Dan's Data letters #189
(page 2)
Publication date: 22 August 2007.Last modified 03-Dec-2011.
Also incompatible with Super Nintendo ports
We have a Sony HDV 108E camera (1 year old). We connect it to our computer via a FireWire cable (using Pinnacle Studio 10 for editing), with a PCI FireWire controller card.
We have three cameras (we're two experienced camera users) that we have connected thousands of times in the last year with no problems.
The Sony camera went to the factory for repairs to the lower casing where the ports are situated. It came back from the factory, we connected it in the usual way and the computer couldn't recognise the camera.
We returned it to the factory and they said that the FireWire port on the camera had burned out due to an electrical power surge caused by the six-pin FireWire cable. Maybe we had tried to insert the cable the wrong way around, and caused this. They said that they have many cameras that experience this problem, especially with Macintosh computers.
Everyone that I have told since hearing this (film production companies, photographic shops) look at me as if I am totally cuckoo.
As the cost of repairing this great camera is almost the same as what paid for it, this problem is most perturbing. We would really appreciate your input, and also advice as to what we should use in future so that this can't happen again.
Cathy and Fleur
Answer:
Yes, it is possible to destroy the FireWire hardware in a camera and/or a computer,
if you jam a 6-pin FireWire plug into the socket backwards. I think doing that usually
just leaves you with a mangled port and/or cable, but stuff can get blown up, too.
The standard six-pin FireWire connector is apparently more susceptible to this than you might think, since its contacts reach out far enough that you don't have to jam the connector in all the way to cause the problem.
(Apparently Sony go out of their way to warn people about this {i.Link is Sony's name for otherwise-standard four-pin FireWire}, and even to warn users to not connect a FireWire cable between a camera and a PC while the PC's turned on. Which, given that one of FireWire's big features is that it's a hot-pluggable system like USB, seems very strange to me.)
I don't think there's any way for you to prove that you did not do this. If Sony insist that you did, then you're screwed, whether or not you actually did.
The only other option for digital camcorder-to-PC connectivity is USB, but FireWire is very much the standard for digital video. I don't know how many cameras offer USB transfer for anything but still images.
Voltage... of MYSTERY!
I encountered a curiosity that I thought you might have an answer to the other day.
I was replacing an outdoor light that's on a dual-switch circuit - one switch upstairs, one switch downstairs, when they're set to the same setting the light turns on (i.e. inverse XOR). At the time I didn't know the exact setting that would turn the circuit on (since, in testing the old light, we'd tried several combinations of both switches with no effect), so I pulled out my trusty multimeter and, standing atop the aluminium ladder with some trepidation, measured the voltage across the circuit.
(I should add that the bare wires were wrapped in electrical tape and I stuck the multimeter probes into that, to prove that I'm not completely loony.)
First measurement: 107 Volts AC.
I checked this twice, making sure that the multimeter was set correctly, because this was frankly not a number I expected.
Second measurement with one switch changed: 240VAC.
OK, so that must be the "on" setting. Write that down on a piece of paper somewhere.
Third measurement, switches in original position: 105VAC.
I checked the amps (using the 10 Amp circuit on the multimeter just in case) on that circuit: 0.000A.
I didn't check the amps on the known-"on" setting, for fear of become a crispy roof-hanging or, worse, frying my multimeter.
So: any idea what I've done wrong? Is it time to call an electrician? Or have I just missed some complicated but perfectly logical explanation?
Paul
Answer:
Your standard dual-switch circuit looks like this:
/-----------\
A---X X-----\
\-----------/ LAMP
/
N---------------------/
A is the active wire, N is the neutral return wire, each X is a switch that can connect the single wire going into it to either the top conductor or the bottom one of the two-wire middle section.
If the two switches are both set the same, both connecting to the top wire or both connecting to the bottom one, then current flows and the light turns on.
If they're different, no current can flow.
So no matter how either switch is set, flicking the other one will cause the light to change state.
Job done, and you don't have to go downstairs to turn the light on or off any more.
In either "off" situation, one of the two conductors between the two switches will still be energised. Since those wires are probably just a standard length of figure-8 cable, the two conductors run right next to each other for the entire length between the two switches. That's more than enough length for there to be considerable capacitive coupling between them. The unenergised conductor will, therefore, have an AC voltage on it, if that voltage has nowhere to go.
If the lamp is present and functional, then it'll connect the capacitively energised conductor to neutral and the voltage will almost vanish. Capacitive coupling of mains voltage through a few millimetres of PVC is not able to transfer any significant power, so even a quite high-resistance connection to neutral or ground will sink all of the volts away. That's what happened when you shorted the "107V" conductor to the neutral wire with your multimeter; a very small AC current actually was flowing, but it was below what the meter could read on its 10A range.
If the lamp is absent or blown, though, the capacitively energised conductor will be insulated from neutral and will stay energised.
(If the 107V conductor had been energised from a source capable of high current, by the way, then blithely sticking an amps-range multimeter across it and neutral would, as you suspected, be a pretty bad idea. A multimeter set to volts mode has a very high resistance; in amps mode it's deliberately trying to be as close to zero ohms as is possible. The 10A range for cheap meters doesn't even have a fuse; hook it up to a mains circuit that can deliver well over ten amps and, just before the house circuit breaker trips, you'll hear the tiny "pop" of a meter that'll never have a 10A range, or possibly any other ranges, ever again.)
Situations like this exist all over the place. Random conductors like yours, signal cables, un-earthed water pipes; all can have quite a lot of floating volts on them. You can even feel the effect of the voltage in certain circumstances. I remember I used to get a tingle if I touched my tongue to the hot tap while taking a bath as a kid (which was far from the strangest experiment I performed at bathtime...). There's also a distinctive "rough" feeling if you run your finger over an unearthed metal appliance casing that has a decent AC voltage on it, for this sort of reason.
Interestingly, induced current issues can also cause CFLs to flash periodically.
NOTE that doing this sort of wiring yourself, if you are not a licensed electrician, is probably illegal where you live. In many countries (including Australia, where I am), it's legal - though often unwise! - to do your own wiring on "non-permanent" things, like electronics kits and appliances, but any sort of "installation" wiring, including everything from the breaker-box to the power and light sockets in your house, is for licensed electricians only. There is a long list of good reasons for this.
If only the ads told the truth
I'm looking to replace my two powerboards here, as the protection LEDs don't light up any more, and because I seemingly have lost quite a bit of stuff in my room, just recently. Namely a hard drive, a motherboard, power supply, D-Link router and an electric blanket. Four of those items died in less than three months. Ouch!
I've got an itchy feeling the powerboards aren't covering the equipment and devices too well, and the mains power might be a little polluted, too. So it's time I grab some new powerboards, in case they're the cause of these recent power issues.
I'm quite interested in a UPS, but for now wouldn't really be able to afford a device that could accommodate my PC. So a couple of powerboards will have to do. I'm used to just using whatever off-the-shelf powerboard I can get from whatever store from whatever town, but I'm curious and inclined to maybe spend a little more this time around just to possibly help alleviate further power struggles.
I understand powerboards don't offer the grandest protection and really, when it comes to direct lightning strikes nothing (at least commercially affordable or available?) would withstand such an attack. UPSes are better, but like I said, affordability's an issue. Plus I would still need to purchase a powerboard or two to provide power to all my zillions of knick-knacks.
So I've decided to go a little upmarket but still buy sensibly. Not sure really what to look for, so I'd like to hear from Dan the Man on what you would recommend.
Is there anything you're particularly fond of in the powerboard market? If not, could you recommend a great sturdy powerboard that'll do the job covering most of what a decent power board should cover - which really, let's face it, isn't a great deal, at least not the heavy stuff.
My price range would be $AU100-$AU200, I'd prefer something that provides eight outlets, telephone not necessary but can't hurt. I want one to run a TV, DVD, VCR, 5.1 speakers and another to run the computer including monitor, DSL modem and router, and maybe one other item that would be hot-swapping a lot, like a mobile phone charger.
Woody
Answer:
An electric blanket died? That's odd. Electric blankets are simple resistive devices,
like a toaster or a bar heater; as such, they're almost immune to damage from bad power.
A spike that can kill a simple heater ought to have blown up almost everything else
that was turned on at the time.
(It could just be a fluke, of course. Electric blankets are built down to a price.)
Realistically, no ordinary "surge protector" powerboard offers any significant protection at all. As I mention in this piece, there's no off-the-shelf product in your price range that'll help much.
You can, however, afford a used power conditioner, like the one I show in that same article. A 1000VA unit like that would be able to run all of the stuff you list by itself (provided your computer isn't unusually heavily stacked), and 2000VA and higher units show up on eBay pretty regularly.
One problem with these devices is that they draw a quite significant amount of power all by themselves, even before you've plugged anything into them. A hundred watts, easily. If you're paying to heat your house already then this is not a big deal - you've just added a new hundred-and-something-watt electric heater - but if you're paying to cool your house, it's bad.
The other down side is that they're very heavy. I managed to get that 1000VA unit posted to me (it was actually rather over Australia Post's 20-kilogram limit...), but there's no affordable way to ship larger units. So you'd have to find one from a seller close to you.
If you manage that, though, your problems will be solved.
Failing that, you can get new mains voltage regulators of more modern design quite cheaply these days. Essentially, they're the power conditioning hardware from a good-quality UPS, without the UPS part; they're smaller and much lighter than old-style ferroresonant conditioners, and they don't waste a ton of power. I don't know what the best models are, and I can't shake my basic suspicion about any power conditioner that doesn't hum like a substation and give you a hernia when you move it, but APC's Line-R 1200VA still looks pretty decent to me.
Any moderately competent computer store ought to be able to get one of those in for you. Then, since you're in Australia, all you've got to solve is the IEC Socket Problem!
Quack Of The Day
Just wondering if you have heard of "The ReBuilder"?
It's a device that the manufacturer claims can treat neuropathy, and a range of other ailments.
My dad is looking at buying one to treat his neuropathy, but after looking at the site I'm convinced the whole thing is a fraud, and that the devices cannot do what the manufacturer claims.
They are not sold here in Australia, and are only available directly from the US manufacturer, and cost around $AU1000 for the "non-basic" one (including shipping). They have a 30-day satisfaction guarantee, but I'm doubtful they actually honour it for non-US orders. Dad is seriously considering buying one, and I've been unable to convince him otherwise.
The problem is, we're pensioners and can ill afford to spend $1000 on something that's useless.
Is it a scam, or does it actually work? Any ideas?
Lester
Answer:
These people do not deserve your father's money.
Isn't it great when the makers of some medical device put "FDA Approved" right up there in the title of their Web site? It gives you the same confidence you'd get if Heinz printed "FDA Approved" in big letters on every bottle of ketchup.
As soon as I saw the "FDA Approved" bit, I knew that the FDA "Approval" they'd have would be a 510(k) certificate. And, yea, my prophetic abilities also told me that the "approval" process would have stopped there, for the device would have been exempted from actual Pre-Market Approval (PMA) testing on the grounds that it was "Substantially Equivalent" to a previous device.
In other words, it doesn't do anything that a previous approved device (usually a lot of previous approved devices) doesn't do.
And, for I am nothing if not a thorough foreteller of the future, I went on to predict that the devices this thing is Substantially Equivalent to are old enough that they've been grandfathered into the US FDA approvals system, and have in fact never been tested for efficacy by the FDA.
I was cheating a bit in my foretelling of the future, because I went through this same sequence a while ago over the wrist-zapper thing mentioned in this column.
Verily, though, the Rebuilder fulfils all of my prophecies. The makers' FDA page refers to registration numbers K844085 and K882980, though only the second one actually seems to exist at the moment, for reasons we'll get to in a second.
Bingo, there it is. "Substantially Equivalent" to other TENS-type devices, which have been on sale in the USA since a couple of years before the FDA required PMA testing.
It should be noted that one of the situations in which the FDA requires a proper Pre-Market Approval (PMA) test even if a device is otherwise Substantially Equivalent is if the device is intended for a different purpose to the previous devices. That rather takes the shine off the Rebuilder people's claim to have discovered a breakthrough cure for neuropathy... using a machine which, according to their own proudly trumpeted application to the FDA, must be in no important way different in construction or use to others that've been on sale for well over thirty years.
So, to recap: Despite the proud trumpeting of "FDA Approval", the FDA explicitly does not certify that The ReBuilder works. Or, indeed, that any other devices like it work.
(I was surprised that it took the guy responsible for the Rebuilder until this page before he started yammering on about patents, too. Cranks love patenting useless things. That doesn't make 'em useful.)
TENS itself is not blatant quackery. There's significant evidence that it treats some kinds of chronic pain quite well for some people. The going rate for a TENS unit seems to be less than $US100, which is not surprising, because they're electrically very simple. It would be easy to connect one to a Rebuilder-style footbath, if you wanted.
(The Rebuilder's alleged "unique waveform" (the subject of its pending patent!) is no doubt incredibly complex and totally not reproducible with five bucks worth of Radio Shack components. Don't believe the haters!)
And now, the fun.
The guy responsible for The Rebuilder is one David B. Phillips, Ph.D (Doctorate in what? From where? Who knows?). He used to have a highly amusing home page (archived here) including an excellent list of his favourite books; now his home page is here, featuring numerous inventions, of varying merit.
I'm going to throw caution to the wind and postulate that Dave's Ph.D isn't in a medical field. Someone who does have a medical doctorate comments, at length, on The Rebuilder here.
In brief: For someone who claims to have cured neuropathy, David B. Phillips, Ph.D appears to be extraordinarily clueless about what the condition actually is. Right down to the basic anatomy of the nerves he claims his device affects.
And, as he says, here is the only actual opinion you can find on the FDA site about The Rebuilder.
It's just a report from a user; I could file my own report in which I claimed that The Rebuilder turned my house into a toadstool. But the point remains: The FDA "approval" that's supposed to be such a big selling point for The ReBuilder is based only on use of the device for pain relief, and even that has never actually been tested by the FDA.
Regarding the guarantee - it's hard to tell which sellers of quack devices honour their (almost universal) money-back guarantees and which ones don't. Some of these people are doubtless complete weasels who ignore warranty claims entirely or impose outrageous fees or conditions, but I think quite a lot of them probably do honour their guarantee, on the rare occasions when someone actually does return their useless device.
(They may then go on to sell the returned devices as new, though...)
It's very easy for people to believe in a device or nostrum that is alleged to treat an inherently variable condition, like neuropathy, which doesn't have readily quantifiable symptoms or distinct endpoints. This includes all chronic pain. Even when such devices do nothing at all, many people will be able to convince themselves that they work.
Add the further filter of a high purchase price, to rule out the people who aren't already filled with that many dollars worth of hope, and a quack's onto an almost sure thing.
After I sent this reply, Lester got back to me. He observed that the ReBuilder site contradicts itself: "It claims the device works by unblocking the nerve signal path, then they say it can be used for pain relief, which presumably means blocking pain signals. They say it has FDA APPROVAL, then they say that's not possible, but it's FDA REGISTERED. Similarly, that it's not a TENS, but then it is one... It's a shame the device doesn't work, they could attach it to their heads to unblock their brains! Then maybe they would at least make SOME sense."
Regarding the blocking/unblocking thing, defective nerves can send signals constantly, so this bit has a grain of truth in it.
All of the best quackery has a grain of truth in it, though, quite possibly because that works so well against scientific debunkers.
When someone says "Mars is red because it's made out of trillions of space foxes, who constantly talk with each other in fluent Cantonese about their plans to destroy humanity by increasing sunspot activity", your typical scientist will naturally latch onto the facts and respond by saying "Well, it's true that Mars is red, though it's more correctly only red-ISH, as you can see in naturally-toned pictures of the surface which are often generated by means of a very interesting process which I'll get to in a moment, and sunspot activity definitely can affect Earth's atmosphere and a number of satellites, though I believe it's a considerable overstatement to say that any peak in the sunspot cycle could directly affect human life..."
By the time the scientist's finished his sentence, the original nutball's sold eight more books.
A while later, Lester got back to me again. His dad bought a ReBuilder. It did nothing noticeable. He returned it, and did indeed get his money back (minus shipping fees).
Before they returned the ReBuilder, Les fed its super-special output waveform into his PC's sound card to have a look at it. He observed that it did indeed look very similar to the "cat motoneuron impulse" shown on the ReBuilder site here. That page probably offers quite a lot of entertainment for actual neurologists.
