Archive for the ‘electronics’ Category

Piercing and Accessories

Sunday, 2 November 2008

I’d like to be able to connect my note-book computer to a better antenna than those built into it.

I could drill a hole in the case, and mount an RP SMA jack there, connected to the internal Wi-Fi card. The patch cord that I would use fot this would cost me $20.50.

An alternative would be to get a new USB or PCMCIA[1] Wi-Fi adapter with a built-in external antenna connector. Setting aside units that I fear would be even cheaper than they are inexpensive, it appears that an adapter with an antenna jack or jacks would cost at least $40, and then not support the forthcoming 802.11n standard.

Thus, basically, if I bought one of these Wi-Fi adapters, then I’d be paying $20 or more to avoid drilling a hole in the case of my computer, and for the convenience of not having to open-up the case whenever I wanted to switch to-or-from the internal antenna that would be disconnected to enable the RP SMA jack. (A patch cord with bulkhead U.FL-R connector instead of an RP SMA jack would spare me that latter awkwardness, but I’ve not found such a cord.)

[1]I don’t much like the idea of surrendering the PCMCIA slot, as I only have one; but I have six USB slots, and have never used more than five at one time.

Matte Display

Friday, 6 June 2008

Speaking — well, writing, actually — of my note-book computer and its display:

Instead of replacing the original glossy display with another, I chose to replace it with a non-glossy matte display. Of course, I did this hoping for some improvement, but the improvement is substantially better than I had anticipated. For example, unlike before, the screen is now comfortably readable when (to conserve power) dimmed to the preset level for running on battery.

Mistaking a map for the territory

Monday, 26 May 2008

A while back, I got a copy of Circuit Analysis by Robbins and Miller, to review material that I’d forgot, and to fill-in lacunæ here and there. On the whole, I think that it’s a pretty good book, though somewhat slow-moving for my tastes.

But to-day I hit a passage that bugs me:

Although we use phasors to represent sinusoidal waveforms, it should be noted that sine waves and phasors are not the same thing. Sinusoidal voltages and currents are real — they are actual quantities that you measure with meters and whose waveforms you see on oscilloscopes. Phasors, on the other hand, are mathematical abstractions that we use to help visualize relationships and solve problems.

Okay, now, for those of you unfamiliar with phasors, these are two-dimensional vectors or complex numbers whose magnitude corresponds to the amplitude of a sinus wave, and whose direction corresponds to the phase of the wave. In the case of a wave with an amplitude of 1 unit, a phasor would be a radial line on a unit circle, bearing the familiar relationship to a sine wave.

There is an isomorphism between the set of phasors and any representation of sinus waves. That is to say that for every representation of sinus waves and operations thereüpon, one can find equivalent phasors and operations thereüpon, and vice versa, such that a one-to-one correspondence between operands and results is maintained. From the perspective of mathematics, a phasor just is a representation of a sinus wave.

This last point does not contradict what Robbins and Miller have said, but now consider how and why we see wave-forms on an oscilloscope. The most familiar graphical representation of sinus waves looks very much like some of the waves that we observe in water, but electricity isn’t water. We cannot look at an ordinary circuit and see its voltage or current; instead, we use devices whose visible behaviour changes to represent voltage or current. These devices might represent that behaviour in various ways; the ways in which they do are determined by various cost considerations (including cultural expectations).

An oscilloscope is designed to present a particular sort of graphical representation of wave-forms. It could instead be designed to present a different sort of graphical representation. If it only had to represent sinus waves, then it could do this with stable phasors. And if it had to represent non-sinus waves, then it could perhaps do this with time-varying phasors (giving the viewer an animated Fourier analysis), though I don’t know that this would be as helpful to us.

The representation of the oscilloscope is a map. As Korzybski noted, the map is not the territory. The phasor is not the voltage or the current, but neither is the representation on the oscilloscope; neither is more or less real than is the other.

Aha! Pronoun trouble!

Sunday, 6 April 2008

I am in favor of gender-neutral wording.

I have no grudge against those who assert that the English masculine pronoun is actually a neuter. In fact, people have got my back up by pretending that it was somehow proved to be a false neuter simply because some collectives of PC academics declared it to be such.

But the fact is that almost no one is always on-the-ball, and most people are never on the ball, and it’s good to keep them from thinking that something is necessarily male or masculine simply because masculine pronouns are used.

My favorite resolution is one that I first observed in academic papers by economists; specifically, they would alternate the genders assigned to hypothetical subjects. (The prevailing practice seemed to be to start with a feminine.) This practice adds a few virtues to simple gender neutrality. First, the personal pronouns are familiar to the reader. Second, in many cases, two subjects subsequently are naturally distinguished by their genders, instead of by more complex constructions. Third, those readers who need to be awakened from sexist presumptions are often actively confronted with one gender where they were expecting the other.

(Naturally, some PC folk will leap on the first masculine or feminine that they spot, before discerning the pattern, and denounce the writing for being gendered. In some cases they do this in a sort of drive-by attack, and it’s pure cost. In some cases, one can show the pattern to them and presumably put them on the road to being more thoughtful in general. In some cases, one does not so much try to get them on-the-ball as just throw the ball at them, in a game of verbal dodge-ball played to drive them from the court.)

Some years ago, various would-be reformers tried to push the idea of introducing a new pronoun — or something like a new pronoun — which (unlike it) would distinctly refer to singular things with personality but would be a neuter. The more clever ideas involved a sort of singularization of they, but all of the candidates that I saw were awkward — some indeed as if their creätors had wanted them to be so — and none really caught-on (though I’m sure that there’s still some small organization or organizations trying to advance such constructs).

Another potential solution is to recast expressions in terms of one. Normally, I use one instead of the generic you. Like most people, I sometimes slip into using you not to refer to my audience, but to a generic person. Often this habit is innocuous, but one doesn’t want to insult one’s audience by seeming to make assertions about them which may indeed be true of oneself yet still offend them. Anyway, one can often serve nicely as referring to a hypothetical person of unspecified gender.

The Woman of Interest asked a question that I find interesting: Is this one a pronoun? As an alternative to the generic you, it plays a rôle otherwise assigned to a pronoun; and, like a pronoun, it has a reflexive form, oneself. Well, if it’s a pronoun, then it’s the only English pronoun with an apostrophe in its genitive, one’s. My mnemonic, used to help people avoid using it’s for the genitive its then fails.

An Economic Fluke

Tuesday, 1 April 2008

To-day’s mail brings a catalogue from MAT Electronics. I always enjoy going through their catalogues (though I fear that one day they will break my heart by offering the very Motorola chip that went-out in my Mitsubishi television set years ago, which I was unable to replace through Motorola, through on-line parts dealers, or through Mission Hills Radio & Television).

Catalogue #117 presents one of the Mysteries of Capitalism. On page 101, they are selling two Fluke multimeters, the Model 10 and the Model 12. The description for the Model 12 declares

The Fluke Model 12 is everything the fluke model 10 is and much more!

What makes this claim interesting is that the Model 10 is priced at US$149.50, and the Model 12 at US$149.95. So apparently the marginal cost of much more! is 45¢.

In fact, the explicitly described additional functionality of the Model 12 is that one can hook it to the circuit and walk away, and the device will thereäfter record maxima and minima, noting the time of each. That could indeed be a very valuable feature. In any event, it’s a feature worth considerably more than 45¢ to almost any sort of technician who would have been willing to pop for a Fluke meter in the first place.

My Bogus Downtown Adventure

Thursday, 6 March 2008

I went downtown for jury duty to-day.

I took the bus, in order to save on the expense of parking. Unfortunately, I completely forgot about having various knives and multi-tools on my person. There were no lockers at the court-house or otherwise nearby, and my car was back in Hillcrest. So I decided to ship my things at the nearby UPS Store. I didn’t want to have to wait until to-morrow to retake possession, so I asked if I could ship them for pick-up at that very same store, and found that I could. That cost me a total of US$6.60, including the envelope.

I got to the juror waiting rooms in time to see the final seconds of the orientation film. I’d seen it once before to-day, and once is one time too many; I was glad to have missed it.

I parked in the reading room, and watched Dark City (1998), to indeed see whether there were any SC 1243 subscriber sets in it. I didn’t spot any. (I did spot a Model 500, most of which were made by Western Electric, and sets or bits of sets that I couldn’t identify without checking references. Also, I am no longer quite as certain that the set at 4:40 is a WECo Model 302, though there’s a Model 302 at about 55:55.) Actually, as I noted to the Woman of Interest, it was probably wise not to include a SC 1243 subscriber set. The design of the 1243 was clearly influenced by the 302, and the sets are normally black like a 302; but their appearance is less utilitarian and more overtly art deco. Dark City is thus a bit more dark for their absence.

Shortly after I finished this peculiar cataloguing of Dark City, the Woman of Interest called. We chatted until about 14:00, at which point she went out with a friend for dinner. In all this time, no one in the jury pool was actually summoned to be seat as a juror. In fact, by the end of the lunch period, the jury services office announced that only one remaining court might need a jury. So, by the time that the Woman of Interest got off the phone, I was expecting to be dismissed soon.

At about 14:15, announcement was made that there was going to be an evacuation drill at 14:30, that we would be directed out of the building and to a public assembly place by sheriff’s deputies, and that afterwards, those who were not present as alternates (selected on a previous day) would be free to leave. This announcement offended most of the jury pool. It is one thing to serve on a jury or to stand-and-wait for such service, another to be convenient subjects to teach deputies and others herding techniques. (After all, almost none of us would expect to be back in the court-house for at least another year, by which time the protocol would probably have changed anyway.) Most jurors simply left. I decided to go through with the drill, as perhaps something interesting might happen.

However, once we were directed out of the building, deputies did not direct us on to the alleged place of public assembly. So we milled-about in front of the building until, after some time, a deputy told us that the place of assembly was at the intersection of Union Street and B Street, and we headed thence. But at C Street, a block south of B Street, we were rerouted eastward by a deputy. No indication was given as to just where were were actually going; I had 15-to-20 pounds of computer on my back and large book and what-not under my arm; and the UPS Store was in the opposite direction. After a bit more than another block, we hit my Fuck you too! point, and I left the herd.

Shipping my knives and tools 0 feet did not work as well as might have been expected. There was different staff at the UPS Store. They struggled with the concept of my having shipped from the store to itself, and kept telling me that the delivery truck had not yet arrived. Apparently, I was the first to use this trick. (Too clever by half, perhaps.) When one of them finally understood that the package should be there without having arrived on a delivery truck, they still couldn’t find the thing. The fellow who had taken the package in the first place was out on an errand, and I had to wait for his return before I could recover my things.

In the context of some construction work, I had trouble locating the bus stop for my return trip home, and ended-up carrying the d_mn’d computer and what-not for an extra four-to-six blocks, in the course of which I got jostled by a hulk who had a commitment to walking slowly and otherwise in such manner as to block everyone behind him. It was apparently during this brief incident that one of the two bus passes that I (qua juror) had been given fell, unnoticed, from my pocket. Although I might never have used it, I regret the loss.

Installation Problem Work-Around

Saturday, 1 March 2008

The fix for the Windows Bluetooth set-up problem was to select Cancel during the portion of the installation that was failing. The set-up routine would then ask for permission to reboot the system. After the system were rebooted, any attempt to use the applications from that package would cause the set-up routine to resume, and it would be able to complete successfully.

So the program was trying to do something that it couldn’t do without the computer first being rebooted. It plainly should have at least suggested that much, instead of plaguing me with requests to activate the Bluetooth unit.

Anyway, I will now be more concerned to get Linux to interact usefully with the phone set by way of Bluetooth.

Tooth Ache

Saturday, 1 March 2008

The Dell Bluetooth module arrived yester-day. Physical installation seemed to go off without a hitch, the little Bluetooth light on the case now lights-up, and my Linux installation sees the device (when it is activated).

However, the Windows program for setting-up a protocol stack isn’t working. It will run for a while, doing no more than showing a little bit of disk activity, then tell me to activate the unit (by pressing Fn+F2). It doesn’t seem to much matter what I do at that point, whether it be to turn the device off and back on, or just turn it off; the program repeats its unhelpful behavior.

The Windows package in which that set-up program was included is obnoxious in other ways. Although it promises otherwise, its only function after a failed or damaged installation is to remove all of the installation. And when one seeks a reïnstallation, it insists upon re-writing the firmware of the unit, which takes a fair amount of time. Partly, this is dat Ol’ Debbil, software that assumes that the user is more stupid than the code.

Filling a Cavity

Thursday, 28 February 2008

Since I now have another Bluetooth device (my cellphone), I am retrofitting my principal computer for Bluetooth capability. I could have got a USB Bluetooth 2.0 dongle for about US$25, but there’s a compartment in the case for a Dell-specific Bluetooth 2.0 module, and Dell sells refurbished modules for about US$20 (counting tax and shipping). The module, like a dongle, connects by way of the USB host interface, albeït not with a standard USB connector.

What I’d like to do is get something installed so that the phone would see the computer as a head-set, and the computer would alert me when the phone were ringing and so forth.

Another virtue of installing the Dell module is that the already present, built-in Bluetooth light will actually do something.