» 2012 How to Spot a Psychopath

Not the publicity he was looking for, instalment 3762

8 May 2012 — dan

A reader, well actually he probably isn't, writes:

From: "japan-best.com webmaster" <postmaster@japan-best.com>
Date: Mon, 07 May 2012 22:27:24 +0900
To: dan@dansdata.com
Subject: Inclusion in one of your articles

Dear Dan

I am Marc with japan-best.com

i read your article here
http://www.dansdata.com/contact.html
and would like the possibility of include my site in it.
I have also took note of yOur paypal adress :-)

You can check us here :
japan-best.com <http://japan-best.com/en/>

I am looking forward to hearing from you and discuss that further

Have a great day

Regards
Marc

Marc, buddy, your Spam-O-Matic might need a little recalibration, there.

My contact-and-donation pages may score surprisingly high for various panhandling Google searches, but that doesn't mean it'd be a good place for you to advertise your site full of allegedly Japanese merchandise.

Including, I now see, some front-page items whose description does not match their pictures.

At first glance, Japan-Best looks like a valid online store, but the more things I click on, the more I think it may actually be a 100%-machine-built lazy-dropshipper paradise. Or, conceivably, just a fancy way of stealing credit card numbers.

Or maybe it's legit, if clumsy, but massively overpriced. Look at this hideous wristwatch, for instance; from Japan-Best, including shipping, it costs twice as much as the same item on eBay.

Between eBay and legit dealers like HobbyLink Japan, I don't think there's much reason for anybody to buy stuff from weird machine-made sites like Japan-Best. But I'm sure a little PayPal baksheesh to get some crafty links inserted in random high-PageRanked Web pages will turn that right around for you, Marc!

UPDATE: Marc quickly replied in the comments below. Then, more than six months later, he decided to e-mail me this:

Date: Thu, 18 Oct 2012 14:30:50 +0900
From: "japan-best.com " <postmaster@japan-best.com>
To: dan@dansdata.com
Subject: remove private infos

japan-best.com here,
Say what you want about the website.
but remove the email adress from the article, you have no right to do that.

So apparently the postmaster@domain address is sooper sekrit private information now. I learn something every day!

This on top of the strangely popular idea among Internet ne'er-do-wells - which is the only reason I'm bothering to add this update to the post - that there's something confidential about e-mail you send to strangers.

It might be polite to not publish the reply address as well as the rest of an unsolicited commercial e-mail from a stranger, but "rights" don't come into it. Well, unless there's some nutty Net-privacy law where the complainant and/or "culprit" live that forbids disclosing such information without consent.

Failing that, there is no more reasonable expectation of privacy of your return address when you send an e-mail to a stranger than there is of your phone number if you telephone a stranger who has Caller ID. People you annoy on the Internet have no legal obligation to keep your identity secret.

And if your address is one of the standard addresses you should expect to find on any mail server...

So I reckon I'll leave it as it is, Marc. Your move, genius.

Posted in Scams, Spam. 7 Comments »

One LED, two LED, red LED, blue LED

4 May 2012 — dan

A reader writes:

Myself and a friend were just reading Big Clive's "Hack your solar garden lights", and we are unsure how he came to those amp readings and the conclusion that two LEDs use less amps than one.

I am assuming we are just missing something, could you please enlighten us?

Daniel

To oversimplify, two LEDs in series have more resistance, so less current flows. But halving the current passing through an LED doesn't necessarily halve its brightness. Standard high-brightness 5mm LEDs generally have a 20-milliamp current draw on the spec sheet, but will glow from much less, and may be considerably more efficient at small currents.

The reason why this is an oversimplification is that LEDs, unlike incandescent-filament lamps, aren't just a relatively simple resistive device.

(And the "relatively" is in that sentence because not even tungsten-filament bulbs are completely straightforward. They have, for instance, a much lower resistance when cold than when operating. And reducing the power of a filament bulb will generally give you a reduction in apparent brightness that's greater than the reduction in power, because the filament will be cooler and more of its output will be down in the invisible infrared. LEDs, in contrast, only know how to make one colour, even when they're only barely creating a tiny spark of light. This is the case for white LEDs too, because to date all of those are actually blue LEDs with a phosphor coating that turns some of the blue light into other colours.)

Instead of being resistors, Light Emitting Diodes are, yes, diodes, with a constant voltage drop across them at a given temperature. But when they're lit they get warmer, causing them to pass more current and glow brighter and get warmer again, which can rapidly lead to destructive thermal runaway unless the LED is restrained in some way, by for instance limiting the source voltage so the LED will just never be able to get hot enough. Or, more commonly, by limiting the maximum possible current.

You can see how this can get complicated. (Power-supply design in general is a surprisingly tricky field.) Just running LEDs from a simple DC source via current-limiting resistors can be a bit complex; proper efficient LED drivers that deliver a set current no matter what LED you plug into them are more complicated again. (The drivers in garden lights are elegant, but like the "joule thief", not actually very efficient.)

Don't let all this put you off monkeying with garden lights, though; as Clive says, they're both easy to modify and so cheap that it doesn't matter if you wreck something. Just add some of the incredibly cheap high-brightness LEDs you can get nowadays (which I mentioned the other day), and you can make all sorts of decorative, and even useful, solar LED lights for close to no money at all.

Posted in Electricity, Electronics, Hacks, Handicrafts. 1 Comment »

Spooky sun sizes

2 May 2012 — dan

A reader writes:

The Oatmeal recommends sites get more traffic and Facebook likes by writing an epic love story involving cage-fighting nuns and tanks, or if that is not possible, explaining why the sun and the moon appear to be the same size in the sky.

Both of these seem right up your alley, but frankly I for some reason find the second one more interesting. Why ARE the sun and moon the same size? Is it just a bizarre coincidence, or is there some astronomical orbit reason for it?

Lucas

I'm afraid it is indeed just a fluke. Which, furthermore, starts to look less amazing when you discover that the sun and moon don't actually have a particularly spooky similarity in size.

I remember reading some flaky book when I was a kid, possibly some von Däniken claptrap or other, that made much of the extraordinarily precise apparent-size match between the 0.55-Earth-diameter moon and the 109-Earth-diameters sun. Surely this cannot be mere coincidence, hence ancient astronauts and Nazi moon bases and the various Stargate series are all documentaries et cetera.

Unfortunately for these otherwise-very-plausible speculations, the sun and moon are not actually the same size in the sky. They can be, but they usually aren't.

The earth's orbit around the sun is not perfectly circular, but it's close. On average it's one astronomical unit (oddly enough), but we're closest, 0.983 AU, in early January, and furthest, 1.017 AU, in early July. The actual sun stays the same size, so from our point of view it ranges from 31.6 to 32.7 minutes of arc.

For visual learners, that's about this much of a range:

(I made this from this NASA picture depicting a gigantic magnetic filament erupting from the surface of the sun. The same filament would not, of course, be there in both January and July.)

The moon's orbit around us is more eccentric than the earth's orbit around the sun, so the moon changes in apparent size much more dramatically than the sun does. It ranges from 29.3 to 34.1 arc-minutes or, to the same scale as the above sun picture...

...this much.

(I took that moon picture myself. Residents of the northern hemisphere are invited to stand on their heads to make it look more familiar.)

(UPDATE: I forgot to mention the moon illusion when I first put this post up. Yes, the moon, and the sun too for that matter, seems bigger when it's near the horizon. No, it actually isn't. If anything, it's smaller!)

Moon and sun size range comparison

Here's the two ranges compared.

The only time when ordinary people really compare the size of the sun and moon is, of course, when there's a total solar eclipse. Then it really does look as if the moon neatly covers the entire sun, helpfully giving us a nice view of the corona, which is normally washed out by the much greater brightness of the body of the sun. (You can actually view the corona from the surface of the earth at other times, but you need special equipment to block out sky-glare.)

At this point, you may be wondering whether the roughly-month-long lunar size cycle and the year-long solar size cycle can coincide with an eclipse in such a way as to put a minimum-size moon in front of a maximum-size sun (well, any size of sun, really, there's not that much difference), so that the moon fails to completely obscure the sun.

Yes, it can; it's called an annular eclipse, and there's one coming shortly, though I won't be able to see it from here in Australia.

Here is a lot more information about all of this.

Psycho Science is a regular feature here. Ask me your science questions, and I'll answer them. Probably.

And then commenters will, I hope, correct at least the most obvious flaws in my answer.

Posted in Psycho Science, Science. 7 Comments »

Hey presto, an old fuel saver is new again!

29 April 2012 — dan

Remember the Moletech, or possibly MTECH, Fuel Saver?

Pretty much your standard magical catalyst-or-something, it got pimped by the Sydney Morning Herald, and those guys who say every hokey fuel saver in the world works said it works too. And then the Herald article disappeared in a way that basically said THIS ARTICLE HAS DISAPPEARED IN A SUSPICIOUS WAY, even as the Australian Government department that was alleged to be testing the device told me they'd never heard of it.

And then the Herald covered their tracks with the professionalism of a small child attempting to rearrange eight cupcakes to conceal the fact that there used to be twelve cupcakes.

(If Asher Moses wants me to ever forget he wrote that piece, and more importantly that he or one of his Herald workmates then stumbled around incompetently trying to pretend the article never existed instead of just saying "whoops, sorry" like a sensible person, he's going to have to kill me. It would appear that Twitter and the SMH actually are a bit similar, dude.)

Aaaaanyway, rejoice, for the Moletech-or-whatever fuel saver still stands ready to relieve you of a few hundred bucks while for-a-certainty paying for itself really really soon with amazing mileage gains. Entirely according to the usual script for BS molecular-magic fuel savers, the Moletech people have opened new marketing vistas and evaded any disappointing online commentary from clearly crazy people who suggest their product might not work by changing the product's name, to "Greentech".

Any doubts you may have about this clearly-unassociated-with-that-Moletech-thing-that-didn't-work product are sure to be dispelled by the new Greentech Web site, whose FAQ page currently contains the following hard evidence:

Q: How does it work?
A: Immediately effect will be observed as soon as the contact between the fuel and Greentech Molecule Enhancer was established.

The Greentech doodad comes in two parts, too, one for the fuel and one for the air intake. I think the Moletech gadget only had one. This makes all the difference, I'm sure.

On the somewhat less... slender... "Main Functions" page, the Greentech people explain that their product does all of the things that magic quantum magnetic moonbeam fuel-saving devices are always claimed to do (plus, oddly, apparently the magical removal of pollen and tobacco smoke and other such things that human beings do not like breathing from the air going into the engine, even though an engine doesn't give two slim shits about whether a bit of pollen made it through the air filter).

How is the Greentech thingy meant to do this?

Why, by reducing Van der Waals forces between fuel molecules, of course! A Canadian distributor rabbits on about this at greater length.

This, as usual, would be either study-of-physics-revolutionising instant-Nobel-prize material, or cause a slow but inevitably apocalyptic unravelling of the very fabric of the planet, depending on whether your view of fuel-saver-company quantum flapdoodle tends more towards the Larry Niven/Iain M. Banks or Peter Watts/J. G. Ballard ends of the sci-fi spectrum.

If it didn't kill us all by next year and actually did what they claim - more power, less fuel consumption, lower exhaust emissions, just like all the rest - then the Greentech doodad would, yet again, be a zillion-dollar product for sale to every maker of internal combustion engines, not something sold to end-users on the Internet.

The Greentech people are proud that they've been selling this thing for more than a decade now, but in all that time they've neither inked monster contracts with Toyota and General Motors, nor been erased by the conspiracy that's the only thing that could possibly have stopped them from doing so.

The abovementioned Canadian distributor hoped for a Sydney-Morning-Herald-like response to their product from Wheels.ca.

They didn't get it.

Posted in Cars, Scams, Science. 4 Comments »

Those poor lemurs

27 April 2012 — dan

A reader writes:

Thought you'd get a laugh out of this one:

http://www.ascendedhealth.com/brown-recluse/bite-treatment.htm

The best part:

Healing Frequency Resonation: These oils have been imprinted with the universal healing frequency of 728 Hz using a modified Lakhovsky/Tesla multi-wave generator embedded with oscillators made from large double-tipped lemurian crystal mined from Minas Gerais, Brazil.

Eric

Dear god, the "Ascended Health" site seems to be genuine. Well, if you click on their "Buy Now" links you do at least get a PayPal page, not a "Ha! We fooled you!" message.

The danger here is subtly greater than that usually posed by using holistic universal healing frequencies, which is to say a placebo, to treat illness. The Ascended Health people claim to be able to treat the usual long list of diseases, but this one page, about treating brown recluse spider bites, is subtly pernicious in an unusual way.

It is generally known that brown recluse bites are Bad News. Especially among Internet-comic fans who know that the exceedingly grody picture on the Wikipedia article for loxoscelism - the results of a decent dose of brown-recluse venom in humans - is of the leg of Jeffrey Rowland, the Wigu/Overcompensating/TopatoCo guy. His depiction of himself in his comics has had a leg-scar for as long as he has.

(Rowland's story was, of course, recently severely beaten by what happened to Peter Watts. Oh, and anybody who at this point is thinking about complaining about links to scary spiders and nasty medical pictures should bear in mind the way in which I have responded to such complaints in the past. I got a million of 'em, kids.)

The thing is, though, that the brown recluse is not actually very dangerous, and even if one bites you, placebo treatment is likely to be effective. And it's an excellent ailment for sellers of useless woo-woo treatments in other ways, too.

Brown recluse bites, you see, often hardly hurt at all at first. It's actually quite difficult to persuade a brown recluse to bite you at all; about the only way for it to happen unless you are a lunatic doing it on purpose is if you put on clothes with a spider inside and thus press it up against your skin. Some spiders are aggressive (including a few of those for which my country, Australia, is so famous), but brown recluses really aren't.

(The Australian version of the forcing-the-spider-to-bite-you situation is redbacks in your boots, or, classically, lurking under the seat in the outside dunny. Redbacks aren't tremendously aggressive, but they're still likely to become quite cross if you sit on them.)

Even if you are bitten by a brown recluse, though, most bites inject little to no venom and do little to no harm. Treatment of such a bite with prayer or reiki or homeopathic antimatter will be entirely successful.

If a brown recluse manages to envenomate you only slightly, the bite will over days develop into a nasty sore that'll take forever to heal, but will heal. Unless you were already rather frail, or the sore gets badly infected, or some other complication develops, you'll once again be fine in due course no matter what treatment, genuine or woo-woo, you get.

If a brown recluse manages to envenomate you really effectively, though, you're in trouble. But the symptoms will still take days to develop.

So what we've got here is a bite that's hard to receive and detect, which may or may not do you any harm at all, and which will be separated from the actual illness it causes, if it causes any, by a significant amount of time.

This is immensely fertile ground for people to fail to correctly figure out what's going on, in both illness and treatment. A given "brown recluse bite" may actually be a bite from some other, less dangerous spider or insect. Or it may be an infected wound, or it may be some random mosquito bite or pimple that's grown in the worried mind of the patient into a terrifying situation, on account of how they're pretty sure they saw a spider yesterday and it may have been brown.

And even if you do have a real and highly envenomated recluse bite, it's not going to eat your entire body in an afternoon like necrotising fasciitis (which, again, is what Peter Watts was lucky enough to get). Hospital treatment for recluse-bite loxoscelism is basically supportive medicine to keep the patient as healthy and happy as possible, and removal of any particularly distasteful dead flesh. If the necrosis is serious enough to threaten a whole limb then the whole necrotising area will be surgically removed, but this is seldom necessary. Basically, you just keep the wound clean and wait for it to go away.

OK, so now let's suppose you've got genuine loxoscelism and you decide to treat it with mental telepathy and the singing of hymns.

Well, if you've got the rare kind that'll take a limb, you'll lose a limb, and possibly your life, because having your arm rot off is not good for you.

If you've got the much more common, much less dangerous form of loxoscelism, though, you'll just be in a lot more pain than if you were doped up in the hospital, and you'll probably wind up with a worse scar. You may manage to get blood poisoning or something, but most likely the disease will follow its natural course, and you'll recover. And believe that you were cured, unpleasant though the process was, by whatever pointless placebo treatment it was that you tried.

(There's also the possibility that woo-woo alternative-medicine treatment will actually be bad for you in and of itself. A significant subset of folk medicines are actively poisonous in one way or another. The Ascended Health "powerful synergistic mixture of special natural magnetic minerals and oils" doesn't sound very likely to be toxic if you're only rubbing it on a wound, but who knows.)

This is the great problem with unscientific medicine, which was all medicine up until the late 19th century. You don't know what the disease is, you don't know how it works, you don't know what the treatment does, you don't know what the confounding factors are, and in the end you may by pure chance actually manage to do some good, but that's not the way to bet.

This is why homeopathy was such a success when Hahnemann invented it in 1796. "Conventional medicine" at the time was likely to involve almost nothing that actually stood a chance of making the patient better, and several things that could kill people who weren't even sick. Compared to that, harmless homeopathic placebos were a giant leap forward.

Today, though, we've got treatments for a vast array of diseases that're much better than placebo. Even when you've got something like a recluse bite for which there is no direct treatment (antivenoms for recluse toxins do exist, but they have to be administered very soon after the bite, which almost never happens when the bite is hardly noticeable), there are still numerous evidence-based things you can do which are proved to make the disease less severe, or at least less unpleasant.

It is, once again, vitally important to take pains to avoid fooling yourself, because you are the easiest person to fool.

(I am aware, by the way, that Lemuria does not really have anything to do with lemurs. Lemuria, hypothesised to be the homeland of the lemurs which Philip Sclater knew of in Madagascar and India but not places logically in between, is yet another new-age trope for which the world can thank the regrettably-not-inimitable-at-all Madame Blavatsky.)

Posted in Medicine, Scams, Science. 4 Comments »

Development of mutant healing factor not guaranteed

26 April 2012 — dan

A reader writes:

I was wondering if you'd heard of the appearance of some pseudosciencey Power Balance-esque magnetic bracelets in the new Avengers movie - and that the bracelets are actually for sale for $200 (!), endorsed by Paramount and Marvel Comics.

I first read about this on a Hijinks Ensue comment post. As a fellow skeptic and longtime reader of your blog, I thought I'd alert you to this scummy product placement.

n

Yep, the Limited Edition Colantotte Magtitan Neo Legend really does seem to combine five forms of pseudoscience, doesn't it?

It's not at all like the admittedly worthless Power Balance wristband, though. Power Balance and similar "hologram" or "ionised" bracelets don't have any identifiable physical properties, or effect on users, that a non-"energy"-enhancing silicone rubber wristband doesn't have, as long of course as the user believes their bracelet is special.

But the Magtitan Whatever Edition has magnets in it. And, as we all know, magnets can do anything.

This is sort of like the problem with debunking psychics, where the true believers say "OK, Mr A proved to be a fake, but Ms B must be genuine!", and then move on to Mr C, Ms D and so on as each new prospect is debunked until the skeptics run out of un-wristband-enhanced energy. Nobody can ever prove that every single "quantum" talisman, psychotronic money magnet, mobile-phone antenna-booster sticker, ultrasonic mosquito repeller, magic electricity saver or miraculous fuel additive is a scam, so chronic credophiles always have a new thing to believe in. And finding a new thing to believe in takes a lot less time than proving the thing doesn't work.

I agree that this product placement is weird, though. You'd think it'd be counterproductive.

"Do you find it entirely plausible that part of the Hulk's transformation invariably includes the manifestation of a pair of indestructible purple pants? Have you never wondered how Tony Stark can pull hundreds of gees and take hits like Superman without ever being turned to red chunky salsa inside his armour? Then do we have a health product for you!"

Posted in Scams, Science. Leave a Comment »

"MY COM-PO-NENTS ARE FUL-LY COM-PAT-I-BLE WITH LE-GO!"

25 April 2012 — dan

Among the greatest of the problems facing modern humanity is, I scarcely need say, the fact that there is no satisfactory way to make a Lego Dalek.

Well, not a little one, anyway.

Source: Flickr user Oblong

This fellow is quite magnificent, but...

Source: Flickr user lloydi

...I think something in excess of half-scale.

This smaller one's not bad either...

Source: Flickr user Neil Crosby

...(you'd want it to be good, since it's at Legoland), but the approximations are already creeping in.

Get just a little smaller and you're reduced to something like this...

Source: Flickr user pasukaru76

...of which the most one can say is that it's identifiable as a Dalek, if you squint.

If you want a Dalek roughly to scale with Lego minifigs, you're reduced to something more like...

Source: Flickr user Kaptain Kobold

...this.

I don't care how many of those you've got...

Source: Flickr user LostCarPark

...they're just silly.

Although I do give Kaptain Kobold credit for this one.

Source: Flickr user Kaptain Kobold

(Safe for work. NOT safe for work.)

These...

Source: Flickr user LostCarPark

...are silly too.

Source: Flickr user jjackowski

Nope.

Source: Flickr user pasukaru76

And this is a nice bit of microscale minimalism, but still not what you'd call faithful to the source material.

But, gentle reader, there is a solution. Though it carries a price - a price you may adjudge too high.

If you want a minifig-scale Dalek that actually looks like a Dalek, you can have it. All you must do is... I fear even to say it... is buy off-brand Lego.

I feel so dirty.

But just look at these little buggers.

Daleks! Made out of Lego-compatible blocks! Properly built up out of pieces, too, not just single-piece lumps!

Each Dalek breaks down into six major pieces and three minor ones. The baseplate, the skirt, the sucker-and-gun section, the shoulders, the neck and the head are all separate and about as Lego-compatible as it's possible for them to be, given their shape. The minor parts are the sucker, gun and eyestalk, all of which fit in holes too small for any other Lego piece or sub-component I can think of right now. The three minor pieces all have to point straight out, not swivel, but the head turns. (So do the shoulder and neck pieces, but not the sucker-and-gun section, which was never able to turn on-screen either, until 2005.)

Thanks to all of those pieces, if you want to make a Special Weapons or Emperor Dalek, it's no problem. The skirts also, of course, provide the perfect plinth for the Lego Davros torso of your choice.

(You can also just stick the head piece on top of a minifig's head and get something that doesn't really look like, but is no more ridiculous than, those preposterous helmets worn by the Daleks' human underlings in Resurrection of the Daleks.)

These not-actually-Lego Daleks are made by Character Options, who make various other licensed action figures and playsets and such. (All eleven Doctors? Fifty quid as action figures, twenty quid as pseudo-Lego.) Their "Character Building" brand has a variety of Lego-compatible Doctor Who sets, mostly just minifig-scale Doctors and companions and monsters. I bought the "Dalek Army Builder Pack", which gives you five red Daleks and nothing else. There are yellow and white Daleks in other sets, and Character Building also has one of those gashapon deals going where you can spend two pounds on a minifig from, thus far, two series, but not know what one you're going to get. You can get a blue Dalek that way if fortune favours you; any other colours, you're thus far going to have to paint yourself.

(You're also going to have to break out the paint if you want the Dalek bumps on the skirts to be a different colour from the skirts. In this scale the bumps are only about four millimetres in diameter, so it's not surprising that Character Options, um, opted, to leave them the same colour as the skirt.)

The Character Options sites lists the Army Builder Pack for £9.99, which is around $16 Australian or US, as I write this. I got mine on eBay for only £10.70 including delivery to Australia from this UK seller (here on eBay US, here on eBay Australia), but they don't have any more for sale as I write this.

There are plenty of other eBay sellers who do have stock, though; this search ought to find them all. The cheapest ones are all selling one individual Dalek parted out from a kit; the cheapest Army Builder set as I write this is £7.99 plus postage. There are plenty of sellers on Amazon, too.

The Character Building Daleks do have one flaw, though, which may be even more of a problem than the fake-Lego problem:

They look a little like Teletubby Daleks.

The Teletubby, a.k.a. Power Ranger, Daleks are the ones last seen on TV in 2010's Victory of the Daleks, when the Doctor was, for once, conclusively outmaneuvered by his enemy, and tricked into reincarnating these purestrain "New Dalek Paradigm" monsters.

(And, incidentally, there were also Spitfires in space.)

I thought Victory was a good episode (and quite funny, which counts for a lot), except for some industrial-grade schmaltz involving an android. But the new colour-coded Daleks at the end, each with their own more or less peculiar name, were not well received by the fans. Especially the... really enthusiastic fans.

The New Paradigm Daleks are big and shiny and brightly coloured, and have a great hunchbacked extension on the rear of their bodies, which gave me the impression that the props had for some reason been designed to have two human operators inside. I'm sure that isn't actually the case - these were Daleks in 2010, not Jabba the Hutt in 1983 - but there the huge lump is, or at least was.

Perhaps the Teletubbies are never coming back. Perhaps they're coming back but along with the older kinds. Who knows. (Free plot idea: The new ones are fat because they are pregnant with a much better design of Dalek.)

Anyway, these little Lego-ish ones do look a bit like them. But they're clearly not the same. The hump is less pronounced, the head isn't positioned way forward on the shoulders, the weapon-and-sucker section doesn't bulge out from almost vertical sides, and they've got that odd zipper-like grille thing on the back, but who cares.

I don't think they quite match any Dalek that's ever been seen on screen, but the Dalek props have, over the years, also failed to match each other in various ways, even if you've managed to erase the Peter Cushing Dalekmania movies and their Daleks armed with fire extinguishers from your mind.

(The New Paradigm Daleks stand significantly taller than the old ones, too; the Character Building ones are about a head taller than a standard minifig with no hat on, but are I think about the same height as the Character Building pseudo-minifigs.)

So if your interest in the racial purity of Daleks is only exceeded by their own, then you may consider these ones unacceptable. But they're really not very Teletubby-ish.

And, c'mon. Lego-compatible Dalek parts!

Haven't you always wanted the Doctor and a companion to be desperately hiding as the sound, tic-tic-tic-tic-tic-tic-tic, of robotic spider-legs approaches, and stops, and then a spray of baleful blue eye-lights spotlight them and the Mark V Travel Machine rears up, twenty feet high, dozens of its blackly shining sense globes irising open to extrude claws and tentacles and saws and injectors and suction feeders and flensers and écraseurs and deglovers, even as its battery of far-too-merciful gunsticks retract, and in a voice that breaks windows it SHRIEKS-

...well, actually these things probably won't greatly help you make that.

But if you let your kid at 'em, imagination ought to fill the gaps.

Posted in MiniReviews, Nerdery, Toys. 4 Comments »

Electrochemical Spuds Of Death

24 April 2012 — dan

A reader writes:

Hello there Mr. Dan. I stumbled across your site whilst googling "can you get hurt making a potato battery". Yep, I googled that.

I (clearly) know little about the electronics/cathode/anode world... but could answer lots of questions about other things non electrical. :)

In planning my son's birthday party, I am considering a potato battery station (sounds odd for a party, but trust me, it fits with the theme).

I have seen several Youtube videos with instructions and examples, some done by children. My main question before I go buy a bag o potatoes and seek out the copper wiring aisle of Walmart is: Can children be hurt doing this? Yes, us grown-up types will be there too, but is there anything I should be concerned about?

Partying Mom

It is theoretically possible to kill yourself with potato batteries, but the chance of a kid managing to achieve this is much, much lower than the chance that one of them will fall over and crack his/her skull in your bathroom, and you probably won't lie awake at night worrying about that.

I could just leave it at that, but of course I won't. This is because I think an understanding of the basics of electrochemistry, which is what potato batteries are all about, is something that all modern humans should have, even if they never put it to use.

You should know why it's warmer in the summer (it's surprising how many people incorrectly say "because then we're closer to the sun", which, even if it were true, would make summer happen at the same time for both the northern and southern hemispheres...), you should know how tax brackets work, and you should also know the basics of the technology that envelops modern humans so completely that we hardly notice it at all.

Sorry, didn't mean to lecture you. This is just something I'm rather passionate about.

Getting back to potato batteries: The power output of an individual potato, or lemon, or what-have-you, "battery" is extremely low, which is why there are few-to-no things you can power from one spud with two pieces of dissimilar metal in it.

"Battery" is in quotes up there because one tuber and two bits of metal are a single electrochemical "cell"; technically, it's not a "battery" unless it has more than one cell in it. (So, of the things sold in the supermarket as "batteries", AAs and Cs and Ds are cells, but 9V or 6V batteries, composed of six and four 1.5-volt internal cells respectively, really are batteries.)

The open-circuit voltage of any electrochemical cell is determined by the electrode potential of the materials you use for the electrodes. If you build the usual kind of potato battery with copper and zinc electrodes (like, a copper or copper-plated coin, and a zinc-plated galvanised nail), each cell will have an open-circuit voltage of 1.1V, but a current capacity into a short circuit of less than a milliamp.

The larger the surface area of the electrodes, the higher the current capacity will be. But even with really big electrodes you'll probably only get half a milliamp into a short circuit - and the more of the cell's current capacity you use, the lower its output voltage will be.

(For comparison, I just grabbed a rather old but unused off-brand "super heavy duty" - meaning, carbon-zinc, not even alkaline - AA cell out of my Drawer Of Many Batteries, and it still reads more than 1.6 volts open circuit, with a short-circuit current capacity of more than 1.5 amps. Here's a PDF datasheet for an Energizer carbon-zinc AA; they've got a sub-site devoted to these things.)

If you make multiple potato batteries and put them in series and/or parallel, you can increase the voltage and/or current capacity of the whole battery, respectively. Two cells in series (both of which can be stabbed into the same potato; just connect the copper of one cell to the zinc of the next) and you get 2.2 volts open circuit and the same miserably tiny current capacity. Two cells in parallel, and you get 1.1 volts but double the current capacity. Six cells, wired up as series strings of three with the two strings in parallel with each other, and you get 3.3 volts and double current capacity. And so on.

(Many people seem to find the concept of series and parallel circuits tricky to grasp. It's another of those bedrock pieces of information about the world that I urge everyone to learn, though, because it explains a great deal of everyday electrical things. Why does one bulb dying in a string of old Christmas lights kill the whole string? Because they're ten or twenty 12V bulbs {depending on your local mains voltage} wired in series to connect directly to the mains. Why, in contrast, can you have a couple of things turned on and a couple of things turned off all plugged into the same powerboard and have everything work? Because the powerboard's outputs are in parallel!)

Getting back to your actual question, this is how you could, if you tried very hard, kill yourself with a potato battery. 30 milliamps across the heart has a pretty good chance of stopping it, and even lower currents have upon occasion been fatal. Kids might be more susceptible, too; I don't know.

Even sweaty skin is a good enough insulator that sundry low-voltage current sources aren't dangerous - grab the terminals of a 12V car battery with bare wet hands and you probably won't even feel a tingle, though a tiny current really will be flowing through your arms and across your chest. But if you stab probes into yourself, into your hands or preferably into your chest right on either side of the heart, then an array of potato batteries big enough to deliver tens of milliamps really could, if connected to the electrodes, kill you.

(One reason why high voltage can be especially dangerous is that it can spark a hole right through the skin, giving it access to your wet salty conductive innards.)

Given, of course, that this particular means of death starts out with stabbing yourself, you could simplify the process by just stabbing your heart directly.

Hence: Not worth worrying about.

(There's also an outside chance that you could poison yourself by eating a potato or lemon or whatever that's been used as a battery for a while, because it'll now be contaminated with various metallic salts. It probably wouldn't do more than make even a small child slightly ill, though, presuming he or she somehow managed to choke the vile-tasting thing down. This situation is even less likely to happen than chest-stabbing, unless you use some particularly delicious fruit instead of a potato or lemon.)

The great problem with potato-battery demonstrations in the past was not, of course, kids somehow killing themselves, but that it was very difficult to do anything with the extremely feeble output of such a battery. Turning even a tiny motor, or lighting even a grain-of-wheat incandescent bulb, was impossible without a ridiculous number of cells. Getting a feeble glow from a grain-of-wheat bulb rated for 12 volts and 80 milliamps could perhaps be done with as few as 50 potato cells, though I suspect you'd need a hundred or more.

So potato batteries usually ended up doing something lame like powering a pocket transistor radio with a piezoelectric earpiece, which is a feat that you can more impressively achieve with no battery at all.

Today, you could similarly fail to impress the youngsters by potato-powering one of those little LCD clocks and kitchen timers that're meant to run from a couple of button cells. Two or three potato cells in series might, at a stretch, be able to run one of those. A far better target, though, is lighting a light-emitting diode (LED).

A modern high-intensity red or amber LED will only want about two volts and a couple of milliamps to light dimly, and will be quite impressively bright at only 10mA. Ten parallel strings each containing two potato cells ought to be enough to give a pretty bright light, and each two-cell "string" could be only one potato.

Here's a red LED...

(image source Flickr user trvance)

...just barely glowing from only three copper/zinc lemon cells in series...

(image source Flickr user s8)

...and here's an excellent example of multiple cells in one lemon...

(image source Flickr user s8)

...which works extremely well because it's cheating, and using a simple four-component circuit (counting the LED) called a "Joule Thief", which I learned about years ago on the excellent Web site of the inimitable Big Clive.

I recommend you provide sufficient spuds and/or lemons, electrodes and alligator-clip leads to make lots of cells, and also provide a grab-bag of water-clear high-intensity LEDs so the kids don't know what colour they've got until they get it to light up.

A lot of LEDs will not cost you a lot of money. I find it mind-blowing that the going price on eBay for a pack of a hundred mixed waterclear high-intensity LEDs has, for some time now, been under five US bucks, delivered. I suggest you get 5mm LEDs, not the 3mm ones that're the absolute cheapest, because the smaller ones are a bit fiddly even for kids' hands.

(I don't actually need any more LEDs, but I just felt morally obliged to buy this hundred-5mm-LED pack, from this seller, for $US2.99 delivered. At this price you could use these things, which were a miracle of the age in the 1970s and have for years now been revolutionising a significant portion of the lighting industry, as notice-board pins. They are literally cheaper than thumbtacks. Even the ones with three different-coloured dies and an invisibly minuscule controller chip built in cost damn close to nothing.)

You should play with this stuff yourself before the party, so you can introduce the kids to the series/parallel idea, and help them if they don't know to chain the cells nose-to-tail (copper to zinc or zinc to copper, not copper to copper or zinc to zinc), and also see which way round you have to connect the LEDs to make them work. (They're light-emitting diodes; they only work one way around. Long leg positive.)

It would also be a really good idea to get the finest, cheapest digital multimeter eBay has to offer, so you don't have to rely on licking the ends of wires to estimate how many volts your potatoes have managed to make. Every home should have a crappy ten-buck yellow plastic multimeter; you may not use it often, but it can be very handy at times. (Put it in the kitchen drawer with the screwdriver, the hammer, the random screws and washers and the polycaprolactone.)

Depending on age and disposition, the kids may figure this all out for themselves, of course. LEDs only work one way round, a battery setup that'll light a 1.8V red LED probably won't light a 3.6V blue or white one, a setup that'll light a blue LED may very satisfyingly turn a red one into...

Dead LED

...a friode, you can series- and parallel-wire LEDs as well as batteries...

While you're shopping for quantum-physics miracles on eBay for three cents each, you could add a couple more things that used to be super-tech and are now super-cheap: Lithium coin cells, and rare-earth magnets.

2016 (20mm diameter, 1.6mm thickness) and 2032 (3.2mm thick) coin cells aren't as cheap as LEDs; if you buy them in a supermarket or pharmacy you can pay dollars for one. Again, though, just hit eBay and you can find fifty for less than 15 US cents each.

Rare-earth magnets can be even cheaper. If you restrict this search to Buy It Now items more suited to the impatient, you can get twenty 8mm-diameter 1mm-thickness neodymium-iron-boron disks for less than ten cents each; hundred-packs drop it to about seven cents apiece.

Why am I suggesting you buy these items?

Because you can light an LED by just pressing its legs to either side of a coin cell...

(image source Flickr user spike55151)