Dan's Data letters #208

Publication date: 1-Jul-2011.
Last modified 20-May-2012.

 

All sparks are not the same

I found the pics of your bomb quite cool.

[More info.]

Just a heads-up the stuff you're playing with is called 'thermite', anyway have fun....

Michael

Answer:
No, it's not.

Sparkler composition includes a powdered reactive metal for the sparks, which is half of a thermite recipe. But the other half of thermite is the oxide of a less reactive metal. Sparkler composition uses a normal sort of fireworks oxidiser instead, usually potassium nitrate, or another of the other common nitrates for different colours.

You sure can use a sparkler to light normal thermite, though; that's the only way I've ever lit it! The only problem with using a sparkler as a fuse for thermite is that it's possible, but not very likely, that the sparks may set the thermite off early.

I've written about thermite a few times.

 

Chargers that don't charge

Batteries seem to be right up your alley.

What do you think of this ReZap gizmo?

Is it as safe as they claim or is it a death trap waiting to happen?

Gilorian

Answer:
It's physically impossible to recharge alkaline batteries (or carbon-zinc, for that matter). The reaction only goes one way. It may work for charging actual rechargeable batteries, but no "alkaline refresher" I've ever seen has done much of anything. They're not dangerous, but they're not useful either.

I wrote about these things a while ago.

I also asked the ReZap people to send me a unit for review. That was in 2003. They've not yet replied.

 

Performing as designed

1. I have Vista Home (a.k.a. what-the-fu**) and I have been told by the incompetent IT guy that I cannot be connected to the University's server because I need to have Vista Premium. Does it sound like something that may be true?

[This letter is rather old, but everything about Windows Vista here also applies to Windows 7.]

2. If true, do you think that I can just buy the CD for the upgrading and do it myself?

3. My computers are beyond slow at booting and shutting down. In my search on the internet, it sounds like I need to optimize the darn things by removing stuff I do not need etc. Do you think this is something I could do on my own as well or am I at high risk to delete very important stuff and screw up the entire thing?

Alessandra

Answer:
I believe "what-the-fu**" was the original name for Vista, yes.

The Home versions of Vista, like the Home versions of Windows XP and Windows 7, are indeed unable to connect to a Domain or Active Directory network. Your university network presumably uses one of these systems - directory services like this are necessary for management of large networks. So you will indeed not be able to connect to the network properly unless you get an OS which does not have this restriction.

(I like this Microsoft page, which talks all about the awesomely fantastic networking options that different Windows 7 editions do have. Accentuate the positive!)

The only version of Vista with "Premium" in its name is Vista Home Premium, which has the same networking limitations as Home Basic. You'd have to upgrade to Vista Business, Enterprise or Ultimate to be able to connect, or any version of Windows 7 that doesn't have "Home" in its name (there's also "Windows 7 Starter", which barely even supports moving the mouse diagonally, but that's not a retail product).

Or you could "downgrade" to some non-Home version of Windows XP (like the common Windows XP Professional, say), which will also solve this problem. Various Linux distributions, and Mac OS, should (emphasis on the should) also be able to connect to the network with no trouble.

Yes, you can just buy the CD and upgrade yourself, especially if you're upgrading to a fancier version of Vista or Win7. Switching to XP is likely to be trickier, and you'd also need to make sure that all of your hardware has WinXP drivers.

With regard to your slow booting and shutting down, there's no way for me to tell what's causing this without actually seeing the system configuration. Vista ain't too speedy at the best of times, and all Windows systems with a lot of stuff running at once will take a long time to start up and shut down. The solution to this problem, if you don't want to leave the computer running all the time, is to just put the system in "stand by" or "hibernate" mode rather than actually turning it off. Resuming from either of these modes will be much faster than booting from scratch, and in hibernate mode the computer really is "off", using the same very small amount of power it uses when you turn it off normally.

(If you want a modern computer to use no power at all, you have to turn it off at the wall. Its "off" draw really should only be about a watt, though, so this is no big deal. Even in "stand by" mode it ought to be drawing less than five watts. Note that your monitor may draw more than this when it's "off".)

Other things that could contribute to slow startup/shutdown:

* Spyware/adware/other-crapware. Most Windows PCs these days that're horribly slow are like that because there's a lot of bad stuff installed on them. Removing serious spyware infestations can be a major undertaking, but it's really not very hard to avoid being infected with this stuff, so if you're a moderately experienced computer user then this is probably not your problem. Microsoft Security Essentials plus the regularly updated Windows Malicious Software Removal Tool now do a very good job of keeping crapware away in the first place.

* Not enough RAM. Vista likes a lot of memory, and all versions of Windows will run a lot slower when they have to make up for missing physical RAM by using the hard-drive "swap file".

If your computer has less than 2Gb of RAM, you are likely to notice a significant improvement if you upgrade, and RAM is so cheap these days that you might as well put at least 4Gb in there (though 32-bit Windows versions will only actually use three-point-something gigabytes, for reasons I explain interminably here).

And yes, you can also remove or disable various applications and Windows components that you don't use. Don't expect miracles from just reducing the number of things that run on startup, but it can indeed make a difference, and it's not even very hard. Try using the built-in MSConfig utility.

 

Real keyboards wake the neighbours

I am a medical transcriptionist for the last 32 years. I like those old clicky keyboards but have one problem. Can't find an adapter that will fit to hook to a USB port. I can find adapters with the small round hole that goes on some of the newer keyboards to adapt to a USB but not an adapter that you can put the larger round plug into and adapt to a USB port.

Got any ideas? My paycheck is depending on being able to pick up some speed here which I can with those old keyboards!

Kaye

Answer:
The "larger round plug" is probably the old "AT" keyboard connector, which actually has the same signal pins as the more modern (but not much more modern!) "PS/2" interface.

All you need to plug an AT keyboard into a PS/2 socket (including the PS/2 socket on a PS/2-to-USB keyboard adapter) is a simple plug converter. What you want is a converter that has a female AT connector on one end, and a male PS/2 plug on the other; they're all over eBay for peanuts, and breed in the desk drawers of anybody who's been working with PC hardware for a decade or three.

The converter can be a short cable, or it can be a little solid plug adapter. The cable is better if you're plugging the PS/2 plug into the back of a computer, and especially if there's a PS/2-to-USB adapter in there too, because it puts less leverage strain on the little socket and also leaves more room for a mouse plug next to the keyboard one.

Now, here is how this can go wrong:

1: If you actually have an ancient XT keyboard instead of an AT one, there is no way to plug it into a modern computer. XT keyboards used the same big DIN plug, but had a different, incompatible interface. They're kind of the Model T Ford to the AT keyboard's Model A.

(Some hobbyists have managed to adapt XT-to-something-modern with custom microcontroller programming, but that's almost completely insane.)

2: Old IBM keyboards can draw a lot of power (by keyboard standards), which can stop them from working with some PS/2-to-USB adapters. To fix this, you can either buy a guaranteed-to-work adapter for a higher price than the usual eBay adapters, or you can keep buying different $3 PS/2-to-USB adapters on eBay until you find one that works.

(Note that the clickykeyboards.com accessories page also has beefy metal AT-to-PS/2 converters.)

Most PCs still have PS/2 sockets on them, by the way; if you've just assumed that yours doesn't, have another look and you may be pleasantly surprised. (My apologies if you've got a Mac, or something else PS/2-less.)

Note that you should turn the computer off when plugging or unplugging a PS/2 mouse or keyboard.

 

Testing the floorboards

Is the charger in your typical UPS capable of charging larger batteries than the battery it originally comes with? I've put together a home UPS system much like the one on your website, but with deep cycle batteries and an external charger.

The UPS uses its own battery, but when the power fails, a relay connects the car batteries in parallel with the UPS battery to yield a longer runtime. When power is restored, the relay flips the car batteries away from the UPS to charging terminals - to which a deep-cycle boat/car charger is connected. So the UPS battery gets recharged by the UPS, and the outboard batteries are recharged separately.

Is this overkill? Do you think I might get almost or just as good charging results just using the charger in the UPS? If so, I'll try that on my next project (an APC 1400 UPS with cheap external car batteries, as you recommend).

Paul

Answer:
A consumer-grade UPS's charger might overheat if charging a battery with higher capacity and lower internal resistance than it expects, and it might have enough brains to decide that something's wrong if the battery takes much longer to charge than it ought to. But it seems that these problems are pretty rare, if they exist at all in current consumer UPSes.

And, of course, you have to give the UPS the basic battery configuration it expects. So if you're upgrading the two series-connected 12V lead-acid batteries in a normal midrange UPS to car batteries, then you'll need to give it two 12V car batteries in series, or four series 6-volters, or whatever other series/parallel configuration adds up to the right voltage and gives you the capacity you want.

My first thought was that your relay system is a bad idea, because all of the batteries connected in parallel contribute about the same amount of power to the UPS, so the UPS's internal batteries will be flat when the bigger external ones still have lots of capacity left. But then I realised that this could actually work rather well, for the same reason!

Normally, a lead-acid battery that's gone flat is a lead-acid battery that's in peril of serious damage from "sulfation". Deep-cycle batteries are built to be resistant to sulfation, and there are little anti-sulfation gadgets that can effectively recondition at least some sulfated batteries, but you still generally want to avoid flattening any lead-acid battery completely.

If you've got big external batteries hooked up in parallel with the little internal batteries, though, then the internal battery won't be able to go completely flat until the external ones are flat too. The external batteries will hold the positive rail up to 12V for as long as their capacity holds out; once the little battery is out of juice it won't actually be charged by the big batteries, but it won't be able to drop below 12V either, and "below 12V" is where severe sulfation happens. (In the general case, it's "below 2V per cell"; a 12V lead-acid battery has six series-connected 2V cells inside it, just as a standard 9V "transistor radio" battery has six 1.5V cells in it.)

If you relied on the UPS charger to charge the big parallel-connected batteries along with the standard little ones, the big ones would hold the terminal voltages lower. That shouldn't result in actual overcharge for the little batteries, though; they'll just be charged as slowly as the big ones, which shouldn't cause any problems. You probably could not bother with the relay and separate charger for the big batteries, unless it's important that the big batteries be recharged quickly.

On the other hand, cheap UPSes may have lousy chargers that overcharge their batteries. They'll overcharge external batteries just the same, but big liquid-electrolyte batteries are much tougher than little "gel cells", so may just need you to top up the electrolyte a bit more often, or something.

If you use the charger in the UPS and just replace the standard small batteries with bigger ones, so you don't have batteries with different capacity connected in parallel, it will probably work fine.

(Dissimilar batteries connected in series are a very bad idea, since the higher-capacity ones will "reverse" the lower-cap ones when the lower-cap ones go flat. Lots of people in the Third World use this sort of setup, though, since old car batteries of all shapes and sizes are used as portable electricity sources for lighting, running tools, phone charging, et cetera. The only way to get big capacity or more than 12V from your horse-drawn "battery cart" is to connect your motley collection of batteries in parallel and/or series, and do your best to configure and use the arrangement in such a way that no batteries get reversed.)

 

My Flexowriter is future-proof

I have old Iomega 150 Bernoulli cartridges with valuable data on them. I can't find anybody who can transfer the data to a CD for me. Or can I find a drive out there to buy. Do you have any ideas you could share with me? Thanks

Lynn

Answer:
Well, maybe those cartridges still have your data on them.

A lot of nerds have a Bernoulli drive sitting in the garage somewhere, but they were never popular enough for you to be likely to find one in a data transfer bureau, which I presume is where you've been looking. I unloaded my own 150Mb Bernoulli drive (which was already old when I wrote this piece for print in 1996...) to a charity shop some years ago.

If you manage to dig a drive up somewhere, I think you probably _will_ be able to connect it to a modern PC reasonably inexpensively. I think they were all SCSI, so you should be able to run them from a cheap old PCI SCSI card (they'd be SCSI-2, I think). Shouldn't be a big deal hooking one up to a PC with an internal SCSI interface, either - servers, old Macs...

I suggest you see if there's a local users' group or similar outfit. The nerdier the user-group is, the more likely it is that someone will have a Bernoulli mouldering away in a cupboard (possibly still hooked up to their Amiga 500).

 

Forget to take medicine, die of massive overdose

It's hilarious, but sad at the same time.

Billy Joel's daughter tried to commit suicide. That's the sad part. She tried to overdose on a Traumeel, basically a vitamin supplement that contains every buzz-word alternative medicine product and apparently helps inflammation problems. That's the hilarious part.

Thought it might tickle you.

Jack

Answer:
Actually, I think they were promoting it as a homeopathic sleep aid, at the time; traumeel.com now says it's an anti-inflammatory. I guess it's whatever you want it to be.

In homeopathic terms, Traumeel is quite a weak product, because its ingredients haven't been diluted nearly as much as is usual and so there probably actually are some molecules of them present. (Stay with me, here.)

To pick one of them, for instance: "Calendula officinalis 2X (Stimulates healing process) 15 mg" means two successive ten-times dilutions of the substance in question, which, if anybody's paying any attention to quality control (which they need not do, because in most countries nobody ever checks), should leave exactly 0.15 milligrams of the substance in each pill.

Homeopathy, however, is meant to use ingredients that produce symptoms of the illness, when taken in macroscopic doses; ultra-dilution is meant to magically - very literally magically; it for instance matters that the person making the remedy "intend" to make a remedy, while he shakes the stuff in a specially prescribed way - reverse the effect. This "dynamization" turns stimulants into sleep aids, carcinogens into cancer cures, and so on.

There's not the slightest reason to suppose that this any of this stuff is true, and there are plenty of people who call themselves homeopaths but ignore the alleged reversal effect, as is the case with Traumeel. "Calendula officinalis" is actually supposed to be an anti-inflammatory in the first place.

This seems to be the norm for mainstream sold-in-pharmacies homeopathic remedies, now. The actual "homeopathic physicians" probably take a very dim view of it, as they continue to bump water that once might have contacted an arsenic molecule on special leather pads in the process of making "arsenicum album", which is of course a general tonic that's good for every part of your body. Arsenic in macroscopic qualities causes death, so homeopathic arsenic must cause... life!

(It's also good for treating fear of death, of course!)

I think the usual drill for homeopaths is that everything they use is absolutely and completely free of any molecules whatsoever of whatever's meant to be in there, even if it's a low "X" dilution that ought to actually have some trace of the substance there (they go up to "C" and "M" numbers, and some of them are also happy to make remedies out of sounds, or "the light of Saturn").

But they're so unorganised that maybe this stuff really does have a fraction of a milligram of all of these various herbs in it, for all the bloody good that'll do anyone even if they do swallow the whole bottle, let alone eight miserable pills.

At the time, it was unkindly observed that the next suicide attempt this unfortunate woman made might have been shooting herself with a water pistol, hurling herself in front of a model train, or hanging herself with a cobweb.

 

It's pronounced Fronkensteen

I'm totally in love with that epic old knife switch of yours...

Knife switch - both blades up

...and hoping you might have some hints as to where I could find such a thing to purchase?

I'm a member of Robots and Dinosaurs, the Sydney Hackerspace, and looking to build a switch like that into the entrance of the place, hooked up to an Internet enabled magical box somewhere such that when the switch is thrown to its On position, our entire web presence (twitter, facebook, mailing list, irc, website), is updated in seconds with the glorious news that the hackerspace is now open to the public!

And also the other thing when turned off afterwards.

Jenna

Answer:
I found my switch with a saved eBay search set to e-mail notify me. After countless little plastic science-classroom switches, and some DIN-rail-mount ones that kind of do qualify as knife switches under the plastic but who cares, and several enormous antenna-isolator switches that were very heavy and very far away from me, my One True Knife Switch finally turned up.

You could actually make one pretty easily, I think. The more elaborate features like umpteen different contacts and spring-loaded arc-preventing speed-contact-breakers get a bit complex, but the basic knife switch is as simple as it looks, and I think making it yourself is about the only way you'd be able to get yourself a really huge Doctor Frankenstein one at anything like a reasonable price.

Everything is easy for the man who does not have to do it himself, of course, but to my mind the most difficult part of the build would be getting your copper-strip-thick-enough-to-also-be-describable-as-copper-bar to be annealed when you want to bend it and work-hardened when you want it to hold shape for the pivoting switch piece, and for the terminals that need to spring-grip the pivoting piece.

Random info: A useful fabrication material, along with the strip/bar stock, might be copper boat nails, which I think are always pretty pure copper, fully work-hardened. It is, if nothing else, an educational demonstration of annealing: A strong person will only barely be able to bend a four-inch boat nail when it's fresh out of the box, but after you heat it red hot and quench it, any pencil-necked geek can bend it like Superman.

 

Also cooks (flexible) hot dogs!

I don't know if you've seen this...

Vilcus electrical thrill machine

...but it's real.

WTF?

Rich

Answer:
No it isn't.

It's an April Fools joke from 2007. (Note the date on the Art Lebedev page, and the "41" in the product path at ThinkGeek.)

Art Lebedev are confusing, because they've got a few genuine products (those outrageous keyboards with screens on the keys), and umpteen other things that're just design studies or jokes. ThinkGeek do joke products every year, too, and this time they collaborated.

Note that using the "Vilcus" as depicted would probably not actually kill you. Current passing between two fingers of one hand won't come anywhere near any vital organs. For a solid life-threatening shock across the chest, you'd probably want to lick your thumbs and then jam them in there good and hard.

If you want to ask me a question, feel free - but please read this and this first.

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