As Election 2004 enters its final week, the Tatertown yard sign wars are escalating. The Bush-Cheney forces up the road have made a somewhat tactical retreat, moving their tire-scarred sign back farther from the road’s edge and between a couple of shrubs. The new location hardly looks like adequate protection from a Dodge 3500 4×4 with the macho pipe grill on the front (no, it’s not mine), but maybe the Dodge driver is displaying a sense of sportsmanship in acknowledging the retreat and avoiding collateral damage. Meanwhile, I noticed yesterday that one of my Kerry/Edwards signs had disappeared. This is no major defeat; in fact, today’s replacement supply run was quite a pleasant task. The local Democrat HQ is a perfect distance from campus for a vigorous lunch-hour walk on a beautiful autumn day, and the walk back to campus, pleasantly acknowledging all the approving remarks from attractive enlightened individuals compatible with my sign, was positively uplifting. In spite of that, it’s not really an errand I wish to have to repeat this week, so I began contemplating techniques for reducing the new sign’s likelihood of going astray, and I was inspired by a single word: “Polywire”. I can see the gleam in the eyes of farm-savvy readers.
For the city slickers, who think fencing is a sport involving foils and epees, polywire is something resembling a thin string that is made of polypropylene fibers interwoven with fine strands of steel. Contrary to what you might think, the primary purpose of the steel is not strength, although it does make it a little more difficult to cut than one would guess at first glance. Its real function is conductivity. Polywire is used for temporary electric fences, and other special purposes where an electrical deterrent might be advantageous.
I ran strands of wire along the top and edges of the sign, where they would be fairly inconspicuous but anybody who grabbed the sign to pull it out of the ground would make firm contact with them. After tying them all togther, I ran a strand from them back to the fence behind the sign, which is reinforced by two strands of high-tensile wire driven by an AC-powered 2-joule low-impedance charger. I just love talking geeky! Of course, any real geek (and there might be at least one EE still reading this) knows that impressive-sounding mumbo-jumbo means little or nothing without more data.
You want data? I got data. The charger came with a chart listing expected output for different fence loads under good conditions. That’s not much better than the above, because what I had cobbled together was hardly a typical fencing application. But voltmeters don’t lie. And, with a meter between the wires on the sign and the ground surrounding it, I got a mildly disappointing but still adequate reading of 3300 volts.
Taken out of context, to those unfamiliar with electric fencing or basic concepts of electricity, that might sound like a more than lethal jolt, especially considering that electric chairs typically use charges ranging from 700-2500 volts. But as the EEs can tell you, actually killing somebody requires a significant current, something lacking by design in a fence circuit. In the world of electric fencing, with extremely short pulses and low currents, 3000 volts is not really an outrageous charge. By comparison, a reading from the fence I had tied the sign to gave a more normal reading of 7000 volts. A quick jolt of high-voltage low-current electricity will give you an extremely unpleasant experience you’ll never want to repeat, with no significant injury. Frodo’s experience a few years ago could attest to both the unpleasantness and the survivability of repeated jolts, but that night of hell was in the pre-blog era of 2001, so it’s not documented here.
After confirming with the meter that anyone who touches the sign will wonder what in the hell hit him (although the full 7000 would be even better), I took a step back and looked at the visual effect, and realized the one drawback to the problem. Although the wires on the sign are unobtrusive and would probably escape notice, the wire running back to the fence is very visible. After some thought, I reluctantly admitted there was no quick solution. I’m just going to hope that anybody who tries to heist this sign does it under cover of darkness when they’re unlikely to notice the wire, or thinks that it’s just a harmless piece of white string that I was stupid enough to tie to the sign to try to hold it in place. With a little more time and planning, I might be able to replace the connecting wire with an insulated wire run along the ground where it’s less visible.
Of course, the biggest downer to this whole scheme is that even if I do succeed in zapping a Republican, I’ll miss all the fun.