Minor Crimes Against Science Education, Part 273

A reader pointed out yet another "water powered clock" to me, and asked:

What do you think? Scam, right? To me it sounds like it's got a battery in it, and water is just a conductor for it. "2 year lifespan" makes me even more certain...

Yes, that's kind of the deal.

Herein, I shall shamelessly reprint and slightly expand something I previously wrote as a comment on Book Of Joe:

Man, I'm tired of things like this. "Fruit Powered Clock", "Water Powered Radio", "Potato Powered Web Server" (that one required rather a lot of potatoes, as I recall). Some of them are complete hoaxes, but the commercial ones all do actually work. Every single one of them is misnamed, though.

In all of these cases, the object or liquid in between the electrodes is not "powering" anything. It is acting as the electrolyte, like the goo inside a flashlight battery or the acid inside your car battery. The actual power comes from an electrochemical reaction between the electrodes. For little gadgets like this one, the electrodes are generally paddles of copper and zinc.

All the electrolyte does is transport ions from one electrode to the other (and collect contamination along the way, which is why you mustn't eat the orange that's been "powering" that clock for the last couple of days). The actual power comes from the electrochemical difference between the material from which the electrodes are made. One electrode will be slowly eaten away, and the other will slowly crust up with crud.

To say otherwise - as the packaging for these devices invariably does - is like saying that your television is "powered by wire".

Science toys are fantastic.

Science toys that're dumbed down until they're lying to us are an own goal.

Nine 0.455-inch guns

Lego Yamato

Behold: Jumpei Mitsui's minifig-scale Yamato (via).

Six years in the making, 6.6 metres long, 150 kilos. (It's only a "waterline" model, of course; it'd weigh even more if it had the whole keel.)

You know, at this scale - about 1:39.8 - a Star Destroyer (a normal one, not some special-order version) would only be about 40.2 metres long (132 feet).

I'm just sayin'.

LED-Brite

A reader writes:

I live in Taiwan, and I just came across a new LED device which seems very cool.

First, here is a link. It's all in Chinese, unfortunately, and I can't read it to translate for you, but there are at least some photos to give you an idea.

'Aurora' LED sign

[Here's a goofy machine-translation, which gives the thing the name "Aurora", which sounds good enough to me. The price, 1699 Hong Kong dollars, is as I write this about $US220.]

Basically, this works like a Lite-Brite, but with LEDs. There is a black PCB, entirely pierced through with holes. It has no wires, and there are no visible electronic components except for the DC input at one corner. You can plug in LEDs on either side, front or back, in any pattern you like. It's powered by either a wall-wart, a small battery pack, or a USB power connector.

A friend of mine here showed it to me tonight, and it was very impressive. Water-resistant, even - he poured a beer all over both sides of one with many lit LEDs, and there was nary a flicker.

Anyway, if you're interested, I could probably find out more about it.

Doug

I immediately, and completely wrongly, picked the Aurora as a cheaper clone of the Bandai Luminodot (dodgy translation), which was all the rage on the gadget blogs a few months ago. Some hipster has presumably bought himself a Luminodot for $US200 delivered on eBay by now, but I sure ain't.

Doug was quick to point out, though, that this thing is not a backlit-plastic-pegs device like the Lite-Brite or Luminodot, but a bunch of little powered breadboard-ish holes, into which you can plug as many or as few LEDs of whatever colour you like, and have 'em all Just Work with no fooling around with supply voltages or current-limiting resistors or fancy driver pucks.

(I think a cheaper version of the Bandai doodad might be makeable with a laptop CCFL backlight panel and little black shutters that open to let light out when you push a peg though them. Or you could do it the Lite-Brite way, and put a new sheet of black paper over the light for the pegs to puncture every time you want to make a new picture.)

Undaunted, I immediately developed total certainty regarding the Aurora's similarity to another light-array gadget.

Peggy 2.0

That gadget is the open-source "Peggy" invented by Evil Mad Scientist Labs, which is now up to version 2, and available as a kit.

The different Peggy versions are capable of various kinds of animation, and can even be used to display (very low-res) video.

The array Doug saw may, like the Peggy, only actually light one row or column of LEDs at a time, but cycle through them too fast for any flicker to be visible. (It may or may not do the same devious multiplexing as the Peggy, and is almost certainly a lot less "hackable".)

The Aurora is clearly being promoted as being useful for commercial signage, as an alternative to the custom-made, ultra-bright LED-array signs that I've seen sprouting around the place.

Doug was under the impression that the retail price "for a board about a foot square" was only around $US30, plus another $US10 for the power supply. That'd make it worth buying just for the amusement value, but doesn't line up with the $HK1699, $US220-ish price on the product page.

Never mind, though; when an odd toy starts being sold on any Web site ending in .tw, its price will probably be in free-fall soon.

ABS plus celluloid

Yep, that's a Lego movie projector all right. The frame-rate's a bit short of 24fps and the film moves a bit while the light's on - but c'mon! Lego movie projector!

Via TechnicBricks, again. That post also mentions the first TechVideo from this year...

...a vending machine made by the same guy, Ricardo Oliveira.

Next project: Electron microscope

Lego 3D scanner

This is a contact-type 3D scanner. Philippe "Philo" Hurbain (co-author of "Extreme NXT", a book about advanced Lego robotics) made it to help him import odd-shaped Lego parts into the LDraw Lego-CAD program.

As you may have noticed, the scanner is itself made out of Lego. I think the only non-Lego parts in it are the actual needle that prods the thing being scanned, and one extra-flexible cable going to a standard NXT light sensor.

All the rest - drive components, sensors, you name it - is 100% Lego. The brain is Mindstorms NXT. Hurbain has made various add-on sensors for Lego robots, but I don't think he's used any of them in this.

Apparently, the new linear-actuator parts are accurate enough for this job, when you drive them with one of the NXT motors, which have built-in position encoders.

More info on Philo's site.

The quarter-size violins of the electronic-instrument world

Everybody who found the SX-150 demo from that post to be agonising listening: The first of these videos is safe for you. The second is not.

This track's held together by the DS-10, of course, which is a proper little music production environment. Both the Stylophone and the SX-150 are sweetened up by a lot of reverb, as well.

But just the same - this is actual music, using the actual particular capabilities of these funny little synths. The SX-150 has My First Analogue Synth tweakability, and the Stylophone lets you do effortless "keyboard" glissandos, including only the "white notes" or - with some more dexterity - the whole chromatic scale.

Play these instruments "dry", though, and you get something more like this:

Still an actual tune, but not exactly easy listening.

You don't often see Lego this muddy

Lego models are usually too fragile to cope with outdoor play. Especially off-road outdoor play.

This one isn't.

Lego off-roader

(Via, once again, the excellent TechnicBricks.)

And yes, those are pneumatic remote-control tubes going to this particular vehicle. Here are lots more pictures from the "Czech Lego Technic Truck Trial Championship 2008", organised by members of this Czech Lego forum.

(Scale-model rock crawling has, by the way, quietly become quite popular. There's even a Tamiya chassis for it now. Here's Kyosho's spider-ish contestant.)

Making off-road Lego models is, I think, a good introduction to real full-scale engineering. A Lego truck trying to negotiate one-inch pebbles is taking similar risks to a full-sized vehicle trying to get over boulders. The Lego truck's much more likely to fail, for much more realistic reasons, than a "normal" off-road toy truck.

This is because of the square-cube law, which makes it easy to make a model that's far stronger than a full-sized version would be. The connections between pieces of Lego are weaker than the connections between the components of a normal off-road R/C toy, which makes the challenge more realistic.

If you build a small bridge out of Lego, you can just stick together a few layers of beam pieces using nothing but the standard stud connectors, and it'll work. This sort of thing doesn't scale at all, though, as many kids facing the classic "Spaghetti Bridge" challenge have discovered. In scale terms, spaghetti behaves like steel.

As, for that matter, do the engineering components available to you in the old Bridge Builder game and its descendants. In those, the girders are stiff and strong, but they're nowhere near long enough to bridge the gaps all by themselves. And the joints with which you stick girders together are all perfect hinges, and not very strong in tension.

Getting a tracked Lego vehicle to work properly offroad, and not throw a track every time a tiny stick or pebble gets jammed in there, would be a serious challenge. It might also give you some sympathy for the people who have to spend three hours with a sledgehammer, a two-by-four and who knows what else, fixing full-sized tracked vehicles that've done the same thing, in some delightful place or other.

Half theremin, half Stylophone

Gakken SX-150

I bought a Gakken SX-150. It's the first electronic musical instrument from their brilliant "Otona no Kagaku" line of "magazine kits", which all come in a funny box with a magazine attached to it that contains instructions for building whatever the thing is.

(Gakken also make the Cross Copter and Mechamo Centipede about which I have previously written.)

The instructions, like Gakken's Web sites, are always in Japanese, but this seldom poses much of a problem. Particularly not in the case of the SX-150, which is quite trivial to put together. As I write this, the Hobbylink Japan page for the SX-150 says "It requires both cement and painting to complete or use. 124 parts" is incorrect. You actually only have to screw the circuit board into the casing, screw down the contacts for the two ends of the ribbon controller and the stylus, and screw down the edges of the little speaker. And put four AAs in it. And cut out and attach the cardboard back panel, if you like.

(I found that Hobbylink Japan had it the cheapest, for Australian shoppers anyway, at about 4380 yen delivered, which is under $US50 as I write this. But it's also out of stock at the moment. The Make: store has it for a higher price, though, as do several other dealers.)

Herewith, a quick SX-150 FAQ.

Does it have to sound like a Stylophone?

No.

The SX-150 doesn't have what you'd call a huge palette of tonal variety - mainly pitch and resonance variations on a, yes, distinctly Stylophone-ish screech - but you can also coax a decent bass tone out of it, as well as various sweeps and bleeps of no use for melodies.

This discussion on monome.org mentions people not seeing the point of the SX-150 until they heard a "mid 90's acid track"; I concur.

Apparently, someone at Gakken said "Let's make a small device with which people will be able to approximately recreate the lead-synth line from Da Hool's "Meet Her At The Love Parade", and somebody else said "Well, it'll need at least a Resonance knob, then", and the SX-150 sort of grew from there.

(Their next product will presumably be the Europa-8, purpose-built to allow you to play the lead synth line from "Axel F".)

The tiny built-in speaker is of course not a bass-monster, but it's easy to plug the SX-150 into other speakers. Its "Output" socket is a fairly hot line-level, so can't drive full-sized headphones very loudly. (It'll probably be OK with little earbud headphones.) It should work fine with any guitar amplifier or effects pedal/unit, though, or with hi-fi gear and headphone amplifiers. I have already connected it to the stereo through an old cheesy digital reverb unit, with entertaining (for me, anyway) results.

Can you actually play a tune on it?

Yes. I was very pleasantly surprised by how musical this tinny little thing actually is.

The standard pitch control on the SX-150 is the prominent black resistance "ribbon" on the front, which you play with the little wired stylus. Left is bass, right is treble, and the total pitch range of the ribbon is a bit more than four octaves.

Some people have achieved tune-playing on an SX-150 by hacking an actual keyboard onto it, with keys connected to the stylus terminal that make contact with the stock ribbon controller at the appropriate points. But you don't need to do that. Even with the standard ribbon, someone with reasonable dexterity can play actual repeatable notes.

The ribbon makes the SX-150 a "fretless" instrument, like a violin or fretless bass. So you'll never actually hit exactly the same note twice. But the pitch-change-per-millimetre is constant - an octave is about 19mm, no matter where on the strip you're playing - and this makes the SX-150 much easier to play than many real fretless instruments. In all regular string instruments, the notes get closer and closer together as they get higher - you can see this effect in the spacing of the frets on fretted instruments.

So in this respect, the SX-150 is like the ondes Martenot or its younger, poorer cousin the Electro-Theremin, which can both make very theremin-y sounds (that's an Electro-Theremin in "Good Vibrations", for instance, not a proper theremin), but are operated by simply moving your hand a set distance for a set pitch change, no matter what pitch you're starting from.

(And then there are trombones, which I have yet to be persuaded do not produce entirely random tones.)

I don't know much about electronics. Can I still do interesting things with an SX-150 (besides just trying to play it)?

Yes. Adding actual new non-trivial features to the SX-150 isn't for beginners, but this thing is genuinely educational, in the very best way. It can teach you things about electronics, and about analogue synthesisers.

Some basic facts: The probe is negative, and the probe-to-strip voltage varies from about 1.6V at the high end of the strip to about 0.8V at the low end. The end-to-end resistance of the strip is about 50 kiloohms.

What this means is that when you connect the probe to the top end of the strip through a multimeter, as I did to get the above numbers, the SX-150 will play a very low note, as a tiny amount of current passes through the multimeter's voltage range.

Many similar tricks are possible. Hold the probe-end in one hand, for instance, lick a finger on the other hand and press it to the top of the strip, and you'll get a low-bass note. Sliding your finger down from there will get you lower and lower bass, far beyond the ability of the tiny speaker to reproduce.

Use a paper-clip as a second stylus, touching the lengthy bit of bare metal on the proper stylus to the paper-clip and then disconnecting it again, with the other end of both stylus and clip touching the ribbon, to create a yodelling effect!

Observe the small but noticeable change in pitch and noise when you hold the stylus close to the tip - so your skin touches the stylus metal - as opposed to holding only the plastic handle!

And the SX-150 is a very limited instrument, of course, of very little use for "real" music. But limitations focus you on what you can do, and this really is a bonsai analogue synthesiser to play with, not just a Stylophone.

Does the "EXT.SOURCE" socket actually do anything?

Yes, imaginary questioner, it does. How convenient that you just asked exactly the right question for me to be able to continue what I just wrote.

The EXT.SOURCE input is a simple example of what all the fuss is about with analogue synthesisers, and the modern software simulations thereof. If you plug a very "hot" signal into that input, it converts amplitude to pitch. Line-level isn't good enough (which is why many people seem to have concluded that it doesn't do anything at all), and most headphone sockets won't go loud enough either; Gakken made this input to interface with their little Theremin. If you've got a loud enough input, though - like a headphone amplifier, or a normal amp turned up only a little bit - there it is; the louder the input, the higher the tone from the SX-150.

This is not very useful, if you don't have the little Theremin. Actually, I think it's probably not terribly useful even if you do. But it helps you make the one great conceptual leap of the analogue synthesiser, especially the modular analogue synth that's a wall of separate "modules" connected together with a spaghetti of patch leads.

That conceptual leap is to realise that audio signals, when conveniently converted to electricity, can readily be transformed in this sort of way. If amplitude becomes pitch a "BOOM tish BOOM tish BOOM tish" drum line becomes "peep boop peep boop peep boop".

That's the whole point of the modular synth. It's all just voltages that different modules create or modify in different ways, and how and where those voltages become actual sounds is entirely up to you.

The SX-150 doesn't take you all the way back to Jean-Jacques and Delia, recording individual oscillator-noises on tape and then endlessly dubbing and splicing. But no mere human has the patience for that. It does, however, give you a real little insight into the dawn of the true synthesiser. So even if you have to pay $US75 for it, I reckon it's a pretty good deal.

UPDATE: Here's someone playing an SX-150.

(The reverb effect later in the clip is, of course, being created by outboard hardware.)

Here's one of many modified versions: