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Lindsey Kuper

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Conductive material [Aug. 6th, 2011|03:01 pm]
Lindsey Kuper

I have two big writing projects to work on today: our wedding ceremony, which needs to be done yesterday (well, actually, it needs to be done in three weeks, but that means it needs to be done yesterday), and an application for Mozilla research funding, which needs to be done by some date which has never been precisely specified, but which is approximately yesterday. Therefore, obviously, I'm working on writing other things. (Have to get them out of the queue first, right? That's how it works, isn't it?) So, here's a little story that's been in the queue for over a year.

At my job last summer, a couple of my colleagues were working on hardware projects that occasionally involved the use of a multimeter, a device for measuring properties of electric circuits.1 One day, it became apparent that the multimeter we had at the office wasn't working. Various co-workers, possibly because they wanted an excuse to mention that they owned a multimeter, volunteered to go home and get their own multimeter as a replacement, but presently it became clear that the office multimeter was not fundamentally unusable. In fact, it just had a blown fuse. "So, really, all you need is a fuse," one person said.

Now, the purpose of a fuse in an electrical device is to prevent too much current from flowing through a circuit. If an acceptable amount of current is flowing, it will flow through the fuse intact. If too much current is flowing, the fuse will blow, sacrificing itself to stop the current so that other, presumably more important parts of the device can be prevented from melting or catching fire or what have you. In the case of a multimeter, too much current will flow through it if you hook it up to a power source in one of any number of wrong ways. For instance, as Wikipedia notes, "A common error when operating a multimeter is to set the meter to measure resistance or current and then connect it directly to a low-impedance voltage source. Unfused meters are often quickly destroyed by such errors; fused meters often survive." The point is that the fuse isn't there to make the device work right under ideal conditions; it's there to guard against inevitable user error. That was what prompted another co-worker to joke, "Oh, you don't really need a fuse. All you need is a piece of conductive material!"

We all went about our business for a while, and eventually a co-worker announced that he'd fixed the multimeter: "I found some conductive material," he said. We all chuckled, assuming that he'd gotten a replacement fuse. "Some conductive material." Heh. Good one.

"A modified paper clip, which will be replaced the next time I get to a store," he reassuringly continued.

That job was pretty great, sometimes.

  1. Incidentally, I knew what a multimeter was not from ever having done any hardware hacking, but from having used one to test audio cables when I was doing odd jobs at Pick-Staiger several years prior, an opportunity afforded me because my sister Maya worked there. You never know when this sort of knowledge will come in handy.

[User Picture]From: gwillen
2011-08-07 11:47 am (UTC)
"So er, before you use the device with the paperclip in it, could you describe how the fuse came to be blown in the first place? ^^;"
(Reply) (Thread)
[User Picture]From: lindseykuper
2011-08-10 05:37 am (UTC)
Yeah, I never asked how the fuse came to be blown in the first place. It wasn't until well after this whole exchange took place that it occurred to me exactly how bad it might be to not have a fuse in there.
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