Dan's Data letters #94
Publication date: 7 March 2004.Last modified 03-Dec-2011.
Drive Of Doom
I recently upgraded the 120Gb Western Digital hard drive in my Windows XP Pro PC, and moved it to an older Windows 2000 box to work as a slave drive to its old 20Gb Quantum Fireball.
The 2000 machine doesn't like its "new" drive, though. With the new drive hooked up as a slave, the point early in the boot process where the system displays the names of the drives it's auto-detected says the boot drive is a "QUANUUM GISECAMLU..." followed by a bunch of random characters. The new drive's name seems to be OK, though.
The weird name wouldn't bother me, except that when the 2000 box gets to the "Verifying DMI Pool Data" part of the boot process, it hangs.
I can get into the BIOS setup program if I reboot; there, the Quantum drive's name is still screwed up (though there isn't room on the screen to display all the weird characters after "GISECAMLU"). Setting the primary slave drive to "None" doesn't fix the problem, but unplugging the drive completely does.
How can I use this drive in this PC?
Don
Answer:
You problem is that Win2000 doesn't like the WinXP-formatted disk. The easiest
way to get around it is to plug the offending drive back into the XP box
and use Disk Management to delete the partition(s) on the drive; the 2000
box should now be fine with it, and you can use 2000's Disk Management to
create a new partition and format it.
This is no good if there's data on the drive that you want to keep, but c'est la vie.
Incidentally, plug-and-go FireWire adapters like the Wiebetech ones I review here are great for situations like this; if there's a bit of room behind the drive, you can plug the adapter in and FireWire-connect it to a different PC, giving full disk management capabilities, without even removing it from the other case you just installed it in! There are cheaper FireWire solutions than the Wiebetech DriveDocks, and there are certainly more reliable ones than a widget held onto the back of a bare drive by nothing but friction, but I keep a DriveDock on the shelf behind me, and have often found it handy.
In some cases, "Verifying DMI Pool..." hangs will keep happening even after you remove the drive that caused the problem. In that case, you can get out of the hole by booting from the your Windows 2000 or XP CD and repairing your Windows install.
Hot juice
My mum got sent a 120 volt juicer from America. I offered to buy a power adaptor for it, but she cleverly pointed out that she had bought one earlier, and didn't need my help.
So we plugged it in and flicked the switch, and immediately fried the juicer. Great big yellow flashes zapped around inside the case, and sent out that burning smell.
The adaptor she had bought was just a plug adaptor, and not a step-down transformer. My question is, is it possible to have the thing repaired, or is it a goner? (I don't recognise the brand, must be an America-only product.)
Chris
Answer:
It's probably not possible to repair the juicer economically. The only thing
inside that's likely to be toast is the motor, but for most appliances the
motor's the principal component, and unlikely to be available as a spare.
If this were The Last Juicer On Earth then you could certainly shoehorn some 240V motor or other in there; the existing switch and wiring are pretty likely to be safe for 240V, provided nothing's melted, and in any case replacing a switch is no big deal compared with replacing a motor. But the time and effort required to source the motor and fit it (it might have the same can size and fit neatly, but it'll probably require some butchery) would, I think, be better put towards buying a new juicer locally.
[Chris got back to me after this exchange, by the way. The solution his mother chose was to convince her relative in the USA to send her another juicer!]
Mystery plugs
Whenever the cable modem gentleman comes to my house, he says, "Whoa! You've got an overloaded signal. I'll have to take it down a bit." Then he puts one (or more!) of these on my cable:
He was extra concerned this last time, as I was discontinuing my television service (Dreaded-Culture-Killing-Box-of-Doom) and that meant "you'll get even more signal coming to your modem". He assures me that without these little guys, the signal would be too strong, and my cable connection would drop more often. Me, being a skeptic, think that the company is just trying to keep me from hogging bandwidth. I've downloaded and uploaded some movie trailers with and without the connectors... but I'm just not savvy enough to tell the difference (maybe you could recommend a test?)
Should I take these things off, or leave them on? What do they do anyway?
Douglas
Answer:
They're attenuators - a plug and a socket with a resistor in between, on
the signal wire. A weaker signal comes out of one end than went into the
other. Yes, it is possible that you have too strong a signal, which
could occasionally exceed the cable modem's input range and cause problems.
It's also possible that the cable guy doesn't know what he's talking about, but if your connection works fine then this is probably not the case.
The cable guy is right about the TV. Unload one branch of the Y-adapter that feeds the TV and the cable modem, and the signal to the remaining branch will be stronger.
The cable company can't degrade your bandwidth by inserting attenuators. Well, they can, but only to zero. If you're connected, you've got the bandwidth you're paying for; if you aren't, you haven't. It might be possible to crank the signal strength down far enough that the user bandwidth was reduced without completely killing the connection, but you'd probably just get frequent complete dropouts. It's much easier for your ISP to limit your bandwidth digitally at their end of the cable (which you can't do anything about) than in an analogue fashion at yours (with attenuators that you can remove).
Whole-house UPS?
I have an APC Smart-UPS 900. It's an older unit and I've had it refurbished once when the batteries went. (Since then I've learned that I can order the batteries myself online fairly inexpensively.)
Well, earlier today the power blinked and the UPS crapped out. Anything attached to it rebooted. So I was thinking the batteries are shot and I should replace them. But I'm not sure they're shot. I'm thinking the unit itself may be shot. So I need a way to test the batteries to see if they're in fact shot. I'm guessing I can attach something with a known draw and figure out how long it should stay on for? Assuming I do, can you recommend a site that'll help me figure out how to calculate things like expected run time? FYI, these particular batteries are Panasonic LC-R0612P1. They are 6 volt sealed lead acid.
Alternatively (this is what I'm leaning towards actually):
In the last several years I've increased the amount of computing equipment in the house, dramatically, and now have something like 6 separate UPS's scattered throughout the house. So, after reading your do it yourself UPS article I am thinking I may try something like this:
1 - Buy a pretty large inverter, maybe 5000 watt.
2 - Hardwire it to specific outlets in the house for battery backup.
3 - Attach enough car batteries to keep things running.
4 - Get a good charger/power supply.
5 - Maybe get some kind of cool looking LCD/digital display to show me the state of the batteries.Of course this creates a few questions:
1 - Do I get a 12, 24 or 48 volt inverter?
2 - Do I need a sine wave inverter or is modified sine wave ok? (Based on your article it sounds like modified sine wave is ok for my application. The load will consist of 4-6 PCs, a few flat panels, 3 or 4 Sun servers, a coup le of small Cisco routers, a Cisco switch, a TiVo, a cable box, a cable modem, a Netgear switch/router, WAP access point, etc, etc.) (Oh, and MAYBE my home theater system...)
3 - How many batteries do I need at a minimum? How do I calculate how adding more will effect runtime?
4 - How do I size the charger/power supply? (If it's a charger I'd be running off A/C and only transfer to battery if power fails. If it's a power supply I'd run off of it all the time, right?)
I will likely add a transfer switch and auto-start generator to the mix. That way I can generator backup the refrigerator, furnace, some lights and the above mentioned battery charger. I'm also thinking this may be more practical then having what I guess would be a fairly large battery bank, both for space reasons and for ongoing maintenance costs.
Why do this you ask? 1. I need more backup power and big UPS's aren't cheap. 2. I could fairly easily customize my runtime by adding off the shelf batteries (though if I get a generator I won't need more batteries). 3. Because it will be a lot of fun!
Mike
Answer:
As you discovered after having your UPS "refurbished", many (most?) man-portable
UPSes use standard interchangeable
sealed-lead-acid bricks, often in the common 12-volt, 7-amp-hour size. They're easy to
buy, but may be annoying to replace. Some UPSes need to be seriously dismantled
to get at the batteries.
The Panasonic LC-R0612P1s in your UPS are similar to the regular bricks, except they're only 6V and have 12Ah nominal capacity. Much the same actual energy density as a 12V 7Ah battery, in other words; many cheap "7Ah" bricks don't really deliver quite that much capacity into a decent load. (Some have higher capacity, though; batteries the same size but with sticker capacity a bit higher than 7Ah are common, and at least some of those stickers must be telling the truth.)
Anyway, if you want a reasonable test load for a battery outside the UPS (to rule out some problem with the UPS itself), head off to your local electronics store and buy a 50-watt 12V halogen downlight lamp and a couple of medium-duty alligator-clip leads (and a base for the lamp, if you want to get fancy). Clip one terminal of the lamp to one terminal of a battery and the other terminal to the other terminal (any way around you like - incandescent bulbs aren't polarised) and you should get an orange glow from the lamp; a 50W 12V lamp running from 6V will draw only about 12.5 watts, and not light up terribly brightly.
A fully-charged 12Ah 6V battery should be able to power a 12.5-watt load for 5.76 hours. If it manages that, or something close to that, then it's probably OK. If you want a harder, faster test, buy more than one lamp and some extra clip-leads and wire more lamps in parallel with the first one - with four lamps, your test time will be only one hour and 26 minutes, at most.
You can expect a battery that's been used for a while to have less than full capacity, but lead-acid batteries that haven't been treated badly generally last for an awful lot of charge cycles. Even cheap gel-electrolyte sealed lead-acid bricks made by the lowest bidder in China ought to be good for several hundred full charge cycles, and many more partial cycles.
SLAs have a life expectancy no matter how they're treated, though; after several years all cheap SLAs are likely to need replacement, even if they've never been discharged significantly. If the batteries are only a couple of years old, though, and haven't had to ride out multiple blackouts, they should still be OK.
Lead-acid batteries don't like being left flat, by the way. If the battery runs flat very quickly then it's already dead, but if it lasts for a respectable fraction of its official capacity, get it back into the UPS and re-charge it soon after the test. Don't leave it overnight, or it'll sulfate and die.
With regard to your giant DIY UPS idea, note that I do not recommend that unqualified people screw with mains wiring. There are non-obvious pitfalls to this, especially when you start running cable in your walls.
By all means buy an inverter and bolt it to the wall yourself, but get a qualified electrician to do the cabling. There's a reason why the law where you live probably says you should do this anyway.
Apart from that, there's nothing wrong with your idea at all. It also makes it possible for you to add the cheap-surplus-solar-panels/home-built-wind generator/waterwheel of your choice, to mildly reduce your utility bill and substantially increase your environmentalist self-righteousness.
I'm not sure what inverter voltage would be best. 12V is widely used, and the right choice for a lot of cheaper gear, but for serious loads the DC currents get ridiculous. 24V is, I think, a good compromise, but I speak as a man who's never done it.
I would get a sine-wave inverter, if you expect to run stuff beyond PCs (like that home theatre and refrigerator). If it's PCs only, then a modern modified-square-wave inverter should be fine.
Sine-wave inverters are still expensive compared with modified square, but they will run everything without problems, and the price difference is a lot smaller than it used to be.
I also can't give you a definite battery count. It depends how much run time you need. Regular car, truck and deep-cycle marine batteries are unfussed about delivering quite ludicrous currents; a 24V system fed by a pair of truck batteries should have no trouble running an average geekhaus, for as long as the capacity lasts.
Basically, just multiply battery amp-hours by voltage, and that's the watt-hours you've got to call on (ignoring inverter losses and power factor), unless you're trying to run a whole house from one mini-size car battery.
Your charger could be pretty wimpy if you don't expect frequent cutover to battery power; a full-time power supply would have to run the whole house, and would thus have to be quite gigantic. I don't think that's what you want. Sorry, but you'll have to ask an alternative-power professional about what kind of charger to get.
Capacity confusion
I have read your old article on digital camera batteries, and also the few questions in your letters section, but I have a small, and quick (hopefully!) question regarding digital camera batteries once again.
To cut it short, I'm buying a Canon PowerShot A70, and I know that when I am shooting, I'll be shooting for a few hours straight. I was planning on buying some Sanyo Ni-MH batteries, and a rapid charger from Battery World (They come as a package). One pack is around $AU80, with the charger and 4 x 2100mAh batteries; the other is $AU100, again with charger and 4 x 2300mAH batteries. The chargers are identical (according to the guy in the shop).
I was wondering how much difference what the extra 200mAH make? No exact answer needed, just maybe an answer to justify the extra $20 or so it costs for the higher amperage batteries.
Lastly, are no name NiMH cells like the cheap ones sold on eBay any good?
Richard
Answer:
There's just about exactly as much difference between different capacity
NiMH cells as you'd expect by doing the maths. A 2.3Ah cell will last less
than 1.1 times as long as a 2.1Ah one, which is to say, you're unlikely
to notice the difference. Nice to have for free, but not worth paying more
than 10% extra for.
It should also be noted that generally speaking, higher-capacity cells are more fragile than lower-capacity ones - but NiMH technology's still being mildly refined, so there's no reason to suppose that current-model 2.3Ah cells will last for any fewer charges than did the first generation of 1.5Ah cells.
Yes, no-name NiMH cells are fine; there's a great deal to be said for buying plain-wrap cells a few steps down from the cutting edge of capacity. After all, even a mere 1.5Ah cell has 65% the capacity of a new and shiny 2.3Ah one - if it costs a quarter as much, then it's likely to be a great choice for your second or third set of batteries!
At the moment, Jaycar here in Australia's selling 1650mAh NiMH AAs for $3.95 each (less, in quantity) and four-packs of 1.8Ah Kingcell AA for $18.95.
I'm sure there are some super-cheap no-name cells out there that don't have as much capacity as the sticker says (if only because they've been sitting on a shelf for five years...), but I generally prefer cheapies to name brand cells; they're clearly better value.
When buying cheap NiMH cells, don't buy a cheap slow charger as well; "bargain" cell-and-charger packs usually come with a crappy charger.
It's not hard to find really cheap rechargeables with no unwanted extras on eBay, though, and if you buy from someone with lots of positive feedback you're pretty likely to get excellent value for money.
Insert Spaceballs Jam Reference Here
I have found an interesting product. I have recently developed a problem with speeding tickets. Then one day I find this "Phazer II" advertised. It is illegal in my state so that lends it some credibility, but really, is it real? If I spend $100 on it, am I going to be out that along with an additional speeding ticket that this "passive jammer" was supposed to prevent?
James
Answer:
No "passive radar jammer" does anything at all. They're a complete
waste of money. If they worked, the US Air Force would be strapping 'em
onto fighter planes.
And yet, as you say, they're often illegal, generally because the FCC (or other similar regulatory body, in other countries) simply takes the fraudulent claims of the manufacturers literally, determines that a device that does what this device is claimed to do would be illegal, and so bans them!
Here's an example of such a ruling, against a better-known brand of passive jammer, which also didn't actually work.
Never mind spending $US100; you might as well make your own. It'll work just as well.
[Actually, thanks to a reader, I stand corrected. The Phazer does do something. It makes your car easier to detect!]
