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A reader writes:

Having read this…

…I became inspired to upgrade my UPS as it’s time to replace the 5.5AH gel cell, so why not kill two birds with one stone.

Unfortunately, I don’t know a heck of a lot about the ratings and other tech jargon behind what will make this all work, so I am sending this email in the hope that perhaps you could take a moment to take a look at what I have and let me know if it seems likely that it will work for a start and then what I should go out to buy to make it happen. I should at this point mention that I live in Thailand, the land where no matter what you want to buy, you can’t find it. But still, given that I have a UPS unit and access to a place that sells cheap car batteries, I figured there may be hope.

Firstly, this is what I have. (The specs are in English at the bottom of the page.) The gel cell inside is a “Model AC-1255″ rated at 12V 5.5AH/20Hz in case that means anything to you.

Does it seem likely that if I connect a car battery (or two) to this device I will be able to achieve similar results to what you did in your article? () Or is this UPS just not up for the task of keep a car battery or two charged and ready for the task at hand.

Out where I live power is OFTEN interrupted, but rarely more than 5-10 minutes at a time (90% of the time it’s just a few seconds), but of course those few seconds are the ones immediately preceding my clicking “submit” on a 2 hour email type-up marathon. I NEED to have some form of UPS going but am not looking for hours of use after power-out. Just enough time for me to shut down the system gracefully.

I would appreciate any insight you could offer to my options and if you need any further information on the bits I have here, just let me know.

Many thanks

David

Fortunately, this is a pretty easy job. If you screw up, though, it can be quite dangerous.

Here are the ways in which you can get it wrong when hooking up new batteries, especially bigger new batteries, to a UPS:

1. A given UPS runs from 24 volts, so it wants two 12V batteries in series; you give it one, or two in parallel.

Danger: Possibly high, if you thus barbecue the batteries with too much charge voltage. You’ll probably just get loud complaints from the UPS, though, and if you’re not completely daft you’ll disconnect the batteries before anything can go pop.

2. The opposite of the above; it wants one battery (as your particular UPS, like most small UPSes, does), but you give it two in series. (Two in parallel would be fine.)

Danger: Will probably kill the UPS. Probably will not set it on fire.

(Home/small-office UPSes are almost always 12V or 24V on the battery side, meaning one or two 12V batteries. Big serious UPSes may run more batteries in series - possibly built out of individual two-volt cells that are each bigger than the whole 12V battery in your UPS - because the higher the voltage the lower the current for a given power output, and big serious UPSes can usually deliver a lot of watts. Lower current is desirable because it means thinner wires and cheaper power transistors and other components. This is also, essentially, why big long-distance power lines run at such high voltages.)

3. You connect the battery or batteries backwards.

Danger: May or may not blow up the UPS. It’s quite easy for the designers to guard against this mistake, but I’ve no idea how many do.

If your new battery is the same type as the old one, you have to be pretty seriously dedicated to screwing up in order to connect it backwards. It’ll probably be connected with two spade lugs of different sizes; getting them the wrong way around can only be achieved if you’re the sort of person who hammers a USB plug into a VGA socket.

If you’re connecting a UPS to a bigger battery that has different connectors, though, it’s usually quite easy to connect it backwards.

Whatever happens, this particular mistake probably won’t set anything on fire.

4. You accidentally short out one or more of the batteries. Even little sealed-lead-acid “gel cells” can deliver a lot of current into a dead short, and very high current delivery is the major design goal of car batteries. The worst possible way to do this is to have a couple of batteries you’re trying to connect in parallel, and to accidentally connect one of them backwards. (This is also what happens if you get the leads mixed up when jump-starting a car. In that situation one of the batteries is usually pretty flat, but a quite stimulating physics demonstration may still ensue.)

Result: From alarming to spectacular. Red-hot wires. Smoke and possibly flame. If you break the short-circuit quickly, though, the batteries themselves should be OK.

If you’re building a battery pack for a cordless drill or R/C car or something, you can do it with discharged cells, which makes accidental short-circuits harmless. You generally can’t do that with lead-acid batteries, because running them flat damages them. On the plus side, if you’re upgrading a UPS battery you’re probably not soldering any cells or batteries together; on the minus side, while you’re running longer wires to connect a bigger battery outside the UPS, there are many opportunities to short the battery out.

(If you’ve got a liquid-electrolyte lead-acid battery, you can drain it of electrolyte while you work, which makes it harmless, just like building a battery pack from flat cells. The best solution if you’re going to be fooling around with wires connected to a high-current-capacity battery is to buy a brand new battery that comes “dry”, and buy your electrolyte separately. Note that lead-acid battery electrolyte is roughly 30% sulfuric acid, and should be treated with respect; battery acid won’t melt the flesh from your bones, but it is still not your friend. This is all overkill for what we’re talking about here, but I want to be as exhaustive as possible in writing about this stuff for the benefit of readers whose situation is not the same as yours.)

By now you are probably just about ready to throw up your hands and trade your computer for a manual typewriter, but I really did mean it when I said this job is pretty easy. You’ll very probably be fine. Take your time, do not mitigate any uncertainty you feel with alcohol, and keep track of which wire’s meant to be positive. If you do not own a cheap plastic multimeter, buy a cheap plastic multimeter. Some basic soldering ability will also be handy for extending power wires, but you’d get away with using wire nuts or something. (You’d probably also get away with twisting wires together and then mummifying them in leccy tape, but doing so makes the ghost of Nikola Tesla cry.)

And now, finally, specific answers to your actual questions.

I don’t know whether your UPS will actually be happy running from a car battery, but it very probably will. I used to be less confident about this, but I’ve done it more times myself now and corresponded with plenty of other people about it, and it really does seem that most, if not all, consumer-market UPSes will work fine from much bigger batteries. They don’t charge a big battery very quickly, but unless your local electricity is a ten-minutes-on, two-hours-off sort of deal, that’s not a problem.

Car batteries are not an ideal choice for running UPSes, because they’ve got less capacity per kilo than batteries made to run, for instance, golf carts or fishing-dinghy trolling motors. Car batteries also don’t like being run flat. But the price/performance ratio for low-end car batteries is much better than that of fancy deep-cycle batteries, and car batteries’ shortcomings are largely irrelevant to someone like you who mainly just wants to ride out short power interruptions, and doesn’t anticipate running from battery power for any great length of time.

(It also seems pretty definite now that lead-acid batteries that’ve “sulfated” because they were run flat and left that way can be rescued, with “desulfator” gadgets. I haven’t done enough research of my own to be able to speak authoritatively about this, though.)

The specs on the side of your battery only matter if you’re trying to buy a new one that’ll fit inside the UPS, without having to know the exact dimensions of your old battery or the one you’re buying. There is unfortunately no standardised naming for SLA batteries, so the “Model AC-1255″ on the sticker is not helpful.

The most common battery in small consumer UPSes is a brick-shaped 12V unit with about a seven amp-hour capacity; the battery you’ve got is I think probably this size, but it doesn’t matter since you’re not after another weedy little gel cell.

(I’ve no idea what the “20Hz” on the sticker means, by the way. Batteries are not alternating-current devices, so whatever that is, I don’t think it’s meant to mean 20 cycles per second.)

One cheap car battery will probably do the job for you just fine. If you needed longer run time then you could add one or more extra car batteries in parallel (preferably identical batteries, by the way, though in relatively low-drain applications like this you can get away with all sorts of unsightly alternatives), but that doesn’t seem to be the case.

Get a set of cheap jumper leads along with your cheap battery as I did, cut ‘em up and splice them onto the UPS’s existing battery leads, hook it up, and enjoy some relatively reliable computing.

There are many clever Lego things on the Web that might encourage grown-ups to drag those dusty boxes out of the attic and make their own tiny Sydney Opera House, PC case, or even alarmingly realistc dissected frog.

You could just about manage a small orrery, or explore the interesting mechanical possibilities of some new non-Technic pieces, or make a zombie diorama or Moonbase module. Or, conceivably, even make a dual-rotor helicopter. It'd even be within the bounds of human belief that you could make a Lego ukelele, which is both easier to build and better-sounding (MP3) than the Lego harpsichord.

And, of course, just building a packaged set isn't very difficult, even if it's one of the Star Wars giants or the upcoming monster Technic Unimog.

But then, there's the stuff people build that clearly makes anything you could possibly create look like the Lego models small children make, of which you have to say "wow, that's a really great, um..." to prompt the child to tell you whether you're looking at a spaceship or a giraffe.

Look at this model of the Jeep Hurricane concept car, for instance. It doesn't have as many features as the actual car, but it has about as many as are physically possible.

Or this StarCraft Siege Tank with working deploy function.

Or this Pilatus PC-21, which would probably actually fly if Buzz Lightyear asked it to.

Or this little roadster, which contains some remarkably compact mechanisms.

Or this minifig-scale Sand Crawler.

Or this working Super 8 movie projector.

Or this outrageous sports car.

Or this gigantic Porsche.

Or this quad-delta-robot brick-sorting workcell.

(As you may have noticed, many of the above links lean very hard on the excellent TechnicBricks blog.)

But perhaps these models are like Raven from Snow Crash. They just relieve you of the vague dissatisfied uncertainty that you might, given the right set of circumstances, become the world's greatest Lego badass, if you tried really really hard.

Now, you can be happy as one of the crowd, with the heights of Lego achievement as safely out of reach as a three-minute fifty-second mile, climbing all of the eight-thousanders without oxygen, or memorising a shuffled deck of cards in 22 seconds.

And then you can get on with making something fun. Possibly out of only two pieces.

"Omni wheels" are wheels whose rims are made out of rollers, installed with their axles perpendicular to the wheel's axle.

If you install the omni wheels so their axles point out diagonally from the vehicle's chassis, as is the case in the above Lego construction, you get full 2D maneuverability, unexciting drive efficiency, and a vehicle that won't roll sideways down a hill.

If you install the omni wheels parallel to the sides of the chassis, then the vehicle will want to roll sideways down a hill. But you may be willing to accept this, in return for something that handles like this demented little beastie:

(Note the camera car, also made from Lego!)

It's called "Metal Grudge" (on account of having the same cartoonish proportions as the tanks in the Metal Slug games), and it's basically just a skid-steer machine, like a tank or "Bobcat" loader.

Plenty of motor power and those crazy flailing omni wheels make it a lot funnier than standard skid steer, though.

Metal Grudge was made by prolific Lego builder Peer Kreuger (so was the slow omniwheel platform).

He's here on Flickr, and here on YouTube.

The fellow who made the Lego 3D scanner that worked by poking things with a needle has now made the more conventional kind of 3D scanner.

With a laser.

As with the last scanner, he's using it to import funny-shaped Lego pieces, like Fabuland heads and trees from 1969, into LDraw.

And, needless to say, the new scanner is once again made out of Lego. It's less of a mechanical achievement than the last one, because the Lego isn't much more than a supporting framework for the DAVID 3D Scanner software, that works with a line laser and a webcam.

It's way faster than the pokey-scanner, though, and has startlingly good resolution. Lego isn't generally much use for making precision mechanisms, but this one seems to work great.

I'll just leave this here.

Design a model in LDD using any of 95 brick types, send it to this "factory", and it makes it.

(Via, needless to say.)

A reader writes:

This seemed right up your alley. I saw this on Gizmodo this morning:

I initially dismissed it as totally fake. After all, it's just a string of pin adapters, and you can't get a flash drive to talk to a parallel port.

But then I thought some more. What if one were to replace the crystal in the USB drive with one of a much lower frequency, and then write a virtual device driver which implements USB using the parallel port pins? This would, of course, make the USB device useless on a regular USB interface, but it seems like it would be possible. And there's also the question of "why on earth would you want to?", but if you're the type to ask that question, you probably wouldn't have seen it in the first place.

Do you have any insight as to why such an approach would or would not work technically?

Ammon

(Anyone can do it!)

This reminds me of the hardware dongle, one of the many wonderful creations of the copy-control industry. Nowadays I think copy-protection dongles are all USB, but there was a time when some lucky users had to daisy-chain multiple parallel-port doodads in order to run multiple protected apps at once.

As you say, there'd surely be some way to connect a USB thumb drive to a parallel port, but not with standard computer-store products. (No, you can't just take a USB-to-parallel adapter and turn it around.)

I'm sure this sort of trick has actually been done many times, to connect modern storage to legacy systems. I don't think it'd be a huge job for one of the modern easy-to-program microcontrollers (Arduino, etc). If you've got some 35-year-old industrial computer that still works fine except its moving-parts storage keeps crapping out when the mining dust or machine-shop shavings get into it, hacking up some way to replace its ancient hard (or floppy, or optical, or tape) drive with Flash RAM is attractive.

There's more than one part of the hack-as-presented that couldn't possibly work, but what I immediately noticed was the green USB-to-mini-DIN adapter, which is probably one of those standard adapters for connecting a USB mouse to a PS/2 port, several of which can usually be found in the desk drawers of anybody who's been using a PC for the last ten years.

Those mouse adapters are, as you say, just pin-adapters, containing no logic; you could in principle do the same job with paper-clips and tape. Mice that work with these distinctive green adapters all have USB and PS/2 compatibility built in, and use one or the other depending on what they reckons they're plugged into. I think any of the green adapters will work with any such mouse, but they won't work with a USB-only mouse, and they definitely won't work with USB devices in general.

This sort of thing is one of the standard causes of support people banging their heads on the desk.

Theorem: The guy who's daisy-chained adapters so he can plug his XT keyboard into his iPad is preferable to the guy who's managed to plug a PCI card into a memory slot by just pushing really, really hard.

Discuss.

I got my pack of Sugru silicone moulding putty today.

I haven’t come up with anything to do with it yet (I’m trying to think of an application that needs both Sugru and polycaprolactone). But I like the packaging.

To save you from going to the full-sized image on Flickr, there’s a warning on the packet that “sugru® contains Methyltris(methylethylketoxime)silane; Gamma-Aminopropyl Triethoxysilane. May produce an allergic reaction”.

If I was one of those people who’re worried about unspecified “chemicals“, I’d expect this stuff to cause complete skeletal eversion within three minutes of exposure.

Note also the blacked-out line on the package. Under the marker ink it says “Use within a year of purchase”. Actually, Sugru’s official shelf life is only six months. Which is a slight bummer, but I only bought one “Smart Hacks Super Pack”, for £11 plus £1.26 postage to me here in Australia. So I’ll probably be able to use it all before it dries up. You clearly shouldn’t use the “buy a huge lifetime-supply sack for a volume discount” technique for Sugru, though.

The only thing I don’t like about Sugru is the manufacturers’ endless use of the word “hack”. All sorts of unremarkable things are today being promoted to the status of hacks. Some of the things you can do with stuff that goes on like putty but turns into silicone rubber in 24 hours definitely qualify as hacks, but I don’t think just putting a more comfortable grip on a knife, cable or nail clipper really counts.

(Several pictures in the Sugru gallery only use the stuff to put little rubber feet on some slippery object. This strikes me as a waste of this quite expensive product, since peel-and-stick self-adhesive rubber feet in all shapes and sizes are easy to find and very cheap. Sugru will probably stick better than your basic rubber foot, but since you can get more than fifty small rubber feet for about five US bucks, I think you’ll have some spares.)

UPDATE:
Here are all of the Sugru pictures on Flickr, including some neat ideas. Here’s the photostream of “projectsugru / Jane ni Dhulchaointigh“, which appears to be some sort of aberrant composite entity formed from the woman who invented Sugru, and the product itself. There’s also a Flickr group called “Sugru Hacks” which only has six images in it so far. Perhaps I should start a “Sugru I-Refuse-To-Use-The-H-Word” group.

UPDATE 2:
Apparently (PDF), methyltris(methylethylketoxime)silane is commonly used as a cross-linker in RTV silicone compositions. There are several related compounds used for the same purpose. Its MSDS (PDF) isn’t very alarming.

Gamma-aminopropyl triethoxysilane, a.k.a. 3-aminopropyl triethoxysilane, seems (PDF) to be another common sealant/adhesive ingredient; it, again like several other silanes, can work as a cross-linker as well, and also as a “coupling agent” that helps polymers stick to surfaces. It seems to be (PDF) rather nastier than methyltris-blah-blah-blah. I presume Sugru contains little enough of it that most people won’t suffer skin irritation. I may need to revise my plan to eat all of my Sugru, though.

(I found the above-linked PDFs on this chemical-company site.)

Before I looked this stuff up, I thought these two long-named chemicals might have been unique to Sugru. There has to be something unusual in Sugru, because it does seem to be a genuinely new product, not just some well-known industrial product being re-packaged at a huge markup for consumers, like Silly Putty or “mouse tape“.

Whatever the secret herbs and spices are, though, they’re not methyltris(methylethylketoxime)silane or gamma-aminopropyl triethoxysilane.

(Apparently Sugru is the first example of a “new class of silicone materials“, the “Formerol” process for making which is patented. I can’t find the patents, though.)

A reader writes:

As soon as I heard about "Steve Durnin's D-Drive, [possibly] the holy grail of infinitely variable transmissions", my BS meter activated and the needle swung to "Possible thermodynamics violation".

But in his favor he's got an actual physical prototype...

...and is attempting to have a metal model made so its input and output power can be tested.

What do you think of the concept, and can you tell how on earth it works? I'm still trying to figure out how this is too different from CVT, other than maybe a wider range.

I'm still wondering if this is somehow impossible, but personally I'm open to the possibility that it's a similar step such as CVT and the in-article claims are typical science-journalism overestimations.

David

Oh no - it's another New Inventors prize-winner!

Fortunately, though, an infinitely-variable transmission (IVT) is not actually in any way related to perpetual motion. All it is, is a continuously-variable transmission (CVT) that has some way to run its variable "gear ratio" all the way down to infinity-to-one, also known as a "driven neutral".

(This is, by the way, not the same as just running the gear ratio up so much, billions or trillions to one, that the final gear in the train is functionally immobile, and could be embedded in concrete without having any effect on the load of the driving motor for some years. A true "driven neutral" could be driven at a trillion RPM for eleventy frajillion years, and never turn the output at all. A transmission that bottoms out at zillion-to-one gearing would, however, be perfectly usable as a real-world infinitely-variable transmission.)

Because it can gear down to infinity-to-one, this does indeed mean that this transmission doesn't need a clutch, which does indeed reduce complexity. Whether a real-world version of the D-Drive would be too big or too heavy or inadequate in some other more complex way for real-world duty, though, I don't know. But there's nothing crackpot-y about the basic idea.

As the video makes clear, the big deal here is making an IVT - actually, a mere CVT, that still needed a clutch, would do - that uses standard gearbox-y sorts of components, or can in some other way handle lots of power and torque without being unmanageably big, expensive and/or quick to wear out.

Normal CVTs have been available in low-torque machinery like motor-scooters for some time, and are now showing up in some mainstream, full-sized cars as well. But they're still a fair distance from ideal.

It's easy to make a CVT, you see. Here's one made out of Lego. It's hard to make a CVT that can handle lots of power. And yes, the fact that most CVTs contain some sort of friction-drive device is a big part of the reason for this.

Note, however, that there's a big difference between dynamic-friction CVTs like this one or the Lego one, in which friction between moving parts transfers power, and static-friction CVTs like this one, in which friction locks components together (as in a clutch!), and they don't wear against each other.

But even here, real-world elements muddy the water and make it hard for someone who doesn't actually work at the engineering coalface to tell whether they're looking at something genuinely new and useful, or something that's not new at all, and/or won't work. Here, for instance, is the NuVinci transmission, a friction-based CVT that spreads the friction stress between numerous relatively lightly-clamped spheres - it's related to the "ball differential" with which R/C car racers are familiar. The NuVinci's makers claim it's useful for high-power, high-torque applications. And maybe they're right. I don't know.

For an excellent example of the ugliness that can happen when somewhat specialised knowledge is repurposed by people who, at best, don't know what they're talking about, look at this particular piece of "water-powered car" nonsense, where the well-known-to-jewelers electric oxyhydrogen torch is claimed to be some sort of incredible over-unity breakthrough. This sort of thing happens all the time - it's just, usually, not quite such a blatant scam.

As the Gizmag article mentions, many commercial CVTs are also deliberately hobbled by car manufacturers. They force the transmission to stick to only a few distinct ratios, and also to want to creep forward when at rest, just like a normal automatic transmission. This isn't a limitation of existing CVT technology, though; it's just deliberately bad implementations of it.

(The manufacturers do this so that people who're used to normal autos won't be freaked out by a CVT. Those of us who'd like the superior technology we pay for to be allowed to actually be superior just throw up our hands, and cross those cars off the worth-buying list.)

I think one trap for the D-Drive could be the second motor that handles the ratio-changing - that might need to spin really, really fast in certain circumstances.

There's also the fact that this is only really an infinitely-variable transmission at one end of the ratio scale. The D-Drive can gear down an infinite amount, and right on through zero to negative (reverse) ratios. But unless I'm missing something, I don't think it can gear up at all. So the output shaft can't ever turn faster than the input shaft. This is a problem if you want to do low-power flat-highway cruising, when the engine's turning quite slowly but the wheels are turning very fast.

Normal cars have significant gear reduction in the differential, though - the "final drive ratio". Perhaps if you make the diff a 1:1 device, which shouldn't make it that much bigger, the D-Drive's output-ratio limitation won't matter.

The reason why I'm saying "might" and "perhaps" so often is that I, like the New Inventors judges, am not actually an expert on the very large number of mechanisms that the human race has invented over the centuries. The simplicity of the D-Drive makes me particularly suspicious. The D-Drive's mode of operation may be a little difficult for people who don't work with mechanisms all day to intuitively grasp, but there aren't many components in there, and none of them are under 100 years old. Actually, that's probably a considerable understatement; I'm not sure when epicyclic gearing became common knowledge among cunning artificers, but I can't help but suspect that a master clockmaker in 1650 wouldn't find any of the D-Drive's components surprising.

Sometimes someone really does invent some quite simple mechanical device, like the D-Drive, that nobody thought of before. But overwhelmingly more often, modern inventors just accidentally re-invent something that was old when James Watt used it.

To get an idea of the diversity of mechanical movements and mechanisms, I suggest you check out one of several long-out-of-copyright books full of the darn things. I think Henry T Brown's 507 Mechanical Movements, Mechanisms and Devices is the most straightforward introduction; it's a slim volume available for free from archive.org here.

(If you'd like a paper edition, which I assure you makes excellent toilet reading, you can get the one I have for eight US bucks from Amazon. Here's a version of it for four dollars.)

And then there's Gardner Dexter Hiscox's Mechanical movements, powers, devices, and appliances, whose full title would take a couple more paragraphs, which is also available for free.

Both of those books carry publication dates in the early twentieth century, but many of the mechanisms in them were already very, very old. Like, "older than metalworking" old. But several of them are still, today, unknown to practically everybody who's not able to give an impromptu lecture about the complementary merits of the cycloidal and Harmonic drives.

(You may, by the way, notice rather a lot of mechanisms in those old books that do the work of a crank. That's because one James Pickard patented the crank in 1780 - plus ça change. This forced James Watt, and many other early-Age-Of-Steam engineers, to find variably practical Heath-Robinson alternatives to that most elegant of mechanisms to get the power of their pistons to bloody turn something. Watt's colleague William Murdoch came up with a kind of basic planetary gearing to replace the crank. Planetary gears have, in the intervening 230-odd years, found countless applications - including the D-Drive!)

Getting back to Mr Durnin and The New Inventors, they both currently allege that the D-Drive is a "completely new method of utilising the forces generated in a gearbox". According to this Metafilter commenter and this patent application, that may not actually be the case, since 18 of the 19 formal Claims made in the application appear to have been turned down. But, again, I could be getting this wrong, because somewhere behind the impenetrable thicket of legalese I suspect the "Written Opinion" may be saying that the final Claim actually is patentable as a separate worthwhile thing. (See also this forum thread.)

This all has me thinking, again, about the repeatedly-demonstrated gullibility of The New Inventors. When I can bring myself to watch the show, I keep thinking - OK, actually sometimes shouting - about how I'd spoil the party by asking at least one out of every four inventors "would you be willing to make a small wager that your device is not fundamentally worthless, or a duplicate of something that's been in production for years?"

(Sometimes, I'd just say "Have you always dreamed of being a rip-off artist, or is it a recent career development?")

The New Inventors seem to not have much of a peer-review system to keep the show free of crackpots, scammers and ignorant inventors who're unaware that their baby was independently invented in 1775. Or maybe there's just a shortage of interesting inventions, like unto Atomic magazine's shortage of interesting letters, so they let even the dodgy ones onto the show as long as they look impressive.

Perhaps the people on the judging panel just studiously avoid saying anything that might attract legal action from an inventor outraged that someone dared to point out that his magic spark plugs strongly resemble 87 previous magic spark plugs out of which the magic appeared to leak rather quickly.

Personally, I suspect that some insight into the newness or otherwise of the D-Drive may lurk in the various kinds of differential steering used in tanks. (Many of those have also been implemented, needless to say, in Lego.) And don't even ask about differential analysers.

It doesn't even take a lot of searching to find other IVTs. Here's one that, like the D-Drive, has no friction (or hydraulic) components. Its highest input-to-output gear ratio is quoted as "five to one", which is weirdly low; perhaps it's meant to be the other way around.

I hope, I really do hope, that the D-Drive turns out to be a proper new and useful device. We can always use another one of those.

But I remain very unconvinced that something this simple, aiming to do this straightforward a task, really is useful, let alone new.

UPDATE: As mentioned in the comments, Gizmag have a new post about this.

To summarise: The D-Drive does not remove all friction components from the drivetrain, because it can only ever be a part of that drivetrain, and needs supporting stuff that'll probably need friction components. And yes, it would need a motor just as powerful as the "main" one to drive the control shaft.

And Steve Durnin is apparently proud of independently coming up with a system similar to Toyota's Hybrid Synergy Drive "Power Split Device". I must be missing something, there, seeing as if this is the case then the D-Drive probably isn't patentable, and probably wouldn't even be particularly marketable.

The brilliant Matthias Wandel, seeing how fast he can get his air engine to spin.

His wooden air engine.

(Just about everything Matthias makes, at least since the old stuff, is wooden. Wooden combination lock. Wooden tank tracks. Wooden marble machines. Wooden Jenga pistol. Wooden pen centrifuge. Wooden pager rotator. Wooden gears. Wooden pipe organ. (Mostly) wooden bandsaw. Wooden binary logic. I don't think the Eyeballing Game and the gear template generator are made of wood, but I haven't examined his server. It could be all ropes and pulleys in there.)

I'm not certain that Matthias' video-based speed-estimation is completely sound. A proper tachometer would probably be a good idea.

There are, of course, a lot of ways to do that. Optical and magnetic sensors, point-and-shoot "non-contact" tachos made to do things like measure the rotational speed of machine tools and model-aeroplane propellers. And of course Lego, shop-bought or home-made (and with or without googly eyes).

Tachometry often involves multipliers or divisors of some sort; the above-linked Lego sensor tops out at only 500RPM, for instance, so you'd need to point it at something geared down from the thing you're actually measuring, to get a reading. And model-plane-prop tachos need to be told how many blades the prop has. For devices like this motor, which spins in the same range of speeds as computer fans, I wonder if you could use a computer fan to measure their speed?

Chop the blades off the rotor of a a standard three-wire computer fan, disable the motor coils (I think the speed sensor is a separate Hall-effect device), connect the de-bladed rotor to the thing whose rotational speed you want to measure, and then either use a frequency counter to measure the pulse rate on the yellow wire, or just plug the cable into a computer motherboard and run a fan-monitor utility.

Anybody tried it?

Shannon's Ultimate Machine, aka the "Most Useless Machine", has become something of a fad.

So of course, people have made Lego versions.

I think this one, announced in this Lugnet post, is my favourite.

Yep - it's clockwork!

The clockwork motor it uses is either this one or this one. There's also this rather rare see-through one. You could probably also use one of the many pull-back motors.

(Bonus points go to anyone who makes a Useless Machine that's powered by the clock escapement from the #8888 Idea Book.)