that others have noticed the phenomenon before. The hypothesis on this thread seems to be that it is the cold of the rapidly expanding gas that kills the ants, an explanation neither Jon or I found satisfying. This video shows the simple test I ran in response, which involved loading a rubber balloon with “canned air,” allowing it to warm to room temperature, and only then exposing the ants. Admittedly, the gas is still expanding here as it flows out of the balloon, but not nearly so much.

This test was conducted on October 15, 2011, at about 8:40 PM, in my garage, which was at a comfortable “room” temperature. The ants had been collected about five hours previously from the site of a sawn-off limb of an oak tree in a friend’s backyard. He identified them as “acrobat ants,” and observed that they give off an unusual “coconut” odor (even when undamaged), which I also observed. The test chamber is made of clear PETE, and is covered with a scrap of paper towel secured with a rubber band. The balloon, fixed to a cut polypropylene syringe body with Parafilm, was charged with gas from a Falcon “DustOff” brand compressed air duster (labeled “contains difluoroethane”) more than an hour before the test, sealed gas-tight by wrapping the needle-cap with Parafilm, and allowed to warm to ambient temperature. To perform the test, the needle-cap was removed, and the paper towel pierced with the needle, allowing gas to flow from the balloon into the test chamber. No temperature change was felt on the test chamber wall. The balloon was left in place for five minutes. No ants survived.

However, when I performed an identical procedure with propane instead of canned air, the ants died just as quickly, which leads me to believe that they are, in fact, simply suffocating.

And, no, to anticipate the comment, I honestly don’t feel great about killing trapped critters like this. But my curiosity won out over my moral compunctions, and is now satisfied. So I don’t anticipate any more of these experiments. Even if the balloon method does not adequately control against the possibility of “cold kill,” the identical effect with propane eliminates the possibility that the fluorocarbon has some unique toxicity, which was what struck my interest in the first place.