Extracting raw data from the Mindflex toy EEG

Last night I posted a full Instructable on how to extract raw data from the Mindflex toy EEG via Bluetooth (headsets can be bought for $15 on ebay and you need one or two $10 HC-06 Bluetooth modules), and indeed how to make it work pretty much like the more expensive Mindwave Mobile (complete software compatibility as far as I can tell if you initialize the toy with an app I link to in the instructions).

You need to make four solder connections, and jump through a few hoops to set up the Bluetooth module.

Good educational project for those with kids.

Follow the instructions at your own risk.  Make sure the headset isn't wired to anything connected to mains while it's on.

Another EEG

Josh Rasmussen encouraged me to run the toy EEG while I was writing book chapter, presumably as a way to get me to make more progress on our joint book arguing for a necessary being.  So, here it is.

Looks to me slightly intermediate between the graphs for blogging and for feeding in the earlier EEGs.

The topic of the chapter is the same as that of the post I was doing in the earlier EEG.

In case anybody is curious, here's how raw data (not from the above, just from some software testing I was doing) looks like.

Amusingly, one can also touch the electrode to one's chest, put one's fingers in the ear clips, and get an ECG.  I think I got my $21 worth of fun. :-)

EEG of me blogging vs. feeding/cleaning

I recently acquired a MindFlex EEG-based toy (on ebay, for a total of $21 with shipping), which is based on a NeuroSky ThinkGear ASIC chip.  As a toy, it's not that great, but if you solder wires to the transmit and ground pins, and hook it up to a TTL-level serial port, you can read the data off it.  By default the data comes processed into a bunch of frequency domains (presumably by running an FFT on the raw potentials), though if you attach your serial port to the receive pin (I ended up shorting that pin to another and had to cut through the blog carefully afterwards; I'm not good at soldering), you can switch to raw data mode, though my bridge hardware isn't fast enough for that.  As a safety measure, it's a good idea to either have the computer be a laptop not plugged into mains or else to bridge from the ASIC to the laptop wirelessly.

I hooked up the mindflex to the BrainLink all-purpose-BlueTooth-interconnect device (coupon code SS72142 gives a 30% discount on everything at SurplusShed this week).  I had some initial technical difficulties.  For some reason, the BrainLink keeps on resetting when it gets a lot of incoming serial data, and so I had to write some custom communication code for it that un-reset when receiving data, instead of just using the standard BrainLink java library.  And I wrote some quick visualization code in java (it's a mess, as I've never written desktop java GUI code before).  If you want to play with the messy code, it's here (it's called brainflex).  (You probably don't have a BrainLink, but any serial-to-BlueTooth adapter should work, as long as you create a new implementation of DataLink, which should be quite easy.)

Anyway, while doing the preceding post, I had the BrainLink on, and recorded the processed EEG.  (The Attention and Meditation data is computed by the chip from the Fourier transform data.)  Here it is:

As control data, I then switched to feeding the toddler and cleaning her and after her:

There is discussion online on whether the BrainFlex toy actually works, or if it's just an illusion-of-control thing, though the NeuroSky folk have research data on their chip that suggests it does do something.

Note that all the regular frequency domains (not the Attention and Meditation, though) are normalized to sum to a constant total.

Beta and alpha seem much more active when blogging than when feeding/cleaning.  On the other hand, the chip's computed Attention value seems rather higher for the feeding/cleaning, which fits with how I felt: the blogging seemed fairly automatic, while the feeding/cleaning involved more conscious attention.

A confound for the experiment is that as I was blogging, I was on the computer, so there would have been electromagnetic interference from that.  I did make sure that the computer was not plugged into the mains, which may have reduced interference.  And another confound was that I knew I was recording myself.  This isn't real science!

Transit of Venus

Here are some photos over the first 45 minutes or so. They are in sequence, but not evenly spaced in time.

This is from my 8" F/4.5 scope, stopped down to about 3", with photo taken hand-held with my Canon G7 camera off the projection funnel.

Here is the last photo in a larger size.  The sunspots were very nicely visible in the funnel (I counted about 15), and I could even see two without a telescope in the #14 welder's glass.  The photo doesn't do justice to the sunspots, especially the nice bright area that was just barely visible at the bottom of the disc.

Eclipse

Here in central Texas, the sun set before the eclipse hit maximum.  But we had some lovely views of the moon gobbling up sunspots as the sun was setting over the lake.  Photos are taken by a Canon G7 camera, using a modified version of the sun funnel for projection.  The scope is an 8" F/4.5.  For the first photo it was stopped down to about 3".  The second photo I think used the full aperture.

And for reference, here's the sun in the afternoon, before the eclipse:

Copper pipe glockenspiel

My 6-year-old son and I built this copper pipe glockenspiel. Full build instructions with more photos are here.

The human battery: Fun experiments to do with kids

Here's a fun set of experiments to do with kids. You need two pennies, two nickels and a voltmeter that can show voltages of the order of 10-50 millivolts. I used this cheap one. Probes with alligator clips make the experiments easier (I bought some alligator clips in Walmart's automotive section and soldered them on probes from an old multimeter), but you can do it with straight probes, too (in that case, replace "attach the probes" should be replaced with "touch the probes").

Experiment 1: Attach the probes to a penny and a nickel, respectively. Set the voltmeter to a scale that will show things of the order 10-50 mV (I used a 2000 mV scale). Have a volunteer hold the penny in one hand and nickel in the other. Measure the voltage. Ideally, the probes should be touching the coins, not the hands. I was getting about 15-35 mV, depending on which kid was holding the coins. If you're not getting much, maybe moisten the volunteers' hands. Then vary the coin combinations.

Experiment 2: Attach the probes to a penny and a nickel, respectively. Get two volunteers, and have each hold one of the coins. Make sure the volunteers aren't touching. Measure the voltage. Should be zero or very low (if the floor is conducting a bit). Now have them hold hands. There should be a very gratifying jump in voltage from this hand-holding switch! Note the voltage (it may take a while for it to stabilize).

Experiment 3: Set it up like for Experiment 2, but instead of having the volunteers hold hands, have the volunteer who is holding the penny hold out the other hand, palm up and outstretched. Put a nickel and a penny on that palm, with the nickel above, in such a way that the penny doesn't touch the skin (so don't put them in the middle of the palm, but maybe more on the heel; or maybe use a quarter instead of the nickel). Then instead of having the volunteers hold hands, have the second volunteer--the one holding the nickel--press a thumb from the free hand onto the penny that is on top of the nickel, being careful to make sure the penny doesn't make contact with the first volunteer's skin. Compare the voltage to that in Experiments 1 and 2. You've now got a two-cell human battery!

There are lots of fun variables to vary. Change the size of the volunteers. Wet or dry hands. See if drinking a lot makes a difference. See if temperature makes a difference (indoor vs. outdoor, say).

You can also do this, which I haven't tried, but it should work. What I did try, though, was this (though I used lime juice), which very gratifyingly powered an LED. When it went out, adding more lime juice turned it back on.

Micrometeorite candidates

The kids and I took apart a defective hard drive yesterday, and I used one of the magnets (in a plastic bag, which I then inverted) to fish for micrometeorites in the soil near a downspout.  I found a few plausible candidates, as well as a bunch of surprisingly pretty microscopic ferrous dust. Here is a particularly pretty area.  The pointer is pointing to a round micrometeorite candidate.  It's stuck to some probably earth-origin stuff--the hard drive magnet magnetized all the samples, so they stick together.  There is also a pretty piece of glass or crystal closer to the top edge.

I ended up preparing a slide with four candidates (one a bit dubious) mounted under a glass coverslip.  It's hard to grab pieces as they are very tiny--though big enough to see naked eye as a tiny dot--and stuck magnetically to other things.  In particular, I lost the round one in the first photo, as it just shot away when I tried to grab it with a toothpick (which looked like a big blunt log under the microscope).  Here's one that didn't get away.  It's about 60% of the size of the ball in the first picture.  You can't tell in the photo, but if you shine the light on this, it's very metallic--a nice silvery object. I ended up perfecting a method for extracting them.  First, I use the toothpick to sweep the area around it clean, looking in the microscope most of the time.  It's confusing, since the miscroscope reverses the view, but eventually the brain gets used to it.  Then I wet the toothpick with acetone.  The micrometeorite candidate sticks to the toothpick.  I then transfer it to a clean piece of glass.  Because the acetone evaporates so quickly, it's easy to just wipe the toothpick on the glass and the micrometeorite drops off.  I lost two promising samples--especially that nice big round one in the first photo--before I got the above two.

From what I've read, rounded things that look like they were partly melted are good candidates.  Here is a less rounded one that ended up on the slide of the four that I saved.  I don't know how it got there, as I only intentionally transferred three to it, if memory saves.  Maybe it accidentally got carried there.  It looks too rough-edged to be a micrometeorite.  However, I've also read that they can avoid atmospheric melting by being small, so maybe rough-edged things count as candidates, too.  It, too, has a nice shine to it, though the photo doesn't show it.

If you try to view these with bright-field microscopy, of course you just get black silhouettes.  What I did is I taped a bright LED flashlight to the microscope, pointing at the sample, and then I took timed exposures, holding the camera to the eyepiece (sometimes with some sort of adapter to keep the camera in place).  For the second two photos, I found a way of adding more light.  I took the microscope outdoors, and then reflected sunlight onto the slide with a mirror (actually, a hard drive platter--they make lovely mirrors). The photos were taken with point and shoot cameras hand-held to microscope eyepieces, with some loose-fitting adapters to make it easier. The first photo was with a Sony P100 through the 10X Huygens eyepiece that the microscope came with. The second and third photos were with a Canon G7 through a Rini 30mm telescope eyepiece, using my home-made telescope-to-microscope eyepiece adapter. Update: I wish I knew how to better identify micrometeorites. The very round one may not be one--see this article.

Analemmatic sundial

I wanted to make something for Instructables' clocks contest, and I settled on a sundial.  I then opted for an analemmatic sundial, where the gnomon is vertical and its location changes.  I haven't made the sundial yet, but I have written a perl script that generates plans for one, with all the dimensions.

This will make a nice educational project to do with kids.  Here are complete instructions.

You can then draw it in chalk on a driveway (and then maybe paint it permanently), and then stand on the correct date (along the vertical center line) with your body being the gnomon.  Or you can just print out the design on a piece of paper, point it correctly, and hold a pencil upright on the correct date (along the vertical center line) to get the time.  You can even use it as a solar compass if you know what time it is.  You hold the pencil upright on the correct date, rotate the sundial until it shows the correct time, and use the "N" arrow.

Would it have been crazy to think everything is made of water?

According to Aristotle, Thales held that the whole physical world is made out of water.  I don't know if Aristotle was an accurate interpreter of Thales, but let's suppose he was.  The claim that the whole physical world is made out of water seems really wacky.

But I think it was quite defensible before we got the successes of modern chemistry.  And I want to sketch one line of thought why.  I am not claiming that this line of thought was in fact Thales'.  But it could have been: it won't rely on any science inaccessible to Thales.  The line of thought has three steps.

Step 1. All liquids are the same substance.

Here is a line of thought towards this.  Granted, obviously samples of liquids differ widely in shape, color, opacity, taste, wholesomeness, viscosity, miscibility, temperature and inebriativeness.  But such variability does not challenge the claim that all liquids are in fact forms of the same substance.  After all, apples differ widely in size, color, taste, wholesomeness and hardness, but they are all fundamentally apples.  Moreover, samples of liquids apparently of the same sort can differ in most if not all of the above properties.  The most obvious are shape and temperature: simply by varying the environment, the shape and temperature of a sample of a liquid can change.  More interestingly, the opacity, taste and inebriativeness of grape juice changes over time.  The viscosity and at least apparent miscibility of honey changes over time.  The taste and wholesomeness of milk change significantly very quickly.  It is a very reasonable hypothesis, then, that mere differences in these observable qualities do not correspond to a fundamental difference in kind, that the grape juice and the wine, or the milk and the yogurt, are one and the same liquid, despite significant differences in causal powers.  But the differences between water and, say, milk or oil seem to be precisely differences in respect of qualities that do not make for different kind of thing.

The alternate hypothesis of explanation of the differences in properties between liquids, and that is that they have different ingredients rather than different properties.  But there was good reason to doubt this alternate explanation.  The significant changes happening in juice, milk and honey apparently do not require the introduction of any additional ingredients, nor the removal of any ingredients.

Step 2. All liquids are water.

If all the liquids are forms of the same kind of substance, we may want to figure out what the basic, generic or fundamental form of that substance is.  And here water seems a very plausible choice.  It is colorless, transparent, tasteless, devoid of medicinal effects except relief of thirst (which it shares with many other common liquids), non-viscous, quite miscible and non-inebriative.  It is reasonable to suppose, for instance, that when water acquires the properties of whiteness, milky taste and a bit of viscosity, it becomes milk.  One might wonder: how does one get water to acquire these properties?  Well, a reasonable thing to say is that female goats make rainwater acquire milky properties.  Certainly, when you stop the access to water, the goats stop making milk (and die).

Water, on this hypothesis, is the fundamental liquid, having the minimal set of properties needed for being a liquid, and when it acquires different properties, we call it by different names.

Step 3. Everything physical is water.

Step 3a. Everything solid is water.

Water can turn into a solid without anything being added to or substracted from it.  One might think that "cold" is being added to it, but supposing cold as a substance may be questionable (though, less so to the Greeks than to us), and besides if cold had to be added to water in order to turn it into ice, it would follow that the formation of ice should reduce the amount of cold in the air.  But the freezing of water does not appear to warm the surrounding air.

Furthermore, metallurgy shows that certain kinds of rocks can be turned into liquid, and then solidified into metals.  Some varieties of mud, which appears to be a particularly viscous liquid, can be solidified into brick or ceramic.  Sand can be melted into a clear liquid, and then solidified into glass.  Since Step 2 hypothesized that all liquids are water, it becomes very plausible to generalize to the hypothesis that all solids are water, too, albeit with the property of solidity.

Step 3b. All gases are water.

When water is heated, it turns into steam, which looks like a cloudy form of air, and hence one can suppose that air is a kind of steam.  Smoke comes from solid objects when these are on fire.  Since solid objects are water by Step 3a, smoke is also water.  It is reasonable to hypothesize that all gases are water.

Step 3c. Fire is water.

This is perhaps the toughest step, intuitively.  Fire and water seem to be opposites.  But one might hypothesize that when water is added to fire, the fiery qualities of the fire simply become diluted by the water. Steam is hot and burns, though it does not glow.  Fire, thus, could be reasonably thought of as a particularly vivid kind of steam.

We can generalize from Steps 2-3c to conclude that everything physical is water.

Final remarks.  On this highly speculative interpretation, Thales' thesis stands in sharp contrast to ingredient-based theories of the natural world, such as we have in modern Mendeleevian and ancient four-element chemistries.  We do not need to posit differences in ingredients to explain differences between things.  We generally don't posit differences in ingredients to explain differences in shape.  So why should we posit them to explain differences in, say, color or taste?

Of course, if a particular ingredient-based theory comes to have significant predictive and explanatory power, Thales' thesis needs to be abandoned.  I do not think the four-elements theory that some other ancients preferred was all that superior in predictive or explanatory power.

Mendeleevian chemistry, on the other hand, was far superior in predictive and explanatory power over either Thalesian or four-elements chemistry.

Hunting for micrometeorites

Inspired by stuff on the web (e.g., here), I went hunting for micrometeorites. I wrapped a magnet with plastic wrap, and ran it through the dirt under one of our house's downspouts. Apparently meteorites have high iron content so magnets capture them. There was some magnetic dust. I then transfered a couple of pieces of it to a microscope slide and had a look. I saw black chunks of stuff with transmitted light, unsurprisingly, but they became pretty and shiny when I shone a flashlight on them. The two largest ones had rough edges. Micrometeorites are supposed to be smoother due to their hot passage through the atmosphere. But moving the slide around, I cam on a smaller piece with smoother edges and interesting texture that matched what one would expect a meteorite to look like. There was some shiny bumpiness, some small pit-like spots and some interesting rod/wave like areas.

I tried to save the tiny piece for future observations. I tried to stick it to some sticky tape, but the goo made it very hard to observe under the microscope. So I ended up dissolving the goo with acetone to recover the piece. As a side-effect, the piece became cleaner and was brightly metallic under the microscope. Unfortunately, I eventually lost it. It was very small, about four or five times longer than wide, and the width was about that of a hair or maybe a touch more. I lost it when I tried to transfer it with the tip of a needle from a dirtier cover glass to a cleaner one, but somehow it just disappeared--I used a powerful loupe to try to find it, but couldn't. Oh well.

At least the kids got to see it. I don't know it was a meteorite, of course. Too bad I lost it before taking a picture.